PatelloFemoral Joint

Acute Patella Dislocation

Acute Patella DislocationPatella Dislocation Skyline




1. Direct lateral blow to patella

- usually with knee partly flexed and quadriceps relaxed


2.  Indirect low energy injury




2 Groups of Patients


1.  Patients with no predisposition to patella instability

- traumatic injury

- contact sports


2.  Patients with anatomic predisposition to instability

- atraumatic / minimally traumatic injury

- young / valgus malalignment / ligamentous laxity / malrotation


Associated injuries 


Osteochondral fracture (40-50%)

- LFC or medial facet patella

- patient will have haemarthrosis

- must identify this group, investigate and manage appropriately




Medial Patellofemoral Ligament (MPFL)

- from MFC between femoral epicondyle and adductor tubercle

- to superolateral border patella

- deep to retinaculum / superficial to capsule


Usually tears off femur


Acts as a checkrein to lateral patella subluxation

- will usually be torn in all patients with patella dislocation


Recurrence rate



- more likely in those predisposed to instability


Reduction technique


Conscious sedation

- knee extended

- medial force on patella

- usually reduces easily

- splint




Haemarthrosis post reduction

- investigate further




AP / Lateral / Skyline

- examine carefully for loose body


Knee Xray Loose Body




Shows loose body and origin





- MPFL tear

- cartilage damage

- loose body


Patella Dislocation Chondral Damage Medial Facet PatellaPatella Dislocation MRI MPFL Disruption Patella SidePatella Dislocation MRI Loose Body Notch


Knee Loose Body PFJPatella DIslocation MRI OCD LFC MPFL Patella Chondral Damage




Non operative




1.  First time dislocator with no associated injury

- splint in full extension with lateral patella pad

- reapproximate torn medial structures

- 4 weeks

- then begin VMO exercises +++


2.  Recurrent dislocator

- splint only initially for symptom relief

- early ROM and rehabilitation

- no role for long term splintage





- loose body

- management of OCD Lesions

- +/- early MPFL repair




Assess Patella and Femoral Lesions


1.  Small pieces cartilage

- remove loose bodies

- microfracture if necessary


Patella Dislocation Loose BodyPatella Small Chondral Lesion


2.  Large Osteochondral Fragment

- usually medial patella or lateral femur

- open approach to knee

- reduce and fix with bioabsorbable compression screws / pins


3.  Large Chondral piece with minimal or no bone

- can attempt suture fixation

- need to warn of risk of failure and need for reoperation

- careful monitoring


4.  Large irreparable chondral lesion

- remove loose body

- microfracture / abrasion initially

- if continue to be asymptomatic, consider alternative procedure

- MACI / mosaicplasty


Patella Dislocation Unsalvageable Chondral LesionPatella Dislocation Removal Medial Facet Cartilage


Early MPFL repair


Patella Dislocation MPFL Disruption Patella Arthroscopy



- ? would recurrence rates be reduced with early repair / reconstruction MPFL




Palmu et al JBJS Am 2008

- RCT of early operative treatment in adolescents < 16

- very high rates of recurrence in both groups (70%)

