Hip

AVN

Background

Bilateral Hip AVN Xray

 

Definition

 

Non-traumatic or traumatic condition of femoral head with bone death

 

Epidemiology

 

20 - 50 yo (average 38)

- M: F 4:1

 

NHx  

 

70-80% with AVN will progress within 1 year

 

Aetiology 

 

AS IT GRIPS 3Cs

 

Alcohol

- > 4000 ml / week

 

Steroids

- > 20mg / day

- often bilateral

 

Idiopathic

- incidence of hypercoagulability

- alcohol probably related to most idiopathic

 

Trauma 

- displaced subcapital

- dislocation

 

Gout, Gaucher's

Rheumatoid, radiation

Infection, increased lipids, inflamm (arteritis)

Pancreatitis, pregnancy

SLE, Sickle cell, smoking

CRF, chemotherapy, Caisson

 

Pathogenesis

 

Fat Embolism Theory

 

Alteration in lipid metabolism

- fat emboli have been demonstrated in subchondral arterioles in femoral head in patients on steroids

- steroids increases fat stores in liver, bm, blood

 

Lipocyte hypertrophy theory

 

Increased bone marrow fat stores & lipocyte hypertrophy 

- increased bone marrow pressure

- leads to decreased blood flow

- lipid lowering drugs shown to improve femoral head blood flow

- may represent a compartment syndrome

- Gaucher, leukaemia

 

Accumulative stress theory

 

Kenzora & Glimcher

- suggests AVN multifactorial

- accumulative insult

- eg alcohol, steroids, illness

 

Multiple hit theory

 

Either have cumulative dose response reaching threshold for AVN eg many different insults 

 

Susceptible individual exposed to aetiological factor

- attempts to explain why small ETOH or steroids causes AVN in some but not others

 

Vascular & Non Vascular Theories

 

1. Vascular 

 

A. Inside vessel

 

Fat Emboli in Alcohol & Steroids

Lipoproteins

?Nitrogen in Caisson Disease

Sickle Cell = Venous occlusion

Hyperlipidaemia of other causes

 

B. Vessel Wall

 

Traumatic disruption - 26 % of subcapital fractures

Vasculitis

Arteriopathy & haemorrhage

 

C. Outside vessel via intraosseous pressure

 

Fat cell hypertrophy 

- steroids / alcohol 

- "Starling" effect

- increased intraosseous hypertension in fixed space

 

Oedematous marrow

- Gaucher cells / leukaemia / DXRT / gout / CRF

 

2.   Non Vascular

 

Chemotherapy / Radiotherapy  

- osteocyte death

 

Steroids

 

Cumulative Risk

- dose x time cortisol ? 2000mg

 

Idiosyncratic

- incidence 3-25%

- onset ~ 6/12 - 3 years

- usually bilateral & multiple sites

 

Mechanism

- steroids cause osteoblastic stem cells to become fat cells 

 

Alcohol 

- MOA uncertain

- ? 2° to both intraosseous HTN & altered fat metabolism with fat emboli

- often affects other sites

 

Caisson Disease

- 2° N2 in blood vessels & extravascular

- compressed air workers ~ 20%

- divers ~ 5% in army

- humeral head > femoral

 

Pathology

 

Starts in Anterior / Superior / Lateral head 

- wedge shaped area

 

Cysts

- regions of bone reabsorption

- fibrous regions on microscopy

 

Crescent Sign 

- subchondral collapse of the necrotic segment

- separation of subchondral plate from necrotic cancellous bone

 

Collapse

- accumulated stress fracture

- 2° OA results

- NHx is progression to collapse in >90%

 

Dead bone is resorbed prior to new bone formation  

- resorption begins just after vascular invasion

- resorption continues until majority of necrotic haversian bone is removed, but almost none of interlamellar bone removed

- only once this has occurred do osteoblasts begin forming new haversian bone

 

It is at the revascularisation phase when the head is at its most susceptible

 

Stages

 

1. Necrosis

 

2. Inflammation / Revascularisation / Resorption

 

3. Repair - osteoblasts, new bone on dead trabeculae 

 

4. Remodelling

 

Four Causes Sclerosis

 

1.  Relative osteopenia in surrounding bone

2.  Marrow saponification

3.  Microfracture

4.  New bone apposition

 

Classification Ficat 1985

 

Stage 0 

 

"Silent contralateral hip" 

- preclinical - non painful

- X-ray normal

- MRI = double Line positive on T2

- cold scan

 

Stage I 

 

Clinically painful

- normal X-ray 

- increased uptake on scan

- MRI positive

 

Hip AVN MRI Anterior headHip AVN MRI T1

 

Stage II

 

Diffuse porosis with

- sclerosis 

- cystic areas of reabsorption

 

HipAVN Type 2Hip AVN Type 2 APHip AVN Type 2 Lateral

 

Transition

- Crescenteric sign / subchondral fracture

 

Stage III

 

Collapse / Flattening

- sequestrum

- preserved joint space

- typically anterolateral head

 

Hip AVN Type 3

 

Stage IV

 

OA superimposed on a deformed head

 

Hip AVN Type IIIHip AVN Type 3Hip AVN Type IV

 

Steinberg 

 

1.  Divided extent of head involved

- most important prognosticator

 

A = Mild <15%

B = Moderate 15-30% 

C = Severe >30%

 

2.  Stages

 

Stage 1: normal xray

Stage 2: sclerosis

Stage 3: crescent sign / subchondral collapse

Stage 4: flattening of femoral head

Stage 5 & 6: OA

 

Kerboul Combined Necrotic Angle 

 

JBJS B 1974

 

Guide to outcome 

- AP + Lat Necrotic Wedge Angle 

- > 200° = Poor

 

CT

 

Limited place

- can eiagnose early collapse & flattening

- 1/3 of Grade II upgraded to grade III by CT

 

Hip AVN CT

 

Te Scan

 

Sensitivity 80%

- non-specific

- most useful to investigate if head vascular after subcapital fracture

 

MRI

 

Sensitivity 100% in one series

- may take up to 7 days to show 

 

Low T1 / High T2

 

T2 Double Line Sign

 

Hip AVN MRI T2 Double Line Sign

 

Two lines virtually diagnostic of AVN

- outer line / low signal intensity

- inner line / hihg signal intensity / hypervascular granulation tissue

 

DDx Transient osteoporosis of the Hip

 

Incidence

- third trimester pregnancy

 

MRI

- oedema into metaphysis or neck

- suspect AVN if collapse 

 

Natural History AVN

 

Asymptomatic Hip

 

Mont et al JBJS Am 2010

- systemic review of asymptomatic hips

- 59% progressed to symptoms or collapse

- small medial lesions progressed to collapse < 10%

- sickle cell high risk, SLE low risk

 

Hernigou JBJS Am 2006

- 91% asymptomatic sickle cell AVN became symptomatic

- 77% collapse

Management

Management Summary

 

Stage 0

 

Natural history mixed

- depends on size of lesion and diagnosis

- treat if becomes asymptomatic

- may benefit from bisphosphonates

 

Stage 1 / Normal X-ray, abnormal MRI

 

Forage: 80% G/E

Bisphosphonates

 

Stage 2 / Abnormal X-ray with cysts and sclerosis

 

A:  As for Stage I

 

B:  Vascularized fibula graft: 80% 

 

Stage 3 / Collapse / Crescent sign

 

A:  Forage: 20% G/E

 

B:  Osteotomy:  80% G/E (CAN < 200o)

 

C:  Trapdoor and BG 80%

 

D:  Vascularised fibula graft: 80% G/E

 

E:  Limited Femoral Head Resurfacing

 

Stage 4

 

A:  Conventional THR

 

B:  Resurfacing 

 

C:  Arthrodesis 

- only if unilateral (<50%)

 

Non operative Management

 

Options

 

Bisphosphonates

ECSW

Hyperbaric oxygen

 

Bisphosphonates

 

Mechanism

- inhibit osteoclast absorption

- limit head collapse

 

Results

 

Lai et al JBJS Am 2005

- RCT of aledronate v control in non traumatic AVN

- 2/29 in treatment group collapsed, 1 had THR

- 19/25 in control group collapsed, 16 had THR

 

ECSW

 

Extracorporeal shock wave therapy

 

Results

 

Wang et al JBJS Am 2005

- RCT of ECSW v forage & bone graft

- 80% improvement and 10% unchanged in ECSW

- 29% improved and 36% unchanged in surgical group

 

Hyperbaric Oxygen

 

Results

 

Camporesi J Arthroplasty 2010

- RCT of stage II AVN treated with hyperbaric O2 or air

- all HBO patients were pain free and non required THR

- 7/9 HBO showed radiographic healing

 

Operative Management

 

Options

 

Femoral head preserving / pre-collapse

- forage

- vascularised bone graft

- non vascularised bone graft

 

Salvage / post collapse

- osteotomy

- limited resurfacing / femoral resurfacing

- THR

 

Femoral Head Preserving

 

Forage / Core Decompression

 

Concept

 

Ficat / Arlet

- initially used for diagnosis of HTN

- then used as treatment

- noticed pain relief of & cessation of progress

 

Theory

- decompress intraosseous hypertension

- promotion of vascular ingrowth

- promotion creeping substitution

 

Issues

 

Provides good pain relief

Does it prevent collapse / alter NHx?

Related to stage and size of lesion

 

Technique

 

Hip Forage Intraoperative

 

Take 6-8 mm core 

- insert guide wire under II

- ensure entry above LT

- 5mm from subchondral bone

- use DHS triple reamer

- NWB 6/52

 

Results Pain Relief

 

Stulberg Clin Orthop 1991

- prospective randomised study

- forage vs nonoperative management

- forage 70% success Ficat stage I to III in Harris Hip scores

- nonoperative success 20% Stage I / 0% Stage II / 10% stage III

 

Results NHx

 

Steinberg J Arthroplasty 1998

- patients post core decompression

- < 15% head involvement stage IA & IIA / only 20% needed THR

- > 15% head involvement stage IB & IIB / 40% needed THR

 

Khoo et al JBJS Br 1995

- RCT non operative v core decompression

- excellent pain relief in decompression group

- 80% developed femoral head collapse in both groups

 

Vascularised Cortical Bone Grafts

 

Concepts

- core decompression and removal necrotic bone

- support of subchondral bone with vascularised fibular graft

- revascularisation

- callous formation / osteoinduction

 

Technique

- approach between TFL and G med

- reamer inserted

- packed with cancellous bone

- fibula segment harvested with peroneal artery and vein

- stabilised with K wire

- anastomosed to LCF

- abutting subchondral bone

 

Results

 

Scully et al JBJS Am 1998

- stage III 

- 81% 4 year survival vascularised fibula graft

- 21% 4 year survival core decompression

 

Berend et al JBJS Am 2003

- stage III disease

- failure with THR as end point

- 64.5% 5 year survival

 

Non vascularised bone graft 

 

Technique

 

1.  Cortical strut graft

 

2.  Lightbulb procedure

- head neck junction

- cancellous bone graft

 

3.  Cartilage trapdoor 

- evacuate necrotic bone

- pack with cancellous bone

 

Results

 

Wang Int Orthop 2010

- trapdoor technique

- excellent or good results in 90 - 100% stage IIA or IIB

 

Salvage

 

Osteotomy

 

Theory

 

Aim is to prevent collapse 

- move the avascular segment away from weightbearing area 

- also decompress intraosseous HTN

- must have sufficient intact femoral head to weight bear upon

 

Indications

 

Stage III 

CNA <200°

Young patient 

Not on steroids

 

Contra-indications

 

Stage III with total head involvement

Stage IV

Steroids

 

Technique

 

CT / MRI  / XR to decide osteotomy direction

 

Usually

- anterolateral AVN 

- undergoes a valgus flexion intertrochanteric osteotomy

 

Results

 

Ha et al JBJS Am 2011

- 113 hips followed up for 4 years

- secondary collapse in 24%, THR required in 12%

- age > 40, stage III, CNA > 2000 and BMI > 24 poor prognostic factors

 

Limited Resurfacing Arthroplasty

 

Concept

 

Restores spericity to femoral head

- limits FAI which may cause progression to OA

- need to have limited acetabular damage at time of surgery

 

Results

 

Mont et al J Arthroplasty 2001

- 30 patients treated after intra-operative inspection acetabulum

- all stage III or IV

- 90% 7 year survival

 

Hemiresurfacing

 

Concept

 

Femoral resurfacing only

- again need good acetabular cartilage

- not as predictable pain relief

 

Results

 

Hungerford et al JBJS Am 1998

- 30 patients stage III or IV

- 61% G/E at 10 years

- remainder needed conversion to THR

- suggested good intermediate option in young patient

 

THR

 

Issues

 

? Failure rate higher than in age matched OA patients

- also worse if caused by ethanol / steroids

 

Results

 

Ortiguera et al J Arthroplasty 1999

- age matched AVN and OA

- 178 patients in each group

- follow up 17 years

- no difference patients over 50

- < 50 significant increased risk aseptic loosening

 

Australian Joint Registry 

- 7 years

- THR Revision rate 5% (4% OA)

- resurfacing 6% (4% OA)

 

 

Acetabular Fractures

Background

Anatomy

 

Unusual anatomic convergence of ilium, pubis and ischium

- covered entirely by hyaline cartilage

- except at acetabular fossa, which is the site of attachment of the ligamentum teres

- deepened by peripheral fibrocartilage labrum

 

2 column theory (Letournel and Judet)

 

Anterior Column 

- superior pubic ramus

- anterior acetabular wall, anterior dome

- anterior iliac spines and anterior ilium

 

Acetabulum Anterior ColumnPelvis Anterior Column

 

Posterior Column 

- ischium

- posterior acetabular wall, posterior dome

- posterior ilium

 

Acetabulum Posterior ColumnCT Pelvis Posterior Column

 

Quadrangular Plate

 

CT Quadrangular Plate

 

Mechanism

 

Axial load applied through femur

- type of fracture depends on position of femur at time of injury

- IR - posterior column

- ER - anterior column

 

Examination

 

Resuscitation EMST

 

Detailed neurological exam

- sciatic nerve damaged in 20% cases with posterior wall or column injury 

- usually peroneal division

 

Careful soft tissue evaluation

- closed degloving injury

- 'Morel-Lavallee' lesion

- the serosanginous fluid collection can be culture positive in up to 30%

 

X-ray / 5 standard views

 

AP / Six X-ray Landmarks

 

Acetabulum Anterior and Posterior WallsAcetabulum Ilioischial Iliopectineal LinesAcetabulum Roof and Teardrop

 

1.  Iliopectineal line 

- along pelvic brim to pubic symphysis

- anterior column

 

2.  Ilioischial Line 

- pelvic brim to ischial tuberosity

- posterior column

- formed by posterior 4/5 of quadrilateral surface ilium

 

3.  The Teardrop 

- lateral: subchondral bone condensation at anterior margin of cotyloid fossa 

- medial:  anterior flat part of quadrilateral surface of iliac bone

 

4.  Roof of acetabulum

 

5.  Anterior rim of acetabulum

- semilunar

 

6.  Post rim of acetabulum

 

Judet views  / 45o obliques

 

Internal Oblique / Obturator Oblique

- affected side rotated forward

- anterior column + posterior wall

 

Judet ViewJudet View Acetabular FractureAcetabular Fracture Judet View

 

External Oblique / Iliac Oblique

- unaffected side rotated forward

- posterior column + anterior wall

 

Inlet view / Outlet view

 

Indicated for pelvic fractures usually

 

Pelvic Fracture Inlet ViewPelvic Fracture Outlet View

 

CT

 

Configuration

 

1-2 mm sections

 

CT reconstruction

- remove head to view acetabulum

- beware volume averaging

- used to guide surgery

 

Acetabular Fracture CT Reconstruction

 

Diagnose

 

Loose bodies

Femoral head fractures

Subtle subluxation

Articular steps

Roof arc measurement

 

Letournel Classification

 

5 Elementary

5 Complex

 

Elementary / One primary fracture line

 

1.  Posterior Wall

- often associated with posterior dislocation

- may be in one or many pieces

- may have marginal impaction fracture

 

Acetabular Fracture Posterior WallAcetabulum Posterior Wall Fracture

 

2.  Posterior Column

- whole posterior column separated in one piece

- fracture greater sciatic notch

- through inferior acetabulum

- into obturator foramen

- through inferior pubic rami

 

Posterior Column Fracture 1Posterior Column Fracture Xray 2Posterior Column Fracture Xray 3

 

Acetabular Fracture Posterior ColumnAcetabular Fracture Posterior Column 2

 

3.  Anterior Wall

 

Acetabular Fracture Anterior Wall

 

4.  Anterior Column

- from ilium above ASIS

- through inferior acetabulum  

- across obturator foramen

- out through inferior rami

 

Acetabular Fracture Anterior WallAcetabular Fracture Anterior Column

 

5.  Transverse

- from greater sciatic notch to AIIS

- obturator foramen not fractured

 

Pelvic Fracture TransverseAcetabular Fracture Transverse CT1Acetabular Fracture Transverse

 

High - above acetabulum 

Low - through acetabulum

 

Complex / More than one primary fracture line

 

1.  Posterior column & posterior wall

 

2.  Transverse & posterior wall

 

3.  T-shaped

- transverse through acetabulum

- inferior fracture line to obturator foramen

 

4.  Anterior & posterior hemi-transverse

 

5.  Both column

- Y Shaped transverse above acetabulum

 

Acetabular Fracture Both Columns 1Acetabular Fracture 2 Column

 

Acetabular Fracture 3D CT Anterior ColumnAcetabular Fracture 3D CT Posterior Column

 

Determinants of outcome

 

1.  Fracture displacement

- < 2mm articular step

 

Acetabular Fracture DisplacedAcetabular Fracture Undisplaced

 

2.  Fracture location

 

Early onset of arthritis and poor clinical results correlate with 

- displacement present at the time of union within the weight bearing dome

- any roof arc measurement less than 45°

- a broken CT subchondral ring

 

A.  Matta roof arc measurements

 

Describe location of fracture lines in relation to roof of acetabulum

- integrity of acetabular roof

- must be no hip subluxation

 

3 roof arc measurements

- AP, 2 Judet's views

- vertical line to centre of head

- line to where fracture enters joint

- the larger the arc, the further the fracture from the roof

- 10o - fracture in roof

- 900 - low fracture

 

Weight bearing dome is intact if angle > 45o on all 3 views

 

B.  CT subchondral arc

- 10 mm below subchondral bone of roof

- similar to xray roof arc measurements

 

Acetabular Fractures CT Subchondral arc 1Acetabular Fracture CT Subchondral Arc 2

 

3.  Stability / Concentric reduction

 

Subluxation

- incongruency between the head and the roof

- poor clinical results are obtained in more than 50% of fractures in which the head is subluxed  

- may also have an element of dynamic instability, with certain posterior wall fractures

 

Acetabular Fractur Non concentric 1Acetabular Fracture Non Concentric 2

 

Any subluxation on CT demonstrates clinical instability

- fractures affecting 40% or more of the posterior wall are usually associated with instability

- fractures less than 40% should be screened for stability under II

 

4.  Other factors

 

Direct cartilage injury at time of impact

Neurological injury

AVN of head

Management

Acute management

 

Resuscitation

 

EMST

Neurovascular assessment

Investigations - exclude Pipkin, NOF

Emergent reduction / skeletal stabilisation

Assess stability

Re-evaluate sciatic nerve

 

Insertion Femoral Steinman Pin

 

Indications

- displaced acetabular fracture

 

Femoral Steinman Pin APFemoral Steinman Pin Lateral

 

Technique

- above blummenstaat's line

- in metaphyseal bone

- minimum 10 pounds weight, may need more

- assess post operative reduction

 

Acetabular Fracture Pre Steinman PinAcetabular Fracture Post Steinman Pin

 

Goals of Management

 

1.  Restore Articular Congruency

2.  Reduce & Maintain Hip in Acetabulum

 

Non operative Management

 

Radiographic factors

 

1.  Articular step < 2mm

2.  Weight bearing roof intact

- Matta Roof > 45o

- CT subchondral roof 10 mm

3.  Congruent reduction

4.  Stable < 40% posterior wall fracture

 

Results

 

Tornetta JBJS Br 1999

- 38 hips with above criteria for 2.7 years

- good or excellent outcome in 91%

- poor outcome related to other injuries

 

Patient factors

 

Elderly

Osteoporotic bone

Pre-existing arthritis

 

The elderly patient can have a THR as salvage if required down the track

 

Operative Management

 

Indications

 

1.  Incongruent reduction

2.  Non intact weight bearing dome

3.  Articular step > 2mm 

4.  Retained fragment

5.  > 40% posterior wall or instability

 

Surgical factors

 

1.  Surgeon experience

- steep learning curve

 

Letournel & Judet Fractures of the Acetabulum 1993

- initial rate non anatomical reduction 32%

- 4 years later 10%

 

2.  Surgical timing

 

Letournel & Judet

- anatomical reduction in only 50% operated after 21 days

- if operate too early, bleeding +++

 

3.  Fracture complexity

 

Matta  JBJS Am 1996

- 262 patients

- 96% elemental fractures anatomically reduced

- 64% complex

 

ORIF 

 

Aim

 

1.  Anatomic reduction

2.  Provisional fixation with lag screws 

3.  Buttressing with curved reconstruction plates 

 

Options

 

1.  Posterior / Kocher-Langenbeck approach

- posterior column / wall

 

2.  Ilioinguinal approach

- anterior column / wall

 

3.  Extended iliofemoral approach

- Smith-Petersen extended over iliac crest

- for transverse / both column fractures

 

4.  Triradiate approach

- Kocher-Langenbeck with anterior extension from GT to ASIS

- wide exposure for both column fractures

- high incidence HO

 

Triradiate approach Both Column Fracture

 

Preferred option is to perform

- ilioinguinal for anterior column / wall

- posterior / Kocher Langenbeck for posterior column / wall

- do both 1 week apart for combined fractures

 

Techniques

 

Posterior Column & Wall Fracture

 

Acetabulum Posterior Wall Plating 1Acetabulum Posterior Wall Plating 2Acetabulum Posterior Wall Plating 3

 

Position

- IDC, radiolucent table, IV Abx

- lateral position but patient rolled excessively over

- patient 45o up from table, exposes posterior

- top leg hip flexed, knee flexed

- bottom leg extended

- blankets under top leg

- lateral support in front of top knee to prevent too much hip flexion

- prevents excessive tension on sciatic nerve

 

Standard posterior approach

- divide fascia lata

- find and protect sciatic nerve at all times

- do so by keeping hip extended and knee flexed

- expose short external rotators, divide 1cm from insertion to preserve blood supply

- usually must divide some of G. max

- elevate G medius from ilium

- steinmann pin in ilium for exposure

- expose ischial tuberosity by elevating biceps femoris, again protecting sciatic nerve at all time

- steinmann pin in ischium

 

Reduction can be aided but applying femoral distracter

- between ilial and ischial pins

 

Expose fracture

- posterior wall fracture, elevate and clean callous

- capsule usually partially avulsed

- ensure no femoral head fractures or loose fragments

- posterior column fracture often up in ilium, can put a plate across it

 

Reduction

- often indirect

- buttress plate from Ischial Tuberosity to Ilium

- contour or use pre-contoured

- screws at plate extremities

- often 2 parallel plates if wall and column fracture

 

II to ensure screws not in acetabulum

 

Anterior Column & Wall Fracture

 

Acetabulum ORIF 2 Column APAcetabulum ORIF 2 Column Judet 1Acetabular ORIF 2 Column Judet 2

  

Position

- radiolucent table

- IDC to decompress bladder

- IV Abx

- sandbag under operative side for some elevation

- need to prep and drape pelvis so can virtually access both ASIS 

- often need to get  across pubis

 

Ilioinguinal approach

 

Curvilinear incision from above pubis to ASIS

- identify and protect LFCN / below ASIS

- divide external oblique 1 cm above inguinal ligament

- identify and protect spermatic cord / round ligament

- divide posterior wall / internal oblique and transversus

 

3 windows (medial / middle / lateral)

- find external iliac artery and vein with peanuts / place sling

- find psoas and femoral nerve / place sling

- find iliopectineal fascia between vessels and psoas and divide with scissors

 

Medial window medial to vessels

- superior pubic rami

- may have to release some of rectus

 

Beware corona mortis

- anomolous vascular connection

- 10 - 15% patients

- between external iliac / epigastric artery

- to obturator artery

 

Middle window between psoas and vessels

- exposes quadrilateral plate

 

Lateral window lateral to psoas

- elevate iliacus off crest to expose fracture in iliac wing

- exposes around to SIJ

 

ORIF

 

1.  Reduce quadrilateral plate

- small T plate / will sit under pelvic reconstruction plate

- separate recon plate

 

ORIF Quadrilateral Plate

 

2.  Plate iliac crest fracture

- long 13 hole plate from pubis

- along superior pubic ramus up onto inner table of ilium

- indirect acetabular reduction

 

Results

 

Judet and Letournel 1980 417 Fractures

- 73% perfect reduction with 84% very good results

- imperfect reduction 55% good results

- infection 5.6% / heterotopic bone 18%

- poor results related to > 3 weeks

 

Matta 1996 258 Fractures

- anatomical reduction 71% with 76% excellent to good results

- poor results related to injuries to femoral head / age / post-operative complications

- AVN 3%

 

Complications

 

Heterotopic Ossification

- ilioinguinal 1%

- Kocher-Langenbeck 7%

- extended Iliofemoral 12%

 

Failure of fixation

 

Acetabular Fracture Failed ORIF 1Acetabular Fracture Failed ORIF 2

 

Very problematic

- often need revision to THR

- pelvic discontinuity must be addressed

 

Acetabular Fracture Failed ORIF CT 1Acetabular Fracture Failed ORIF CT 2THR Post Acetabular Fracture

 

DVT 

- rate very high

- prevent with mechanical and chemical prophylaxis

 

Sciatic nerve injury 2% 

- especially with posterior approach

 

AVN 2%

- higher with posterior dislocations and Pipkin fractures

 

Infections 

- occur in 2-5%

- increased in the presence of Morel-Lavallee lesion

 

Arthritis

- the most common complication

- anatomic reduction - 10%, usually after 10 years

- imperfect reduction - 45%, usually before 10 years 2,6

 

Hip OA post Acetabular FractureHip OA post Acetabular Fracture

 

Bladder and spermatic cord injury

 

Hernia formation

 

Vascular injury

 

External iliac vein

- control distally with vessiloop

- suture with 5.0 / 6.0 prolene on noncutting needle

 

 

 

 

 

Arthrodesis

IndicationsHip Fusion

 

Young adult 

- 16 - 30 years old

- monoarticular disease

- heavy demand 

 

Exhausted options of osteotomy

- risk of THA failure  / multiple revision surgeries considered too high

 

Aims of arthrodesis

 

Maximise bony contact

Minimise shortening

Provide rigid internal fixation

Compress the fusion site

Facilitate future conversion to THR

 

Contraindications

 

AVN

- difficulties in obtaining arthrodesis without femoral bone stock

 

Poor bone stock due other causes

 

Bilateral hip disease

- need ROM in other hip 90o

- in order to compensate in gait

 

Polyarticular disease eg Rheumatoid arthritis

- likely to develop hip / knee / back OA

 

Degenerative disc disease

- lumbar spine ROM important to compensate in gait and ability to sit in chair

 

Stiff ipsilateral knee or contralateral hip 

 

Advantages

 

Good pain relief

 

No activity restriction

- most patients employed

- can return to normal jobs, even heavy labour

- most able to walk > 1 mile

 

Long term solution c.f. THA

 

Disadvantages

 

Functionally inferior to THA

 

Increased stress on other joints

 

1.  Lumbar spine 

- 50% back pain

- most common reason for converting to THR

 

2.  Ipsilateral knee 

- 50% knee pain and instability

- increase rotation demanded in knee due to arthrodesis

 

3.  Contralateral hip

- has to compensate with increased ROM

- may predispose to OA

- will certainly worsen any underlying arthritis

 

Difficulties with certain activities

 

Squatting

Supine sex

Running

Sitting erect in chair

Difficulty putting on shoes

 

Gait abnormalities

 

Increased energy requirements

- increased oxygen consumption

- gait 50% less efficient

 

Increased lumbar lordosis to compensate 

- decreases stride length

- shortened stance phase

- contralateral hip has increased mobility compared to normal

 

Surgery

 

Concepts

 

To retain option of conversion to THR 

- don't use pelvic osteotomy

- preserve abductors

 

Types

 

1.  Intra-articular

- most common

- allows disease to be addressed

- better correction of deformity

- difficult in paediatrics due to large amount of cartilage present

 

2.  Extra-articular

 

3.  Combined

- usually use combination 

 

Position

 

Sagittal / 25° flexion

- <20° flexion - difficult to sit

- >25° flexion - difficult to walk due to LLD

 

Coronal / 5° adduction

- never abduction: can't walk, fall over even with 5° abduction

- too much adduction: LLD

 

Rotation / 15° ER 

 

< 2 cm LLD

 

Complications

 

Pseudarthrosis - 10% 

Mal-positioning

 

Methods to Increase Union

 

1.  Inter-trochanteric / subtrochanteric osteotomy 

- can increase union rate by decreasing lever arm of abductors

- come back 6/52 later and fix intertrochanteric fracture

 

2.  Vascularised bony extra-articular method

- iliac crest with Tensor Fascia Lata still attached

- the graft is inserted into trough in the anterior joint

 

Options

 

1.  Lateral cobra plate

- detach GT

- pelvis to femur

- nil pelvis osteotomy

 

Hip Fusion Cobra Plate

 

2.  DHS

- Sunderland method

 

Hip Fusion APHip Fusion Lateral 2

 

3.  Anterior plating

- Smith Peterson approach

 

4.  Double plating

- anterior and lateral plate

 

Sunderland Method

 

Intra-articular approach /  2 hole DHS

 

Technique

 

Radiolucent table with II

- supine

 

Smith Peterson approach

- leave abductors intact

- dislocate hip anteriorly

- between sartorius and TFL

- between G medius and Rectus Femoris

- take off reflected head

 

Remove cartilage from head & acetabulum

- cup arthroplasty instruments useful

- approximate raw surfaces

- pack cancellous autograft

- position hip & hold with guide-wires temporarily

- place one guide wire central in head

 

Check position of hip

- need to be able to do intra-operative Thomas test

- FFD 25o / Add 5o / ER 15o

 

Fix with 150° DHS

- through joint into thick supra-acetabular area of ilium

- supplement with additional screws as necessary

- +/- Sub-Trochanteric Osteotomy

 

Spica at 2/52 for final position 

- NWB until xray union union

 

Schneider Technique 

 

Previously very popular technique

- don't use now as THR conversion not possible 

 

Characterised by pelvic osteotomy

- increases surface area for fusion

- pelvic osteotomy compromises future THR conversion

 

Femoral head compressed into osteotomised pelvis

- Lateral Cobra plate fixed to pelvis

 

Kostuik

 

Lack of head technique

- for post AVN or failed THR

- using a lateral Cobra plate & inserting the neck into the acetabulum

 

Lateral approach with GT osteotomy

- reflect abductors cephalad

- denude acetabular cartilage

- apply lateral cobra plate

- fix the GT to the arthrodesis with screws and place graft at the site

- +/- anterior plate

 

Britian Technique 

 

Extra-articular arthrodesis

- ischio-femoral arthrodesis

- oblique subtrochanteric osteotomy

- place tibial cortical graft from inferior femur to osteotomy in ischium

- medialize femur on graft

- spica

 

Results of Arthrodesis

 

Sponseller JBJS 1984 (classic report)

 

53 patients at 20 years post fusion

- average age 14 years

- back pain 60% / similar incidence back pain to general POP

- ipsilateral knee pain 40%

- contralateral hip 20%

- pain was unrelated to length of arthrodesis

- high functional abilities / played sport

- knee laxity of MCL was common 2° to hip excesssive adduction in fusion

- 15% conversion to THR (for back or knee pain)

 

TKR with fused Hip

 

Technically difficult

- have knee over edge of bed

- only way to get high flexion of knee for insertion tibial prosthesis

 

Poor results

- poor ROM

 

Best to revise arthrodesis first

- not if abductors not functioning

 

Conversion to THR

 

Indication 

- back pain main indication

- ipsilateral knee pain

- contralateral hip pain 

 

Issues

 

1. Abductors 

- adequate function related to good outcome

- test by palpation preoperatively

 

2. Reason for fusion ?infection

 

