THA

Indications for THA

Osteoarthritis

- abnormal morphology

- loss of head neck offset

- bony impingement on acetabulum

AVN

Acetabular trauma and PTOA

Types

1.  Standard trochanteric osteotomy

2.  Sliding trochanteric osteotomy

3.  Extended trochanteric osteotomy

Standard Trochanteric osteotomy

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

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

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

Definition

Chronic, non metabolic bone disorder

Characterised by increased bone resorption, bone formation and remodelling

Epidemiology

Rare < 40

1 – 3 % population over 60

M > F

Aetiology

Unknown

Paramyxovirus implicated

- measles

- RSV

- canine distemper virus

Electron Microscope

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

Cemented cup and femur via posterior approach

Set up

- on side

- charnley supports posterior on sacrum

- anteriorly on ASIS

- patient slightly tilted backwards

- avoids cup retroversion

Posterior Approach

- identify short ER

Goal

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