- up to 50% of this group had contralateral patella problems


Silanpaa et al Am J Sports Med 2008

- compared operative and non operative treatment

- all operative patients had arthroscopic repair of medial retinaculum

- equal (20%) redislocation in each group


Christiansen et al Arthroscopy 2008

- RCT comparing non operative to open MPFL femoral repair

- redislocation rates the same in each group


Camanho et al Arthroscopy 2009

- RCT of operative v non operative

- excluded patients with flat trochlea / valgus > 15o / patella alta

- in surgical group determined if injury on patella side or femoral side

- 7 from patella repaired arthroscopically

- 10 from femur repaired open with anchors

- 0/17 in surgical group redislocated

- 8/16 in surgical group redislocated




1.  Can repair MPFL but if anatomically predisposed to instability

- will still redislocate and rerupture MPFL

- exclude valgus / alta / flat patella


2.  If attempting early repair, need to address specific MPFL pathology


Open Technique


Very important to determine if torn from patella or medial epicondyle

- MRI very useful


Medical epicondyle avulsion

- over medial epicondyle

- divide deep fascia

- elevate VMO

- identify MPFL

- repair using bone anchors


MPFL repair medial epicondyle


Arthroscopic technique


Pass spinal needle medial to patella

- insert 1 PDS

- retrieve laterally with loop retriever

- repeat multiple times

- mini - incision and tie from outside in




Bipartite Patella



Patella may develop from one or multiple ossification centres at 3 years


Failure of centres to fuse may produce bipartite or tripartite patella

- usually bilateral and painless


Classically superolateral


Classification Saupe


I   Inferior Pole 5%

II  Lateral 20%

III Superolateral 75%


Bipartite patella SuperolateralBipartite patella




Bipartite Patella CT




1.  Overuse

- pain may result from repetitive microtrauma 

- injury to synchondrosis

- point tender & swollen


2. Acute injury

- can get acute injury with minor separation

- reports of bipartite patella healing post injury

- check SLR to ensure quadriceps tendon intact





- confirms quadriceps tendon intact

- look for increased uptake ? symptomatic


Bipartite patella MRI


Bone scan

- shown to have increased uptake in symptomatic / asymptomatic knees




Non operative Management


Majority will settle with non operative management

- mmobilisation for 4 weeks

- avoid impact sports


Ultrasound / Exogen

- reports of healing bipartite patella post injury


Operative Management




Lateral release


Adachi et al Arthroscopy 2002

- lateral release performed

- excellent results in 13 and good in 4

- nearly 2/3 healed and remainder partially healed

- bone union more likely in patients < 15


Mori et al Am J Sports Med 1995

- 15/16 united at 8 months post lateral release


Removal of bipartite patella

A. Open

- easiest

- often need to reattach quadriceps tendon with anchors


B. Arthroscopic


Bipartite PatellaBipartite Patella

Chondromalacia Patellae



Patella Chondromalacia


Softening and fibrillation of articular cartilage of patella



- softening and fibrillation often seen in asymptomatic population

- can have typical anterior knee pain without retro-patellar changes




Female adolescent

- recent increase in activity


Query on continuum to OA

May be a separate pathology




Unknown / varied





- direct trauma

- PFJ dislocation



- PFJ instability

- LPPS (lat patellar pressure syndrome)

- quadriceps imbalance

- VMO weakness




Idiopathically abnormal cartilage unable to tolerate load

- inflammatory arthritis

- recurrent haemarthrosis

- sepsis



- repeated intra-articular steroids

- prolonged immobilisation



- primary OA




Basal degeneration of cartilage at deep level

- pain due to nerve endings in subchondral bone being stimulated by variations in pressure