3. Bony loss at acetabulum & femur

 

4. LLD

- average 2cm

 

5. Skin

 

6.  Higher failure than 1° THR

 

Results

 

Good relief of LBP

- less so hip and knee

- most patients happy

- hip scores change little (owing to good results from arthrodesis)

 

LL equality achieved

 

Improved ROM

 

Gait poor for a couple of years

- related to abductor function

- intensive physio required

 

Survival

- 80% 10 year

- increased risk of infection

 

Arthroscopy

Indications

 

Removal of loose / foreign bodies

 

Hip Scope Loose BodyHip Scope Loose Body RetrievalHip Loose Body

 

Synovial biopsy / subtotal synovectomy / synovial chondromatosis

Management of labral tears / CAM Lesions

Osteochondritis dissecans / chondral lesions

Treatment of pyarthrosis

 

Position

 

Supine 

Lateral decubitus

II and traction

 

Hip Arthroscopy Set up

 

Distraction

 

Forces

- both longitudinal & lateral in direction with vector parallel to femoral neck

- force required to distract femoral head varies considerably 

- range from 25 lb to 200 lb in unanesthetised adult volunteers

- majority performed with 50 lb (225 N) or less 

- important to limit periods of distraction with higher forces

 

Aids

1.  GA & skeletal muscle relaxation

2.  Negative intra-articular pressure

- released via joint capsule puncture with spinal needle + saline

- reduces force for distraction by 1/2

- "vacuum effect"

 

Portals

 

Anterolateral

- viewing portal

 

Anterior

- working portal

 

Posterolateral

- working portal

 

Portal Placement

 

Hip Arthroscopy DistractionHip Arthroscopy InsufflationHip Arthroscopy Trochar InsertionHip Arthroscopy Cannular

 

Anterolateral portal / viewing portal

 

Anterolateral Portal 1Anterolateral Portal 2Anterolateral Portal 3

 

Insertion point

- 2 cm anterior to GT

- superior aspect of GT

 

Inserted under fluoroscopic guidance

- spinal needle directed medially & superiorly at 45° in each plane

- aim towards sourcil but under labrum

- joint distraction increases space in joint

- joint distended with normal saline

- guide wire inserted / blunt trochar / cannula

 

Dangers

- LFCN - may result in partial or complete neuropraxia

 

Hip Arthroscopy Anterolateral InstrumentationHip Scope Air Arthrogram

 

Anterior portal / working portal

 

Anterior Portal 1Anterior Portal 2Hip Scope Nerves at Risk

 

Intersection of perpendicular lines

- superior aspect of GT and inferiorly from ASIS

 

Inserted under direct vision

- guide wire / trochar / cannula

 

Dangers

- femoral NV bundle is 3 to 4 cm medial to insertion site 

- if placed inferior to neck ascending branch of lateral femoral circumflex artery is at risk

 

Hip Scope Anterior PortalHip Scope Anterior Portal 1Hip Scope Anterior Portal 2

 

Posterolateral Portal

 

Insertion point

- 2 cm posterior to GT

- level with superior border GT

 

Uses

- insert drainage portal

- improves visualisation

 

Danger

- sciatic nerve especially if foot ER during insertion

 

Posterior PortalHip Scope Nerves at Risk 2

 

Examination

 

Central compartment

- femoral head in acetabulum

- examine chondral surfaces

- examine labrum / debride / repair

 

Hip Arthroscopy Central Compartment

 

Peripheral

- head neck junction

- hip flexed, traction removed

- capsulotomy often required

- removal of CAM lesions

 

Hip Arthroscopy Peripheral Compartment

 

Complications

 

Nerves

 

LFCN - anterolateral portal

Pudendal - traction

Sciatic - from traction / posterolateral portal

 

Pressure necrosis

 

Foot, scrotum, or perineum 

 

Cartilage

 

Scuffing of articular surfaces 

 

Infection

 

Rare 

 

 

Femoral Head Fractures

Incidence

 

5-15% of posterior dislocations

 

Aetiology

 

Posterior hip dislocation

 

Pipkin Classification

 

Type I - head fracture below fovea

 

Undisplaced

- non operative

 

Displaced

- excise fragment if small

- ORIF fragment if large (can contribute to instability)

 

Pipkin Fracture Type 1

 

Type II - head fracture above fovea

 

Undisplaced

- rare, usually unstable

 

Displaced

- excise if small

- ORIF if large

 

Type III - Type I/II with NOF fracture

 

Issue

- very high incidence of AVN

 

Mangement

- ORIF young patient

- hemiarthroplasty / THR older patient

 

Pipkin Fracture Type 3

 

Type IV - Type I/II/III associated with acetabular fracture

 

Pipkin 4 Fracture

 

Non operative management

 

Indications

 

Type 1

- < 2mm displacement

- stable hip

- congruent joint

 

Type 2

- rarely anatomic

- usually unstable

 

Surgical Management

 

Choice of Approach

 

Fragment usually anteromedial

 

Type 1 and II

- anterior or anterolateral approach

- Smith Petersen / Watson Jones

- careful capsulotomy to preserve blood supply

- deep branch MCFA runs along superior femoral neck

 

Pipkin Open 1Pipkin Open 2Pipkin Open 3Pipkin ORIF

 

Type III

- anterolateral approach / Watson Jones

- ORIF NOF + fix/excise Pipkin fracture in young patient

- very high incidence AVN

- THR > 60

 

Type IV

 

A.  Associated with posterior dislocation / non operative acetabular fracture

 

Posterior approach

- this can make it difficult to access fragment

- need IR +++

- can attempt posterior to anterior screw fixation

 

Anterior approach

- if stable and no acetabular fracture requring ORIF

- involves making anterior capsulotomy

- patient already has posterior capsular defect

 

B.  Associated with posterior acetabular wall fracture that needs ORIF (>40%)

- posterior approach

 

C.  Associated with anterior acetabular fracture

- ilioinguinal with SP extension

 

Anterior Approaches

 

Many options

- Hardinge

- Watson Jones

- Smith Peterson 

- Ganz osteotomy

 

Any of these are blood supply preserving if perform safe capsulotomy

- avoid capsulotomy along superior neck

- Z capsulotomy

- capsulotomy along anterior acetabular rim superior to inferior

- along inferior femoral neck

- down medial femur

 

Ganz trochanteric flip osteotomy

- trochanteric slide

- gluteus medius and sastus lateralis attached / digastric

- osteotomy with saw posterior to anterior

- leave short external rotators attached to preserve deep branch MCFA

- slide GT fragment anteriorly

- capsulotomy as above

- allows access to anterior aspect femoral head

- dislocate femoral head anteriorly / surgical dislocation

 

Smith-Petersen approach

- good approach if only Pipkin fracture needs fixation

- higher risk of HO

 

Complications

 

Sciatic nerve injury 4%

- traumatic

- iatrogenic

 

Infection 3%

 

Recurrent instability

- large femoral head fracture excised

- posterior wall fracture

- rarely due to labral tear

 

AVN

 

HO

- increased with anterior approach

 

OA

 

Results

 

Giannoudis et al Injury 2009

- systematic review

- Pipkin I: excision gave better results than fixation

- Pipkin II: ORIF
- AVN 11% / OA 20% / HO 17%

- no difference between trochanteric flip / anterior or posterior approach

 

Chen et al Int Orthop 2010

- RCT of excision v non operative for Pipkin 1 in fracture dislocation

- better outcomes in excision

 

Femoral Osteotomy

Background

Indications

 

OA

Prevention OA i.e SUFE / Perthes / DDH

Deformity

Non union

Coxa Vara

 

OA

 

Rationale

 

Most OA is secondary to pre-existing disease 

- predisposes to articular cartilage failure

- failure of cartilage can be halted by decrease in load

- osteotomy corrects the underlying deformity

 

Pain relief achieved by

 

1.  Mechanical 

- decrease in unit load 

 

2.  Biological 

- decrease intra-osseous pressure

 

Conditions

 

1.  Dysplasia 45%

2.  Perthes   20%

3.  SUFE 10%

 

Indications

 

< 25 - 30 years

 

Natural History

 

OA by age 50 in

- 50% with DDH / Perthes

- 20% with SUFE

 

Aims

 

1.  Correct deformity

2.  Increase congruency / decrease unit load

3.  Decrease JRF

 

Types of Osteotomy

 

Direction

- varus / valgus

- flexion / extension

- combination

 

Reconstructive

- before OA begins

- age < 25 years

- Biological plasticity remains

- at-risk hip / painful hip ~ Ganz

- i.e. difficult to justify in the non painful hip

 

Salvage

- before end stage OA occurs

- age < 50 years

- pathogenesis secondary to malalignment

- moderate OA where congruence increased by osteotomy

 

Examination

 

ROM important

 

1.  Flexion / extension arc

- >/= 90° to consider osteotomy

 

2.  Abduction / adduction arc 

- correction should not exceed arc

 

Flexion / adduction contractures common

- correct with valgus / extension osteotomy

 

X-ray

 

AP pelvis

 

True lateral (Faux Profile) 

- lateral of pelvis with patient turned 25° to xray beam     

- to assess anterior uncovering

- VCA angle

 

Maximum Abduction / Adduction AP 

 

Von Rosen

- maximum abduction & IR

 

3D CT

 

Fluoroscopy

 

MRI 

 

Examine nature of joint surface

 

 

 

Techniques

Osteotomy Options

 

Varus

Valgus

Extension

Flexion / Internal Rotation

Neck Lengthening

 

Varus Osteotomy / Pauwels Type I

 

Indications

 

DDH 

- improve coverage

- rarely done alone

- only if little or no acetabular dysplasia

- CE > 15 - 20o

 

Perthes 

- improve coverage

 

AVN 

- if medial head involved (unusual)

 

Coxa Valga > 135°

- lateral subluxation of head

- signs of lateral overload i.e. eccentric sourcil

- adduction contracture

 

Requirements

- spherical head 

- increased congruity in max abduction

- minimum 15o abduction

 

Contraindication 

- lateral head osteophyte

 

Technique

- subtrochanteric osteotomy

- medial shaft displacement 10 - 15 mm

- 120o Synthes locking plate with offset

 

Valgus Intertrochanteric / Pauwels Type II

 

Indications

 

1.  AVN

- to unload anterolateral head

- usually valgus flexion

 

2.  Subcapital fracture nonunion

 

3.  Severe medial OA with medial osteophytes

- capital drop osteophyte

- inferomedial femoral head osteophyte

- acts as fulcrum against acetabular osteophyte

- widens the superolateral joint surface

 

4.  Coxa vara

- congenital / developmental

- fibrous dysplasia

 

5.  Protrusio in young patient

 

6.  Fixed abduction contracture

 

Requirement

 

90° flexion & 15° adduction

 

Technique

 

Calculate osteotomy

- mostly would be aiming for neck shaft angle 145 - 150o

 

Example coxa vara

- current neck shaft angle i.e. 110o

- desired neck shaft angle i.e. 145o

- require a 25correction

 

Fixation

- use a 145o plate and screw

- place screw in centre of femoral neck and head

- thus when fixate the plate on femoral shaft, will have obtained desired correction

 

Rotation

- mark proximal and distal femur with drill holes

- allows maintenance of current rotation / correction if required

 

Osteotomy

- use 2 K wires

- usually performed at level of lesser trochanter

- insert distal wire parallel

- insert second wire at desired angle

- check with II / angle measurement devices

- may wish to insert distal steinman pin to control distal fragment

- anterior and posterior homan retractors

- osteotomy with saw

 

Close osteotomy

- apply plate

- use compression device Synthes

 

Extension Intertrochanteric Osteotomy

 

Indication

 

In association with correction in coronal plane

Anterior uncovering of femoral head in DDH

FFD / flexion contracture

 

Effect

- improved anterior covering of head

- eliminates FFD

 

Flexion / Internal Rotation Intertrochanteric Osteotomy

 

Indication

 

Severe SUFE 

 

Technique

 

Imhauser Technique

 

 

 

Femoroacetabular Impingement

DefinitionHip CAM CT 1

 

Aberrant morphology involving the proximal femur and acetabulum

- usually between the femoral neck and the acetabular rim

- during terminal motion of the hip

 

Can cause pain secondary to labral and chondral lesions

- may lead to early OA

 

Aetiology

 

Childhood conditions

- Perthes

- DDH

- SUFE

 

Post trauma

- prior femoral neck fracture

 

Acetabular retroversion

- posteriorly orientated acetabular opening

- relative prominence of anterior rim

- crossing of anterior and posterior walls on the AP radiograph

 

Acetabular Crossover Sign

 

Previous periacetabular osteotomy

 

Coxa

- profunda (deep socket)

- breva

- magna

- vara

 

Protrusio

 

Types

 

Cam

Pincer

Mixed

 

Cam impingement 

 

Between head and acetabulum 

 

Abnormal femoral head morphology

- often with flexion

- damage to anterior labrum and shearing of cartilage (carpet lesions)

 

Usually young men

 

CAM lesion x-rayHip Cam LesionHip CT Anterior Cam Lesion

 

Pincer impingement 

 

Between neck and acetabulum

 

Hip Pincer Impingement

 

Due to overcoverage of femoral head

- profunda, protrusio

- acetabular retroversion / relative anterior rim overcoverage

 

Damage to anterior labrum

 

Epidemiology

 

Young active males

- CAM impingement

 

Middle aged athletic women

- pincer impingement

 

History

 

Groin pain

- with rest

- with activity

 

Pain with flexion

 

Clicking from labral tear

 

Examination

 

Typically limited ROM

 

AP impingement 

- IR / flexion /  adduction

- most common

 

Posteroinferior impingement

- full extension and external rotation

 

X-ray

 

True AP

- coccyx and symphysis pubis within 1-2cm of each other 

- for assesment of retroversion / crossover sign

- bony prominence junction anterolateral head and neck

- ossification of labrum

- acetabular spurs

 

Hip Cam Lesion Xray

 

Lateral 

- shows CAM

 

CT reconstruction

 

Very good for bony morphology

 

Case 1

 

CAM Lesion CT

 

Case 2

 

Hip Cam CT SagittalHip CT Cam 3DHip Cam CT 3D 2HIp Cam CT 3D 3

 

MRA

 

Labral lesions

 

Hip MRI Labral Tear CoronalHip CAM Anterior Labral Degenerative TearHip MRI Labral Lesion

 

Femoral head morphology / Alpha angle

 

T1 axial MRI

- circle drawn on circumference of femoral head

- line from centre to where head extends beyond circle

- line drawn to centre of femoral neck at its narrowest

- angle > 55o may be indicative of CAM

 

Hip MRI Anterior CAMHip CAM Alpha Angle

 

Beta angle

 

Distance between pathological head-neck junction and acetabular rim

- hip in 90o flexion

 

Management

 

Non Operative

 

Activity modification

Stretching

Usually problem does not resolve

 

Operative

 

Options

 

Open femoral head arthoplasty with surgical dislocation

Hip arthroscopy

 

Open femoral head arthoplasty

 

A.  Surgical dislocation of femoral head

 

Ganz Osteotomy

- preservation of blood supply

- deep branch of medial circumflex artery most important

- runs posterior to obturator externus

- emerges at superior border of quadratus femoris

- over short external rotators

- then retinacular vessels up anterosuperior neck

 

Approach

- must preserve short external rotators

- trochanteric osteotomy

- greater trochanter slid anteriorly

- has abductors and vas lateralis attached

- capsule divided in lazy S

- preserving capsule over anterosuperior neck 

- reflected subperiosteally off neck (like banana skin)

- dividing lig teres and dislocating hip

 

B.  Femoral head osteoplasty

- allow flexion of 120o

- rotation of 40o

 

3.  Acetabular debridement 

- debridement acetabular chondral flaps

- osteotomy of the acetabular rim (up to 1cm)

- reattachment / debridement of labral lesions

 

Arthroscopy 

 

Indications

- debridement of labral tears

- femoral head osteoplasty

 

Technique

 

Position

- patient supine

- foot IR full initially, leg extended

- traction applied

 

Hip Arthroscopy Portal Insertion II

 

Anterolateral viewing portal

- hip distracted

- under II vision

- guide wire in place

- dilators, insert cannula

 

Anterior working portal

- triangulate, using II

- anterior labral and CAM resection

 

Hip Arthroscopy Anterior Portal

 

Posterior working portal

- accessory for labrum and rim

 

Assess Cartilage

 

Hip Arthroscopy Chondral DamageHip Arthroscopy Carpet Lesion

 

Assess for Labral Tears

 

Hip Arthroscopy Degenerative Labral Tear From CAM lesionHip scope normal acetabular Labrum

 

Labral resection

- with long resector

 

Hip Arthroscopy Initial ViewHip Arthroscopy Post Labral Resection

 

Acetabular rim resection

- if necessary

- long burr

- difficult to know extent of resection required

- check on II

 

CAM resection

- flex hip, ER

- T capsulotomy to expose CAM lesion

- performed with long thin scapel

- burr resection of CAM lesion

- again, under II guidance

- put hip through range to ensure adequate debridement

- T capsulotomy exposes CAM well

- isolated reports of hip dislocation

 

Hip Arthroscopy Labral and Rim ResectionHip Arthroscopy CAM Lesion ExposedHip Arthroscopy CAM resection

 

FAI Cam Resection 1FAI Cam Resection 2FAI Cam Resection 3

 

Results

 

Labrum

 

Larson et al Arthroscopy 2009

- retrospective comparison of labral debridement v fixation in CAM / Pincer

- significantly improved hip scores in repair grou

- 67% G/E in debridement

- 90% G/E in fixation

 

Athletes with CAM

 

Singh et al Arthroscopy 2010

- 27 Australian Rules Playes

- treatment of chondral lesions / labral lesions / majority with CAM lesions

- high level of satisfaction and 26/27 returned to high level sport

 

OA

 

Byrd et al Arthroscopy 2009

- 10 year follow up

- 80% good results if no OA

- 7/8 with OA had THR at mean of 6 years

 

 

Hip Dislocation

IncidencePosterior Hip Dislocation

 

Young men

 

Posterior / Anterior 9:1

 

Aetiology

 

High velocity injury

- head direction at impact decides direction of dislocation

 

Anterior Dislocation 

 

Externally rotated & abducted leg

- flexion = inferior dislocation

- extension = pubic dislocation

 

Posterior Dislocation

 

Axial compression of adducted leg

- more flexion causes pure dislocation without fracture

 

Anatomy

 

Inherently stable joint

- large head on smaller neck

- allows deep seating of femoral head

- acetabulum deepened by labrum

- capsule reinforced by ilio/pubo/ischio femoral ligaments

 

40% femoral head in contact with articular cartilage

10% in contact with labrum

 

Blood supply

 

Majority by deep branch of Medial Circumflex Femoral Artery

- minimal by medial epiphyseal artery via ligamentum teres

- little to non via LCFA

 

MCFA

- arises medial aspect of profunda

- along posterior intertrochanteric crest extracapsular / back of femoral neck

- passes between iliopsoas and pectineus medially

- runs along inferior border of obturator externus, above adductor brevis

- deep to quadratus femoris

- emerges between quadratus and inferior gemellus

- runs over conjoint tendon (2 gemelli and obturator internus)

- then penetrates capsule between conjoint and piriformis

- runs along superior aspect of neck to femoral head

 

Transverse branch (to ischium) and ascending branch (to trochanteric fossa0

- arise anterior to quadratus

 

Must protect this deep branch MCFA in a posterior approach

 

With dislocation and capsular tears

- some ascending cervical branches stretched/kinked

- emergent reduction can improve blood flow to femoral head

 

Associated Injuries

 

50-95% have other injury

 

Acetabular fracture

 

Femoral head fracture / Pipkin fracture

 

Sciatic nerve 10% / posterior dislocation

 

Patella fracture

 

PCL

 

Femoral artery injury - anterior dislocation

 

Femoral shaft fracture

- reduce head via steinman pin in proximal fragment

- then IMN femur

 

Classification

 

Direction

 

1. Medial / Central

- really medial displacement with acetabular fracture

 

2. Anterior 

- pubic / obturator / perineal

 

3. Posterior

 

Posterior Hip Dislocation Lateral

 

Pathoanatomy

 

Capsule & Ligamentum teres torn

 

Labral tears & muscular injuries also occur

 

Y / iliofemoral ligament often intact with posterior dislocation

- blocks reduction

- bony fragments also block reduction

 

Clinical Features / Xray

 

Posterior dislocation

- leg shortened, flexed, adducted & internally rotated 

- head small on xray

 

Posterior Hip Dislocation

 

Anterior dislocation 

- leg short and externally rotated

- head larger on xray

 

Check NV status / sciatic nerve

 

Management

 

Immediate

 

Assess & manage life threatening injuries

- EMST / ATLS principles

 

Principles

 

1. Emergent reduction

- closed +/- open

- reduce risk AVN 

 

AVN

- < 6 hours 10%

- 20% - 50% if >24 hours

 

2.  Assess stability

 

Posterior wall fracture > 40%

- need ORIF for stability

 

Hip Dislocation Posterior Wall FractureHip Dislocation Posterior Wall Fracture

 

Posterior wall fracture < 40%

- can be unstable

- EUA after reduction to assess stability

- should be able to flex to 90o and some IR without instability

 

3. Screen for retained fragments

 

Compulsory CT

- xray will not detect fragments < 2mm

 

Hip Dislocation Loose Body

 

Remove / ORIF depending on size of fragment and location / Pipkin type

 

4. Reconstruct acetabulum if unstable or incongruent

 

Closed Reduction Posterior Dislocation

 

Technique

 

Full muscle paralysis on radiolucent table 

- supine

- assistant places downward pressure on ASIS

- operator up on bed grasping leg

- flex hip to 90o, flex knee to 90o

 

Technique

- ER head around acetabulum / axial traction or

- IR head around acetabulum / axial traction

 

Post reduction

- check concentric reduction on II

- check stability in flexion

 

Unstable reduction

- skeletal traction / femoral steinman pin

 

Post op

 

NV examination when patient awake

- ensure sciatic nerve working

- ensure hasn't become entrapped with reduction

 

CT

 

Closed Reduction Anterior Dislocation

 

Technique

- as above

- traction in line with femur flexed

- internal rotation maneuver

 

Irreducible Dislocations

 

Incidence

- 2-15%

 

Causes

 

1.  Capsule / Labrum / Ligamentum teres

2.  Muscle interposition

- anterior usually rectus / psoas

- posterior usually piriformis / G maximus

3. Bone fragment

4.  Muscle tone

- patient requires relaxant

 

Management

 

Open reduction

 

Non-concentric Reduction

 

Esssential to obtain X-ray and CT after reduction

 

X-ray

- head - teardrop distance must equal contralateral side

 

CT

- only with CT can < 2mm fragments be seen

 

Pipkin Infrafoveal CT

 

MRI

- may be needed to see labral tears blocking reduction

 

Open reduction

 

Indications

 

1.  Irreducible dislocation

 

2.  Non-concentric reduction

- loose bodies / interposed tissue

 

3.  Post operative sciatic nerve palsy

 

4.  Unstable posterior acetabular fracture

 

5.  Associated NOF fracture

 

6.  ORIF Pipkin fracture

 

Approach 

 

Usually from direction of dislocation

- preserve intact capsule

- preserve remaining blood supply

- i.e. with posterior dislocation the posterior capsule will be torn

- provides entry into joint

 

Posterior Approach

 

Aim to preserve intact anterior capsule and blood supply

- beware sciatic nerve

- divide piriformis and conjoint tendon away from insertion to preserve deep branch MCFA

- may need to extend posterior capsular rent

- allows direct visualisation of blocks to reduction

- blocks include G. max, piriformis, capsule, bony fragments

- may need to excise ligamentum teres

- explore acetabulum for loose bodies

- close capsule afterwards

- may need to excise L Teres

 

Other issues

 

Posterior acetabular fracture

- ORIF if > 40% or unstable

 

Pipkin fracture

- manage as per Femoral Head Fractures

 

Subcapital fracture

- Watson Jones / Smith Peterson approach

- supplementary lateral approach to insert fixation

 

Post Operative

 

NWB for 6/52

 

Bone scan re vascularity 

 

Issue

- °AVN = FWB

- AVN = consider bisphosphonates

 

Yue et al J Orthop Trauma 2001

- 5/54 low blood flow on early SPECT

- no correlation with AVN

 

Complications

 

AVN

 

Related to

- time to reduction <12/24

- velocity of injury

- open reduction vs closed (x4)

- direction (anterior < posterior)

 

Timing

- < 6/24 = 2-10%

- > 12/24 = 52%

 

Direction

- posterior 17%

- anterior 2%

 

Tends to be localised

- revascularisation occurs on reduction

- damage to lateral & medial epiphyseal artery

- metaphyseal blood supply remains

- occurs in first 18 months

 

OA 

 

Incidence

- 15 - 20 %

 

Causes 

- AVN

- instability

- incongruous reduction

- cartilage damage at time of dislocation

 

Philippon et al Arthroscopy 2009

- hip arthroscopy post traumatic dislocation in 14 athletes

- all had chondral defects, 11 had loose fragments

- all patients had labral tears

 

Sciatic Nerve Palsy 

 

Posterior dislocation

- 8 - 19%

- more common after fracture / dislocation

 

Type

- usually partial CPN

- usually resolves

 

Only explore if onset after MUA

 

Else observe

 

Instability < 1%

 

Myostitis Ossificans

 

Uncommon

- usually little functional problem

Hip Fractures

Intertrochanteric Fractures

DefinitionHip Intertrochanteric Fracture Type 3

 

Fracture which extends between the trochanters of the proximal femur

- lower limit is inferior border of lesser tuberosity

 

Anatomy

 

Extra capsular / well vascularized

 

The key to stability is the posteromedial cortex

 

Epidemiology

 

Elderly

- 90% > 65

- peak at 80 years

 

F:M 2:1

 

NHx 1st year

- 1/3 die

- 1/3 worse function

- 1/3 same function

 

Mechanism of injury

 

Low energy injuries in osteoporotic patient

- direct = blow to GT

- indirect = torque force secondary to fall

 

Signs

 

Leg

- shortened

- externally rotated

- groin pain with leg movement

 

Prevention

 

Judicious use of medications

- avoid confusing / sedating

 

Poor vision

- adapt home environment

- avoid slippery rugs etc

 

Adapt bathrooms for safety / stability

 

Hip pads

 

Dx Occult Hip Fractures

 

Definition

 

Hip pain

Normal Xray

 

Investigations

 

CT scan

- easily obtained in emergency departments

 

Bone Scan

- 100% sensitive at 72 hours

 

MRI

- sensitive within 24 hours

- more expensive and difficult to obtain

 

Results

 

Lubovsky et al Injury 2005

- compared CT and MRI

- MRI more accurate

- 4/6 CT inaccurate

 

Evans Classification 

 

Two main types

- Type 1 Intertrochanteric

- Type 2 Reverse Oblique

 

Stability

- depends on medial cortical reduction

 

Unstable

- collapse into varus or shaft medialises

- comminuted PM cortex

- reverse oblique

- subtrochanteric extension

 

Type 1 Intertrochanteric

 

1.  2 part undisplaced & stable

 

Hip Intertrochanteric Fracture Type 3

 

2.  2 part displaced, but stable on reduction

 

Hip Displaced Intertrochanteric Fracture

 

3.  3 part with posterolateral support (GT fracture)

 

4. 3 part without posteromedial support (LT fracture)

 

Hip Intertrochanteric fracture Type 4

 

5. 4 part without posterolateral or medial support (combination 3 and 4)

 

Four Part Inter trochanteric fracture

 

Type II Reverse Oblique Type

 

 

Inherently unstable

- 2° tendency of femoral shaft fragment to shift medially

 

Modified Boyd Classification

 

Type I   21%

- nondisplaced & stable 

 

Type II   36%

- stable, but displaced fractures

- stable construct with pin and plate

 

Type III   28%

- unstable with pin and plate

- large posteromedial comminution 

 

Type IV  15%

- intertrochanteric with subtrochanteric component

 

Isolated GT Fracture

 

Isolated Greater Trochanter Fracture

 

Management

 

Non operative

 

Issues

 

Little place for non operative treatment

 

Immobilization = Severe morbidity

- bed sores

- chest infection

- non-union

 

Indications

 

Unit for surgery

 

Incomplete fractures

 

Alam et al JBJS Br 2005

- 5 partial intertrochanteric fractures treated non operatively, 3 operatively

- no refractures

- similar length of hosptial stay

 

Operative

 

Medical Workup

 

1.  Improve any reversible medical disease

 

Otherwise surgery in first 24 hours

 

Consider Cause of fall

- exclude medical cause

- TIA / UTI / MI / Arrythmia

 

Treat

- electrolyte imbalance / anaemia

- pneumonia / UTI

- arrythmias

 

2.  Patient on anticoagulation

- operate if on plavix

- on warfarin, wait or use FFP to reduce INR < 1.6

 

Timing

 

Zuckerman et al JBJS Am 1995

- delay > 2 days increases mortality within the first postoperative year

 

Goal

 

Obtain stable anatomical reduction and allow early mobilisation

 

Options

 

Sliding Hip Screw and Plate

Intramedullary Hip Screw

Calcar Replacing Prosthesis

 

Post operative

 

Mobilise +++

 

DVT prophylaxis

- chemical and mechanical

 

Nutrition

 

Foster et al J Orthop Trauma 1990

- higher morbidity if albumin< 3 (70%) than > 3 (17%)

 

Prevent secondary fractures

- vitamin D + calcium to all patients

- bisphosphonates if tolerated

 

Sliding hip screw and Plate

 

Hip Pin and Plate APHip Pin and Plate Lateral

 

Mechanism

 

Plate is a lateral tension band whilst the sliding screw allows controlled fracture impaction

 

Contraindications

1.  No lateral buttress 

2.  Reverse oblique fracture

3.  Subtrochanteric extension

 

Technique

 

Set up

- traction table with anatomic reduction

- traction, adduction, IR

- other leg: hip and knee flexed with hip abducted to allow II

- lateral approach to femur

 

Guide wire

- centred in femoral head in 2 planes 

- tip-apex distance < 25 mm

 

Tip - apex distance

- from tip of screw to apex femoral head

- accumulative on AP and lateral

- strong predictor of cut out

- < 25 mm, virtually zero

- > 25 mm, increases cut out

 

Measure angle

- wire in centre of neck / centre of head

- usually 130o prosthesis

- often only 135o available / need to be lower in neck

- being in the centre of the head is most important

 

Ream to within 5 mm of end of wire

- tap

- insert screw / tip apex distance < 25 mm

- attach plate

 

Options for improving stability

 

A.  Valgus Osteotomy for unstable Fractures

 

Theory

- reduces shear force

- increases compression

- stronger construct

 

Technique

- 135° plate placed in at 120°

- valgises proximal fragment 

- medializes shaft

- +/- lateral wedge removed / Sarmiento Valgus Osteotomy

 

Cochrane Database Sytemic Review 2009

- no evidence for improved outcome

- higher blood loss

 

B.  Trochanteric stabilisation plate

 

Theory

- buttresses the GT and prevents lateral displacement

 

Madsen et al J Orthop Trauma 1998

- compared first generation Gamma nail / CHS and DSH/TSP in unstable fractures

- DHS/ TSP had lowest rate of varus malunion / lag screw cutout / excessive lag screw sliding with medialisation

- CHS still had lowest rate of reoperation

 

Intra-medullary Hip Screw

 

Hip Intertrochanteri Fracture IMNHip Intertrochanteric IMN Lateral

 

Mechanical Advantages

- load sharing rather than load bearing

- decreases lever arm

- supports medial cortex

- less distance for collapse

 

Theoretical Surgical Advantages

- smaller incision / mini invasive

- reduced blood loss

- shorter surgical times

 

Indications

- reverse oblique

- unstable fracture / loss of lateral buttress / loss posteromedial support

- intertrochanteric extension

- pathological fractures

 

History

 

First generation Gamma Nail (Stryker) had 5% distal femoral fracture rate

 

Reasons for distal fracture

- fit and fill caused increased distal stresses (higher fracture with 16 mm diameter nail)

- no anterior bow

- poor distal locking technique (missed holes caused fractures)

- 2 distal screws

 

Second Generation intra-medullary hip screws

 

IMHS / Gamma Nail

- trochanteric entry

- decreased distal diameter

- shorter length (180 mm v 200mm)

- only 4o valgus offset

- 125 - 130o angle

- one distal screw with jig

 

Hip Reverse Obliquity Fracture IMN

 

Results

 

Second Generation IMN v Sliding hip screws

- several prospective randomised studies

- very similar rates of complications

- similar cut out, blood loss, time of operation

- slight risk femoral fracture IMN

- learning curve for IMN (25 cases)

 

Cochrance database review 2008

- no evidence of superiority of IMN over sliding hip screw

- increased complications with nail

 

3.  Calcar replacing prosthesis

 

Indications

- salvage of failure of fixation

- severe comminution

- RA

 

Problems

- high cost

- higher morbidity / mortality

- high risk of dislocation

 

Complications

 

1.  Screw Cut Out 6%

 

Hip Pin and Plate Screw Cut outIntertrochanteric NOF Screw Cut out

 

Causes

- poor screw position

- 150° screw

- high tip apex distance

 

Options

- 95o DCS

- THR / calcar replacing prosthesis

 

THR Issues

 

A.  Cemented femoral component

- cement will come out screw holes

- Option 1:  leave screws in laterally, and strip medially to insert small screws

- Option 2:  use uncemented stem

 

B.  Length of femoral stem

- should bypass distal screw hole by 2 cortical diameters

 

C.  Calcar

- normal stem usually sufficient if LT healed back on

 

THR Post Pin and PlateIntertrochanteric NOF Calcar Replacing THR

 

Barrel Impingement / Excessive Lateral sliding / Shaft medialisation

 

Cause

 

1.  Long screw

2.  Collapse with insufficent lateral buttress

3.  Reverse obliquity fracture

 

Intertrochanteric Fracture Barrel Impingement

 

Management

 

1.  Fracture united

- remove screw

 

2.  Fracture non union

- revise fixation in young patient

- THR

 

Lateral Slide Off Proximal Fragment

 

Femoral medialisation

 

Due to

- insufficient lateral cortex

- reverse obliquity fracture

 

Use 95° plate

 

Non Union

 

Uncommon / 1%

- exclude infection

 

Presentation

- continued pain (case 1)

- hardware failure (case 2)

 

Case 1

 

NOF Intertrochanteric Non unionNOF Intertrochanteric Nonunion CT

 

Case 2

 

Hip Broken Intertan NailHip Broken Intertan Non Union salvage

 

Options

 

A. Closing lateral wedge valgising osteotomy + graft

- success 90% / indicated in younger patients

B.  95 degree DCS Plate

C.  Revision IMN

D.  THR

 

Infection 2-5%

 

Intertrochanteric Infected NonunionIntertrochanteric Infected Nonunion Spacer

 

Malrotation

 

Cause

- posterior sag of femur in unstable fracture

- get malrotation if use excessive IR to "reduce" fracture on II

 

Periprosthetic fracture

 

Usually fracture at tip of plate

- remove distal screws and insert retrograde nail

 

Subcapital Fractures

Background

DefinitionGarden 3 Displaced Subcapital

 

Fracture distal to articular surface & proximal to intertrochanteric region

 

Epidemiology

 

On average 4 years younger than intertrochanteric fracture

 

One year mortality as high as 36%

 

Only 1/3 will return to pre-fracture living environment

 

Mechanism of Injury

 

Direct or Indirect

 

1.  Direct blow GT 

 

2.  Posterior cortex impingement on rim

- 2° to ER

- acts as a fulcrum

 

3.  Bending torque > threshold 

- major trauma in young

 

4.  Violent muscle contraction

 

5. Cyclical loading / Insufficiency fracture

 

Risks

 

Osteoporosis

Osteomalaica

Co-morbidity

Dementia

Poor mobility / vision

 

Blood Supply

 

Medial and lateral circumflex femoral arteries

- extracapsular anastomosis at base of neck

- retinacular / ascending cervical branches

- intra-capsular branches

 

Majority via MCFA

- almost none to head via LCFA

- small amount via medial epiphyseal via ligamentum teres

 

MCFA

- medial aspect of profunda

- along posterior intertrochanteric crest extracapsular

- between iliopsoas laterally and pectineus medially

- runs along inferior border of obturator externus, deep to quadratus femoris

- emerges at superior aspect quadratus femoris

- runs anterior to conjoint tendon then penetrates capsule

- runs along superior aspect of neck

 

LCFA

- arises lateral aspect of profunda

- transverse branch runs under sartorius and rectus over vas lateralis to supply proximal femur

 

Garden's Classification

 

Type I 

 

Incomplete valgus impacted fracture

 

Subcapital NOF Garden 1 CTSubcapital NOF Garden 1 Xray

 

Type II 

 

Complete fracture, undisplaced

 

Type III 

 

Displaced with capsule intact 

- trabeculae don't line up with acetabulum

 

Subcapital NOF Garden 3

 

Type IV 

 

Displaced 

- trabeculae line up with acetabulum

 

Subcapital Fracture Garden 4

 

Eliasson Acta Orthop Scanda 1988

- best to divide into displaced / undisplaced

- based on work showing poor interobserver reliablity with Garden's

 

Pauwel's Classification

 

Relates vertical shear vector

- more vertical the fracture

- increased risk of non union

 

Type I:    < 30° from horizontal

Type II:   30 - 50° from horizontal

Type III:  > 50° from horizontal 

 

Subcapital Fracture Pauwels Type III

 

Problem 2° to parallax error

 

Complications

 

AVN

 

Undisplaced < 10%

Displaced 20 - 33% (variable, not complete)

 

Non union

 

Undisplaced 5%

Displaced up to 33%

 

This complication is more likely to need surgery

 

Clinical presentation

 

Pain

 

Short & ER leg

 

Management

 

Medical Workup

 

1.  Improve any reversible medical disease

 

Otherwise surgery in first 24 hours

 

Consider Cause of fall

- exclude medical cause

- TIA / UTI / MI / Arrythmia

 

Treat

- electrolyte imbalance / anaemia

- pneumonia / UTI

- arrythmias

 

2.  Patient on anticoagulation

- operate if on plavix

- on warfarin, wait or use FFP to reduce INR < 1.6

 

Management

 

Algorithm

 

Displaced v undisplaced

Age of patient

 

Undisplaced Subcapital

 

Cannulated screws

DHS + derotation screw

 

Displaced Subcapital Algorithm

 

1.  Expected life > Prothesis Survival

 

ORIF

- anatomical reduction / closed or open

- compressive screws / DHS + derotation screw

 

2.  Expected life < Prothesis Survival

 

Hemiarthroplasty < 5 years survival

THR 5-15 years survival

 

Rogmark et al JBJS Am 2002

- multicenter RCT patients > 70 years with displaced fracture

- ORIF 43% failure

- hemiarthroplasty 6% failure

 

Displaced Arthroplasty

Indications

 

Patient > 70

 

Gjertsen et al JBJS Am 2010

- 4335 patients > 70 with displaced subcapital fractures

- minimum 1 year follow up

- 1 year mortality same in each group / 25%

- 22% reoperation in ORIF v 3% in hemiarthroplasty

- more pain / higher dissatisfaction / lower quality life in ORIF group

 

Options

 

Hemiarthroplasty

- unipolar monoblock

- unipolar modular

- bipolar

 

THR

 

Burgers et al Int Orthopaedics 2012

- THR v hemiarthroplasty

- 8 trials involving nearly 1000 patients

- THR 4% revision v HA 7% revision

- THR 9% dislocation v HA 3%

- THR 94 WOMAC v 78 HA

 

Hopley BMJ 2010

- THR may lead to lower reoperation rates and better functional outcomes compared with HA in older patients

- heterogeneity across the available trials preclude definitive statements

 

Ingull Int Orthop 2013

- RCT of cemented unipolar v bipolar HA

- 4 year follow-up in 120 patients aged 80 or more

- better EQ-5D in bipolar

- no difference in revision rates / acetabular erosion / HHS

 

Li et al PLoS One 2013

- meta-analysis of cemented v uncemented HA in elderly

- cemented better hip function, less postoperative pain, fewer intra-operative complications but longer surgical time

- no difference in revision rate

 

Australian Joint Registry 2010 Revision Rates

 

1.  > 85 

- unipolar monoblock 3.4% 7 years

- unipolar modular 2.1% 5 years

- bipolar 2.9% 7 year

 

2.  75-84

- unipolar monoblock 8.5% 9 years

- unipolar modular 5.5% 7 years

- bipolar 3.5% 7 years

 

3.  < 75 

- unipolar monoblock 17.5% 7 year

- unipolar modular 13.4% 7 year

- bipolar 6% 7 year revision rate

 

Hemiarthroplasty

 

Issues

 

Types

 

Unipolar

- non modular - Austin Moore / Thompsons /

- modular

 

Bipolar

 

Fixation

 

Cement

- minimises fracture risk

- reduced risk thigh pain

- slightly increased cardiac risk with cement

 

Australian Joint Registry

- revision rates lower for cemented than uncemented

- for all types of hemiarthroplasty for NOF fractures

 

Approach

 

Posterior approach

- increased short term morbidity

- may increase dislocation risk

 

Hardinge

- take off anterior 1/3 abductor tendons

 

Prosthesis Options

 

Austin Moore

- press fit non modular unipolar

- only 2 sizes of stem

- small patients can fracture femur

- larger patients the stem can be loose

- AJR: 7.8% 9 year revision rate

 

Hip Austin Moore

 

Thompson's

- cemented non modular prosthesis

- no offset options

- AJR: 5.1% 7 year revision rate

 

Thompsons Hemiarthroplasty

 

Modular Unipolar

- based on standard THR concepts

- trial and insert femoral component / cemented or uncemented

- can use standard or high offset

- opportunity to adjust neck length

- attach head

 

Modular Hemiarthroplasty

 

Bipolar 

 

Hip Bipolar

 

Concept

- metal femoral head articulates with polyethylene socket

- reduces motion at acetabular / metal interface

- in theory reduces acetabular cartilage wear / degeneration / pain

 

Advantages

- less dislocation compared with THR

- less acetabular wear / protrusio compared with unipolar

- less pain compared with unipolar

- more motion

- lower revision rates compared with unipolar (AJR)

 

Disadvantage

- high cost (close to some THR)

- may need open reduction in dislocation if femoral head disassociates from socket

- loss of motion interface / becomes unipolar)

 

Complications

 

Infection

 

Dislocation

- similar to THR in long term

 

Hemiarthoplasty dislocatedBipolar Dislocation

 

GT Fracture

 

Hip Hemiarthroplasty GT Fracture

 

LLD

 

Hip Hemiarthroplasty LLD

 

Loosening

 

Groin pain from acetabular cartilage erosion

- most common complication

 

Severe acetabular wear

 

Bipolar Acetabular Destruction 1Bipolar Acetabular Destruction 2

 

Bipolar Acetabular Destruction Revision 1Bipolar Acetabular Destruction Revision 2

 

THR

 

Indications

 

Acetabular disease (RA, Paget's, OA)

Young, active, mobile patient

 

Issues

 

1.  Dislocation

 

Increased early dislocation rate

Long term dislocation rate similar to hemiarthroplasty

 

Keating et al Health Technol Assess 2005

- randomised study of bipolar v THR

- 2.7% dislocation rate v 4.3%

 

2. Revision / Survivorship

 

Good long term survival

 

Lee et al JBJS Am 1998

- 94% 10 year survival

 

3. Function

 

Parker et al Cochrane Database Review

- THA has better functional outcome

 

Bekerom et al JBJS Br 2010

- RCT of hemiarthroplasty v THR in over 70

- 252 patients 5 year follow up

- no difference in Harris Hip scores, revision rate

- increased early and late dislocation in THR

- did not recommend THR in over 70

Displaced ORIF

Indications

 

< 60 with good bone stock and preserved joint space

 

Reduction

 

Union rates increased with anatomical reduction

 

Options

- closed reduction

- open reduction / if closed reduction fails

 

Accept

- no varus

- < 15o valgus

- < 10o AP plane

 

Assessment of reduction

 

1.  Femoral neck shaft angle

 

2.  Garden alignment index

- angle of compression trabeculae to femoral shaft on AP should be 160o

- angle of compression trabeculae to femoral shaft on lateral should be 180o

 

3.  Lowell's alignment theory

- head neck junction should make a smooth S / reverse S on all views

 

4.  Restoration of Shentons line

 

Closed Reduction

 

Set up

 

Traction table / radiolucent table

 

Leadbetter Maneuver

 

FATI CAR

- flexion / adduction / traction / IR 

- circumduction / abduction

- reduction Check in extension

- "Foot in Palm Test"

- if sufficiently reduced will sit without ER

 

ORIF

 

Cannulated screws / DHS + derotation screw

 

Aminian JOT 2007

- biomechanical study of strength of fixation of vertical fractures

- locking plate > dynamic condylar screw > dynamic hip screw / 3 cannulated screws

 

Capsulotomy

 

Theory

- decrease intracapsular pressure

- in animal models increases blood flow

 

Options

- open capsulotomy via Smith Peterson

- percutaneous needle drainage of hematoma

 

Open Reduction

 

Set up

 

Radiolucent table

- floppy lateral with sandbag under affected hip

 

Technique Watson Jones approach

 

Lateral incision

- divide fascia lata

- interval between G medius and TFL

- can take some of G medius off to aid exposure

- flexing hip 20-30o helps exposure

- take reflected head of rectus femoris off anterior capsule

 

"T" ant capsulotomy / Z shaped

- avoid dissecting superior aspect of femoral neck where major artery of MCFA runs

- vertical limb down anterior edge acetabulum / preserve labrum

- horizontal limb along inferior aspect of femoral neck

 

Steinman pin in femoral head

- allows manipulation and reduction

- may need second steinman pin in femur

- obtain anatomical reduction under direct vision

 

Separate lateral approach

- split ITB and vastus lateralis

- fixation of reduction

 

Check reduction on II

- ensure no varus on AP

- obtain lateral by adducting and IR hip / ensure good reduction on lateral

 

Ensure 2 guide wires centrally in femoral head

- 2 hole DHS + derotation screw (strongest)

- 3 or 4 cannulated screws

 

Open subcapital ORIF

 

Technique Smith Petersen

 

Smith Petersen Approach 1Smith Petersen Approach 2Smith Petersen Approach ORIF

 

Options

 

Unstable fracture

- augment with a plate on inferior neck

 

Displaced Subcapital Inferior PlateDisplaced ORIF Lateral

 

Results

 

Age

 

Rogmark et al JBJS Am 2002

- multicenter RCT patients > 70 years with displaced fracture

- ORIF 43% failure

- hemiarthroplasty 6% failure

 

Timing

 

Jain et al JBJS Am 2002

- retrospective review of displaced fractures in 29 patients < 60

- significant reduction in AVN if fixed within 12 hours

 

Complications

 

AVN

 

Subcapital NOF AVN

 

Incidence

 

Undisplaced <10%

Displaced  20-33% 

 

Risk factors

 

Displacement

Injury velocity

Delay in Reduction

Non-anatomical Reduction

 

Pathology

 

Whole head or small wedge 

- most common anterosuperiorlateral

 

Revascularization  

- existing med and lateral epiphyseal blood vessels

- metaphyseal BV crossing fracture

- reduced by mal-reduction / non union

 

Only 30% with AVN will need re operation

 

Management Options

 

Older patient

- arthroplasty

 

Younger patient

- forage / vascularized fibula graft / non vascularised bone graft

- osteotomy

 

Non-Union

 

Incidence 

 

9-33%

 

Risk Factors

 

Intial displacement

Non anatomical reduction

Instability

No compression across fracture

Vascularity - can unite if avascular

 

Failed Subcapital ORIFSubcapital ORIF Lateral

 

Subcapital Nonunion 1Subcapital Nonunion 2

 

Management

 

Older patient

- arthroplasty

 

Young patient

- valgus osteotomy

 

Subcapital NOF Non UnionSubcapital NOF Nonunion CTTHR post Subcapital Nonunion

 

Valgus osteotomy

 

Indications

- patient must have at least 15o adduction

 

Template

- aim to reduce the angle of the neck fracture to between 20 - 30o from horizontal

- this places it perpendicular to the forces acting across the hip

- measure angle of fracture from horizontal (usually 40 - 50o up to 70o)

- difference is angle of correction (20 - 30o)

 

Technique

- insert guide wire in centre of head / for screw

- place K wire superiorly in same plane as this wire at level of LT

- second K wire below at angle of required osteotomy

- resect bone piece

- apply appropriately angle device

- ensure straight line down femur in AP and lateral if need subsequent THR

Undisplaced Management

Definition

 

Garden 1 / 2

 

Algorithm

 

ORIF

- ~ 15% displacement rate with non operative management

- increased risk of non union

- reduced hospital in patient stays

 

Options

 

Cannulated screws

DHS + derotation screw

 

3 cannulated screws

 

Hip Cannulated Screws

 

Technique

- lateral on traction table

- adequate reduction / no varus

- small incision

- 1 x inferior screw, 2 x superior screws

- ensure inferior screw entry is above LT to prevent fracture

- ensure threads cross fracture site entirely to obtain compression

- need correct screw length so screw head can compress against cortex

 

DHS and derotation screw

 

Subcapital Fracture DHS Derotation Screw

 

Results

 

Parker et al Acta Orthop Scand 1998 69

- meta-analysis of 25 randomised trials

- no superiority of pin and plate over 3 cannulated screws

- less blood loss with cannulated screws

 

 

 

 

Subtrochanteric Fractures

Definition

 

Fracture below lesser trochanter / proximal 5 cm femur

 

 Subtrochanteric Fracture Long SpiralSubtrochanteri Fracture

 

Aetiology

 

Young patients / high velocity injuries

Old patients / osteoporosis

 

Fixation techniques

 

Plate

 

A. 95o Dynamic Condylar Screw / DCS plate

 

Indication

- revision

- very short proximal fragment

 

Pai J Orthop Trauma 1996

- 16 cases without no bone graft

- union in 15/16

 

B. Locking plates

 

Burkes JOT 2012

- 18 pertrochanteric fractures treated with Synthes locking plate

- catastrophic failure in 7 (37%)

- poor Harris Hip Scores in remainder

- postulated that construct too stiff

 

Forward JOT 2012

- biomechanical comparison of subtrochanteric fixation

- IMN strongest

- 90 degree condylar and locking plate similar strengths

 

IMN

 

Cephalomedullary nails / screws into femoral head

- reconstruction nail

- IMHS / Gamma Nail / Intertan

 

Advantage

- load sharing

 

Subtrochanteric Intertan NailSubtrochanteric Femur Fracture Gamma NailReconstruction NailReconstruction Nail Spiral Blade

 

Outcomes

 

Lee et al J Trauma 2007

- RCT of DCS v recon nail in 66 young patients with comminuted subtrochanteric fractures

- no significant difference in union rates

 

Rahme et al J Orthop Surg 2007

- RCT 58 patients

- revision rate 28% in plate group v 0% in IMN

 

Technique IMN

 

Issue

 

Varus position associated with non union

 

Shukla Injury 2007

- case series of subtrochanteric fractures treated with IMN

- all nonunion occured with varus > 10 degrees

 

Deformity

 

Subtrochanteric FractureSubtrochanteric Lateral

 

Usual with short proximal fragments

- proximal fragment abducted, ER and flexed

- difficult to obtain trochanteric entry and straight shot down femur

- tendency for guide wire to go medial

- difficult to avoid fixing proximal fragment in varus

 

Reduce proximal fragment first

- avoid lateral entry on trochanter

- avoid varus

- allows accurate passing of guide wire

 

Reduction techniques

 

Percutaneous

- ball tipped spikes / steinman pin to proximal fragment

- reduce varus

 

Open

- percutaneous clamp / temporary reduction of fracture

- cerclage wiring - involve soft tissue stripping / may block femoral head screws

 

Cerclage wires

- can hold reduction

 

Afsari JBJS Am 2010

- cerclage reduction of displaced subtrochanteric fractures

- 43/44 fracture united

- good outcomes, if soft tissue dissection minimized

 

 Subtrochanteric Varus APSubtrochanteric Femur Varus Lateral

 

Complications

 

Varus Malunion

 

Causes

- trendelenberg gait

- LLD

- increases risk non union
 

Malreduction

 

May need to open reduce fracture before nailing

 

Subtrochanteric Fracture Malreduced0001Subtrochanteric Fracture Malreduced0002

 

Non union

 

Subtrochanteric Fracture Nonunion

 

Causes

 

Non antomical reduction (varus / flexion / persistent displacement)

Excessive soft tissue stripping

Infection - must exclude with blood tests

 

Presentation

 

Pain

 

Failure Hardware / Broken nail

- use guide wires with hook at tip

- catch distal end of nail and retrieve

 

Management Options

 

A. 95 degree condylar plate

- reduction of malunion / takedown non union

- bone graft

 

Subtrochanteric NonunionDCS 95 degree

 

B.  Exchange nailing

- need to be able to obtain reduction

 

Subtrochanteric non union Broken IntertanSubtrochanteric Nonunion Revision Nail

 

C.  THR / calcar replacing

 

Calcar Replacing Prosthesis

 

Screw Cutout

 

Recon Nail Cut outRecon Nail Cutout LateralRecon Nail Cutout Salvage

Outcome Measures

Please refer to excellent website for details of all scores

www.orthopaedicscores.com

 

1.  Disease specific outcome measures

 

Surgeon assessment

Traditional

 

Harris Hip Score

 

JBJS Am 1969

 

A.  Patient History (90 points)

- pain, walking distance, limp, support

- stairs, sitting, shoes, public transport

 

B.  Patient Examination (10 points)

- ROM values

 

Score

- < 70 poor

- 70 - 80 fair

- 80 - 90 good

- 90 - 100 excellint

 

Mayo Hip scores

 

80 points clinical

 

20 points xray

 

2.  Patient specific outcome measures

 

Assesses broader range of issues

- patient assessment

 

Oxford Hip scores

 

Assess

- pain

- function

- ROM

 

Entirely patient history

 

SF-36

 

Medical outcomes short form 36

 

WOMAC

 

Western Ontario McMaster Osteoarthritis Index

Symptoms / Pain / Function

 

 

 

Pelvic Fractures

Background

Anatomy

Pelvis Anatomy

 

Pelvis is a true ring

- any anterior fracture must have a posterior injury as well

- integrity of the posterior sacroiliac complex is key

 

Bony Anatomy

 

2 innominate bones + sacrum

Symphysis pubis < 5mm

SI joint 2-4 mm

 

Soft Tissue Anatomy

 

Suspension bridge like complex of post ligaments

 

1.  Posterior sacroiliac ligaments 

- are strongest in body

- maintain sacrum in position in pelvis

 

2.  Anterior sacroiliac ligaments

- flat and strong 

- resist ER and shearing forces

- they do not have the strength of posterior ligaments

 

3.  Iliolumbar ligaments 

- iliac crest to transverse process of L5

 

4.  Sacrospinous ligaments

- transversely from lateral edge of sacrum to ischial spine

- resist ER of pelvis

 

5.  Sacrotuberous ligaments 

- from sacroiliac complex posterior to sacrospinous ligament

- pass down to ischial tuberosity

- resist vertical shear

 

Sacrospinous and Sacrotuberous are complementary 

- running at 90o to each other 

- adapted to the major forces acting upon the pelvis

 

Injury Patterns

 

Mechanisms

 

ER

IR

Vertical shear

 

Young and Burgess Classification

 

APC / Anterior Posterior Compression

 

APC 1 - 1-2 cm diastasis, minimal SIJ diastasis anteriorly

 

Pelvic Fracture APC 2

 

APC 2 - ST/SS + anterior SIJ disrupted

 

Pelvis APC 2Pelvic Fracture APC 2

 

APC 3 - complete SIJ disruption, nil vertical displacement

 

LC / Lateral Compression

 

LC1 - pubic rami + sacral compression same side

 

Pelvic Lateral Compression Fracture LC1

 

LC2 - pubic rami + iliac wing fracture

 

Pelvic Fracture LC2

 

LC3 - pubic rami + contralateral open book

 

Vertical Shear

 

Through SIJ or sometimes iliac wing / sacrum

 

Vertical Shear Sacral Fracture

 

CM / combined mechanism

 

Tile Classification

 

Type A: Stable (posterior arch intact)

 

A1: Avulsion injury
A2: Iliac-wing or anterior-arch fracture due to a direct blow
A3: Transverse sacrococcygeal fracture

 

Type B: Partially stable (incomplete disruption of posterior arch)

 

B1:  Open-book injury (external rotation)
B2:  Lateral-compression injury (internal rotation)
B2-1: Ipsilateral anterior and posterior injuries
B2-2: Contralateral (bucket-handle) injuries
B3:  Bilateral

 

Type C: Unstable (complete disruption of posterior arch)

 

C1: Unilateral
C1-1: Iliac fracture
C1-2: Sacroiliac fracture-dislocation
C1-3: Sacral fracture
C2: Bilateral, with one side type B, one side type C
C3: Bilateral

 

Open book injuries

 

Definition

- external rotation force

- no vertical displacement

 

Stages

 

Stage I - symphysis open < 2.5cm

Stage II - symphysis open > 2.5cm

Stage III - >2.5cm with peroneal wound

 

Is continuum with increasing external rotation force

- < 2.5cm posterior SIJ ligaments intact (like pregnancy)

- as progresses further the anterior SIJ ligaments rupture

- eventually posterior complex can be incompetent and have vertically unstable pelvis

- essentially have hemi-pelvectomy

 

Lateral compression

 

Mechanism

- IR force applied to ileum or more commonly to greater trochanter

- as pelvis is compressed risk of pelvic viscera injury especially bladder is great

- with increasing IR posterior structures may yield

- usually anterior sacroiliac crush is so stable that reduction is difficult

 

LC1

- ipsilateral

- superior and inferior rami fractured or

- superior ramus fracture with symphysis disrupted or

- locked symphysis

 

LC3

- bucket Handle

- contra-lateral ER / open book

- usually direct blow to pelvis

- fractured pelvis rotates like a bucket handle

- leads to LLD

- to reduce LLD need rotatory moment rather than traction

 

Stability

 

Stable

 

2 Types

- APC 1 & 2

- lateral compression injury

 

Unstable

 

Instability in the vertical plane

- no integrity of posterior ligamentous complex

- disruption of sacrospinous / sacrotuberous and posterior SI ligaments

 

Radiographic signs of instability

- SIJ > 5mm in any plane

- posterior fracture displacement

- avulsion 5th lumbar transverse process

- avulsion ischial spine (SS ligament)

- avulsion lateral border sacrum (ST ligament)

 

Sacrospinous Ligament Avulsion

 

X-rays

 

Inlet view

- 40o caudal

- shows AP displacement of sacrum c.f. pelvis

- anterior and posterior sacral borders

- enables insertion of SI screws

 

Pelvis Inlet viewPelvis Inlet

 

Outlet view

- 40o cephalad

- vertical displacement of sacrum relative to ilium

- to check reduction of vertical shear in OT

- enables insertion of SI screws

 

Pelvis Outlet ViewPelvis Outlet

 

CT scan

 

Better defines posterior injury

 

 

Management Acute

EMST / ATLS PrinciplesPelvic Fracture APC

 

Usually polytrauma

- 10% mortality

 

Aims

1. Volume replacement

2. Reduce pelvic ring

3. Stop exsanguination

- external stabilisation / surgery / embolisation

 

Associated Local Injuries

 

Arterial bleeders

- internal pudendal most common

- iliolumbar / SGA / IGA / lateral sacral / internal iliac

 

Retroperitoneal veins / bone bleeding

- 85% of bleeding

 

Compound injury

- urethra, vagina, rectum, peroneum

- need diverting colostomy prior to any anterior approach

- retrograde urethrogram for blood at meatus +/- retropubic catheter

- triple antibiotics (penicillin / gentamicin / metronidazole)

 

Pelvic Fracture Retrograde Urethrogram Normal

 

Neurological Damage

- L5/S1 most common

- L2 - S4 possible

 

Depends on location of sacral fracture and displacement

1.  Lateral to foramen - 6%

2.  Through foramen - 28%

3.  Medial to foramen - 57%

 

Sacral Fracture Transforaminal

 

Morel - Lavalle Lesion

- skin degloving

- high risk of contamination

- don't place incisions through this region

- needs debridement prior to definitive surgery

 

Intra-abdominal bleeding

- 32%

 

Management of bleeding / Liverpool Protocol / NSW Institute of Trauma

 

Options

- external fracture stabilisation

- embolisation

- surgical control

 

Basics

 

Embolisation 

- good for small arterial bleeders

- not haemodynamically compromised patient with massive bleeding

- unable to embolise large vessels and patient will die whilst attempting technique

 

Direct surgical control 

- rarely indicated and seldom successful

- main indications for open surgery are the open pelvic fracture and

- massive vessel injury leading to a patient in extremis from hypovolaemic shock

 

If patient is in extremis 

- i.e. BP < 60mmHg with no response to fluid management

- thoracic and abdominal bleeding ruled out

- blood loss is retroperitoneal

- need immediate laparotomy and cross clamping of aorta to buy time / allow haemostasis and vessel repair

 

Management with angiography services available

 

1.  Small allquots fluid (100-200 mls) to maintain SBP 80 -90 mm Hg +

stabilise pelvis with non invasive device

 

2.  Abdominal fast scan

 

A.  Negative

- immediate interventional angiography

- if becomes stable, ICU, manage pelvic fracture

- if unstable, repeat fast scan

- if positive, OT

- if negative, repeat angiogram

 

B.  Positive

- laparotomy

- external fixation

- remain unstable, immediate interventional angiogram

 

Mx without angiography services available

 

1.  Manage initially as above

 

2.  Abdominal fast scan

 

A.  Negative or unknown

- if SBP < 70 mm Hg

- OT for surgical control of bleeding and pelvic packing

- await retrieval for interventional angiography

 

B.  Positive

- OT for laparotomy and external fixation

- await retrieval for interventional angiography if continues unstable

 

Provisional Stabilisation

 

Pelvic binder

- simple, easy to use

- adequately reduces pelvic space

 

C clamp

 

Enables posterior control

- contra-indicated in iliac wing fracture

- in sacral comminution can over compress

 

Entry point of steinmann pins

- intersection of 2 lines

- line parallel with femur

- line back from ASIS

 

Complications

- too anterior, perforate ilium, organ damage

- too posterior, enter greater sciatic notch with nerve and vessel damage

 

External Fixation

 

Decreases pelvic volume

- indicated in open book and unstable pelvis

- rarely required for lateral compression fractures

- simple 4 or 6 pin frame in iliac crest

- pins at 45o to each other

- rarely definitive as has nursing issues

 

Outomes

 

Mortality

 

Dalal et al J Trauma 1989

- review of 345 patients with relation to mortality

- brain injury compounded by shock major cause in LC

- shock, sepsis and ARDS in APC due to major abdominal trauma

 

Open fractures

 

Dente et al Am J Surg 2005

- 44 open pelvic fractures

- mortality 45% at average day 17

- concurrent intra-abdominal injury 89% mortality

- vertical shear fractures universally fatal

- pelvic sepsis 60% mortality

 

Angiogram / Embolisation

 

Miller et al J Trauma 2003

- 28 patients hemodynamically unstable pelvic fractures

- classified as non responders if BP < 90 after 2 units blood

- 26 had angiography, 73% had an arterial bleeder embolised

- recommended angio as first line treatment in non responders

 

Pelvic Packing

 

Cothren et al J Trauma 2007

- 28 patients hemodynamically unstable from pelvic fractures

- had external fixation and pelvic packing

- no deaths from acute bleeding

 

Fast scan

 

Fuchholtz et al J Trauma 2004

- 31 patients with unstable pelvic fractures and free fluid on FAST

- all but 1 had intra-abdominal pathology requiring surgery

- FAST negative in 49 patients, 3 of whom went on to require laparotomy

 

 

 

Management Definitive

APC compression

 

Indications

 

Non Operative

- < 2.5 cm displacement

- indicates SS and ST intact

- nil posterior opening

 

Operative

 

1.  > 2.5 cm

- single anterior plate through Pfannelstiel incision

 

2.  Posterior SIJ disruption

- reduction and posterior stabilisation

- usually with SI screws

- if comminuted may need posterior plating

- anterior plate

 

Pelvic APC ORIF 1Pelvic APC ORIF 2Pelvis APC ORIF 3

 

Pfannenstiel approach / Plating Pubic Symphysis

 

Technique

 

Set up

- supine on radiolucent table

- IDC to decompress bladder

 

Incision 2cm above pubis

- through fat and fascia

- avoid detaching rectus

- usually part torn off already

 