Different to pathology of OA

-"Basal Degeneration" compared with surface 




Grade 1 

- localised softening with no break in surface


Grade 2 

- fibrillation or fissured


Patella Fibrillation ArthroscopyPatella Grade 2 Chondromalaciae


Grade 3 

- fissuring to bone

- crab meat appearance


Patella Grade 3 ArthroscopyChondromalacia Patella Grade 3


Grade 4 

- bone exposed / full thickness chondral defect


Patella Grade 4 Arthroscopy





- dull aching discomfort anterior knee

- cinema sign / sitting flexed generates pain

- stairs

- catch & pseudo-locking

- swelling




PFJ crepitus

- seen in 60% asymptomatic teens


Exclude malalignment




Exclude malalignment







Quadriceps exercises

Activity modification

Cut out brace & taping

Hyaluronic acid injections






Patellar Shaving


Federico et al Am J Sports Med 1997

- arthroscopic shaving in 36 patients with grade 2 or worse

- no malalignment

- all had some improvement

- only 50% good or excellent result


Full thickness chondral defect


Local Excision & Subchondral Drilling / Abrasion


Lateral Release




Gobi et al Am J Sports Med 2009

- chondral lesions on patella and trochlea

- all had reasonable symptomatic results

- tended to decline over time in patella and with multiple lesion





DDx Anterior Knee Pain



Jumper's knee / Tendonitis



- prepatellar most common

- Pes anserinus 


Excessive Lateral Pressure Syndrome / Patella Tilt


Hoffa's Disease / Fat Pad Syndrome


ITB Syndrome





- RA

- Synovial Chondromatosis

- Meniscal tears


- PF Arthritis

- Tumours - hemangiomas 

- Referred Pain - hip / back /ankle

- Cruciate ligament insufficiency / reconstruction


Adolescent Knee Pain


Bipartite / Multipartite Patella 


Sinding Larsen Johannsen


Maltracking /alignment 

- ELPL / alta / baja 



- local inflammatory around avulsions of apophysis

- self -limiting

- rarely requires surgical management


Menelaus-Batten Syndrome

- Johannson- Larsen's disease that affects upper pole patella

- may see fragmentation


Hypermobile patella

- ligamentous laxity



Fat Pad Syndrome



Hoffa's syndrome

- impingement of the fat pad with knee ROM





Diagnosis of exclusion




May be more prevalent in patients with intact ligamentum mucosum




Hoffa's sign

- apply pressure to fat pad each side of patella tendon with knee in flexion

- extend knee

- will cause impingement



- behind patella tendon into fat pad

- will relieve pain




See increased signal in fat pad


Fat Pad Impingement MRIFat Pad Impingement 2




EpidemiologyPatella OA Medial Facet


1 in 10 patients with symptomatic knees have isolated PFJ OA





Repetitive deep flexion


Lateral patella tightness

Blunt trauma




Anterior knee pain

- rising from chair

- ascending stairs






Patella tilt




Tender patella

- especially lateral facet


Pain with movement PFJ




Laurin View

- assess tilt


Patella OA Tilt


Merchant view

- assess subluxation


Patella OA Subluxation




Patella OA Lateral




PFJ OA ArthroscopyPFJ OA Arthroscopy


Patella Grade 4 ArthroscopyPatella Trochela Grade 4 Damage




Non Operative




- glucosamine


Cut out braces



- hydrotherapy




1.  Lateral release



- lateral tilt

- lateral facet OA

- lateral retinacular tightness

- limited goals


Patella Tilt Moderate OAPatella Tilt Moderate OA MRI


Lateral release




Aderinto et al Arthroscopy 2002

- retrospective study of 49 patients

- 80% patients felt some reduction in pain

- at 2 - 3 year follow up, 33% very satisfied and 26% satisfied

- 41% unsatisfied


2.  TTT


A.  Anterior transfer of TT


Maquet procedure


Elevation of TTT with insertion bone graft

- originally described elevating by 2.5 cm

- problems with skin necrosis / prominence TT / tendonitis

- reduced to only 1 cm and recommended via an anterolateral incision


Maquet APMaquet Lateral




Largely discarded

- causes superior patella tilt


Schmid Clin Orthop Related Research 1993

- 35 knees

- 80% good, remainder fair or poor


B.  Anteromedial transfer of TT




Oblique osteotomy 45˚

- enables antero-medial transfer of tibial tuberosity

- unloads the PFJ and the lateral facet simultaneously


Fulkerson Osteotomy APFulkerson Osteotomy Lateral




Fulkerson et al Am J Sports Med 1990

- 93% good or excellent results in 30 patients at 2 years

- 75% good in 12 patients at 5 years, no excellent


3.  Facetectomy



- previous fracture

- isolated OA to one facet



- open

- arthroscopic


Open procedure


Midline incision

- open retinaculum medial or lateral

- excise medial or lateral facet

- leave central ridge to ensure tracking


Patella Medial OA post FracturePatella Medial Facet OA Post Fracture Arthroscopy




Paulos et al Arthroscopy 2008

- arthroscopic lateral release and partial lateral facetectomy

- 80% very satisfied or satisfied


4.  Patellectomy



- doesn't completely relieve pain (leaves trochlea)

- extensor weakness and lag / problems with stair descent



- open retinaculum

- excise patella in full

- close retinaculum tightly

- VMO advancement

- this increases strength and decreases lag


Patellectomy LateralPatellectomy Skyline


5.  PFJR


Predates TKR by 10 years




Good results in 

- OA from trauma without malalignment


Poorer results in OA from unknown cause

- risk developing femoro-tibial OA

- need revision



- isolated PJF OA

- < 60 years old




Inflammatory conditions

Patella maltracking and malalignment

Tibiofemoral arthritis / medial or lateral joint pain




Correct large Q angles preop with TTT

- some correction of maltracking can be obtained intra-op via component positioning and lateral release




PF instability

Progressive tibio-femoral degeneration

Loosening rare (< 1%)




Avon (Stryker)

LCS (Depuy)