Reduction techniques

- during the reduction care must be taken to avoid trapping bladder or urethra in the symphysis when closing the clamp

 

A.  Assistant may apply pressure over each iliac crest or an external fixator can be applied

B.  Large pointed reduction clamp can be placed onto each pubic tubercle or through holes drilled in the bone

C.  Expose the medial obturator foramen and application of pelvic reduction forceps thru the medial aspect of the foramen

 

Superiorly applied plate

- pelvic reconstruction plate

 

Pelvis Pubic Symphysis Plate 1Pelvis Pubic Symphysis Plate 2Pelvis Pubic Symphysis Plate 3

 

Iliosacral Screws

 

Contra-indication

 

Posterior sacral comminution / foraminal fracture

- may be better with anterior / posterior plating

 

Technique
 

Radiolucent table with II

- 45o cephalad and caudal

- inlet and outlet view

 

Must reduce joint / fracture initially

- reduce vertically with traction on limb / outlet view

- reduce AP usually via compression / inlet view

 

Guide wire insertion

 

Anatomic safe zone

- between S1 foramen and sup ala on outlet view (outlet view)

- between neural canal and anterior body  (inlet view)

 

Pelvis Sacroiliac Screws InletPelvis Sacroiliac Outlet

 

Insert 6.5 mm cannulated screw with compression

 

Dangers

 

S1 nerve root inferiorly

Vessels and ureter anteriorly

Cauda equina posteriorly

L5 nerve root superiorly

 

Post operative

 

Check screw position with CT

NWB 6/52

 

Complications

 

S1 nerve root injury

SI osteoarthritis

Malunion

Failure of fixation

 

Results

 

Routt et al J Orthop Trauma 1997

- 177 patients treated with percutaneous SI screws

- open reduction required if unable to obtain closed reduction < 1cm widening

- inadequate II due to obesity or abdominal contrast in 18 patients

- 5 misplaced screws due to surgeon error with 1 transient L5 neuropraxia

- fixation failure in 7 patients usually due to head injury / non compliance / delayed union

- non union in 2 patients

 

Sacro-iliac Plating

 

A.  Anterior

 

Pelvic Anterior Sacroiliac Plate 1Pelvis Anterior Sacroiliac Plate 2Pelvis Anterior Sacroiliac Plate 3

 

Indications

- combination with anterior approaches

- anterior plating of pubic symphysis

- anterior approach acetabulum required

 

Technique

- use lateral window of ilioinguinal or stoppa approach

- L5 nerve root at risk

 

B.  Posterior

 

Indication

- comminuted posterior sacral injury

 

Technique

- patient prone

- vertical incision 1 cm lateral to PSIS

- from crest to sciatic notch

- incise and reflect G maximus

- apply transverse plate

- soft tissue can be a problem

 

Lateral Compression Fracture

 

Indications for ORIF

 

LLD  2.5 cm

 

Significant internal rotation

- risk of impingement

- especially young female / interfere with birth passage

 

Lateral Compression ORIF

 

Options

 

External rotation external fixation

 

Vertically Unstable Fractures

 

Management

 

Intial

 

Femoral steiman pin + 20lb weight to reduce vertical displacement

External fixation to pelvis

 

Definitive

 

Anterior plate

 

Posterior stabilisation

- posterior SI screws / anterior or posterior plate

 

Results

 

Griffin et al J Orthop Trauma 2006

- retrospective review of 62 patients treated with SI screws

- 4 failures in patients with vertical sacral fractures

- recommended plate fixation in this group

 

Non Ring Pelvic Fractures

Psoas Avulsion

 

Psoas Avulsion

 

Ileum Fracture

 

Ileum Fracture

 

ASIS Avulsion

 

Sartorius

 

AIIS Avulsion

 

Rectus femoris

 

Ischial Tuberosity avulsion

 

Hamstrings

- see article on hamstring avulsion

 

 

 

 

Proximal Hamstring Tear

Epidemiology

 

Adolescent apophyseal avulsion

- treat non operatively

- unless displaced > 2 cm

 

Adult

- soft tissue avulsion

 

Aetiology

 

Usually associated with sporting activities

- skiing

- water skiing

 

Violent contraction

- knee extended

- hip flexing

 

Anatomy

 

Biceps / Semimembranosus / Semitendinosus all attach here

 

Symptoms

 

Pain

Unble to run

 

Chronic tears

- may have some neuralgia symptoms

 

Signs

 

Large haematoma / bruise

Palpable defect

Distal retraction of muscle into thigh with contraction

 

Proximal Hamstring Rupture Bruise

 

Xray

 

May see bony avulsion

 

MRI

 

Proximal Hamstring Avulsion MRI CoronalProximal Hamstring Avulsion MRI Axial

 

Management

 

Non operative

 

Results

 

Harris et al Int J Sports Med 2011

- systematic review

- better subjective outcome / return to sport / hamstring strength with repair c.f. non operative

- better outcomes with acute (< 4 weeks) than chronic repair

 

Operative

 

Surgical Technique

 

Patient prone

- knee flexed over sterile gowns

 

Incision

- longitudinal incision centred on ischial tuberosity

- starting at gluteal crease

 

Superficial dissection

- divide fascia in line with incision

- preserve posterior femoral cutaneous nerve

- identify and elevate inferior edge of gluteus maximus

 

Deep dissection

- identify and preserve sciatic nerve (lateral to hamstring)

- identify hamstring tendon

- repair with multiple large suture anchors

- ensure no kinking of sciatic nerve at end of case

 

Hamstring Repair Sciatic NerveHamstring Repair Sciatic Nerve 2

 

Proximal Hamstring Rupture Post Op

 

Post op

- splint with knee flexed

- prevent hip flexion

- crutches

 

Proximal Hamstring Brace

 

Complications

 

Residual weakness (60 - 90% other side)

Neuralgia

 

Chronic > 4 weeks

 

More difficult

- careful dissection of sciatic nerve from adhesions

- release hamstring tendon

 

Augment options

- autologous ITB

- allograft

 

Results

 

Sarimo et al Am J Sports Med 2008 36

- 41 patients

- 5 chronic requiring achilles allograft

- 96% would have it done again, 80% return to sport

- no difference in strength between acute and chronic

 

Cohen Am J Sports Med 2012

- 52 patients

- 40 acute, 12 chronic

- 98% satisfied

- minimal difference in outcome between acute and chronic

 

Murray KSSTA 2009

- achilles allograft recon of chronic (6 months) rupture

- good outcome

Snapping Hip

Causes

 

Most common

- fascia lata on greater trochanter

- iliopsoas on lesser trochanter

 

1.  Intra-articular structures

- labrum

- ligamentum Teres

- loose bodies

- synovial chondromatosis

- osteochondoma

 

2.  Extra-articular structures

- fascia lata on greater trochanter (common) 

- iliopsoas on lesser trochanter / iliopectineal eminence 

- long head biceps femoris over ischial tuberosity

- iliofemoral ligament over femoral head

 

Iliotibial Band over GT

 

Symptoms

 

Usually painless

Can often be produced voluntarily

 

Examination

 

Hip flexion and internal rotation causes readily palpable snapping sensation

- tight iliotibial band subluxates over the greater trochanter

 

Management

 

Majority of patients no treatment required

- rest

- iliotibial band stretching exercises

- NSAIDS +/- local corticosteroid injections

 

Surgery

- rare persistent cases 

- elliptical resection of the iliotibial band over the greater trochanter + greater trochanteric bursectomy 

 

Iliopsoas Tendon

 

Symptoms

- snapping sensation felt in the groin as the hip is extended from a flexed position

- palpated as the supine patient extends the hip from a position of flexion / abduction & external rotation

 

Management

 

Non operative as above

 

Surgery

- resistant cases

- psoas lengthening

- resection prominence of lesser trochanter

- psoas division (can be done arthroscopically)

 

 

 

Sportsman's Hernia

Definition

 

Groin pain in athletes

- secondary to tear in external oblique fascia

 

Epidemiology

 

Sports with aggressive adduction

- hockey / soccer

 

Pathology

 

Tears in external oblique fascia

- tend to be central

- around spermatic cord and ilioinguinal nerve

- pain may be from nerve entrapment

 

DDx

 

Adductor Longus Tear

Osteitis Pubis

 

Symphysis Pubitis

 

Hip pathology

 

NHx

 

Adductor longus tears

- get better with time

- rarely need surgery

- pain stays below goin

 

Sports Hernia

- may have nerve / ilioinguinal symptoms

- above groin

- often get worse

 

Examination

 

Adductor longus tears

- tender over tendon

- pain / weakness on resisted adduction

 

Sports hernia

- tender over inguinal ring

- may have palpable dilatation of external inguinal ring

- pain with resisted sit up

- pain with resisted leg flexion

 

Dynamic ultrasound

 

May be useful in very experienced hands

 

MRI

 

Can be difficult to see

Is often a clinical diagnosis

 

Management

 

Non Operative

 

Rest

Exclude other diagnosis

 

Operative

 

Hernia repair

 

Technique

- expose external oblique fascia

- identify and protect spermatic cord

- identify tears / pathology

- release ilioinguinal nerve

- repair primarily or with gortex mesh

 

Ilioinguinal nerve

- some surgeons cut the nerve

- risk neuroma

- suprapubic numbness only

 

Can combine with adductor tenotomy

 

 

 

 

 

THR Australian Joint Registry

 

2009 / Revision Rates 8 year

 

Prosthesis Type All Diagnosis 7 year

 

Unipolar Monoblock 6.8%

Unipolar Modular 6.8%

Bipolar Hemi 4.2%

 

Cemented THR 3.8%

Cementless THR 4.4%

Hybrid THR 3.9%

 

Total Resurfacing 5.4%

Thrust Plate 3.0%

 

Revision for OA 8 year

 

Conventional THR  4.0%

Total Resurfacing   5.3%

 

Partial Hip Replacement

Cemented better than cementless in all categories

 

Hemiarthroplasty

 

1.  > 85 

- unipolar monoblock 3.4% 7 years

- unipolar modular 2.1% 5 years

- bipolar 2.9% 7 year

 

2.  75-84

- unipolar monoblock 8.5% 9 years

- unipolar modular 5.5% 7 years

- bipolar 3.5% 7 years

 

3.  < 75 

- unipolar monoblock 17.5% 7 year

- unipolar modular 13.4% 7 year

- bipolar 6% 7 year revision rate

 

Primary Conventional THR

 

By Age

 

< 55   4.9%

55-64  4.6%

65-74  3.6%

>75     3.7%

 

By Gender

 

Female  3.8%

Male     4.3%

 

By Fixation

 

Cemented    3.9%

Cementless  4.4%

Hybrid         3.4%

 

By Age & Fixation

 

< 55      hybrid (4.6) < cementless (4.8)

55-64     hybrid (3.6) < cementless (4.7)  < cemented (6.1)

65-74     hybrid (3.2) < cemented (3.8) < cementless (3.9)

> 75      cemented (3.1) < Hybrid (3.3) < cementless (4.2)

 

By Diagnosis

 

AVN 5.1%

DDH 3.5%

NOF  5.2%

OA    4.0%

RA    5.4%

 

By Bearing Surface

 

Ceramic / Ceramic  3.9%

Metal / Poly             3.2%

Ceramic / Poly         4.1%

Metal / Metal           7.7% (Head sizes > 28mm)

 

By Head Size

 

Ceramic / Ceramic

</= 28          4.6%

> 28              3.5%

 

Metal / Poly

>/= 28          3.9%

> 28              3.0%

 

By Cemented THR

 

MS30/Low Profile cup     1.0%

Exeter/Exeter                3.2%

Exeter / Contemporary   6.6%

Spectron / Reflection      6.9%

 

By Cementless THR

 

Securefit Plus / Trident  2.8%

Mallory Head                5.5%

Synergy/Reflection        3.8%

ABGII/ABGII                 5.6%

 

By Hybrid THR

 

Definition / Vitalock        1.5

Exeter/Vitalock              3.6%

Spectron/Reflection        5.4%

 

Identified as higher than expected

 

Corail / ASR 

 

Hip Resurfacing

 

13 300 procedures

 

Best outcome

- male < 65 with OA

- able to get > 50 mm head size

- 3.9% 9 year

 

Revision rate

 

Cumulative revision rate

- 7.2% 9 years for OA

 

Birmingham Resurfacing

- 6.2% 9 year

 

Reasons for revision

- fracture 36%

- loosening 33%

- metal sensitivity 7%

 

Revision by diagnosis 7 years

- OA 5.8%

- DDH 14%

- AVN 6%

 

Revision by prosthesis

- BHR 96.5% 5 year

 

Revision by age 7 years

- < 55     5.6%

- 55 - 64  5.8%

- > 65     7.3%

 

Revision by sex 7 years

- male 4.5%

- female 9.3%

 

Revision by head size 7 years

- < 44mm:    13.8%

- 45 - 49mm: 8.8%

- 50 - 54mm: 3.7%

- > 55mm:     2.2%

 

Revision

 

Type

 

Femoral only 21.5%

Acetabular only 37.1%

Combined         35.8%

 

Reason

 

Loosening 45.7%

Dislocation           14.8%

Lysis                    10.1%

Fracture                9.2%

Infection               9.1%

Wear Acetabulum   3.3%

Pain                      2.1%

 

Re-revision Rate

 

Minor (head, liner)   19.4% 5 year

Major Partial            14.1% 5 year

Major Total               8.2%   3 year

THR Complications

DVT Prevention

 

ANZ Working Party on the Management and Prevention of Venous Thromboembolism 2007

 

Note

 

Top 6 conditions associated with DVT

- stroke

- THR

- multi trauma

- TKR

- hip fracture

- spinal cord injury

 

Not one of the 12 doctors was an orthopaedic surgeon

 

Agents

 

Heparin / LMWH / fondaparinux

- confirmed effectiveness

 

Aspirin

- not recommended

- at best weak effect in some people

 

Warfarin

- a role in some high risk surgical patient

- requires monitoring

 

Timing

 

Inconclusive in many areas

 

Recommend 28 - 35 days in

- hip fracture

- THR

 

Epidural Catheter

 

No anticoagulant within 12 hours of inserting / 6 hours of withdrawing epidural catheter

 

Mechanical compression

 

Graduated compression / intermittent pneumatic compression / foot pumps have all been shown to work

 

Recommended to combine with chemoprophylaxis

 

Use unless contra-indicated

- severe peripheral arterial disease or neuropathy

 

Specific Recommendations

 

THR / Hip Fracture

 

Enoxaparin 40 mg / day commencing 6 - 8 hours post op for 28 - 35 days 

 

TKR / Multi-trauma / Prior VTE / Cancer

 

Enoxaparin 40 mg / day commencing 6 - 8 hours post op

Post op for 5 - 10 days

 

Major Surgery (any surgery > 45 minutes)

 

Enoxaparin 20 mg / day commencing 6 - 8 hours post op for 5 - 10 days

 

High risk patients

 

Oestrogen therapy

Pregnancy

Obesity

Strong FHx VTE

 

Contraindications to chemoprophylaxis

 

Active bleeding

High risk bleeding

- hemophilia

- platelets < 50

- history GI bleeding

Severe hepatic disease (INR < 1.3)

Allergic to heparin

High risk of falls

Palliative Management

 

 

 

Dislocation

IncidenceTHR Dislocation

 

2-3% of cases 

- doubles with infrequent operator

- second most common reason for revision after loosening

 

Australian Joint Registry

- dislocation accounts for 14.8% of revisions

 

Positions

 

Posterior dislocation

- hip flexed, adducted, IR

- 80%

- usually getting out of chair

 

Anterior dislocation

- hip extended, adducted, ER

 

THR Anterior Dislocation

 

Timing

 

Early < 6/ 52

- majority of single dislocations

- usually excessive hip position by patient

- before adequate muscle control & soft tissue healing

- after six weeks strong pseudocapsule forms about hip

- adds to stability +++

 

Chance of recurrence 40%

 

Late > 6 weeks

- represents majority of recurrent dislocations

- sually due to increase in ROM & activity

- manifests unrecognised impingement / malposition

 

Chance of recurrence 60%

 

Factors

 

Surgeon factors

- experience

- approach

- component position

- component design

- soft tissue balance

- impingment

 

Patient factors

- soft tissue

- cognitive disorders

- NM disorders

- NOF fracture

- revision

 

Surgeon Factors

 

1.  Surgeon Experience

- < 30 THR per year

- 2 x dislocation rate

 

2.  Approach

 

A.  Increased with posterior approach

- common in early papers

- reduced with short ER repair / use of large heads / component position

- now equivalent rates to anterolateral

 

B.  Transtrochanteric

- increased with trochanteric non union x6

 

3.  Component position

 

Dislocated THR Open Acetabulum

 

A.  Acetabular safe zones

- abduction 40 +/- 10o

- anteversion 15 - 30o

 

B.  Excessive femoral anteversion

- especially when combined with excessive acetabular anteversion

- predisposes to anterior dislocation

 

C.  Ranawat concept of combined anteversion

- acetabular + femoral anterversion

- 25 - 35o for men

- 35 - 45o for women

 

D.  May wish to increase anteversion in posterior approach and reduce it in the anterior approach

 

4.  Component design

 

A.  Increased head size

 

THR Big Head Dislocation

 

Increased size increases head-neck ratio

- reduces impingement / increases arc of motion

 

Increased jump distance

- seated deeper in acetabulum

- decreases jump distance

- greater translation before dislocation

 

B.  Liner profile

- posteriorly elevated profiles

- i.e. neutral liners v 10o elevated rim liners

- theoretically more stable

- reduces dislocation rates early, but not late

- can cause impingement in extension and ER

- this may lead to dislocation and increased wear

- can put hood in variety of positions

- usually postero-superior

 

5.  Soft tissue tension

 

A.  Restore LLD and offset

- reduced offset associated with increased dislocation

- reduces ST tension

- increases risk of impingement

 

B.  Dislocations reduced with careful capsular and soft tissue repair

- reduces dislocation rate in posterior approach

 

6.  Impingement

- when two non articular surfaces come into contact during joint ROM

- decrease by increasing head neck ratio

- may be liner / osteophyte / excessive capsule

- always put hip through ROM

- ensure in full extension and ER, no posterior impingment

- ensure in flexion 90o and IR, no anterior impingment

 

Patient Factors

 

1.  Soft tissue function

- previous hip surgery 

- revision THR

- weak abductors

 

2.  Cognitive disorders

- dementia / delerium

- alcoholism

 

3.  NM disorders

 

4.  Women

 

5.  Post THR for Neck of Femur fracture

- no stabilising capsular hypertrophy / fibrosis seen in OA

 

6.  Revision

- dislocation rates higher in revision setting

 

Prevention

 

Pre-operative education

- avoid dislocation in first 6 weeks

 

Template

- restore offset and leg length

 

Approach

 

Posterior approach

- careful short ER repair

 

Trochanteric osteotomy

- large flat surface

- strong repair

- protected WB /52

 

Component positioning

 

A. Extrapelvic Landmarks

- careful patient positioning

- patient stable

- ASIS perpendicular to floor

- use guides on acetabular insertion jigs

 

B.  Intrapelvic Landmarks

- transverse acetabular ligament

- anterior and posterior acetabular walls if no osteophytes

 

Component design

- liner lip posterosuperior

 

Prevent impingement

- remove wall osteophytes

- restore offset

- anterior capsule can cause impingement

- avoid excess cement

 

Large head neck ratio

 

Trial reduction

- flex to 90o, IR 45o, adduct 20o

- full extension, ER 45o

- ensure stability

- restore offset

- check LLD

 

Post operative

- avoid extremes of position

- abduction pillow

- knee immobiliser in confused patients / limits hip flexion

- post-op education

- no driving, high chairs, low cars 6 weeks

- no crossing legs ever

 

Management

 

Early 

- MUA 

- re-educated

- mobilise as tolerated

 

Late

 

1st episode 

- treat with reduction

 

Recurrence 

- treat with abduction brace 

- 20° flexion / Abudction / ER

- for 6/52

 

Repeated 

- revision

 

X-ray evaluation

 

A.  Component malposition

 

1.  Acetabular Abduction

 

Easy to assess on AP

 

THR Acetabulum Closed < 45 degreesTHR Acetabulum open > 45 degreesTHR Dislocation Abducted Acetabular Component

 

2.  Acetabular Anteversion

 

Much more difficult to assess

- compare ellipse of acetabulum on AP pelvis and AP hip

 

Concept

- AP pelvis the beam is centred over the pelvis

- AP hip the beam is centred over the hip

 

If cup anteverted

- looks flat on AP pelvis

- looks elliptical on AP hip

 

If cup retroverted

- looks elliptical on AP pelvis

- looks flat on AP hip

 

THR AP Pelvis Elliptical CUpTHR AP Hip Straight Cup

 

B.  Other

 

Eccentric liner wear

- draw lines on paper, compare each side

- thickness not equal both sides with wear

 

THR Poly Wear

 

Loosening

 

Insufficient offset

 

Surgical Revision

 

Need to decide cause of problem

- preoperative and intraoperative

- malposition / impingement / soft tissue

- have options available to address each problem

 

Initial

 

1.  Impingement 

- removal of osteophytes or cement

- exchange components to improve head neck ratio

- may need to adjust component malposition

 

2.  Malposition 

- assess stem + cup on CT

 

Options

- change for Augmented polyethylene lining (if uncemented cup)

- revise component positioning

- larger head technology

 

3.  Incorrect tissue tension 

- longer neck / correct offset

 

4.  Worn liner

- exchange liner

 

5. Abductor insufficiency 

- trochanteric advancement

- increase femoral offset (modular head, lateralised liner)

 

Salvage

 

1.  Constrained cups

 

THR Constrained CUp

 

Concept

- an acetabular component that uses a mechanism to restrain the femoral head within the cup

- can be implanted denovo or cemented into well fixed cup

- usually has a metal locking ring

 

Indication

- deficient soft tissues

- paralysed abductors

- GT non union

 

Varieties

A.  Cup and monopolar liner with locking ring

B.  Bipolar constrained liner with locking ring

 

Problems

 

A. A constrained cup may still dislocate

- usually require surgery to relocate / require revision

 

THR Dislocation Constrained Liner 1THR Dislocation Constrained Liner 2

 

B. Inhibit ROM and transmit significant forces, which may contribute to early loosening

 

2.  Failure or Unreliable patients 

 

Options

- bipolar hemiarthroplasty

- girdlestones

 

 

Heterotopic Ossification

DefinitionHO Brooker 4

 

Extraskeletal bone formation in periarticular tissues 

- HA crystals within osteoid matrix

 

Different to calcification 

- osteoid matrix laid down

 

Types

 

1.  Myositis Ossificans

- post traumatic

 

2.  Heterotopic Ossification / associated with TJR

 

3.  Neoplastic Ossification

 

Epidemiology

 

Occurs 50-70% THR's

- significant in 20%

- clinically significant in 1%

 

More common in men x 2

 

Risk factors

 

High 

- previous hip / other hip HO

- incidence is 80%

 

Moderate

- hypertrophic OA

- active Ankylosing Spondylitis

- hyperostosis

- DISH 

- active Paget's 

- fracture (acetabular trauma, pre or intra operative)

 

Low

- THR

- posterior approach < Hardinge < transtrochanteric

 

Pathology

 

Similar cascade to fracture healing

- unknown trigger

- undifferentiated mesenchymal cells differentiate in osteoblasts

- occurs within first few days

- produce osteoid

- mineralised to bone (mature lamellar bone)

 

Two Precursor cells about the Hip / Friedenstein

 

1.  Determined Osteogenic Progenitor Cells

- from bone marrow

- develop into osteoblasts with inflammation

 

2.  Inducible Osteogenic Progenitor Cells

- need BMP to develop into osteoblasts

 

Brooker Classification

 

Only Type IV interferes with function

 

Type I:  Isolated islands of bone

 

Heterotropic Bone Brooker 1

 

Type II:  Bony spurs from pelves and proximal femur, gap > 1 cm

 

Heterotropic Bone Brooker 2

 

Type III:  Gap < 1 cm

 

Heterotropic Bone Brooker 3

 

Type IV:  Apparent ankylosis

 

Heterotropic Bone Brooker 4

 

Clinical Features

 

Usually none

- pain usually as it matures

- decreased ROM

- dislocation 2° impingement (rare due to loss of ROM)

- nerve irritation

- trochanteric bursitis

- hip can appear red, swollen and tender

 

X-ray

 

New bone in peri prosthetic soft tissues

- visible by 3-6/52

- extent determined by 3/12

 

Maturation continues for 12-18/12 

 

Bone Scan

 

Increased uptake = continued activity

- remain increased for 12/12

 

Bloods

 

Rise in serum alkaline phosphatase post surgery

- associated with HO

 

Management

 

1.  Prevention 

 

Identify at patients risk preoperatively

- Ankylosing Spondylitis / Pagets / Previous HO / DISH

 

A.  Surgical Technique

 

Gentle handling of tissues

- avoid muscle stripping

- lavage tissues

- drain wound

 

B.  NSAID

 

Indomethacin 50 mg bd for 1 week

- significant reduction in risk of HO

- 7 days as effective as 14 days

- as effective as postoperative radiation

 

Risk of GIT side-effects ~ 20%

- interaction with anticoagulants

- double risk of significant bleeding with DVT prophylaxis

 

Results

 

Knelles JBJS 1997

- 685 Primary THR

- 50mg bd Indocid for 1 week

- as effective as 1 x 7 Gy Post-op

 

C.  DXRT

 

For very high risk patients

- previous HO / indocid contraindicated because of PUD

- post surgical excision of HO

 

Dosing

- 700 Rad / 7 Gy < day 5

- 800 Rad 6h pre-op prevents HO

 

Side effects

1.  Delay incorporation of bone graft / union of trochanter

2.  May delay porous ingrowth with uncemented components

3.  Can make patient nauseous

4.  Nil evidence wound problems (shielded, low dose)

5.  Risk of malignancy - nil evidence at this low dose

 

D. Biphosphonates

 

Delay calcification and delay Xray appearance of bone 

- doesn't prevent osteoid formation

- calcification occurs once drug stopped

- no longer used

 

2.  Surgical Excision

 

Indications

 

Significant symptoms / reduced ROM & > Brooker III

- revision of prosthesis

 

Timing

 

Usually 12-18 / 12 post-operatively

- mature appearance on XR

- cold Bone Scan

- serum ALP normal

 

Prophylaxis

 

Radiotherapy post oeratively as high risk 

 

Results

 

Usually increased ROM

- unreliable effect on pain

- bone often reforms

 

Case

 

THR HO Brooker 4THR HO Brooker 4 Poster ExcisionTHR Post HO Excision Dislocation

 

 

 

 

 

 

 

 

Infected THR

Risk factors

 

Patient 

 

Advanced age

Immunosuppression - steroids / Rheumatoid / DM

Malnutrition - Lymphocyte count / Transferrin / Albumin

Vascular disease

Obesity

Poor skin i.e. psoriasis

Previous infection in joint

Infection elsewhere - i.e. UTi

Prolonged hospital admission

Revision surgery

 

Operative Factors

 

Preoperative

- preoperative wash

- preoperative shave

- admission day of surgery to clean ward

- groin, nasal, axilla swabs clear

- clear urine (MCS preop)

- no skin breaks

 

Operative Period

- laminar flow

- minimal theatre traffic

- IV Abx on induction

- shields

- alcoholic prep

- prep drapes

- short procedure duration

- care of soft tissues

- ABx cement

- wound closure / drains / hemostasis

 

Postoperative Period

- wound haematoma & drainage

- skin necrosis

- post operative ABx

- management remote infections i.e. UTI

- care with dental procedures

 

Incidence

 

Current rate 0.27 - 2 % 

 

Increased risk with high-risk patients (2%)

- immuno-compromised

- recurrent bacteraemia

- revision > 2%

- RA

 

Microbiology

 

S. epidermis most common with S. aureus second

- together make up two thirds of all infections

 

MRSA increasing in prevalence

Also vancomycin resistant S. aureus

 

Also

- streptococcus

- S. capitus

- pseudomonas

- coliforms

- anaerobes

- mixed 1/4

 

Symptoms

 

Usually worsening hip pain

- often minimal constitutional symptoms

 

X-ray

 

Progressive / rapid lysis / bone loss

May be normal appearing xray

 

Infected THR progressive bone loss and lysis

 

Investigations

 

For full details, please see Investigation of Pain in THR Complications section

 

Ultrasound

 

Fluid collection about hip

 

Bloods

 

CRP > 10 and ESR > 30 very suspicious

 

Bone scan

 

Reveal increased uptake about both components

- blood flow, blood pool and delayed uptake phases

- more than 12/12 post implantation

 

Specificity increased by WC scan

 

Aspiration

 

Under II control

- off antibiotics

- confirm infection

 

THR Aspiration

 

Pathology

 

1.  Prosthesis in bone

- difficult for antibiotics to access

- poor blood supply

- similar to osteomyelitis

 

2.  Glycocalyx 

 

Bacteria have two forms

A.  Planktonic form 

- individual free floating cells

B.  Sessile form 

- exist within biofilm of glycocalyx

- 500x more resistant than planktonic form

 

Glycocalyx is a slime layer of polysaccharides produced by bacteria 

- protective barrier against antimicrobial and host defences

- helps bacteria to exist and survive on synthetic substances

- biofilm requires minimum time to form

- infection can be irradicated by Abx while still in planktonic phase but not once form biofilm

 

3.  Prosthesis Surface Properties

 

CO-Cr more susceptible to infection than titanium

- may be related to faster osseointegration by titanium

 

Polished surfaces less susceptible

- smaller surface area for bacteria to adhere

- shorter distance for host cell to travel

 

Classification Gustilo 1993

 

1.  Early post-operative

- < 1/12

- febrile patient

- red swollen discharging wound

 

2.  Late post-operative

- indolent (low virulent)

- > 1/12

 

Typically

- well patient

- healed wound

- worsening of pain

- never pain-free interval

 

3.  Acute haematogenous

- antecedent bacteraemia

- can occur several years after surgery

 

Typically

- well patient

- previously well functioning hip

- UTi or other source of infection

- hip now very painful

 

4. Positive intra-operative culture

- presumptive diagnosis aseptic loosening

- intra-operative m/c/s comes back positive (2 out of 5)

- treat with 6 weeks Abx -> success rate 90% 

 

Management

 

Goals

 

Eradicate infection

Relieve pain

Restore function

 

Options

 

1.  ABx suppression

2.  Debridement and prosthesis retention

3.  One stage revision

4.  Two stage revision

5.  Three stage revision

6.  Resection arthroplasty

 

1. Antibiotic Suppression

 

Indications

 

1.  Gustillo Type 4 

- 90% success

 

2.  Elderly and frail

 

Require

 

Known sensitive organism

Stable prosthesis

Tolerable oral Abx

 

Treatment

 

Indefinite

- 50% retention of prosthesis at 3 years 

 

2. Debridement with Retention THR

 

Indications

 

Time

- symptoms < 4/52

 

Stability

- well fixed prosthesis

 

Microbe

- known sensitive organism

 

Host

- Cierny A / B / C

 

Treatment

 

No Abx until

- swab and tissue for M/C/S

- or after positive blood culture

 

Operation

 

Excision of all necrotic and infected tissue

- ensure implant well fixed

- exchange liner (if uncemented)

- wash +++

- monofilament nylon sutures

- drain

 

IV Abx 6/52

 

Vanco / genta initially until swabs available

- ID consult

 

Results

 

1.  Early post-op infection in cemented well fixed THR

- success = 75% 

 

2.  Early post- op infection in uncemented 

- worse results

- due to lack of cement obstruction

- required 2 stage revision if no bone ingrowth

 

3.  Acute haematogenous

- only 50% success 

- often immunocompromised

 

4.  Chronic late

- poor results 

- window of opportunity lost

 

3. One-Stage Revision

 

Infected THR Pre One stage revisionInfected THR Post One Stage Revision

 

Concept

 

Controversial

- remove prosthesis, debride and replace at single sitting

- lower success rate than two stage

- usually indicated in older, more frail patient

- meticulous debridement critical

- treat infection like cancer

 

Indications

 

Timing

- late onset

 

Host

- healthy host

 

Microbe

- sensitive organisms (gm+)

 

Stability

- no sinuses / good wound

- adequate bone stock

 

Technique

 

Debridement all necrotic and infected tissue

- removal of implants and all cement

- aided by extended trochanteric osteotomy

- wash +++

- re-drape, new instruments

 

Reimplant cemented polished femur and all poly cup

- must use ABx PMMA

- already has tobramycin in it

- add powder form vancomycin 

- 2-3 gram in each packet of cement

- each vanco vial is 0.5g

- femur and acetabulum

 

Can implant poly liner from uncemented acetabulum only

- more ABx cement can be impregnated

- large head for stability

 

Post operative

- IV Ab's 6/52

 

Antibiotics must be

- thermostable (excludes tetracycline & chloramphenicol)

- powder form (not genta)

- low allergenic potential

- elute from the cement

- effective against the infecting organism

- Palacos better as higher surface porosity

 

Results

 

80% long term survival

 

4. Two-Stage Revision

 

Gold Standard

 

Indications

 

Chronic late

Acute haematogenous

 

Advantages

 

Improved success rate compared with single stage

- success 90% with ABx cement

- 2 opportunities for debridement

 

Disadvantages

 

1.  2 procedures required

- difficult for patient between stages

 

2.  Revision surgery more difficult

- scar formation 

- shortening

- distortion of anatomy

 

3.  Increased cost / Longer time

 

First stage

 

Complete debridement

- removal all implants and cement

- meticulous debridement necrotic an infected soft tissue

- insert spacer

 

A.  Ball of ABx Cement

 

Infected THR Cement Ball

 

Advantage

- leeches ABx

- maintain space for revison hip

 

Disadvantage

- very uncomfortable

- o mobility benefit to patient

- can cause bony erosion

 

B.  Abx cement in mould

 

Infected THR Cement Spacer Fracture

 

Disadvantage

- poor function

- fractures / breaks

- painful

- difficult to mobilise

- can cause further bone loss

 

C.  Company produced cement spacer

 

Prostalac

- metal spine

- can dislocate / cause bone loss / cause femur fracture

 

Infected THR Prostalac SpacerInfected THR Dislocated ProstalacProstalac Femur Fracture

 

D.  All poly liner and cemented stem

 

Infected THR Kiwi Hip Spacer

 

Concept of the "kiwi" hip

- +++ Abx cement

- cheap polished femur loosely cemented in

- uncemented poly liner to increase cement load in acetabulum

 

Advantage

- stable construct

- patient can mobilise

- no rush to revise

 

Disadvantage

- cost

 

E.  Antibiotic Coated Nail

 

Infected THR NailAntibiotic Coated Nail

 

Second Stage

 

Timing

- Abx minimum 6/52

- at least 2 - 4 weeks off ABx

- consider hip aspiration

- normal CRP / ESR

- intra-operative FFS at time of surgery

 

5. Three stage Revision

 

A.  Remove implants - 4-6/52 Abx

B.  Bone graft defects - 3-12/12

C.  Revise components when graft incorporated

 

6. Resection Arthroplasty (Girdlestone)

 

Described in 1928 for TB

 

Infected THR GIrdlestones

 

Indications

- medically unfit for further revision surgery

- refusal for further revision surgery

- sepsis control / virulent bug

- unrevisable due to bone loss

- unlikely to become mobile

 

Advantage

 

Effective control of infection (95%)

 

Disadvantage

 

Poor function

- pain

- limp

- require walking aid

- 5cm average LLD

- increased energy expenditure 250%

 

Leaves pateint with nearly useless pseudoarthrosis

- weight bearing almost impossible

- severe shortening

- consider only as last resort

 

Post operative

- used to recommend 6/52 traction

- makes no difference

 

7. Amputation

 

Technique

- hip disarticulation

 

Indications

 

Life-threatening infection

Severe loss of ST & bone stock

Vascular injury

 

Incidence

 

Performed in 0.1%

 

 

 

Intra-operative Fracture

THR Acetabular Fracture

 

Incidence

 

Increased incidence with press-fit component

- especially if under ream

 

Prevention

 

Don't under-ream >1mm

 

In osteopenic bone 

- line to line reaming

- i.e. ream to outer diameter of cup

 

This also avoids leaving gaps at floor 

- very common if under-ream by 2mm

 

Management Intra-operatively

 

Intra-operative undisplaced fracture + Stable cup

- 2-4 screws through cup

- TWB 2-3 months

 

Intraoperative displaced fracture

- remove cup

- plate posterior column if factured

- screw fixation anterior column

- additional screws in cup

- +/- antiprotrusio ring                    

- TWB 2-3 months

 

THR Fractured AcetabulumTHR Fractured Acetabulum 2THR Fractured Acetabulum 3

 

Diagnosis Post operatively

 

Can be difficult to diagnose & image

- if unexplained groin pain post-op & press-fit cup 

- look for fracture with multiple oblique views etc

- CT

- may see callous formation

 

THR Intraoperative Acetabular Fracture

 

Post-operative early

 

1. Non or minimally displaced

- recognised immediate post-op

- TWB 3 months

 

2. Displaced fracture unstable

- ORIF & revise cup

 

Post-operative late

 

Peterson & Lewallen JBJS Aug 1996

 

Type 1

- cup clinically & radiologically stable

- no treatment

 

Type 2

- cup unstable

- revise as above

 

THR Femoral Fracture

 

THR Femoral Intraoperative FractureUncement Femur Intraoperative Fracture

 

Incidence

 

Increased incidence with press-fit components

- act like splitting wedge

 

Fracture may occur during

 

1. Dislocation

2. Reaming or broaching

3. Impaction of component

4. R/O cement or old components 

 

Prevention

 

During dislocation

 

Beware in elderly, osteoporotic patient and in revision

- adequate exposure

- only 1 person manipulate femur

 

If difficult dislocation

- complete ST release

- removal of acetabular osteophytes

- ankylosed joint or protrusio, division of neck in situ & piecemeal removal of femoral head

 

During femoral preparation

 

Pre-op templating of component size

- use of reamers before broaching to remove endosteal bone

- gentle broaching with pause if failing to advance

- sufficient broaching for easy prosthesis insertion

 

Avoid creation of stress risers i.e. cracks, defects, windows

 

If cracks or defects created

- bypass with implant by 2-3 cortical diameters distally

- minimise cement extravasation as prevents healing of defect

- use cerclage wires to prevent propogation of fracture

 

During component insertion

- gentle impaction with pause if failing to advance

- uncemented components often 1 - 2 mm proud of equivalent sized broach

 

Management

 

Vertical split not beyond LT

- cerclage wire

 

Vertical split beyond LT 

- cerclage wires

- longer stem

 

Perforation of shaft

- bypass defect

- fixate with plate

 

 

 

 

Investigation of Pain

Aetiology

 

Intrinsic

 

Infection

 

Loosening

 

Thigh pain in uncemented

- micro motion at distal end of stem

- modulus mismatch

 

Stress fracture / insufficiency fracture

- pubic rami, sacral

 

Intra-operative fracture

 

Prosthesis failure

 

Subtle instability

 

Extrinsic

 

Muscular tendonitis

- irritation of Psoas

- stretching of Adductors

- vas lateralis herniation

 

Trochanteric bursitis / tear G medius

 

Non-union of Trochanteric Osteotomy

 

THR GT Nonunion

 

HO

 

Lumbar / Knee / Pelvic / Abdominal pathology

 

History

 

Nature of Pain

 

°Pain-free interval  

- indolent infection

- pathology elsewhere (pain same as pre-op)

- poor implant fixation

- impingement

 

Pain-free interval 

- loosening

- infection

- implant failure

 

Mechanical pain 

- loosening

 

Start up pain

- pain with initial movement

- recedes as implant settles

- loosening symptoms

 

Rest pain / night pain 

- infection

- tumour

 

Location

 

Buttock / groin pain 

- cetabular pathology

 

Thigh / knee pain 

- Femoral pathology

 

Pain over GT suggests

- trochanteric bursitis / tear G medius

- Non-union of trochanteric osteotomy

 

Pain in other locations 

- spinal stenosis 

- knee OA 

 

Radiating below knee

- radiculopathy

 

Infection

 

Drainage postoperative suggests +++ infection if > 1/12 post-op

History of bacteraemia suggests infection

Prolonged in hospital ABx treatment

 

Examination

 

Pain with ROM 

- loosening - extremes of motion

- infection - pain throughout motion

- implant failure

 

Tenderness over GT

 

Wound 

- induration, erythema & drainage

 

Spine, knee & vascular  exam

 

Groin for inguinal hernia

 

Xray

 

Problems

 

1. May be normal in face of pathology

- serial comparison very important

 

2. Difficult to differentiate infection v loosening on XR

 

Infection

 

Infected THR Endosteal ScallopingInfected THR Periosteal New Bone

 

1. Radiolucent lines

2. Focal Osteolysis with Endosteal scalloping

3. Periosteal new bone 

- almost pathognomonic

- usually at junction meta / diaphysis on medial side

- only seen in 1-2%

 

Loosening

 

Easier to identify loosening in femur than acetabulum

- femur 90% accuracy

- acetabulum 65% accuracy

 

Lucent lines don't necessarily represent problem

- may be present in well-fixed prosthesis (retrieval studies)

- due to remodelling

 

WCC

 

Little value

- increased in 15%

- raised only if sepsis +++

 

ESR 

 

> 30 mm = 80% sensitivy & specificity for infection

 

Problems

- takes 6 - 12 / 12 to normalise post OT

- very non specific, increased in RA and remote pathology

- can be raised in aseptic loosening

 

CRP 

 

> 10 mg/l = 90% sensitiviy & specificity

- rarely increased with loosening

 

More predicable response post OT

- peak 2/7 (~400)

- normal after 3 /52

 

In the absence of other causes of elevation

 

If CRP is negative can be confident is no infection

- negative predictive value 99%

 

If CRP is positive is still a 20% chance that is no infection

- positive predictive value 75%

 

IF both ESR > 30 and CRP >10, 84% probability of sepsis

 

Te99 Scan

 

Bone scan may show increased uptake from

- infection

- loosening

- HO

- Paget's

- stress fracture

- large uncemented stem (modulus mismatch)

- tumors

- RSD

 

Advantage

- pathology unlikely if negative

 

Disadvantage

- very sensitive

- poor specificty

- doesn't differentiate cause

 

Lieberman et al JBJS Br  1993

- no benefit of NMBS over x-ray in diagnosis of infection or loosening

 

Residual activity 

 

Cemented 

- majority return to normal by 1 year

- 20% remain hot at portions of stem / GT / LT past 1 year

 

Uncemented 

- can remain hot for 2 years 

- can remain hot at distal stem for many years

 

Infected prosthesis

 

All phases increased & usually diffuse in 3 phases

- highly suggestive of infection

- can get focal uptake similar to loosening but rarer

 

Loose prosthesis

- localised increased uptake on delayed phase only

- motion of prosthesis causes increased bone turnover due to bone resorption 

- increased uptake @ GT & LT alone may be normal post op change

- well advanced loosening can show diffuse uptake as for an infected hip

 

THR Bone Scan NormalTHR Hot Cup Quiscent Femur

 

Stress sites 

- will see localised area of uptake on scan

- corresponds with cortical thickening on plain XRs

 

Insufficiency fracture

- occur in osteopaenic patients

- pubic rami fractures may cause groin pain

- sacral fractures may cause posterior hip pain

 

Indium 111 Labelled WC Scan 

 

Uncertain role 

- expensive, difficult 

- have to harvest WC

 

More specific for infection

- especially when combine with bone scan

- sensitivity 92%

- range specificity 75 - 100%

 

Aspiration

 

THR Aspiration

 

Technique

- no Abx >4 weeks

- II control & with contrast / confirm in joint

- no LA (bacteriostatic)

- aspirate hip joint x 3 specimens

- if only 1 specimen positive then repeat

 

If dry, inject normal saline & aspirate 

- controversial

 

> 65% PMN infection likely

> 1600 white cells microlitre

 

Results

 

Harris & Barrack JBJS 1996

- 2% positive rate if aspirate all hips

- therefore be selective

 

Lachiewicz et al JBJS Am 1996

- hip pain and elevate ESR

- 92% sensitivity & 97% specificity

 

HCLA

 

Crawford et al JBJS 1998

- 95-100% sensitivity

- ff good results from LA expect same from THR

- demonstrates that the pain is from the hip

 

Intra-Operative Frozen Section

 

PMN Cell Count 

- 40x power, count white cells in that field

- average over 10 fields

 

Mirra 1976 > 5phpf

- 84% sens, 96% spec

 

Lonner 1996 > 10phpf

- 84% sens, 99% spec

 

Intra Operative gram stain & m/c/s

 

Gold Standard

- 10% false positive

- Gram stain sensitivity < 20%, but very specific

 

All revisions no antibiotics for 4 weeks prior

 

Surgical Opinion

 

Sensitivity 70%

Specificity 85%

 

Management

 

Algorithm

 

Xray N / Scan N / ESR & CRP N

- not infected

- explore extrinsic causes

 

Xray Loose / ESR & CRP raised 

- infected

- 2 stage revision with intra-operative M/C/S

 

Xray normal / Hot scan / Raised ESR & CRP 

- infected

- 2 stage revision

- intra operative FFS to confirm

 

Xray / Scan / ESR / CRP all equivocal 

 

Aspirate

 

 

Leg Length Discrepancy

Issue

 

Most common reason for litigation against orthopaedic surgeons in THR

Usually from lengthening

 

Complications of LLD

 

1.  Nerve palsy

 

Sciatic nerve - tolerate average 4.4cm lengthening

 

Common peroneal nerve - tolerate average 2.7 cm lengthening

 

Lengthen by up to 15-20% of the resting nerve length

- but in reality is unknown and multifactorial

 

2.  Lower back pain / scoliosis

 

THR LLDTHR LLD with secondary scoliosis

 

3.  Abnormal gait

 

2 - 4 cm discrepancy

- significant increase in oxygen consumption

- also risk of falls

 

Assessment of LLD

 

Preoperative

 

Examination

 

Functional LLD

- blocks

 

Apparent LLD

- umbilicus to medial malleolus

 

True LLD

- ASIS to medial malleolus

 

Apparent shortening

- FFD & adduction hip

 

Apparent lengthening

- abduction contracture 

- scoliosis, fixed pelvic tilt

 

Consent

 

Very important

- must mention LLD

 

X-ray Assessment

 

AP pelvis 

- both femurs IR 15o

- compensate for anteversion

 

Templating

 

THR Template LLDTHR Leg Length Ischial LineCentre of Rotation Ranawat Method

 

1.  Establish Centre of rotation

 

Acetabular Templating

A.  Ilioischial line / Inter-tear drop line / Superior edge acetabulum

B.  Ranawat

- intersection of ilioishial and shenton's

- 5 mm laterally

- 1/5 pelvis up and 1/5 pelvis in

C.  Rule of thumb

- 2 cm horizontal and 4 cm vertical from teardrop

 

2.  Calculate LLD

- draw line LT / ischial tuberosity / inferior teardrop

- up to centre of femoral head / centre of rotation

- beware adducted hip on x-ray / false shortening

 

LLD with hip adduction

 

3.  Femoral Templating

 

A.  Size implant

B.  Determine offset

C.  Determine femoral osteotomy from lesser trochanter to restore LLD

 

Intra-operative

 

1.  Leg to leg comparison

 

Careful patient positioning

- ASIS perpendicular to floor and patient stable

- ability to palpate both knees and feet

- small pillow to prevent adduction of superior leg

- feel LLD before surgery in this position

- upper femur often feels 1 cm short even if no LLD due to adduction

- aim to reduce LLD to normal after reduction of THR at end of case

 

2.  Intra-operative measurement

 

System

- proximal pin in superoacetabular region

- distally diathermy mark in vas lateralis

- calliper measures horizontal distance (LLD) and vertical distance (offset)

- must place leg in similar position each time to measure leg distance

 

3.  Tests

 

Shuck test

- distract femoral head from acetabulum

- should be only few mm of shuck with correct tension

 

Drop Kick Test

- with thigh extended, knee should remain flexed

- if tension too tight, knee will extend

 

ROM

- if hip tension too tight, ROM especially IR / ER / extension is limited

 

Postoperative

 

Transient Perception of LLD

- 14% patients

- usually passes

- may have had LLD before which has been adjusted

- will then feel that leg is longer / which is true

 

Overlengthening

- may get back pain

 

Shortening

- abductor weakness

- even dislocation

 

Management

 

Delay using shoe lift for 6/12

- allows perceived LLD to resolve

 

Rarely revision surgery is required

- persistent neurological pain

- beware instability

 

 

 

 

Nerve Injury

Epidemiology

 

Primary THR 1%

Revision THR 3%

DDH  5%

 

Sciatic nerve 90% of nerve palsy

 

Other

- femoral nerve

- CPN

- ulna / radial nerve from positioning

 

Aetiology

 

Direct 

 

Laceration

- exposure / sciatic and superior gluteal nerve

- drill reamer / obturator nerve

- spike of cement / obturator nerve

 

Thermal

- diathermy

- cement / obturator nerve

 

Indirect

 

Compression

- cerclage wires

- anterior acetabular retractors / femoral nerve

- posterior femoral retractors / sciatic nerve

 

Haematoma

- post op sciatic nerve palsy

 

Strap / Pillow (COPN)

 

Traction

- LLD > 4cm

- dislocation

 

Prognosis Nerve injury

 

Femoral > COPN  > Sciatic

- most have some residual loss

- 80% incomplete recovery over 18 month period

- none after this

 

Good prognostic signs

- retention of motor function

- recovery of motor function initial few days

 

Document neurological status prior to indexed procedure

 

Poor prognostic signs

- nil recovery by 7 months

- causalgia

- elderly

- poor medical condition

- DM, alcoholism

- spinal stenosis (double crush)

- smoking, steroids

 

Superior Gluteal Nerve

 

Anatomy

- L4/5 S1

- sciatic notch above piriformis

- runs between G. medius and minimus

- supplies G. medius and minimus & TFL

 

Injury

- anterior / SP approach injure branches to TFL

- lateral / Hardinge approach respect safe zone in G. medius 3-5 cm proximal to GT

 

Obturator Nerve

 

Anatomy

- L2-4 posterior division

- along sacral alar

- emerge obturator foramen

- sensation to medial thigh

- adductor muscles

 

Injury

- screws / cement / reamers / retractors

- antero-inferior quadrant of acetabulum

 

Sciatic Nerve

 

Epidemiology

- most frequently injured nerve

- 1.5%

 

Anatomy

 

L4/5 S1-3

- emerges at G. sciatic notch

- usually tibial and peroneal components combined

- below piriformis

- below gluteals and above short ER

 

Variations

- can be in tibial and CPN divisions

- one or both divisions can run through piriformis

- both emerge above pirifomis

- always treat pirifomis with care in posterior approach

 

Runs over long head of biceps femoris under gluteal insertion

- passes between LHB and adductor magnus

- SHB only thigh muscles supplied by CPN component

 

Motor

- CPN: DF and evertors

- Tibial: PF and invertors

 

Sensory

- Sural: medial sural from tibial / lateral sural from CPN

- Superficial and Deep Peroneal nerve

- Tibial nerve

 

Aetiology

 

Traction 

- > 4cm lengthening in DDH 30% nerve palsy

- 0% if less than 4 cm

 

Compression

- posterior retractors / posterior acetabular wall

- post operative haematoma (CT scan)

- wires or cables (around femur)

- sutures (in closure at end of case)

 

Direct laceration

- revision surgery

- posterior approach

- DDH, Protrusio (nerve in abnormal position)

 

Ischaemia

 

CPN division

 

More vulnerable than Tibial branch

- fixed at fibular head

- more superficial than sciatic nerve

- less surrounding connective tissue

 

Examination

 

Sciatic nerve / CPN only / Tibial nerve only (very rare)

 

NCS

 

Determine if CPN at level of hip or knee

- function of short head of biceps

 

Management

 

Explore if cause is haematoma

- delayed onset or late progression of palsy in setting of haematoma 

- CT may be useful to diagnose

 

Explore if believe major direct injury

- transection or entrapment in cerclage wires

- sutured

 

Otherwise few indications to explore

 

Femoral Nerve

 

Anatomy

 

L2-4

- enters femoral triangle between psoas and iliacus

- power to quadriceps

- sensation to medial thigh and calf

 

Aetiology

 

Compression

- anterior retractors above psoas in anterior approaches to the hip

- iliacus hematoma / bleeding tendencies

 

Femoral nerve blocks

 

Injury

- cement extrusion / screws AS quadrant

 

Clinically

 

Anteromedial numbness

Difficulty climbing stairs

 

Prognosis

 

Very rare 0.4%

- usually recovers in full

 

 

 

 

 

Periprosthetic Fracture

TypesTHR Periprosthetic Fracture

 

Peri-operative

- incurred during operation

 

Post operative

- related to osteolysis / trauma / infection

 

Follow up

 

1994 National Institutes of Health Consensus on THR

 

Regular radiographic follow-up to avoid massive osteolysis & fracture

 

Incidence

 

Primary

 

0.6% cemented

0.4% uncemented

 

Revision

 

2.5% cemented revision

1.5% uncemented revision

 

Aetiology

 

1. Bone damage at insertion

- eccentric reaming

- perforation

- fracture

 

2. Osteolysis

 

3. Trauma

 

4. Infection

 

5. Osteoporosis

 

Vancouver Classification

 

Type A (4%)

 

Avulsion GT or LT

 

A1 Stem well fixed

A2 Stem loose

 

Type B (87%)

 

Fracture near stem tip or around stem

 

B1 Stem well fixed (20%)

B2 Stem loose (44%)

B3 Stem loose with marked osteolysis (36%)

 

Type C (10%)

 

Fracture distal to tip

 

Management

 

Most important is whether prosthesis is stable

- if loose requires revision

 

Type A

 

Avulsion GT or LT

 

Management

 

GT

- undisplaced - no treatment required

- ORIF GT if displaced > 2.5 cm / disruption to abductors

 

THR Periprosthetic Type A THR Periprosthetic Fracture A PlatingVancouver A Displaced GTVancouver A GT Wire Fixation

 

LT

- cerclage LT if large and supportive

 

Type B1 

 

Fracture around stem, likely well fixed

 

THR Periprosthetic Fracture B1THR Periprosthetic Fracture B1 Lateral

 

Options

 

1.  ORIF with cable plate + proximal unicortical locking screws +/- Cortical strut graft

 

Cable plate alone

- 90% union

 

Locking Cable plate + single strut graft

- 98% union

- distal bicortical screws

- proximal unicortical screws supplemented with cables

 

Cortical Strut Graft

 

2.  Long stem revision

 

Cemented

 

THR Periprosthetic Revision Long Cemented FemurTHR Periprosthetic Revision Cemented Femur 2

 

Uncemented

 

THR Periprosthetic Fracture Type B1THR Fracture Long Stem Revision

 

Type B2

 

Fracture around stem, femoral component loose

 

THR Periprosthetic Fracture B2Periprosthetic Fracture Vancouver B2

 

Options

 

Long stem revision

- distal fit (cemented / uncemented)

- must bypass distal extent of fracture by at least 2 cortical diameters

 

THR Periprosthetic Fracture B1 Long stem cemented revision

 

May in addition use

- cable plate + unicortical locking screws

- 1 x strut allograft

- autogenous BG + BMP to fracture site

 

Revision THR Periprosthetic Fracture Uncemented Stem Strut GraftRevision THR Periprosthetic Fracture Uncemented Stem Strut Graft 2Revision THR Periprosthetic Fracture Uncemented Stem Strut Graft 3Revision THR Periprosthetic Fracture Uncemented Stem Strut Graft 4

 

Vancouver B2 PFFRevision PFF with Modular Uncemented and Strut Allograft

 

Type B3

 

Fracture around stem with marked osteolysis

 

THR Vancouver B3 APTHR Vancouver B3 Lateral

 

Options

 

Young patient

- segmental allograft / prosthesis composite

 

Elderly

- tumour type proximal femoral replacement

 

Type C 

 

Fracture distal to tip of stem

 

Options

 

1.  ORIF Cable Plate

- can use MIPO

- overlap femoral stem to avoid stress riser

 

THR Periprosthetic Type C Plating

 

2.  ORIF Cable Plate + cortical strut graft

 

2.  Strut allograft alone

- use 2 x 1/2 femurs fresh frozen

- span fracture 10cm above & below

- 4 wires above & below

- preserve blood supply to linea aspera

- autogenous graft to fracture site

 

THR Consent

 

THR Complications

 

Early

 

Infection (1% risk deep infection)

Wound Haematoma

Bleeding / Transfusion

Dislocation (2 - 3% recurrent)

NVI

Fracture

DVT/PE (Fatal PE 1/1000 with chemoprophylaxis)

LLD (average 1cm, stability more important)

Medical complications

- pneumonia, UTI, CVA. IHD

Death

 

Late

 

Limp (LLD, 1 year with anterolateral approach)

Loosening / Revision (95% 10 year survival)

HO (1% Problematic)

Thigh pain (uncemented stems)

Continued pain

Thigh Pain Uncemented Femur

Epidemiology

 

Ranges

- up to 4%

 

Clinical

 

Focal pain

- typically anterolateral thigh

- often tender

- corresponds to tip of stem

 

Aetiology

 

1.  Instability

 

Types

- early

- late / failed bony ingrowth

 

Cause

- micromotion at distal stem

- disadvantage of proximal coating

 

2.  Mismatch modulus of elasticity

 

A.  Component material

- mismatch between femoral component and surrounding bone

- lower with titanium stems compared with cobalt chrome stems

- titanium components less stiff & tend to have lower incidence of thigh pain

 

B.  Stem size

- more commonly seen in larger stems

- increases relative stiffness of stem compared to bone

 

3.  Stem design

- distal flutes can decrease distal stiffness

- fully porous coating decreases incidence, but increases proximal stress shielding

 

4.  Osteoporotic bone

- more commonly seen with lower bone quality

 

DDx

 

Loosening

- start up pain

 

Infection

 

Xray

 

Loosening

- migration

- progressive radiolucent lines

- abscence of spot welds

 

Bone Scan

 

No correlation of findings with thigh pain

 

Management

 

Non operative

 

Up to 2 years

- allows for remodelling

 

NSAIDS

Physio

 

Operative

 

1.  Cerclage wire cortical strut grafts

 

Theory

- improve bony rigidity over distal stem

 

Technique

- application to lateral femur

- overlap tip proximally and distally 8 cm

- must get host bone integration

- periosteal elevation / bone graft / rigid fixation

- TWB 6 weeks post op

 

Results

- good results reported

 

2.  Revision

 

 

 

 

 

Vascular Injury

Vessels at risk

 

Extra-pelvic blood vessels

 

Femoral Artery

MCFA

LCFA

Profunda Femoris

Obturator artery

 

Intrapelvic vessels

 

External iliac artery and vein

Obturator artery

Superior and inferior gluteal

 

External Iliac Vessels

 

Anatomy

- anterior division of common iliacs / L5-S1

- runs down medial border of Psoas

- some psoas between EIA & intrapelvic surface of anterior column

- EIV accompanies EIA

 

Injury

 

Screws 

Cement

 

Screws

 

Screws may penetrate VAN

- can be delayed diagnosis

- significant intrapelvic bleeding may occur before diagnosis

- AS quadrant: minimal protective ST interposition and often poor bone stock

- vein more at risk than artery

 

CementIntrapelvic cement THR

 

Aetiology

- heat

- kinking or occlusion from bolus

- erosion from spicule

- avulsion secondary to removal

 

Avoid cement intrusion into pelvis with wire mesh 

 

Removal of intrapelvic cement

- required in revision for infection

- define NV relationships

- angiography / MRA preoperatively

- may require separate intrapelvic exposure

- alert general surgeons / vascular surgeons

 

Femoral blood vessels

 

Most commonly injured

 

Anatomy

- common femoral artery is continuation of EIA as passes under inguinal ligament

- passes anterior to hip capsule

- separated from it by psoas

 

Injury

 

Anterior retractors / dissection

Anterior quadrant screws and drills

 

Obturator AV

 

Anatomy

 

VAN traverse lateral wall together

- separated from quadrilateral plate by obturator internus

- lie at superolat aspect of obturator foramen

- exit pelvis via obturator canal

 

Injury

 

Screws in AI quad

Retractor under transverse acetabular ligament

 

Management

 

Bleeding at inferior transverse ligament

- can be very difficult to ligate

- pack with swab

- hold swab with inferior retractor

- finish acetabulum

- will usually be controlled

 

Other option is to embolise if still bleeding

 

Superor Gluteal BV

 

Anatomy

 

Branch Posterior Division IIA

- close to posterior column

- exits greater sciatic notch above piriformis

 

Injury

 

Screw near sciatic notch

 

Inferior Gluteal & Internal Pudendal AV

 

Anatomy

 

Branch anterior division IIA

- exit pelvis between piriformis & coccygeus

- close to posterior column near ischial spine

- internal pudendal artery re-enters pelvis through lesser notch

- IGA pass under piriformis

 

Injury

 

Very long screws through posterior column

 

Management on table torrential bleeding

 

Pack wound, tell anaesthetist & vascular surgeon & obtain proximal & distal control

 

Notify anaethetist

 

IV fluids

Coags,  FBC, platelets,  cross match

Transfuse blood

Organise cell saver

 

Control bleeding

 

Pack & wait

- uncontrollable, get proximal control

 

Call Vascular surgeon

 

Ilioinguinal approach

- clamp IIA, vessiloop IIV

 

Retro-peritoneal approach

- Rutherford-Morrison incision

- retroperitoneal approach

 

Post-operatively

- angiography

- transcatheter embolisation

 

 

THR Difficult

Arthrodesis Conversion

Indications

 

Severe LBP 

- most common indication

 

Ipsilateral knee pain

- less beneficial

 

Malposition

- especially abduction

 

Contraindications

 

Absent abductor mechanism

Flail

Active infection

Insufficient bone stock

 

Examination

 

LLD

 

Assessment abductor function

 

1.  Palpation whilst asking patient to contract

2.  MRI

 

Issues

 

1.  Difficulty prepping & draping

 

2.  Exposure

- identify sciatic nerve

- perform GT osteotomy

- may require adductor & psoas tenotomy

 

3.  LLD

- maximum 4cm lengthening 

- use ASIS pin as LLD guide

 

Xrays

 

Hip Fusion 1Hip Fusion THR 1

 

Hip Fusion 2Hip Fusion THR 2

 

Hip Fusion 4Hip Fusion THR 4

 

Hip Fusion 5HIp Fusion THR 5

 

Results

 

Joshi et al JBJS Am 2002

- 208 hips converted at average 51 years

- average follow up 9 years

- 83% good to excellent function

- 96% 10 year survival

- 15 nerve palsies

 

Complications

 

Loosening

Infection

Sciatic nerve palsy

HO

Residual LLD

Poor abductor function

 

 

DDH

ConceptTHR Dysplasia Subtrochanteric Osteotomy + Mesh Impaction Bone Graft

 

THR in dysplastic hips has a higher failure rate

- due to anatomic abnormalities

- due to generally younger age

 

Aim

 

Restore normal biomechanics and preserve bone stock

 

Issues

 

Soft tissues

 

Sciatic nerve in abnormal position / danger

Hamstring  / adductors / RF tight

Horizontal abductors - function less efficiently

Thick hourglass capsule

Thickened psoas tendon

 

Acetabulum

 

Low subluxation

- shallow with wide opening

- small

- deficient anterior / lateral / superior

- better bone stock posteriorly

 

DDH Anterior Acetabular Insufficiency

 

High dislocation

- small pelvis

- thin & soft acetabular wall

- gross anteversion

 

Femur 

 

Increased anteversion

- valgus neck shaft angle

 

Narrow tapered femoral canal

- tight isthmus

- AP diameter > ML

 

Posterior displacement of the greater tuberosity

 

LLD

 

Can be very short

- maximum sciatic nerve can be lengthened is 4 cm

 

Crowe Classification

 

Based on extent of proximal migration of femoral head compared to the height of the undeformed femoral head

- femoral head is 20% height of pelvis

- measure the vertical distance between the inter-teardrop distance and the head neck junction

- this distance as a ratio of the femoral head

 

Crowe I:  Proximal displacement < 50% femoral head (10% pelvis)

 

DDH Crowe 1

 

Crowe II:  Proximal displacement femoral head 50-75%                            

 

DDH Crowe 2Crowe 2 DDHCrowe 2 DDH Lateral

 

Crowe III: Proximal displacement femoral head 75 - 100%

 

DDH Crowe 3DDH Crowe 3DDH Crowe 3 Lateral

 

Crowe IV:  Proximal displacement femoral head >100% (20% pelvis)

 

Efekhar Classification

 