Odumenya et al JBJS Br 2010

- 5 year follow up of 50 patients

- no revisions


Ackroyd et al JBJS Br 2007

- 109 patients followed up for 5 years

- survival rate 96%

- 80% good outcomes

- 28% had radiological progression of OA


Lonner et al JBJS Am 2006

- revision of 12 PFJR revised to TKR

- for progressive tibio-femoral OA or patella catching / maltracking

- good results

- all PS, no augments or stems required


Results Australian Joint Registry


7 year revision rate of 22.4%

- males and young age highest risk revision



- progression of disease 35%

- loosening 21%

- pain 11%


6.  TKR


Patella Baja

Patella Baja







- trauma

- post ACL reconstruction / TKR

- chronic quadriceps rupture




Decreases ROM

Associated with early OA of the PFJ




Blackburne-Peel ratio at 30 degrees flexion


Patella Baja Blackburne Peele




Excise lower third patella tendon

Patella tendon reconstruction with achilles tendon allograft

Tibial tubercle osteotomy and proximalization



Proximalization fo the tibial tuberosity


Proximalization of Tibial tuberosity 1Proximalization tibial tuberosity 2


Patella BajaPost proximalization tibial tuberosity

Patella Fracture



Direct blow

- most common



- forced knee flexion with foot fixed / maximally contracted quadriceps




1.  Vertical


Patella Fracture Vertical


2.  Transverse


Patella Fracture DisplacedPatella Fracture Displaced AP


3.  Burst / Stellate


Patella Fracture Stellate




Non operative





- biomechanically stable


Undisplaced transverse fractures

- < 2mm

- extensor mechanism intact

- able to straight leg raise


Patella Fracture TransverseUndisplaced patella fracture






Displaced transverse fractures




1.  TBW


Patella TBW LateralPatella TBW AP


2.  Cerclage wire +/- ORIF

- stellate fractures


3.  Lag screws


4.  Patellectomy



- unreconstructable fracture



- extension lag / weakness

- anterior instability


Gunal et al JBJS Br 1996

- patients with at least 5 fragments

- advocated VMO advancement

- additional medial parapatellar incision

- advance laterally and distally

- demonstrated improved strength and decreased lag


Patellectomy Lateral


Late Management


Malunion Patella Fractures


Partial patellectomy

- remove part of medial or lateral facet

- good functional and pain relief


Non Union Patella Fragment


Patella Fracture nonunionPatella Fracture NonunionPatella Fracture Nonunion CT


Patella Fracture Nonunion



Patella Instability



Dislocated Patella


Repeated dislocation of patella with minimal trauma

- 15-20% of paediatric acute patella dislocations

- more common girls 

- often bilateral


Dislocation occurs unexpectedly when quadriceps contracted with knee in flexion 




Usually lateral


Medial is usually iatrogenic

- excessive lateral release

- lateral release for incorrect reasons

- overtightening of medial structures






Usually one ossification centre usually that appears at age 3 & closes soon after puberty




Retropatellar surface has 7 facets

- 3 on lateral side

- 1 extra on medial side (odd facet)


Patella Medial and Lateral Facets


Lateral surface larger than medial

- lateral cartilage thicker than medial

- medial & lateral separated by median ridge 


Medial facet & odd facet are separated by another long ridge




Tracking is dynamic 

- lateral in full extension

- more medial & central with flexion


Relies on normal static and dynamic stabilisers


Static Constraints


1.  Bony contours of femur

- prominence of LFC anteriorly

2.  Normal rotational profile

3.  MPFL is constant / static checkrein to patella


Dynamic Constraints


Quadriceps is dynamic stabilizer

- VMO fibers attach to patella at 65° angle


Biomechanics Goodfellow 1976


0°         No PF contact


20°       Most distal part patella contacts trochlea


0-30°    Median patella ridge lies lateral to the centre of the trochlea


30-60°  Patella moves medially to be centered in groove


60-90°  Deeply engaged in trochlear groove & is held by ST tension


90°       Entire articular surface contacts except odd facet


>90°    Patella tilts so that medial facet articulates with the MFC


135°    Odd facet contacts lateral border of MFC


Aetiology Patella Instability


Complicated / Multifactorial


Valgus malalignment

Ligamentous laxity

Insufficient medial structures (MPFL rupture / medial retinaculum laxity / VMO atrophy)

Tight lateral retinaculum

Trochlea dysplasia

Patella alta

Abnormal rotational profile (femoral anteversion / external tibial torsion)



- patella alta / baja

- trochlea / patella hypoplasia / dysplasia 


Soft tissue

- VMO atrophy / medial retinaculum laxity / torn MPFL

- tight lateral structures (capsule, retinaculum, ITB)

- ligamentous laxity



- femoral anteversion

- external tibial torsion

- genu valgum






Beware unrelenting pain

- chondral damage

- patella tilt / lateral patella syndrome




Traumatic vs. atraumatic onset

Direction of instability 

Age first dislocation

Subsequent dislocations

- mechanism, frequency

- ? voluntar

Treatment to date 






Generalised ligamentous laxity  


Wynne-Davies Criteria

- positive if 3 of 5 bilateral signs

- hyperextension of the MCP joints parallel to  forearm 

- touch thumb passively to forearm

- elbows hyperextend beyond 0o

- knees hyperextend beyond 0o

- ankle DF > 45o


Patient Standing


Valgus Malalignment




1.  Squinting patella

- with femoral anteversion patellae point inwards when standing


2.  Grasshopper eyes

- patella sits high & lateral due to patella alta




In toeing

- internally rotated foot progression angle

- indicates femoral anteversion / tibial torsion


Patella Tracking


Patient sitting over side of bed

- flex and extend knee

- compare normal to abnormal side (if not bilateral)