A Elongated dysplastic acetabulum

B Intermediate acetabulum

C High false acetabulum

D High but no false acetabulum

 

Examination

 

Pelvic tilt

Lumbosacral flexibility

Fixed hip deformities

Real and apparent LLD

Previous scars

 

Operative Management

 

Aim

 

Restore hip centre

Acetabular bony coverage

Restore LLD

 

Technical Factors

 

Soft tissue release

- capsule / psoas / adductors / abductors

- abductor slide or release from ilium

- protect sciatic nerve

 

Acetabulum

- need small components

- restore centre of rotation / bring down to true floor

- may need to augment superolateral acetabulum

 

Femur

- small components

- correct femoral anteversion

- restore offset as best able

- may require trochanteric slide

 

LLD

- > 4 cm need femoral osteotomy

 

Acetabular component

 

Options

 

1.  Restore normal hip centre

2.  High hip centre

3.  Medialise cup 

 

Restore normal hip centre

 

A.  Recreate centre of rotation

 

Place in true acetabulum

- transverse ligament is anatomical landmark

 

Template hip centre

- inter-tear drop line is inferior margin

- ilio-ischial line is medial margin

- superior edge acetabulum lateral margin

 

B.  Need for augmentation

 

Superior defect must be < 30%

 

Options

- bulk femoral head autograft

- mesh + impaction bone graft

- reinforcement rings / cages

- augmented cups

 

Acetabulum Reconstruction

 

Bulk Femoral Head Autograft 

 

DDH Bulk Femoral Head Autograft

 

Advantage

- restore hip centre

- improve bone stock for revisions

 

Technique

- fashion femoral head into 7 graft

- screw into place with 2 x 6.5 mm cancellous screws

- ream into inferior aspect of graft

 

Spangehl et al JBJS Am 2001

- 44 hips followed up for 7.5 years

- femoral autograft with uncemented cup

- 4 revisions / 10%

- acceptable early results

 

Harris JBJS 1997

- 55 autogenous bulk autograft + cemented acetabulum

- average follow up 16.5 years

- average age of patient at time of surgery 42 years

- average size of acetabulum 40mm

- average coverage of cup by graft 49%

- 29% (16/55) revised and further 31% (17/55) radiographically loose

- those grafts 30% or less of cup coverage were well fixed at 16 years

- the greater the coverage of bone graft initially, the greater the rate of late revision

- most hips did well for initial 5 - 10 years

 

Mesh + Impaction Bone Grafting

 

DDH THR Rim Mesh Allograft

 

Reinforcement ring / cage + bone graft

 

Technique

- morcellised bone graft

- support with acetabular reinforcement ring

- usually screwed into ilium and ischium

- cement acetabular component into ring

 

Muller JBJS 1998

- 87 hips, majority Crowe 3

- Muller acetabular roof reinforcement ring

- autograft and cemented polyethylene cup

- 10% revision at 9.4 years

 

Ganz J Arthroplasty 2005

- 33 cases at 10.8 years

- 3 revisions (9%)

- 2 of the revisions had structural allograft

 

DDH augmented cups

 

High Hip Centre

 

DDH THR High Hip Centre

 

Advantage

- allows coverage by native bone

- decreases need for femoral shortening

 

Disadvantages

- very small acetabular component

- very thin poly

- abnormal hip biomechanics

- risk of bony impingement 

- may lateralise hip centre

 

Results

 

Kaneuji et al J Arthroplasty 2009

- 30 hips followed up for 15 years

- mild superior hip centre compared to contralateral normal hip (13 mm average)

- 1/30 revised

 

Socket medialisation / acetabuloplasty / medial protrusio technique

 

Technique

- controlled medialisation with deliberated over-reaming

- can deliberately fracture medial wall

 

Advantage

- improves lateral coverage

- decreases JRF through medialisation

 

Disadvantage

- loss of medial bone stock compromising future revision

- risk of early catastrophic component migration medially into pelvis

 

Results

 

Femur

 

Issues

 

Small and narrow

Excess anteversion

 

Management

 

Small components

 

Uncemented

 

Need to be modular

 

A.  Abnormal shape of proximal femur

- difficult to obtain press fit / risk fracture

- diaphyseal press fit

- small modular metaphyseal component

 

B.  Need modularity to adjust anteversion

- SROM prosthesis

- dial in version

 

Cemented DDH prothesis

 

Design

- smaller with minimal metaphyseal flare

- this allows stem to be orientated independently of patients anteversion

 

LLD / Abductor Tension

 

Issues

 

Only lengthen sciatic nerve 4cm

Abductors very tight and prevent lengthening

Difficulty reducing hip

 

Difficulty reducing hip

 

1.  Psoas release

2.  Subtrochanteric osteotomy

3.  GT osteotomy

 

Tight abductors

 

Trochanteric slide allows

- acetabular exposure

- retensioning abductors

- reposition abductor insertion to correct anteversion

 

LLD

 

Subtrochanteric osteotomy

 

THR DDH Subtrochanteric Osteotomy

 

Advantage

- acetabular exposure (lift up)

- correction anteversion

- shortening femur 

 

Technique

- mark rotation with 2 x small drill holes

- make osteotomy

- transverse osteotomy allows rotational adjustment

- step cut more difficult but gives rotational stability

- insert trial femur proximally

- reduce hip joint

- calculate resection based on overlap of proximal and distal femoral segments

- uncemented or cemented stem

- use bone resected as onlay

 

Management Algorithm

 

Acetabulum

 

Crowe I

 

Mildly dysplastic

- minimal deformity, good bone stock

- small standard cup medialised for coverage

- < 30% uncovering allowed

- small femoral stem

 

Crowe II / III

 

Usually very deficient laterally

- due to femoral head eroding acetabulum

- restore hip centre by reaming medially

- then need to provide superolateral coverage

- autograft + mesh / allograft / DDH cup / tantalum

 

Crowe IV

 

Usually good bone stock in true acetabulum

- femoral head has not eroded bone

- recreate acetabulum and place small component

- use teardrop and fovea as landmarks

 

Femur

 

Crowe I/II

 

Minimal LLD

- sess femoral shortening required

- avoid excessive anteversion based on abnormal femoral neck

- otherwise get anterior instability and loss ER

 

Crowe III/IV

 

If greater than 4cm LLD

- need to shorten femur

Neuromuscular

Categories

 

Decreased tone

- Polio

- Down's syndrome

- spina bifida

 

Increased tone

- cerbral palsy

- Parkinson's

- CVA

 

Polio

 

Rare

- case reports only

 

Down's Syndrome

 

Acetabular dysplasia not uncommon in this group

 

Results

 

Kloschos et al JBJS Br 2002

- 6 patients

- 7 year follow up

- all doing well

 

Cerebral Palsy

 

Options 

- THR

- resection arthroplasty

- pelvic support osteotomy

- arthrodesis

 

THR offers best pain relief and function

 

Problems

 

Young patient

- abnormal muscle strength

- spasticity and contractures

- co-operation issues

- functional demand is low

 

Results

 

Schroeder et al Int Orthop 2010

- 18 THR in ambulatory patients

- 10 year follow up

- 1 recurrent dislocation

- 3 aseptic loosenings

 

Parkinson's disease

 

Issues

- poor neurological status

- progressive worsening with dementia

- high risk dislocation

 

Results

 

Weber Int Orthop 2002

- no dislocations in 58 primary THR for Parkinson's

 

Osteogenesis Imperfecta

 

OI THR

 

 

 

Perthes

Issues

 

Femur

 

Multiplanar deformity

- worsend by previous surgery

- may require osteotomy

 

Acetabulum

 

Dysplasia often present

- not as severe as in DDH

 

LLD

 

Can be significant

 

Abductors

 

Have been short for long time

- difficult to restore length

- may require trochanteric slide

 

Perthes OA previous osteotomyPerthes THR

 

 

Bilateral Severe Perthes Hip OABilateral Perthes THR

 

Protusio

Definition

 

Migration of the femoral head past the medial wall of the acetabulum / ilioischial line 

 

Centre edge angle > 40o

 

Aetiology

 

Primary 

 

Otto's Disease

- bilateral in one third

- middle aged females

- pain & decreased ROM early 

- coxa vara & OA common

- ? causally related to osteomalacia

 

Bilateral Hip Protrusio

 

Secondary

 

PROFSHAMN

- Paget's

- RA

- osteomalacia / OI

- fracture / central dislocation

- septic arthritis especially TB

- hemiarthroplasty

- Ankylosing Spondylitis 

- Marfan's syndrome, malignancy

- Neurofibromatosis

 

Charnley classification 1978

 

Defined medial wall of acetabulum as ilioischial line

 

Grade I  1-5mm                                Grade II  6-15 mm                            Grade III   >15 mm

 

Hip Protrusio Grade 1                                                               Hip Protrusio Grade 3

 

Eldstein & Murphy 1983

 

Medial wall is acetabular line & ilio-ischial line

- men acetabular line 2mm lateral to ilioischial line

- women 1mm medial to ilio-ischial line is normal

 

Grade Men Women  
I 3 - 8 mm 6 - 11 mm  
II 8 - 13 mm 12 - 17 mm  
III > 13 mm > 17 mm with fragmentation  

NHx 

 

Inexorable progression of deformity

- axis of migration is same direction as joint reaction force in stance phase 

 

Management

 

Medical Workup

 

Identify and treat any underlying cause

- FBC, ESR, RF, ANA, ELFT, Ca

 

Options

 

A.  Skeletally immature 

 

Triradiate fusion

- can combine with valgising osteotomy

 

Steel et al JPO 1996 

- 22 patients with Marfan's syndrome

- 12 of 19 restored to normal

- 4 improved

- 3 unchanged

 

B.  Young adult 

 

Valgising intertrochanteric femoral osteotomy (VITO)

- patient < 40, minimal OA 

- may delay THR for 10 years

 

Aim for 20-30° valgus correction

- if neck shaft angle is 130° aim for 155°

- trapezoid shortening to minimise LLD

 

Lateralization of femur to restore mechanical alignment

 

Require soft tissue release especially psoas

 

C.  Middle aged / elderly

 

THR

 

THR Protrusio

 

Principle

 

Place hip center anatomically 

 

Restore joint biomechanics

- outcome depends on cup position

- adequacy of correction of the deformity & biomechanics correlates with long-term prosthetic survival

- medial joint positioning leads to high medial stresses

 

Results

 

Ranawat JBJS Am 1980 

- 35 hips with protrusio secondary to RA

- 16 of 17 THR >10 mm from hip centre loosened

- 13 THR with <5 mm out good survival

 

Determine Hip Centre 

 

1.  Teardrop

- average 2 cm vertical & 4 cm horizontal from teardrop

- average coordinates reported in normal adults 14 mm vertical & 37 mm horizontal

 

Hip Protrusio Teardrop Method Centre Rotation

 

2.  Ranawat Method 

 

Hip Protrusio Ranawat Method Centre Rotation

 

Draw parallel horizontal lines at the levels of the iliac crests and ischial tuberosity and mark 3 points

- Point 1: 5mm lateral to intersection of Shenton's and Kohler's lines

- Point 2: located superior to point 1 by a distance 1/5 of the pelvic height

- Point 3: similar distance horizontally from vertical line

 

Isosceles triangle between 1/2/3 locates the acetabulum 

- line 2/3 through subchondral bone

 

Management Bone Defects

 

1.  Assess medial wall integrity with CT

 

Hip Protrusio CT Medial Wall IntactHip Protrusio CT Medial Wall Intact 2

 

2.  Algorithm / Ranawat J Arthroplasty 1986

 

A.  < 5mm - no graft required

 

Hip Protrusio Grade 1THR Protrusio Type 1

 

B.  > 5mm but medial wall intact - morcellised bone graft

 

Hip Protrusio Type 3THR Protrusio Medial Morcellised Bone Graft

 

C.  No medial wall - mesh / cage + morcellised bone graft

 

Technique

 

Preoperative

- template LLD (max 4cm)

- define acetabular defect with CT

- ensure intact medially

 

Approach

 

1.  Sciatic nerve is nearer the joint than normal

- identify and protect early

 

2.  Dislocation of the hip can be difficult

- femoral osteotomy in situ + femoral head removal piecemeal may be required

- trochanteric osteotomy may be required for exposure

 

Reaming

- enlarge rim only

- avoid creating peripheral defect

 

Contained acetabular defect

 

Morcellised bone graft

- rim fit uncemented cup

- cemented cup

 

Uncontained acetabular defect

 

A.  Wire mesh / bone gaft / cemented cup

B.  Wafer bone graft / morcellised bone graft / cage / cemented cup

 

 

THR Primary

Background & Technique

IssuesTHR Uncemented

 

Templating

Approach

Fixation

Bearing Surface

Head Size

Offset

 

Indications

 

Disabling hip pain

Severe functional impairment

Failed non operative management

 

Not Indicated 

 

Painless deformity

Stiffness

LLD

 

Aetiology

 

1° OA

 

2° (accounts for maybe 50% OA hip)

 

Secondary OA

 

SUFE                                                          

 

Hip OA Post SUFEBilateral SUFEHip OA Post Sufe 2

 

DDH

 

DDH Crowe 1

 

Perthes

 

Hip OA PerthesHip OA Perthes 2Hip OA Perthes 3Hip OA Perthes previous osteotomy

 

Trauma                

 

Hip OA post Acetabular FractureHip OA post displaced Acetabular FractureHip OA Post NOF FractureHip OA post subcapital fracture

 

Paget's                                                                                                                             

 

Hip OA PagetsPagets Bone Scan  

 

AVN

                  

HIp OA Bilateral AVN

 

Coxa Vara                                                                                                                     

 

Hip OA Coxa VaraHip OA Coxa Vara 2                                              

 

Sepsis

 

Hip OA Post Sepsis

 

Tumour

RA

 

Contraindications

 

1.  Five Absolute

 

Active infection

Charcot

Flail / Neuromuscular impairment

Hypovascular

Inadequate soft tissue cover

 

2.  Five Relative

 

Young patient

Heavy demand

Obese

Poor compliance

Poor mental state

 

Pre-op Evaluation

 

General

- mobility

- life expectancy

- fitness for anaesthetic - ardiopulmonary

- urinary status / TURP before THR

- teeth

- NSAID / aspirin / plavix / warfarin

 

Hip

- abductor strength

- LLD

- contractures

- vascularity 

- check skin / scars

 

Medical workup

 

PMHx

- DM / RA / Hemophilia / Marfan's etc

 

Beware difficult hip

- DDH

 

Medical / Anaesthetic Review

 

CXR / ECG / FBC / UE / Coags / GP&H

 

Medications

- cease Aspirin / Warfarin

- steroids

- diabetic medications

 

Education & Advice

 

Informed consent

- infection

- NVI

- blood transfusion

- LLD

- dislocation

- fracture

- DVT / PE

- limp

- revision

 

Rehab starts pre-operatively

- home modifications

- discuss precautions (high chair, pillow at night)

- physio

- driving (usually not for 6 weeks)

- social worker / occupational therapy

- work arrangements

 

Equipment

 

X-ray

 

Requirements

 

1.  AP pelvis / AP of hip showing proximal femur / Lateral

 

2.  Lower extremities internally rotated 15° to 20° 

- to allow proper offset templating

- can roll patient if severe OA

 

3.  Magnification marker

- most XR departments use bulky tray placed in compartment

- 2 inches below table top

- resulting in magnification of 15% to 20%

- degree of magnification directly related to distance from bone to cassette

- obese magnification can be > 25%

- thin patient can be < 15%

 

Template 

 

Component Position

 

Leg length 

 

Neck-shaft angle 

 

Femoral offset 

 

Degree of acetabular dysplasia 

 

Acetabular bone defects

 

CT scan

 

Hip OA previous Acetabular fractureHip OA CT Anterior wall discontinuousHip OA Posterior Wall Intact

 

Consider

 

Fixation - cemented v uncemented

 

Bearing surfaces

 

THR Technique

 

Position

- on side on bed

- pressure area care / CPN / ulna nerve

- pelvis perpendicular to bed

- completely stable

- Charnley hip supports

- able to palpate both knees and feet for leg length

- small pillow between legs / comparable position

- saline bag under armpit

- TEDS / SCDs lower leg

 

Antibiotics

 

Antibiotics at induction

- broad spectrum: first generation cephalosporin

- allergy: vancomycin / clindomycin

- repeat if operation longer than half life / 2 hours

 

Approach

 

Options

- Posterior / Kocher-Langenbech

- Lateral / Hardinge

- Transtrochanteric / Charnley 

- Anterior / Smith Petersen

 

LLD

 

1.  Position of knees

- comparable position

- check LLD prior to incision

- aim to recreate equal LLD

- note:  adduction of superior leg will artificially shorten leg in this position

 

2.  Intra-operative

- pin in superior acetabulum

- mark on femur

- recheck with femur always in same position

- can measure LLD and offset

 

Acetabulum

 

Exposure

- anterior acetabular retractor / beware femoral nerve

- inferior acetabular retractor / beware obturator artery

- avoid posterior retractors / beware sciatic nerve

 

Preparation

- remove labrum and capsule

- may need to remove curtain osteophytes

- define true floor with gouge at transverse notch 

 

Reamer

- medialise initially to true floor

- medialisation decreases JRF

- to bleeding bone

- preserve anterior and posterior walls

 

Cemented cup

- ream 2 mm > cup size for cement mantle

- leave transverse ligament intact

- low viscosity cement / Palacos

 

Uncemented cup

- young ream 1 mm < cup size

- old ream 2 mm < cup size

 

Acetabular Orientation

 

Closure

- 40+/-10°

- 45o to bed

 

Anteversion

- 15 - 30°

- increase in posterior approach

- use pelvis as perpendicular to floor

- use inferior transverse ligament

 

Femoral Stem

 

Entry point

- bow chisel

- start lateral and posterior

- follow bow of femur

- pass reamers

- find centre of femur

- check not perforating femur 

 

Incremental increase in broaches

 

Uncemented

- until broach rotationally stable

- don't wash away good cancellous bone

 

Cemented

- leave some cancellous bone

- allows cement interdigitation

 

Orientation

- anatomical anteversion 15°

- neutral or slight valgus

 

Trial

- offset / neck length / head size / LLD / stability

 

Insert definitive component and retrial

- ensure stability / LLD

- apply definitive head

 

Closure

- irrigate to remove particles

- +/- drain

- pressure dressings

 

Post-operative Management

 

4 x doses broad spectrum antibiotics

Check Hb and electrolytes next day

Analgesia

Abduction Pillow - 6/52 nightime

TEDS / Compression - 6/52

Anticoagulation - 6/52

 

Early mobilisation with Physio

 

Precautions until pseuodocapsule forms

- no flexion >90°  6/52

- limit IR / adduction

- sit in high chair 6/52

- no driving / 6/52

Bearing Surfaces

Wear

 

The removal of material, with the generation of wear particles under an applied load and in relative motion

 

Tribology is the study of wear and lubrication

 

Wear mechanisms

 

Adhesion

- bonding of the surfaces when pressed together

- may pull away material from the weaker surface

 

Abrasion

- asperities on the harder surface cut and plough 

- remove materials from the softer surface

 

Fatigue

- repetitive local stresses exceed fatigue strength

 

Wear Modes

 

Mode 1

- from motion of two surfaces rubbing together

- as intended

 

Mode 2

- primary surface against a non intended secondary surface

- head eroded through poly and up against metal backing

 

Mode 3

- two primary surfaces with a third body

- roughens surface

- increases mode 1 wear

 

Mode 4

- two secondary surfaces / backside wear

- creates third bodies

- i.e. screw fretting or between liner and metal backing

 

Wear types

 

Linear Wear 

- radiographic change in thickness of socket at maximal point of wear  

- based on 2D Xray

 

Volumetric Wear 

- volume of particulate poly created

- calculated based on trigonometric formula

- in turn based on measured linear wear & square of radius of articulating head

- probably represents underestimation of actual volume of wear particles produced 

 

Now more sophisticated computer based systems more accurately estimate wear

 

Fluid-film lubrication

 

Completely separates surfaces

- when fluid film height is thicker than height of asperities on the surface

- decreases roughness

- decreases wear

 

Variables in amount of wear

 

Type of bearing surface 

Head size 

Acetabular orientation

Weight 

Sex 

 

Polyethylene

 

Repeating chain of ethylene monomers

 

Advantages

- low cost

- multiple options i.e. elevate rim

- high wear resistance

- no toxicity

 

Disadvantage

 

Wear particles very bioactive

 

Factors in Poly wear

 

1.  Preparation of poly effects longevity 

A.  Machined from extruded polyethylene bar stock 

B.  Compression moulded directly from the polyethylene resin

 

2.  Sterilisation & Aging

A.  Surface treatment

- ethylene oxide gas

B  Gamma irradiation

- in vacuum causes cross linking which decreases wear

- in air get oxidation which increases wear

 

3.  Highly cross linked

 

Occurs when free radicals from a covalent bond between PE molecules

 

Advantage

- improved wear resistance

- up to 95% wear reduction compared with normal poly

- ability to use larger head sizes

- normal liner must be 8 mm

- can decrease this thickness to allow larger heads

 

Disadvantage

- decreased yield and tensile strength

- like ceramic, is more brittle with increased wear resistance

 

4.  UHMWPE

- ultra high molecular weight polyethylene

 

5.  Poly thickness

 

Thicker poly diminishes stresses in subchondral bone & within poly

 

Metal heads / CoCr

 

THR Metal on Poly

 

Ceramic heads on poly

 

THR Ceramic on Poly

 

Types

- Alumina AL2O2

- Zirconia ZrO2

 

Harder

- more difficult to scratch

- reduce abrasive wear

 

Smoother

- can be polished to lower surface roughness

 

Wettability

- hydrophilic

- improved lubrication and lower friction

 

Wear

- 0.2 mm / yearr on 2D& 3D models

- may be reduced by 50% compared with metal on poly

 

Ceramic on ceramic

 

Advantages

 

Highest wear resistance

- invitro 0.007mm3 / million cycles

- CoCr / poly 70-90mm3 / million cycles

 

Wettability

- excellent lubrication

 

Smoothness

- can be highly polished

 

No toxicity

 

Disadvantages

 

Position sensitivity

 

Liner chipping

- must take care during insertion

 

Fracture risk

- was a worldwide recall of zirconia heads in 2001

- due to unexpectedly high fracture rate in zirconia heads from one manufacturer

- now about 1 / 10 000

 

No hooded liner available

 

May need to revise ceramic with ceramic

- particles remaining may be hard than new bearing surgace

 

Squeaking

 

Trunion damage in revision

- new ceramic head may not lock to new trunion

- can use ceramic head with metal neck augment inside it

 

Metal on Metal

 

THR Metal on Metal

 

History

 

Popular in the 1960's

- McKee-Farrar replacements

- abandoned

- partly because of poorer results than Charnley low friction arthroplasty

- partly metal sensitivity concerns

 

Interest was aroused when it was noticed in some patents very good survival rates at 20 years and beyond

- discrepancy between some patients doing very poorly and some patients doing very well

 

Second generation design

 

Important concept of clearance

 

Difference in radius between the two surfaces

- reducing clearance and producing an exact fit is worse

- creates equatorial contact with cold welding and seizure

 

Prefer controlled clearance 0.06-0.1mm

- creates polar contact rather than equatorial contact

 

New machining far superior

 

Wear 

 

Decrease wear

 

Reduced linear and volumetric wear

- initial run in perior then steady state

- linear wear < 0.003 mm / year

 

Reasons

- increase smoothness

- thicker film

- polar bearing not circumferential

 

Strict control over manufacture essential

- early failures due to poor manufacturing

 

Advantage

 

Very high wear resistance

- 1 / 60 of metal / poly

 

Large heads

- decreases dislocation / improves ROM / function

 

Disadvantages

 

Increased ion levels

 

Serum / blood / RBC / urine increased levels Co & Cr

- up to 500 times the number of poly particles per year

- tends to decrease with time

- effects unknown

 

Best to measure serum levels in Nmols/l

- range for well functioning implant is 15 - 30 for Co and Cr

- increasing levels or levels several time normal of concern

- can imply a failing implant

 

Carcinogenesis

- no evidence for this

- metal on metal follow up for 50 years (McKee-Fararr)

 

Delayed type hypersensitivity

 

Cause unknown

- lymphocyte reaction

- very rare (1/1000)

- may cause unexplained pain

 

Patient can get large inflammatory reaction

- can cause tissue destruction +++

- lose abuctors etc

- difficult salvage

 

AJR 7 years

 

Ceramic / Ceramic  3.9%

Metal / Poly             3.2%

Ceramic / Poly         4.1%

Metal / Metal           7.7% (Head sizes > 28mm)

 

 

Biomechanics

Introduction

 

Peak pressures during gait

- between heel strike and early mid stance

- increases in both JRF and abductor activity

 

Chair rising 

- triples pressures

 

Hip forces

 

Single Leg Stance / Free Body Diagram of the hip

 

Calculation

- force exerted by the abductors

- balance effective body weight acting on the head of the femur

- equal magnitude, opposite direction

 

Abductor muscle force

- both a horizontal and a vertical component  

- assumed to be oriented at 30° with respect to a vertical axis

- this adds to the forces across the hip

 

Problem

- only G medius tension is calculated 

- a gross oversimplification

- need to consider G max. & other muscles

- ground reaction force is under calculated

- GRF recorded in prosthetic femur is much higher than FBD would suggest

 

Forces

 

Body weight during one-legged stance 

- 5/6 BW (1/6 BW is weight of leg patient standing on)

- effective body weight will act in a vertical direction

 

Single leg stance 3x BW

Walk ~4x BW

Jog~ 6x BW

Stumble ~9x BW

 

Adbuctor lurch

 

Shifting the body weight over the centre of the hip joint

- eliminating the need for the abductors to balance body weight

- reduce joint reaction force

 

Impact of walking aids

 

Walking with cane in contralateral hand

- analytical and in vivo studies 

- clearly shown reduces the joint force

 

Mechanism

- moment arm of the cane is much larger than that of the abductor muscles

- lower muscle forces are now required to balance the effective BW moment

 

Implications of rotational moments

 

Longitudinally and posteriorly directed loads

- most critical in generating stem fractures

- most fractures start at the anterolateral corner.

 

Posteriorly directed forces

- occur when the hip is flexed

- result in retroversion of the stem

- may play a significant part in loosening femoral stems

 

Clinical implications of hip joint geometry

 

Mechanical ability of the abductors are affected by

- head-neck angle

- neck length

- joint centre position

 

Aims

- recreate centre of rotation

- decrease JRF

- increase offset

- Increase abductor strength

 

Joint centre

 

Joint forces are minimized when the joint centre is moved medially, inferiorly, and anteriorly

- maximizes the moment-generating capacity of the abductors 

 

OA displaces femoral head laterally, superiorly, and posteriorly

- largest joint forces and moments are generated in this position

 

Lateral and distal joint centre 

- decreases the abductor's moment arm 

- therefore preventing contralateral pelvic drop now requires an increased muscle force

- increases the joint's compressive force

 

Superior joint centre

- inferior functional outcome

- decreased abductor strength

- loss of passive hip flexion

- can compensate with increased neck length   

 

Higher contact force / increased wear and loosening

- superior and lateral joint centre

- decreased femoral offset

- decreased abductor moment arms 

 

Head Neck Angle

 

Varus hip

- decreased head-neck angle 

- increases the mechanical advantage of the abductors

- therefore should minimise joint contact forces

- also improves stability with increased congruence

 

Valgus Stem

- decreased bending moment or shear on stem

- increased axial stem loading

 

If excessive

- increases knee valgus strain

- lengthens limb

- superior dislocation

 

Varus Stem

- increases shear on neck

- decreases axial loading

 

If excessive

- shortens femur

- increases dislocation

 

Neck length

 

Decreasing the neck length 

- similar to increasing the head-neck angle (valgus) 

- compromise the abductor function and increase the joint reaction force

 

 

Cemented Exeter Technique

Cemented cup and femur via posterior approachTHR Cemented Exeter

 

Set up

- on side

- charnley supports posterior on sacrum

- anteriorly on ASIS

- patient slightly tilted backwards

- avoids cup retroversion

 

Posterior Approach

- identify short ER

- open interval between G medius and piriformis with scissors, insert anterior retractor

- do the same with inferior aspect of quadratus

- diathermy all visible bleeders now

- 2 x stay sutures in short ER with 1 ethibond, clip and cut

- take off short ER and capsule with diathermy, superior radial cut in capsule to labrum

- dislocate hip

- second running stay suture in capsule with Ethibond

 

Releases

- release posterior capsule from short ER to mobilise better as flap for repair

- release superior capsule from labrum, also anterior capsule from labrum delicately with knife

- place specific Exeter anterior retractor

- divide inferior capsule delicately with diathermy, leave inferior transverse ligament intact

- place rolled swab here, place inferior retractor

- anterior retractor is tied to charnley support with weight and chain

- inferior retractor has weight attached, supported by assistant

- insert Norfolk-Norwich retractor superiorly

 

Cup

 

Remove labrum

- identify floor by removing osteophyte / reaming medially /  or can use 2.5 mm drill and measure floor depth

- ream in increased sized until fits in AP diameter

- need to remove all cortical bone, can do so with smaller reamer

- many drill holes required superiorly, this is the area where good interdigitation is critical and important

- drill holes in ischium and superior pubic rami as per charnley

- dry acetabulum with swabs and peroxide

- place reamings with spoon at inferior acetabular ligament and compress, this prevents cement leaking inferiorly

- trial cup, can use cup with peripheral poly lip to pressurise, cut to size

- insert ball of cement when no longer sticky

- compress till 5 minutes, twist pressuriser to remove

- dry blood with swab on a stick

- insert cup on insertion device

- place inferior cup first, medialise +++, then set closure and anteversion

 

Avoid

 

THR Cemented Exeter Inferior Cement LeakTHR Cemented Cup Excessively OpenTHR Cemented Exeter Medial Cement Penetration

 

Femoral Stem

 

Femur

- held vertical by assistant

- fish mouth elevator to elevate femur

- gluteal retractor holds gluteals

 

Entry point

- box chisel

- start lateral and posterior

- follow bow of femur

- pass 2 x reamers

- find centre of femur

- check not perforating femur 

 

Incremental increase in broaches

- leave some cancellous bone

- allows cement interdigitation

 

Orientation

- anatomical anteversion 15°

- in neutral or slight valgus

- >5° varus increases failure

- line up with patella as insert

 

Trial

- offset

- neck length

- head size

- check stability and LLD

 

Cement

 

1st generation 

- all by hand

 

2nd 

- plug, lavage, retrograde fill   

 

3rd 

- vacuum centrifuge, pressurisation 

 

Technique

- cement restrictor 1 cm beyond tip

(makes easier to get out if needed)

- wash cancellous bone with water

- H2O2 gauze (lyses RBC), suction

- vacuum centrifuge Abx impregnated high viscosity cement

- baby suction catheter

- retrograde filling with cement gun

- fill at 1 minute

- pressurisation til fat emerges (warn anaesthetist)

- slow insertion stem at 4 minutes, follow lateral wall

- clean cement away

- maintain constant pressure til hard

 

Retrial

- ensure stability / LLD

- apply definitive head

 

Closure

- capsule and ER sutures passed through drill holes in GT

- use suture passer

 

Clinical History

History

 

SOFI

 

Symptoms

Other joints / other specific

Function

Interventions (surgery, physio, injections)

 

PMHx / PSHx / Meds / Allergies

 

Social History

- occupation

- dwelling

- smoking / alcohol

 

Symptoms

 

"What is your problem?"

 

PAIN (NILDOCARP)

 

Nature (Sharp or Dull)

Intensity (1-10)

Location - point for me?

Duration - how long?

Onset

- specific details of injury ?

- rest / night / start-up

Concomitant Factors 

- locking / clicking / swelling

Aggravating Factors

Relieving Factors

Radiation

Pattern / frequency

 

Associated symptoms

- leg lengths

- stiffness

 

Causal factors 

- AVN -> steroids, alcohol, RTx / CTx

- RA / other inflammatory conditions

- CDH / DDH / SUFE / Perthes

 

Other joints

 

Knee / Back

Signs inflammatory condition

 

Functional Assessment

 

Lower limb (Modified Harris Hip Score)

1.  Shoes & socks

2.  Stick / Walking aid

3.  Limp

4.  Stairs

5.  Walking time/distance

6.  Public transport / In or out of Car?

7.  Run or Squat if young adult

8.  Prop at speed if sportsman

 

Little old lady gets out of bed, puts her shoes on, picks up her stick, & limps to the door

- climbs down the stairs, walks two blocks to the bus, & pushes over the jogger doing squats

 

Disability

"What can't you do that you used to be able to do?"

 

1.  Occupational

2.  Recreational - sports, hobbies

3.  ADL's

- recreational

- showering / toileting / cooking / shopping

 

Interventions

 

ELMPOPI

 

Education

 

Lifestyle modification

- weight loss

 

Physio

 

Orthotics - stick

 

Pharmaceuticals

- symptomatic (NSAIDS, narcotics)

- disease modifying (steroids, anti-rheumatoid)

 

Injections

 

 

Fixation

Background

Cemented Acetabulum

IndicationsTHR Cemented Acetabulum

 

Neoplastic / metastatic

Severe osteoporosis

Pagets

 

Longetivity

 

Ranawat 

- longevity directly related to quality of cement penetration into acetabulum

 

Types

 

Reflection all Poly (S&N)

Exeter all Poly (Stryker)

Zimmer ZCA

 

Cemented ZCA cup

 

Pathology

 

Retrieval studies from successful THR's

- fibrous membrane found at least in part

- begins at periphery of bone-cement interface 

- mechanical testing shows the most stable are those with least membrane

 

Metal Backing

 

Theory that more rigid implant construct could more evenly distribute stresses to surrounding acetabulum 

- cement & subchondral bone would be protected from fatigue failure

 

Actually perform poorly compared with all poly

- reasons for inferior clinical outcomes not well understood

- accelerated wear of polyethylene suggested as cause

 

Loosening

 

Process of loosening may be result of cellular rather than mechanical process

- determined by host reaction to polyethylene debris

 

Signs

- obvious migration in comparison previous films

- cement mantle fracture

- progressive > 2 mm lucency cement / poly interface

(c.f. cement-bone interface)

 

Charnley & De Lee - 3 zones

1 - superior 1/3

2 - middle 1/3

3 - inferior 1/3

 

Cemented Cup 3 Zone LysisCemented Cup Lysis Zone 1

 

Results

 

AJR 2010

 

9 year

 

Exeter / Contemporary   6.0%

Exeter / Exeter              4.9%

Spectron Reflection        9.0%

MS30 / Low Profile Cup  1.7%

 

CPT / ZCA 7 year            %2.9

 

 

Cemented Femur

THR Cemented Femur

Goals in femoral cementing

 

Optimize cement-bone interface

Cement mantle free of defects

Minimum 2 mm thickness

Femoral component centred in cement mantle

 

Survival

 

Swedish Joint Registry

 

Reflection All Poly / Spectron 92% 10 year

 

Exeter All Poly / Exeter 93% 14 year

 

Surface

 

1.  Polished

- Ra less than 1 micrometer

- polished stems create little abrasion

- allow subsidence and keep cement in compressive loading 

 

2.  Matte 

- Ra less than 2 micrometer

- matte finish will not create excessive abrasion unless stem allows large micromotion 

- allows some mechanical interlock with cement

 

3.  Rough 

- Ra greater than 2 micrometer

-  expected to cause excessive abrasion

 

Studies have shown increase aseptic loosening and revision rate with matte finish

- failed ~10% at 10 years

- c.f. 4% at 20 years for polished

 

Reason

 

Creep is time dependent deformation

- creep of cement is related to age

- creep at 1 day is 3.25 x at 7 days

- creep allows stabilization

- cycles of creep, followed by stress relaxation leads to stem subsidence in the mantle

- Matte finish prevented subsidence

 

Collar

 

Controversy exists over the use of collared prosthesis

- results in increased load transfer from implant to proximal femur compared to collarless implants

 

A.  May reduce stress shielding of proximal femur & reduce strain in proximal medial cement mantle

 

B.  Prevents subsidence

 

Exeter stem 

 

Behaves as a Morse taper in the cement mantle

- transmits both torsional & compressive loads

- generates hoop stresses in the cement which allows it to expand slightly

 

Characteristics

 

1.  Smooth polished surface

- no sites of stress concentration

 

2.  Broader laterally than medially 

- helps to diffuse the compressive stress medially 

 

3.  Tapered shape from proximal to distal 

- allows controlled subsidence within the cement column; 

 

4.  Cobalt-chromium alloy stems 

- are used in most stems

- generate less particulate debris than titanium implants

 

5.  Triple taper concept

- femoral component tapers to a point in both the AP and lateral planes

- in addition, the stem is more narrow medially and widens laterally

 

Advantage low porosity cement

- Cement fails in fatigue

- Centrifugation decreases pore size in cement 

- approximately 200 to 400 nm in diameter 

- results in an increase in cross-sectional area

- 25% increase in ultimate tensile strain 

- 125% increase in tension-compression fatigue strength  

- Similar benefits demonstrated with vacuum mixing

 

Cement Issues

 

Cement viscosity

- in vitro and in vivo tests 

- structural superiority of high viscosity over low viscosity cement

- i.e. Simplex (highly viscous) v Palacos (low viscosity)

 

Pressurisation

- strength of cement-bone interface directly related to depth of penetration of cement into bone

- pressurization increases penetration

 

Centralisers 

- achieve more uniform cement mantle 

- especially zone 5 & 6

 

Cement Mantle

 

Ideal cement mantle thickness has not been defined

- autopsy studies - crack incidence greatest when mantle < 2 mm

- issues with the varus stem

 

Varus stem 

- associated with higher incidence of aseptic loosening

- results in thin or nonexistent cement mantle in proximal medial & distal lateral zones

 

Antibiotics 

- in relatively small doses effect on mechanical characteristics of PMMA negligible

- must be heat labile

- vancomycin / tobramycin / gentamicin

 

Cementing techniques

 

First-generation 

- finger-packing doughy cement 

- no cement restrictor

 

Second-generation 

- cement restrictor

- cleaning with pulsatile lavage  

- cement inserted retrograde using cement gun 

 

Third-generation 

- vacuum centrifuge (reduce porosity)

- pressurization of cement mantle 

- surface modifications on implants 

 

Fourth-generation 

- stem centralization proximal & distally

- ensure adequate & symmetric cement mantle

 

Barrack grading system for cement technique

 

Aseptic loosening correlates with cement technique

 

A. Complete filling of proximal portion of diaphysis 

- difficult to distinguish cortex from cement

- commonly referred to as "white-out"

 

THR Type 1 Cemented Femur

 

B. Near complete filling of diaphysis 

- can distinguish cortex from cement in some areas

 

Type 2 Cemented Femur

 

C. Divided into C1 & C2

 

C1

- Incomplete cement mantle in proximal portion

- > 50% of cement-bone interface demonstrates radiolucencies

 

THR Type 3 Cemented Femur

 

C2

- Mantle < 1 mm thick or metal is up against bone

 

THR Type 3b Cemented Femur

 

D. Cement mantle with gross deficiencies 

- no cement below the stem, major defects in the mantle, or multiple large voids in the mantle

 

Failure

 

Endpoints 

- need for revision surgery

- clinical failure (a painful arthroplasty)

- radiographic failure (loose implant)

 

Mechanisms of Failure

 

Mechanical factors

- debonding between stem & cement initially occurs at cement-metal interface

- produces high peak stresses in cement mantle proximally & near distal tip of stem 

- initiates cement cracks esp areas of thin cement / adjacent to mantle defects / pores initiate & propagate 

 

Biologic processes 

- then become more important

- particulate polymeric debris gains access to endosteal bone

- stimulates foreign-body reaction 

- bone resorption with fibrous tissue membrane beginning at pseudo-capsule extending along cement-bone interface

 

Harris Categories 

 

"Definitely loose"

- migration of prosthesis

- cement mantle fracture

 

Cemented Femur Definitely Loose

 

"Probably loose" 

- continuous radiolucent line at cement-implant

 

Cemented Femur Probably Loose

 

"Possibly loose" 

- radiolucent line cement - bone

 

Cemented Femur Possibly Loose

 

Autopsy studies 

 

Radiolucencies most commonly related to skeletal remodelling

- not to the formation of soft-tissue membrane between cement & bone

- inner cortex commonly forms adjacent to cement mantle

- not distinguishable from cement on Xray

- 2nd medullary canal forms between inner & outer cortex 

- appears as radiolucency on Xray

- non-progressive

 

Uncemented Acetabulum

GoalTHR Uncemented

 

Initial mechanical stability

- adequacy of locking between component and bone

 

Need initial press fit for mechanical stability

Long term require biological fixation

 

Advantage

 

Can change liner

- multiple revision options i.e. for dislocation

 

Simple to remove

- Zimmer Xplant

 

Design

 

1.   Smooth

- relied on mechanical interlock for stability and long term fixation

- unacceptable early revision rates

- initial press fit, but no biological fixation

 

2.  Threaded

- universally bad results

- due to small contact area between bone and implant

 

3.  Smooth HA coated

- improved but still inferior results

 

4.  Porous coated

- allows ingrowth

- much better results compared to smooth components

- titanium or HA

 

5.  Hemispherical

- oversized cup

- initial press fit

 

6.  Flattened hemispherical

- rim fit

 

Requirements

 

1.  Material must be biocompatible

- titanium mesh

- cobalt chromium beads

- HA

- all of these materials have been shown to be adequate provided pore size is correct

 

2.  Surface must have optimal pore size

- between 100 and 400um

 

3.  Component must be placed in intimate contact with viable host bone

 

Press fit

- < 0.5 mm gaps 

- require tight peripheral press fit with complete seating

- maximises surface are available for ingrowth

- maximises area for stress transfer

 

Technique

- 1-2 mm underream

- risks are acetabular fracture and underseating

 

Acetabular Underseating

 

4.  Adequate initial stability to allow reliable ingrowth

- micromotion > 40 um generates fibrous tissue 

 

Options

- press fit with supplemental screw fixation

- line to line reaming with supplemental screws

- spikes

- pegs

 

Supplemental screw fixation

- 2 x bicortical screws

- provide similar stability as press fit

 

Uncemented Cup with screws

 

Screw problems

- can get backside wear / fretting

- holes can provide route for particle wear

 

Technique Uncemented Cup

 

Centre reamer in desired hemisphere of acetabulum

- begin 6 - 10 mm below templated size (44)

- medialise initially

- remainder reaming in direction of final component position

- 45o abduction

- 20 - 30o abduction

- increase until contact anterior and posterior

- AP diameter is what determines cup size

- petechial bleeding

- don't take away all subchondral bone

- continually assess posterior / anterior walls - must preserve

 

Can bone graft base and reverse ream

- especially with flattened hemisphere

 

Insert component 1 - 2 mm larger

- ensure seating (remove insertion handle and probe base)

- ensure stability

- add screws if any doubt

 

Screw placement

 

 Acetabulum Wasielewski Safe Zones

 

Wasielewski et al JBJS 1990

- anatomical cadaveric study

- line ASIS to centre acetabulum & ischial tuberosity

- line perpendicular to this 

- four quadrants 

- safe quadrants = 2 posterior quadrants

- posterior screws do not emerge within pelvis

 

Structures at risk

 

AS quadrant

- external iliac vein > artery

- vessels can be within 0.5 cm of the inner cortex of the pelvis

- become closer with increasing age

- in the anterior quadrants 25mm screws often too large

 

AI quadrant

- obturator nerve & vessels

- femoral artery 

 

PS quadrant

- sciatic nerve / superior gluteal nerve & vessels in danger at greater sciatic notch

- aim screw between 2 cortices of ilium

- direct towards SIJ

- can tolerate 85 mm

 

PI quadrant

- internal pudenal vessels

- inferior gluteal nerve & vessels

- maximum screw length is 25 mm

 

Complications

 

Acetabular fracture

 

Increased risk

- > 2 mm underream

- acetabular sizes < 52

- elderly (consider line to line reaming and use of screws, or use cement)

 

Management

- screws

- posterior column plating

- cage

 

THR Uncemented Cup Acetabular Fracture

 

Failure of liner fixation / acetabular fixation

 

Acetabular spin out

- insufficient initial fixation

- failure biological fixation

 

THR Uncemented Cup Spin out

 

Liner spin out

- must ensure fixation method is sufficiently engaged

 

Errant Screw placement

 

Anterior quadrants

- can cause catastrophic haemorrhage

 

Management

- angiogram  / embolism

- laparotomy / pelvic packing

 

Loosening

 

Loosening Uncemented Cup

 

Can be very difficult to identify with uncemented acetabulum

 

 

 

 

Uncemented Femur

GoalTHR Uncemented

 

Initial press fit

- implant geometry fits the cortical bone in the proximal femur

- good initial mechanical stability

 

Biological fixation for success

- good press fit

- minimal micromotion

- bony or fibrous tissue ingrowth or ongrowth

 

Longetivity

- avoidance adverse stem bone stiffness ratios

- fixation surface that provides a transitional stress transfer from the proximal femur to the diaphysis

- avoid extreme stress shielding or excessive rigidity

 

Press fit

 

True Press-Fit in Bone 

 

Bone is a viscoelastic material

- implies that its elastic recoil will become less with time

- the amount that bone will "creep" or undergo stress-relaxation depends on its density

- cortical bone has less viscoelastic behavior than cancellous bone

- the fact that bone will relax and lose elasticity over time limits the amount of time over which a true press-fit can be maintained in bone

- once the initial press-fit dissipates,a prosthesis may move under load in the bone and either re-establish a press-fit or become loose

 

Non porous coated uncemented implants are commonly referred to as press fit implants

 

Design

 

Proximal metaphyseal filling

- curved, anatomic stem

- most common

- tight proximal fit

 

Distal isthmus filling

- straight stem

- used more commonly in revision

 

Techniques of Initial Fixation

 

Definition Rigid Fixation

- micromotion <150 microns

- ideal 50-100

 

A.  'Press fit' (1-2mm undersized) technique

- bone expands around prosthesis

- generates hoop stresses

- femur and acetabulum

 

B.  Line to line fit

- bone is prepared to same size as implant

- extensive porous coating with stem

 

Contraindications

 

Stove pipe femurs (Dorr < 0.75)

Poor bone stock

 

Proximal femoral geometry / Dorr calcar-to-canal ratio

 

Important if considering uncemented prosthesis

 

3 types - 501's, Stove pipe, Flares

- measure canal at LT & 10cm below 

- inner diameter at midportion of LT divided by diameter 10 cm distal

- must be <75% for uncemented prosthesis

 

Type A 

- ratio < 0.5 

- cortices seen on both AP & lat

- most amenable to uncemented component

 

Dorr A Femur

 

Type B 

- between 0.5 and 0.75 

- thinning of post cortex on lateral

- intermediate

 

Dorr B Femur

 

Type C 

- > 0.75 

- thinning of cortices on both views 

- "stovepipe" femur

- favours use of cemented stem

 

Biologic fixation

 

Two types

 

1.  Ingrowth 

- porous coating

- HA coated

- combinations

 

2.  Ongrowth 

- grit blasted

- increases roughness

- typically needs to be entire surface 

 

Ingrowth

 

Pore size

- optimum pore size 50-350 microns (ideal 50-150)

 

Porosity

- 40-50%

 

Pore depth

- deeper pores better

- increased shear strength with loading

 

Mechanism of porous coating

 

Titanium plasma sprayed

- often used to create pores

- then covered with HA to supplement

 

Tricalcium phosphate

- also used

 

HA coating

- sprayed on as a porous coating

- osteoconductive

- surface dissolution to Ca and Phosphate

- stimulates osteoblasts

 

Extent of Porous coating

 

Complete / incomplete

- both proximal and distal fixation are important

- is a trade off between fixation and shielding

 

Extensively coated implants

- improve likelihood of solid fixation

- distal loading of bone

- get mainly diaphyseal spot welding

- increase proximal stress shielding

- same problem with cemented implants

 

Femur Fully Coated Proximal Shielding

 

Proximal porous coating

- proximal loading of bone

- minimises proximal shielding

- more common

 

Materials

 

Rigidity

 

Want less rigidity to minimise stress shielding

 

Stiffness related to 

- modulus

- fourth power of the stem radius

- solid v slotted / fluted stems

 

Young's modulus of Elasticity

 

Bone 12

Titanium 117

Cobalt-chromium 210

 

Minimise rigidity

 

1.  Titanium alloy v cobalt chromium

- less structural rigidity

- lower modulus of elasticity

- 2 - 3 x less stiff

 

2.  Implant size

- as size increases, rigidity increases

 

3.  Design

- some stems have a coronal slot to decrease rigidity

 

Osteointegration

 

Engh et al categories

 

1.  Osseointegration

2.  Stable Fibrous ingrowth

3.  Unstable fixation

 

A.  Signs of osteo-integration

 

Take 1 year to see

 

1.  Spot welds

- densification of endosteal bone

- usually in the region of termination of the porous coating on the implant

 

THR Spot Weld

 

2.  Absence of any radiodense reactive lines

- may occur around the smooth portion of the implant

- this is where bone ingrowth is not expected to occur

- they should not be present adjacent to the porous coating

 

3.  Calcar atrophy

- this change is sometimes subtle

 

4.  Increased cancellous density / cortical hypertrophy distal to the coated region

 

B.  Failed bone ingrowth / successful stabilization by fibrous tissue ingrowth 

 

1. Parallel Sclerotic lines 

- remodelling signs around the porous surface 

 

2.  Less atrophy of the medial femoral neck

 

2.  No progressive migration 

 

3.  No local cortical hypertrophy / spot welding

 

C. Signs of frank implant instability 

 

1.  Component migration

- usually by subsidence and varus tilt

 

2. Progressive luceny on serial radiographs

 

3.  Development of inferior pedestal

 

THR Subsidence Uncemented Component

 

Complications

 

Fracture

- slow careful insertion / make sure is advancing with each blow

- can prevent or treat with cerclage wire

- assess stability

- revert to cemented stem if unable to obtain stability with press fit

 

Uncemented Femur Intraoperative Fracture

 

Thigh pain

 

Causes

 

1.  Initial instability (lack of press fit)

2.  Failed bony ingrowth / Late instability

3.  Micromotion at distal stem

- disadvantage of proximal coating

- will usually resolve over 2 years

- only 1% severe pain

4.  Mismatch modulus of elasticity

- lower with titanium

- tend to have lower incidence of thigh pain

- smaller stems

5.  Osteoporotic bone

 

Treatment

- can cerclage wire cortical strut grafts

- improve bony rigidity over distal stem

 

Stress shielding

 

Most common with distal press fit / fixation

 

THR Proximal Stress Shielding

 

Osteolysis

Head size

THR Large Head

Issues

 

Wear

Stability

Normal feel of hip

Increased ROM

 

Wear

 

Large head

- increase volumetric wear

- less penetrative / linear  wear

 

Small head

- increased linear wear

- decreased volumetric wear

 

Livermore's studies showed

- 32mm highest volumetric wear

- 22mm highest linear wear

- determined 28 mm optimal size

 

High volumetric wear in metal on poly generates high levels of particles stimulating osteolysis

 

Stability

 

Head size affects dislocation because of two variables

 

1.  Primary arc range

 

Distance head can move before impinging and levering out

 

Increase by

A.  Increasing head:neck ratio - increases the primary arc range

B.  Tapering neck

C.  Modifying rim of cup

 

2.  Excursion distance

 

The distance the head must travel in order to dislocate once the neck begins to impinge

- jump distance

- half head diameter

 

Problem

 

Large head size does not exclude dislocation

 

THR Dislocated Birmingham

 

Methods to increase head size

 

Ceramic on ceramic

- size currently limited

- maximum is 36 mm alumina heads

 

Metal on metal

- potentially decrease wear with increased size

- due to improved fluid film and boundary lubrication

 

Australian Joint Registry 2010

- increased revision rates with metal on metal

- most evident with larger sizes > 32 mm

- many company's prosthesis, not just one

- especially in females and younger patients

 

Metal on highly cross linked poly

- increased wear resistance

- can use thinner liners

- able to use larger heads

 

 

 

Offset

Definition

 

The perpendicular distance from the centre of the femoral head to the long axis of the femur

 

Harris 1992

- aim for supra-physiologic offset 

- avoid making offset less than original at all costs & makes longer if possible

 

Soft tissue balancing equals restoring femoral offset

 

Effect of short offset

 

1.  Abductor lurch / Trendelenburg gait

2.  Increased JRF / increased wear rates

3.  Weak abduction increases O2 consumption

4.  Impingement

5.  Lax soft tiiues can cause dislocation

 

Decreased offset leaves the abductors lax  

- doing so means they have to act with increased force

- increases the joint reaction forces across the hip.

- rsult of this is increased wear rates

 

Sakalkale et al Clin Orthop 2001

- 17 patients bilateral THR

- one STD, one high offset

- liner wear 0.21mm c.f. 0.01 mm /year

 

Increased offset

 

Advantage

- decreases JRF

- tightens lax abductors

 

Disadvantage

- theoretical increase in torque forces on stem and cement in flexion

- cadaver studies demonstrate increased offset doesn't increase torque forces on cement & bone

- torque increased in the stem but it is below the fatigue threshold modern stems

 

Factors affecting offset

- neck shaft angle

- head neck length

- anteversion

- femoral osteotomy level

- position of acetabulum

 

How to increase offset

 

1. Decreasing neck shaft angle

- more varus neck shaft angle

- increases torque on implant

 

2. Increasing Head /  Neck length

- improves abductor tension

- worsens LLD

 

3.  Medialising femoral neck whilst lengthening femoral neck

- technique in high offset stems

- maintains neck shaft angle

 

4.  Advancing GT

- increases abductor offset

 

5.  Acetabular component

 

Lateralised liners

- increase offset whilst preserving leg length

- can worsen body weight lever arm

- do so only when increasing femoral offset insufficient

 

Medialising centre of rotation

- decreases offset

 

Checking Soft Tissue Tension and Offset

 

1.  Preoperative templating

- normal side

- aiming to reproduce normal biomechanics

 

A.  Limb length

B.  Acetabular component

C.  Femoral component

 

2. Intraoperative measurement

 

Measurement jigs

- 2 fixed reference points

- limb in consistent position

- measure length and offset

- usually pin in supra-acetabular area

- second in GT

 

3.  Intraoperative maneuvers

 

Shuck test

- distraction of hip joint with in line traction

 

Dropkick test

- hip extended, bend knee to 90o

- if too tight, RF is taut and passively extends the knee

 

Leg to leg comparison

- feel knees when legs is similar positions

- feel tension of abductors

 

Rotation

- external rotation in extension

- flexion

 

 

Templating

AimTHR Templating

 

Reproduce the normal anatomical centre of rotation

Restore femoral offset 

Maintain equal leg lengths 

 

Usually template off normal hip

 

Template

 

1. LLD

2. Offset

3. Femoral component

4. Acetabular component

5. Osteotomy / femoral seating

 

Require

 

AP pelvis

- hips internally rotated 10-15o

- accounts for anteversion

- allows true neck shaft angle

- otherwise will underestimate true femoral offset

 

AP centred femoral head

 

Lateral hip joint

- used for planning location of proximal femoral opening in the piriformis fossa

 

Magnification

- product of distance between pelvis and film

- increased in obese patients

- less in thin patients

- can use magnification marker which is know to be 10 cm

 

Leg Length

 

1.  Horizontal line through two points at inferior aspect of ischial tuberosities

- compare to lesser tuberosity

 

THR Minimal LLD Template

 

2.  Acetabular teardrop

- vertical line to centre of femoral head

- calculate difference

- multiply by 0.8 to account for 20% magnification

 

THR Template Severe LLD

 

Tear drop more reliable

- less affected by rotation

- closer to centre of rotation of hip

 

Note: ensure one femur is not abducted, adducted

 

Acetabular component

 

THR Template Acetabulum

 

Always template before femoral component

- establish centre of rotation

 

Technique

 

Establish landmarks

- line through teardrops

- ilioischial line

- superolateral margin of acetabulum

 

Position

- apex just lateral to the teardrop

- medial border just lateral to ilioischial line

 

Orientation

- 45o relative to horizontal plane

- 20o anteversion on lateral x-ray

- sufficient superolateral cover

- reproduce any uncovering intra-operatively

 

Mark centre of rotation

 

Specific cases

 

1. Protrusio

- template to teardrop and ilioischial line

- ream only to obtain adequate peripheral support

- calculate amount of medial bone graft

 

2.  Medial osteophytes / lateralised cup

- again template from teardrop / ilioischial line

- ream medially

- ensure same amount of superolateral coverage as with templating

 

3.  Dysplastic acetabulum

- insufficient acetabular coverage

- superolateral migration of femoral head

- restore hip centre

- calculate SL uncoverage

- if sufficient posterior wall and only uncovered anterolateral bone graft not required

- otherwise augment with femoral head / high hip centre / augmented cups

 

Femoral component

 

THR Template Femur

 

Aim

- template size

- calculate LLD / neck cut

- restore offset

 

X-ray

- AP with femur internally rotated 20o

- puts true neck shaft angle in plane of film

 

Component size

 

Cemented

- 2 mm cement mantle

 

Uncemented

A.  Proximal coated / metaphyseal fit

- optimal medial and lateral endosteal cortical fit of proximal femur

B.  Fully porous coated

- optimal endosteal contact in diaphyses

- 4-5cm of scratch fit

 

LLD / Femoral Osteotomy

 

Calculate LLD

- place centre of femoral component measured amount above centre rotation

- mark neck cut

 

Offset

 

If femoral head medial to centre of rotation

- offset is increased and this will decrease JRF

 

If femoral head lateral to centre of rotation

- offset is decreased / avoid

 

 

 

Trochanteric Osteotomy

Types

 

1.  Standard trochanteric osteotomy

2.  Sliding trochanteric osteotomy

3.  Extended trochanteric osteotomy

 

Standard Trochanteric osteotomy

 

Standard Trochanteric OsteotomyStandard GT Osteotomy Wire Fixation

 

Concept

- detach GT with only abductors attached

 

Indication

- increasing exposure to acetabulum in difficult cases

- retensioning abductors

 

Problem

- difficulty fixation / unstable

- most hip surgeons now use sliding osteotomy

 

Technique

- detach proximal attachment of vastus lateralis

- pass retractor deep to G medius / minimus and superficial to capsule

- saw osteotomy from lateral aspect of GT angled up towards retractor

- detach any short external rotators and reflect superiorly

 

Fixation

- 3 - 4 intraosseous wires

- claw plate

 

GT Osteotomy Plate Fixation

 

Modification / Chevron Osteotomy

- increased stability

- decreased non union

 

Complications

- non union

- migration

- wire breakage / painful hardware

 

GT Osteotomy Broken WiresGT Osteotomy Broken WireGT Osteotomy Failed Plate

 

Trochanteric Slide

 

Concept

- PA osteotomy

- vastus lateralis and G medius left attached to fragment

- fragment retracted anteriorly

 

Advantage

- increased inherent stability

- vastus lateralis prevents proximal migration

 

Technique

- retractor superiorly deep to minimus and superior to capsule

- posterior elevation of vastus lateralis

- retractor under vastus lateralis insertion

- oscillating saw anterior to posterior

 

Fixation

- wires

- grip plate

 

Extended Trochanteric osteotomy

 

Concept

 

Osteotomy lateral 1/3 to 1/2 of trochanter & femur

- posterior to anterior longitudinal cut

- short distal transverse cut

- levers / hinges open anteriorly

- maintains anterior vasculature / muscle attachment

 

Indications


1.  Aid exposure
2.  Removal cement (especially infection)
3.  Removal well fixed uncemented prosthesis
4.  Removal cement plug / bone very poor / risk of perforation high
5.  Abnormalities of the proximal femur


Contraindications / Relative


1.  Impaction bone grafting
2.  Cementing revision prosthesis

 

Technique ETO
 

Length
- measured from tip GT
- 2 – 15 cm long

- determined from preoperative template
- need to preserve diaphysis if using distal press fit uncemented stem


Timing
- usually after implant removal
- may not be possible


Site
- elevate vas lateralis forward
- expose linea aspera
- expose posterior femur


Osteotomy
- use drill holes to mark osteotomy

- drill both cortices
- thin oscillating saw
- cut down through anterior and posterior femur in line with GT
- through both cortices
- transverse cut distally through 1/3 diameter
- lever open


Fixation
- 3 x cerclage cables
- protect sciatic nerve / palpate / pass wires posterior to anterior
- submuscular

 

Results
 

98 – 100% union rate by 6/12

 

 

THR Resurfacing

ConceptBirmingham Hip Resurfacing

 

Femur

- removal of femoral head cartilage

- resurfacing with metal

- cemented / uncemented

 

Acetabulum

- standard technique

 

Bearing surface

- metal on metal

 

Indications

 

Relatively young man (40 - 50)

OA

 

Absolute Contra-indications

 

Severe bone loss femoral head

Large femoral neck cyst

Small acetabulum

 

Relative Contra-indications

 

Osteoporosis

Age > 65

BMI > 35

 

Caution

 

RA

Female

AVN femoral head

 

Advantages (many theoretical)

 

1.  Bone preservation

- preserves femoral bone stock

- however makes acetabular preparation more difficult

 

2.  Improved stress transfer to proximal femur

- less proximal stress shielding

- improved proximal bone density

 

3.  Reduced dislocation rates

- heads 36-54 have reduced rates compared with 22-32

- can occur though if poor technique or component loosening

 

Dislocated Birmingham Hip ResurfacingDislocated Birmingham Resurfacing

 

4.  Better kinetics

- faster walking speeds

- may be better ROM

- possible better proprioception

- may be element of selection bias (i.e. is done in younger, fitter patients)

 

4.  Easier revision of femoral component

- better bone stock

- simply recut and use stem

 

6.  Possible improved longetivity

- very low wear rates metal on metal

 

Disadvantages

 

1.  Poor modularity

- difficult to adjust LLD

- difficult to adjust offset

- patients with very abnormal abnormality better off with conventional THA

 

2.  Not suitable for elderly / poor bone stock

- increased risk femoral neck fracture

 

3.  Femoral neck fracture

 

 

4.  Metal ions

- in serum, RBC, urine

 

Problems

- risk metal sensitivity

- risk carcinogenesis / teratogenesis

- CI in woman of child bearing age

 

5.  Loosening

 

Complications

 

Femoral Neck Fracture

 

Incidence 0-4%

- 1.5% in a study of 3500 BHR in Australia (JBJS Br 2005)

- early in learning curve

- early in prosthesis life

 

Risk Factors

- decreased bone mass / osteoporosis

- elderly

- inflammatory arthritis

- females (risk x2)(AJR)

- femoral head and neck cysts

- femoral neck notching

- varus femoral component (< 130o neck shaft angle)

- cup impingement on neck

- improper implant seating

- AVN femoral Head

 

BHR femoral neck notchingBHR Femoral Neck Notching 2

 

Revision

- relatively simple

- recut neck

- femoral implant with large metal head

 

Revision BHR

 

Early loosening

 

Machining

 

Initially due to poor early manufacturing

- decreased clearance

- inadequate polar bearing

- increased peripheral bearing, seizing, cold welding and loosening

 

Modern machining

- small surface asperities

- improved fluid film lubrication

- polar bearing with small clearances

- very low wear and little particle production

 

Causes

 

A.  Oversized heads / notching

 

BHR Oversized Femoral HeadBHR Loosening

 

B.  Varus Femoral Component

 

BHR Valgus v Varus Femoral Component

 

C.  Femoral head AVN

 

Due to extensive releases required to expose / surgically dislocate femoral head

 

BHR Femoral Head AVN

 

D.  Open Acetabular Component

 

Theorised to cause point loading

- increased metal wear

- best to close cup

 

BHR Open v Closed Acetabular Component

 

E.  Other

 

BHR Acetabular Component Protrusio

 

Australian Joint Registry 2010

 

13 300 procedures

 

Best outcome

- male < 65 with OA

- able to get > 50 mm head size

- 3.9% 9 year

 

Revision rate

 

Cumulative

- 7.2% 9 years for OA

 

Birmingham Resurfacing

- 6.2% 9 year

 

Reasons for revision

- fracture 36%

- loosening 33%

- metal sensitivity 7%

 

Revision by diagnosis 7 years

- OA 5.8%

- DDH 14%

- AVN 6%

 

Revision by prosthesis

- BHR 96.5% 5 year

 

Revision by age 7 years

- < 55     5.6%

- 55 - 64  5.8%

- > 65     7.3%

 

Revision by sex 7 years

- male 4.5%

- female 9.3%

 

Revision by head size 7 years

- < 44mm:    13.8%

- 45 - 49mm: 8.8%

- 50 - 54mm: 3.7%

- > 55mm:     2.2%

THR Revision

A Osteolysis and Loosening

DefinitionRevision THR Osteolysis

 

Biological response to particulate matter

- characterised by periprosthetic osteolysis

- stimulated by wear debris

- debris gains access to any area accessible by fluid

 

Sources of particulate debris

 

1.  Wear

 

Mechanisms of wear

A.  Adhesion

B.  Abrasion

C.  Fatigue

 

Modes of wear

 

1.  Motion between 2 surfaces designed for motion

2.  Primary bearing surface against an non intended bearing surface

- i.e. femoral head against acetabular shell when liner has worn out

3.  Interposed third body particles i.e. bone or cement

4.  Two non bearing surfaces together i.e. back sided fretting, morse taper fretting, screws

 

2.  Corrosion

 

Electrochemical process releasing metal ions

- modular interfaces i.e. head neck

- metal on metal bearings

 

Types of wear particles

 

Polyethylene

PMMA

Cobalt alloy

Titanium alloy

 

Morphology of wear particles

 

Usually less than 1um in size

 

Biological response to wear particles

 

Small particles phagocytosed by macrophages

- unable to digest

- stimulate release of cytotoxic factors

- TNF

- aggregates more macrophages

- release TNF, IL1, IL6, PGE2

- stimulated osteoclastic bone resorption

 

Poly wear

 

THR Poly WearTHR Eccentric Poly Wear

 

Lucent Zones

 

Gruen Zones

 

Femur:  Gruen Zones

 

AP 1-7

Zone 1:   Greater trochanter

Zone 4:   Tip

Zone 7:   Lesser trochanter

 

Lateral 8-14

Zone 8:   Anterior-superior

Zone 11: Tip

Zone 14: Posterior-superior

 

Charnley Zones

 

Acetabulum: Charnley Zones

 

Zone 1:  Superior 1/3

Zone 2:  Middle 1/3

Zone 3:  Inferior 1/3

 

Loosening

 

Concepts

 

1.  Easier to identify loosening in femur than acetabulum

- femur 90% accuracy

- acetabulum 65% accuracy

 

2.  More difficult to identify in uncemented prosthesis

 

3.  Lucent lines don't necessarily represent problem

- may be present in well-fixed prosthesis (retrieval studies)

- often due to remodelling 

 

Cemented Femur

 

Signs of cemented femoral component loosening

O'Neil & Harris JBJS Am'84

 

1.  Possible

 

Bone-cement lucency < 50% total

- may be due to poor cementing technique

- loosening if progressive

 

Cemented Femur Possible Loose

 

2.  Probable

 

Cement-implant radiolucent line >2mm wide

- progressive

 

Cemented Femur Probably Loose

 

3.  Definite

 

1.  Cement fracture

2.  Femoral stem fracture

3.  New lucency cement - implant interface

4.  Stem migration 

 

THR Probably LooseTHR Exeter Stem Fracture

 

A.  Subsidence

- 1-2 mm normal in first year

- > 5 mm abnormal

- measure from tip GT to head neck junction

 

B.  Medial midstem pivot

- pivots about midstem

- proximal medial, distal lateral

- poor cement superomedial or inferolateral

 

C.  Calcar pivot / bending cantilever

- distal fix strong, but proximally loose

- breakdown of proximal cement

- bone destruction

 

Uncemented femur

 

Engh classification

 

Types based on presence of radiolucent lines (RLL)

 

I.  Stable bony ingrowth

 

Take one year to see

A.  Spot welds at end of porous coating

B.  Absence of RLL next to porous coating

- may have RLL next to non porous coated areas

C.  Calcar atrophy secondary to stress shielding

 

THR Uncemented Proximal Stress ShieldingTHR Uncemented Stem Spot Weld APTHR Uncemented Stem Spot Weld Lateral

 

II Stable fibrous ingrowth

A.  No spot welds

B.  Parallel sclerotic lines / RLL about porous coating

C.  No migration

 

THR Uncemented Stem Stable sclerotic lines

 

III Unstable fibrous ingrowth

A.  Component migration

B.  Progressive increase RLL

- divergent RLL

C.  Pedestal formation (bony hypertrophy at tip)

 

THR Uncemented Subsidence

 

Uncemented Acetabular Component

 

Concepts

 

Bone ingrowth into component averages only 12% 

- even with 84% bone contact

 

Non continuous radiolucent lines 

- commonly found in press fit acetabular components 

- are often not progressive

 

Radiographic signs of ingrowth fixation

 

Moore et al CORR 2006

- 3 or more 97% stable

- 2 or less, 83% unstable

 

Five signs

- absence of radiolucent lines

- presence of a superolateral buttress

- medial bone stress-shielding

- radial trabeculae

- inferomedial buttress

 

THR Uncemented Cup Superolateral Buttress 2

 

Radiographic signs of loosening

 

5 signs

- radiolucent lines that appear after two years

- progression of radiolucent lines after two years

- radiolucent lines in all three zones

- radiolucent lines 2 mm or wider in any zone

- migration > 2mm

 

Loose Uncemented CupLoose Uncemented Cup 2

 

Engh Classification

 

I  Osse-ointegration

 

A  No RLL

B  One RLL zone 1 or 2

C  RLL zones 1 & 2

 

THR Uncemented Cup Stable RLL Zone 1Uncemented Cup No RLL

 

II Stable fibrous ingrowth

- <2mm zone 3

 

Uncemented Cup Stable Fibrous Ingrowth

 

III Unstable fibrous ingrowth

- >2mm RLL in zone 3

B Assessment Bone Loss

IndicationsRevision THR CT scan Bone Defects

 

1.  Loosening
2.  Infection
3.  Instability
4.  Periprosthetic fracture


Objective


1.  Exclude infection
2.  Re-establish the structural integrity & bone stock
3.  Establish normal Joint mechanics
- restore the centre of rotation of the hip
4.  Initial rigid fixation of bone graft
5.  Adequate containment of the new prosthesis

 

Aetiology Bone Loss


1.  Osteolysis
2.  Surgical / iatrogenic (with implant removal)
3.  Acetabular dysplasia
4.  Fracture
5.  Infection

 

Preoperative Assessment


1.  Exclude infection
2.  Quantify bone loss

 

Classifications

 

Femoral

- Paprosky

- AAOS

 

Acetabular

- AAOS
- Paprosky

 

Femoral Bone Loss

 

Paprosky Classification
 

I Minimal metaphyseal cancellous bone loss / intact diaphysis
- i.e. seen after removal of uncemented component without biological ingrowth on surface
 

II Extensive metaphyseal cancellous bone loss / intact diaphysis
- often seen after removal of cemented prosthesis

 

Revision THR Paprosky II FemurRevision THR Paprosky II


IIIA Metaphysis severely damaged / > 4cm diaphyseal bone for distal fixation
- grossly loose femoral component
- first generation cementing techniques

 

Revision THR Paprosky IIIA FemurRevision THR Paprosky IIIA 3


IIIB Metaphysis severely damaged / < 4cm diaphyseal bone for distal fixation
- cemented with cement restrictor
- uncemented with substantial distal osteolysis

 

Infected THR Paprosky Type IIIA


IV Extensive metaphyseal and diaphyseal bone loss / isthmus non supportive

 

AAOS Classification


I Segmental
- proximal (partial or complete)           
- intercalary
- greater trochanter


II Cavitary
- cancellous
- cortical
- ectasia (dilatation)


III Combined segmental and cavity


IV Malalignment
- rotational
- angular


V Femoral Stenosis


VI Femoral Discontinuity

 

Acetabular Bone Loss
 

AAOS Classification


Type I    Segmental deficiencies

Peripheral -  superior / anterior / posterior

Central - medial wall absent

 

Revision THR Anterior wall segmental defect


Type II    Cavitary deficiencies


Peripheral  -  superior / anterior / posterior
Central - medial wall intact

 

Revision THR Cavitatory Deficiency CupRevision THR Contained Defect Cup CTRevision THR Cemented Cup Anterior Wall Intact


Type III    Combined deficiencies


Type IV     Pelvic discontinuity

 

Separation of anterior and posterior columns


Type V    Arthrodesis

 

Paprosky Classification


Based on ability of the remaining host bone

- to provide initial stability to a hemispherical cementless acetabular component

- until ingrowth occurs


Type 1    

 

Undistorted rim
- anterior and posterior columns intact
- no superior migration

- may have some contained deformities
- ishium, teardrop and Kohlers line intact


Type 2

 

Distorted but intact rim
- can support a hemispherical cementless implant

 

Revision THR Paprosky Type 2 Cup

 

Some distortion, minimal superior migration
- at least 50% good support by host bone
- anterior and posterior columns intact
- no substantial osteolysis of ischium or teardrop

 

2A

- superomedial migration but superior rim intact

 

Revision Acetabulum Paprosky Type IIA

 

2B

- < 1/3 superior deficit

- remainder is still supportive

- replace with allograft for bone stock

 

2C

- medial migration to Kohlers, but wall intact

- rim is supportive

- manage as for protrusio

 

Revision Acetabulum Paprosky Type IICRevision THR Superior Migration Cup but Rim intact


Type 3

 

Non supportive rim
- columns not supportive, superior migration> 3 cm

- require structural allograft for support

 

Revision THR Type 3 Acetabulum


4 radiographic criteria


1.  Superior migration of the hip centre
- indicates damage to anterior and posterior columns
- supero-medial indicates greater damage to anterior column
- supero-lateral indicates greater damage to posterior column


2.  Ischial osteolysis
- bone loss inferior posterior column


3.  Teardrop osteolysis
- inferior anterior column and medial wall


4.  Position of the implant relative to Kohler’s line
- deficiency of anterior column

 

3A

-  > 40% host bone contact

-  < 50% rim missing

 

3B

- < 40% host bone contact

- > 50% rim missing

 

 

C Approach and Implant Removal

Pre-operative Planning


CT / quantify bone loss
X match 4 units
Cell saver
Anaesthetic review
Bone graft (cortical, cancellous)
Component removal gear

- extraction gear for femur / liners

- cement removers for cemented femur

- curved osteotomes for cemented cup

- X-plant for uncemented cup
Revision long stem femoral implants
Revision acetabular implants including cages

 

Exposure


Posterior approach
- often easiest in revision
- good for ETO

 

Recreate fascial and muscular layers

- aids exposure and closure

Wide exposure of hip joint
- removal of all pseudocapsule
- expose entire proximal femur & acetabulum

 

Extended Trochanteric osteotomy

 

Concept

 

Osteotomy lateral 1/3 to 1/2 of trochanter / femur

- posterior to anterior longitudinal cut

- short distal transverse cut

- levers / hinges open anteriorly

- maintains anterior vasculature / muscle attachment

 

Indications


1.  Aid exposure
2.  Removal cement (especially infection)
3.  Removal well fixed uncemented prosthesis
4.  Removal cement plug / bone very poor / risk of perforation high
5.  Abnormalities of the proximal femur


Contraindications / Relative


1.  Impaction bone grafting
2.  Cementing revision prosthesis

 

Technique ETO
 

Length
- measured from tip GT
- 2 – 15 cm long
- need to preserve diaphysis if using distal press fit uncemented stem


Timing
- usually after implant removal
- may not be possible


Site
- elevate vas lateralis forward
- expose linea aspera
- expose posterior femur


Osteotomy
- use drill holes to mark osteotomy

- drill both cortices
- thin oscillating saw
- cut down through anterior and posterior femur in line with GT
- through both cortices
- transverse cut distally through 1/3 diameter
- lever open


Fixation
- 3 x cerclage cables, tension
- protect sciatic nerve
- submuscular

 

Results
 

98 – 100% union rate by 6/12

 

Removal Femoral Implant


A.  Cemented

 

Initially

- must clear shoulder of prosthesis
- must ensure no GT overhang or will fracture on removal


Extraction devices
- stem often easily removed if cemented
- extraction devices hook around proximal prosthesis & backslap
- can release cement – implant interface
- combination flexible osteotomes, micro sagittal saw, small burr


Cement removal
- aided by ETO
- use arthroscopy light down femur


Cement removal kit
- flexible osteotomes, reverse hooks, cement splitters
- split cement radially & then removed
- can use high-speed burr
- may require distal window


Removal of cement plug
- remove proximal cement
- drill guide in centraliser
- insert tap, then extract

 

Need to be very careful to avoid inadvertant perforation


B.  Uncemented


Can be very difficult to remove a well fixed stem

- i.e. if removing for infection


Consider component design
- proximally coated
- extensively coated


Breakdown osseointegration
- flexible osteotomes
- sagittal saw
- very difficult
- can perform ETO about stem


Extraction devices

- company specific

- hook under neck

 

Broken Stems
- stem is invariably well fixed distally
- osteotomy to site of fracture
- +/- distal window


Acetabulum Removal

 

Acetabular revision only


1.  Leave femoral component in situ

 

Indications

- femur not loose / damaged / good orientation

- need to be able to match new cup / poly to femoral head

 

Technique
- can remove head if modular (use company device to lever off)
- make anterior pocket for femoral stem

- protect trunion with swab

 

Note

- can be a problem putting a ceramic head on an old trunion

- if needed, can get a ceramic head with a metal liner for trunion


2. Removal of cemented Femoral component / Re-cement a smaller prosthesis into a well fixed cement mantle

 

Revision Cup Only Cement in Cement Femur PreRevision Cup Only Cement in Cement Femur Post


Removal
- as above

 

Re-cement prosthesis

- ensure cement mantle clean and dry

- trial small component

- cement in cement revison with high viscosity cement

- insert cement when very viscous

- put in new prosthesis very early

 

Removal Cemented Acetabulum


1.  General principle is to loosen poly cup from cement
- do so with curved gouges
- between cement & cup
- cement then removed piecemeal


2.  Can simply ream out the poly


3.  Insert threaded extractor through drill hole in poly
- then disimpact poly from cement

 

Uncemented Acetabulum


Options
- may just be changing liner and leaving cup
- may need to remove well fixed cup i.e. infection

- may be removing loose cup


Liner

1.  Company specific removal instruments
- need to disengage locking mechanism


2.  Simply lever out liner with osteotomes


3. Drill hole in liner 4.5 mm
- insert 6.5 mm screw to push liner out


Metal Shell

1.  Curved osteotomes
- risk bone loss


2.  Zimmer Explant Acetabular Removal System
- 3 sizes depending on implant size
- central head to sit in liner
- must remove screws first, then replace liner
- diamond blades cut between cup and bone
- initial blade short
- second is thin and full radius
 

Intrapelvic acetabulum / cement

 

Intrapelvic Cement

 

Issue


Can be life threatening if just pulled out from standard approach
 

Workup


Preoperative contrast studies

General surgeon / vascular surgeon available

 

Options


A.  No aneurysm
- lateral window of ilioinguinal
- elevate iliacus subperiosteally from table of ilium
- remove under direct vision


B.  False aneurysm
- Rutherford Morison approach
- general / vascular surgeon

 

 

D Reimplantation Acetabulum

Principles of Acetabular reconstructionRevision Acetabulum Post Paprosky Type IIIC

 

Restore centre of rotation
Restore acetabular integrity
Component containment
Secure fixation


Preoperatively planning


Know components in situ (esp if leaving femur)
Quantify and grade bone defects
Beware intrapelvic cement / cup (angiogram)

 

Basic Guidelines

 

> 50% host bone contact

- use press fit uncemented cup augmented with screws

 

< 50% host bone contact

- use metal augment in elderly to reconstruct defect

- use allograft augment in young to reconstruct defect

- press fit cup if able

- otherwise must use cage


Paprosky Type I, II A and B

 

I Rim intact

II A Mild superior migration / superior rim intact

II B < 30% superior rim missing


1.  Uncemented Jumbo rim fit cup


Indications
- > 50% host bone available for ingrowth
- > 2/3 rim intact


Technique
- implant in usual position
- preferentially ream anteriorly
- preserve posterior column
- some uncovering superiorly allowed
- usually augment with screws
- +/- postoperatively NWB 6/52


Results
- 12-15 year survival between 81-96%

 

Revison THR Type I AcetabulumRevision THR Jumbo Cup 2

 

2.  Impaction Bone Graft +/- Mesh + Cemented Cup

 

Revision Acetabulum Type IIIBRevision Acetabulum Type IIB Superior Mesh and Impaction Bone Graft

 

Type IIC

 

Type IIC: Medial wall deficiency but intact


Options


A.  Particulate graft medially, jumbo cup

 

Revision THR Type IIC AcetabulumRevision THR IIC Jumbo Cup + medial bone graft

 

B. Impaction bone graft, cemented cup

 

Revision Acetabulum Type IICRevision Acetabulum Type IIC Impaction Bone Grafting

 

C.  Cement +++

 

Indicated in elderly patients

 

Revision Acetabulum Type IIcRevision Acetabulum Cement +++

 

Segmental Medial Wall deficiency


A.  Allograft + Antiprotrusio Cages + Cemented Cup

 

Types
- Ganz / Muller / Burch Schneider

- variations on them

- hook or screws into ilium

- hook or screws onto ischium

- can have extension for screws onto pubis

 

Revision THR Burch Schneider Cage
 

B.  Mesh + Impaction Bone grafting

 

Type IIIA defects

 

Type IIIA

- Rim < 50% missing, > 40% host bone contact

- want to reconstruct defect but don't need cage

 

1.  Uncemented rim fit cup / screws / Structural bone graft


Indications
- defect superolateral rim < 50% to support cup
- > 50% host bone contact

- allograft will not grow onto uncemented cup

- allograft to reconstuct defect


Technique
- femoral head allograft reconstruction (no 7 shape)
- fix with 6.5 mm screws
- tap first to prevent fracture
- ream into bone


2.  Impaction bone graft +/- mesh + cemented cup
 

Revision THR Type IIC AcetabulumRevision THR Impaction Bone Graft Acetabulum

 

Technique


1.  If required, convert uncontained defect into contained defect
- use titanium mesh fixed with screws
- acetabular rim or medial wall mesh (Stryker)

 

Revision THR Type IIIC Acetabulum Mesh Impaction Bone GraftRevision THR Type IIIA Acetabulum Pre IBG


2.  Impact morcellised cancellous bone graft
- tamps or reverse reaming
- progressively smaller impactors
- need 5 mm of bone graft


3.  Insert prosthesis / Cemented poly liner


Results


- 85% 12 year survival
- 80% 15 year survival


Important Points


1.  Rigorous technique important


2.  Fresh frozen allograft
- does this perform better than irradiated BG


3.  TWB 6 – 12/52

 

3.  Trabecular metal components


New material made of element tantalum

1.  Interconnecting porous material
- 80% porous
- allows 2-3 X bony ingrowth


2.  Less stiff
- improved remodelling of BG underneath


3.  High cancellous bone coefficient of friction
- excellent initial stability
- may need less than traditional 50% host bone contact
- may not need screws


Ream host bone for press fit cut
- trial then secure trabecular augment with screws
- press fit cup with cement between augment and cup
- screw augmentation of cup
 

4.  Bilobed uncemented acetabular components

 

Bilobed Revision Cup


Indications
- superolateral deficiency
- revision
- DDH cups


Problems
- can be difficult to get version right
 

Type IIIC

 

Type IIIC

- < 50% rim intact, < 40% contact

- must reconstruct for stability

- unable to use uncemented component

- use bone graft to reconstruct

- need cage for stability

 

1.  Structural Allograft + Cage

 

Revision Acetabulum Bulk Structural Allograft + Cage


Indications
- when inadequate bone stock precludes the use of uncemented acetabular components


Theory
- cannot implant onto allograft
- graft under the cage
- secure with cage
- cement poly into it


Technique
- allograft reconstruction of rim with femoral head
- allograft particulate material in base
- secure cage to posterior column ilium and ischium
- 3 screws in each
- cement all poly cup into cage


Results
- 75% 10 – 15 year survival
 

Option:  Custom-made triflange components


CT guided model of pelvis
- custom made acetabular cage
- fits defect exactly
- flanges perfectly designed and not malleable to improve strength
- HA coated
- cement poly cup into it


Indications
- massive defects


Results
- 90% 4.5 year survival in complicated patients

 

2.  Impaction Bone Graft +/- Mesh + Cage + Cemented cup

 

Revision THR Type 3B AcetabulumRevision THR Acetabular Mesh Bone Graft Cage

 

Pelvic discontinuity

 

Revision THR Pelvic Discontinuity0001Revision THR Pelvic Discontinuity 2Revision THR Pelvic Discontinuity 3


1.  Plate and bone graft posterior column

 

Revision THR Plate Posterior ColumnRevision THR Plate Posterior Column Lateral


2.  Plate + Cage reconstruction
 

 

3.  Cup Cage Reconstruction

 

Technique

- large tantalam cup inserted for reconstitution of discontinuity

- bone graft inserted

- cage, cement in cup

 

Revision THR Cup Cage0001Revision THR Cup Cage0002Revision THR Cup Cage0003

 

E Reimplantation Femur

Implant Options

 

1.  Long stem cemented revision femoral stem

 

Modern cementing techniques
- removal of neocortex


Advantage
- use in all cases
- good with elderly fragile bone
- can use Abx cement (decreases infection rate)


Indications
- Paprosky Types I – IV
- very versatile

 

Technique

- complete removal / debridement of neocortex

- modern cementing techniques


Howie JBJS Br 2007
- 219 patients, 9 year follow up
- collarless double taper
- 98% 10 year survival


Problems
- ? increased non union with ETO

 

2.  Extensively porous coated diaphyseal fitting uncemented stem


Indications
- Paprosky Types I, II, IIIA


Results
- 90- 95% 10 year survival


Problems
- fracture
- stress shielding with additional proximal bone loss
 

3.  Modular diaphyseal fitting, proximal filling uncemented stem

 

Revision THR Modular Long Stem UncementedModular Revision Implants


Design
- press fit metaphyseal segment
- slotted diaphyseal segment
- initial stability through distal fixation


Indications
- Paprosky Types I – IIIB


Smith J Athroplasty 1997
- nil revisions at 5 years
- 7% radiographically loose
 

Type 3 Revision Femur 2

 

4.  Impaction bone grafting


Concept
- morcellised bone graft is osteoconductive, not osteoinduction
- resorption and eventual replacement new bone
- 6 – 12 months
- process is incomplete
 

Van der Donk Clin Orthop 2002
- 30% complete 6/12

- 90% complete 12/12

 

Requirements
1.  Particulate cancellous autograft 7-10 mm
2.  Contained defect
3.  Ability to convert uncontained into contained (i.e. mesh)


Issues
- technically demanding
- takes time
- need axial and rotational stability
- avoid stem subsidence > 5 mm


Indications
1. Uncemented distal fixation not possible (< 4cm diaphysis)
2. When reconstruction of proximal bone stock important
- young patient in whom biological solution more desirable


Technique


Templating
- choose stem 2 cortical diameters longer than most distal lytic area


Exposure
- full exposure of proximal femur
- removal stem & cement

 

Can leave distal plug
- not infected
- > 2 cm past planned tip location


Create contained defect
- reconstitute femoral tube
- create contained defect
- wire mesh & cerclage wire
- prophylactically cerclage wire shaft if diaphysis flimsy


Distal Occlusion
- threaded intramedullary plug inserted on guide rod
- impacters tested to see max depth of insertion before abutment on canal
- morsellised allograft inserted
- impactor & slap hammer slid over guide wire
- graft impacted to predetermined depth
- continued by introducing more chips with larger impacters
- stopped when level is 10 cm from tip of GT


Proximal Impaction
- appropriate proximal impactor equivalent to selected stem used
- used to force chips against walls of canal
- then larger distal impactor used
- alternated till canal filled
- should be firm neo-canal


Trial Reduction
- trial stem inserted
- depth of insertion marked
- proximal impactor driven in another 5 mm
- creates room for cement


Prosthesis
- cemented polished collarless double tapered stem


Post-op
- NWB for ? 3/52
- then gradual inc over next 3/ 12


Results


Halliday JBJS Br 2003
- 90.5% 10 year survival

Elting Clin Orthop 1995
- 93% graft incorporation
- stem subsidence in 48%

Elridge JBJS Br 1996
- > 5 mm subsidence in 22%

 

Management Plan


Assess Metaphyseal & Diaphyseal Bone Stock

Grade Paprosky, then manage appropriately


Paprosky Type 1

 

Definition


Minimal metaphyseal cancellous bone loss
Intact diaphysis     


Options

 

Simple revision
- can use standard or any revision stems


A. Uncemented
- standard length proximal fit and fill
- need appropriate initial stability


B. Cemented standard length stem
- must remove neocortex
- need good cement interdigitation

Izquierdo JBJS Br 1994
- 90.5% 19 year survival

 

Revision Femur Type 1 Standard Cemented Stem Pre opRevision Femur Type 1 Standard Cemented Stem Post op


C. Cement onto old mantle
- clean and dry mantle critical
- thin layer of blood 85% reduction shear strength

Lieberman et al JBJS Br 1993
- 19 cases
- no loosening at 5 years in all

 

Revision Femur Paprosky 1 Revision Femur Paprosky 1 Cement in old Cement Mantle

 

Type 2

 

Definition


Extensive metaphyseal cancellous bone loss
Diaphysis intact


Options

 

A.  Extensively porous coated diaphyseal fitting implant


Paprosky 90& osteointegrated

 

Calcar Replacement Uncemented Stem


B.  Long stem cemented revision stem

 

Revision Femur Long Stem Cemented Femoral Component


C.  Modular diaphyseal fitting, metaphyseal filling uncemented prosthesis


D.  Impaction bone grafting

 

Type 3A

 

Definition


Metaphysis non supportive
> 4 cm diaphysis proximal to isthmus

 

Type 3 A FemurType 3A Femur Lateral


A.  Extensively porous coated diaphyseal fitting implant

 

Type 3 Revision Femur


Paprosky 20/22 91% osseointegrated


B.  Long stem cemented revision stem

 

Revision Femur Long stem Cemented Component


C.  Modular uncemented

 

D.  Impaction bone grafting

 

Revision Femur Type IIIA Pre Impaction Bone GraftingRevision Femur Type IIIA Post Mesh and Impaction Bone Grafting

 

Type 3B

 

Definition


Metaphysis non supportive
< 4cm diaphysis proximal to isthmus

 

Options


A.  Extensively coated diaphyseal fitting

Paprosky 4/8 failed

- i.e. need > 4cm of diaphysis for this to work


B.  Long stem cemented revision stem


C.  Modular uncemented, stem with flutes for rotational stability


D.  Impaction bone grafting

 

Revision Femur Type 3 Mesh and Impaction Bone Grafting

 

Type 4

 

Definition


Metaphysis and diaphysis extensively damaged
Isthmus non supportive

 

Options


A.  Long stem cemented revision stem


B.  Impaction bone grafting

 

Management Bone Defects

 

1.  Segmental defects


A.  Must bypass any cortical defect by two cortical diameters to reduce fracture risk

B.  Cortical Strut onlay grafts
 

2.  Extensive proximal bone loss

 

A.  Calcar replacing

 

Calcar Replacing THRCalcar Replacing Hip Replacement


Indications
- proximal segmental defect < 3cm


McLaughlin JBJS Am 1996
- 38 hips 11 years
- 80% survival
- another 10% radiologically loose
- 20% dislocation rate

 

B.  Napkin ring  / Calcar graft Allograft


Indications
- circumferential proximal defects < 3cm


Results
- poor
- 40-60% resorption

 

C.  Proximal Femoral Replacement / Tumour prosthesis


Results disappointing
- however design may be improving


Malkani JBJS Br 1995
- 33 hips 11 years
- poor function (50% severe limp or unable to walk)
- 64% 12 years survival
- 22% dislocation

 

D.  Bulk Structural Proximal Femoral Allograft


Indications
- proximal defect > 3 cm


Technique
- desired stem cemented into allograft
- press fit distally into host femur
- step cut graft host junction
- secure cerclage wire and onlay cortical strut
- proximal host bone wrapped around allograft with ABD preservation

- very important – abductor mechanism must be secured and protected


Gross 1998
- 200 patients, 5 years follow up
- 12.5% revision
- revised for infection, dislocation, graft-host non union

 

Transient Osteoporosis Hip

Definition

 

Self limiting syndrome of unknown aetiology

- hip pain associated with osteoporosis of proximal femur 

 

DDx

 

AVN

- AVN of the hip in pregnancy is rare but possible

- TOH tends to be diffuse on MRI, while AVN is localised

- extends to neck and metaphysis

- transient osteoporosis has normal bone scan

 

Incidence

 

Rare

- M: F 3:1

 

Two Groups

1. Men 40-50 years old

2. Women usually 3rd trimester of pregnancy

 

Aetiology

 

Unknown / Theories

- ischaemia

- RSD

- virus / toxin

 

Only predisposing factor is pregnancy

 

Pathology

 

Biopsy shows many features in common with AVN, but it is non-specific

- edematous fluid & marrow

- inflammation

- fat necrosis

- reactive bone formation

- widely spaced trabeculae

 

Clinical Features

 

Acute onset

- AVN tends to be insidious

 

Mechanical hip pain

- usually FROM

 

Rarely sub-capital fracture results

 

Natural History

 

Three distinct temporal phases

 

1. Initial 

- sudden onset severe pain

- disability >> signs

- lasts 1/12

 

2. Plateau

- symptoms stabilise

- osteopenia seen on xray

- lasts 2/12

 

3. Regression

- lasts 3/12

 

X-ray

 

Shows diffuse osteopenia of entire proximal femur 

- 1/12 after onset

- may have "Phantom" appearance of proximal femur 

- rarely the pelvis can be affected too

 

MRI

 

Key is that with TOH the MRI changes are diffusely affecting the proximal femur

- AVN it is localized to a portion of the head

 

Marrow oedema

- TI decreased SI 

- T2 increased SI due to oedema

 

DDx

 

Radiologically 

 

AVN

Osteoporosis 2° joint disease

Metabolic cause osteopenia

Permeative - neoplasia 

 

Management

 

Pregnancy

 

NHx

 

Self limiting condition

- rapidly improves after delivery

 

Need to prevent fracture

- protected weight bearing in pregnancy

 

NOF

 

Management

- simultaneous pinning & LSCS

 

Non pregnancy

 

Bisphosphonates

 

Varenna et al Bone 2002

- 16 cases treated with IV pamidronate

- resolution of symptoms and normalisation of MRI findings

 

 

 

Trochanteric Bursitis & Gluteus Medius

Trochanteric Bursitis

 

Mechanism

 

Repetitive friction of iliotibial tract over GT

 

Aetiology

 

Overuse in athletes

Common post THR

 

May be associated with gluteus medius tears

 

Symptoms

 

Pain over upper lateral thigh with activity

- often related to hip flexion

 

Examination

 

Localised tenderness & swelling over & posterior to GT

 

Pain with resisted abduction

 

DDx

 

Tears in gluteus medius

Stress fractures

Iliopsoas tendonitis

Intra-articular hip pathology

Spinal pathology

Tumour

 

MRI

 

May demonstrate fluid in bursa

 

Non operative Management

 

HCLA injection

- virtually all respond to HCLA but may need several

- almost never need surgery

 

Operative Management

 

Bursectomy

 

Baker et al Arthroscopy 2007

- arthroscopic resection bursa in 30 patients

- successful in all but one who went on to have a successful open bursectomy

 

Bursectomy + ITB lengthening

 

Craig et al ANZ J Surg 2007

- open proximal Z lengthening ITB in 17 patients

- one poor result

- one patient had a secondary repair gluteus minimus with excellent result

 

Distal ITB lengthening

 

Pretell Int Orthop 2009

- distal lengthening in 13 patients average age 50

- 12/13 good results

- 1 post op seroma

 

Tears Gluteus Medius and Minimus

 

Aetiology

 

Sporting injuries

Falls

LLD

 

Diagnosis

 

MRI

 

Ultrasound

 

Non operative Management

 

Rest / physio

- stretching +++

- eccentric exercises

- correction of LLD with shoe lift

 

HCLA

 

ECSW

 

PRP

 

Operative Management

 

Technique

 

Repair of tears + bursectomy

- open or arthroscopic

 

Results

 

Voos et al Am J Sports Med 2009

- arthroscopic repair tendon tears in 10 patients

- all had complete resolution of symptoms

 

Lequesne Joint Bone Spine 2008

- open repair in 8 patients

- lateral tears of gluteus medius all seen on MRI

- 3 gluteus medius tears were not seen on MRI

- good results in 7/8 patients