- lateral subluxation of patella as knee approaches full extension

- patella sharply deviates laterally in terminal extension 

- indicates some degree of mal-tracking


Patella J Tracking Enlocated in FlexionPatella J Tracking Extension


Knee Examination


Previous incisions

VMO wasting



- exclude extensive mechanism tightness

- symmetrical heels to buttocks


Knee extended (3)


1.  Tenderness

- lateral retinaculum 

- retropatellar space

- Bassett's sign (tender medial epicondyle / acute MPFL avulsion)


2.  Clarke's Test / patella grind

- produces anterior knee pain with PFJ pathology

- compress patella and ask patient to contract quads

- very non specific test


3.  Patellar tilt test


Patella Tilt 1Patella TIlt Normal


Evaluates tension of lateral restraint 

- patient supine and relaxed with knees extended 

- examiner's thumb on lateral aspect of patella

- lateral edge of patella elevated from the lateral condyle and medial edge depressed 


Abnormal if unable to tilt lateral patella to horizontal


Knee flexed 30o over pillow (3)


1.  Q (quadriceps) angle 


Patella Instability Increased Q Angle



- line from ASIS to centre of patella 

- line from centre of patella to tibial tuberosity

- angle subtended is Q angle 



- normal 10o men, 15o women

- abnormal if > 15o in males and > 20o in females 


Causes increased Q angle

- femoral anteversion (squinting patellae) 

- external tibial torsion

- lateral tibial tuberosity

- genu valgum 


2.  Sage mobility


Test at 30o flexion

- move patella medially and laterally

- graded in number of quadrants patella displaces 

- > 50% displacement = insufficient restraints 


Patella Lateral HypermobilityPatella Medial Hypermobility


Lateral glide 

- >3 quadrants suggests incompetent med restraints 


Medial glide

- > 3 suggests incompetent lateral restraint / hypermobile patella

- < 1 suggests tight lateral retinaculum


3.  Apprehension test (Fairbank)


Patient supine and relaxed 

- place relaxed knee at 30 degrees & push patella laterally as flex

- can also do with knee flexed over edge of bed

- positive test is a quads contraction & apprehension


Rotational Profile




1.  Lateral border of feet

- if curved, metatarsus adductus 


2.   External tibial torsion

- intermalleolar axis > 30o

- Thigh foot angle > 15o


Thigh Foot Angle 20 DegreesThigh Foot Angle 35 Degrees


3.  Femoral anteversion

- IR > 45o

- Gage's trochanteric angle > 15 - 20o


Increased Femoral Anteversion



AP / Long Leg Views


Quantify Valgus Malalignment


Patella Instability Long Leg Views Valgus MalalignmentValgus Knee


Lateral Xray


1.  Assess Patella Alta


30o flexion


A.  Blumensaat's line / Inaccurate


Knee flexed to 30o

- line should just touch inferior pole of patella

- pole above line - alta

- pole below line - baja


Patella Height Normal Blumensaat's LinePatella Alta Blumensaat's LinePatella Alta Blumensaat's Line


B.  Blackburn-Peele ratio / Best and Most accurate


Distance between tibial and patella articular surface

- divided by patella articular surface

- patella alta > 1


Patella Baja Blackburn PeelePatella Alta Blackburn Peele


C.  Insall ratio

- less accurate, probably because more difficult to measure

- ratios also difficult to remember and calculate

- length of patella tendon v length patella

- patella alta LT : LP 1.2

- patella baja LT : LP <1


Patella Height Normal Insall RatioPatella Alta Insall Ratio


2.  Assess Trochlea Dysplasia


Dejour Crossover Sign

- lateral x-ray at 30o with condyles superimposed

- identify base of trochlea



- clearly defined trochlea groove


Trochlea Anatomy NormalTrochlea Normal Anatomy Diagram


Abnormal / Crossover

- line of floor of trochlea crosses lateral lip of condyle

- indicates trochlea is deficient proximally


Trochlea Crossover


Trochlea depth

- < 8 mm shallow


Dejour grading system 1 - IV


Patellofemoral view


1.  Skyline view



- 45o

- shoot throught film


Look for


- bony avulsion MPFL


MPFL Bony Avulsion


2.  Laurin view / patella tilt



- knee 20o, camera at bottom


Assessment patella tilt

- first line anterior aspect both condyles

- line lateral facet

- should diverge laterally


Patella tilt

- lines parallel or open medially


Patella Laurin View NormalPatella Tilt Laurin ViewPatella Tilt


3.  Merchant view / patella subluxation



- 40o flexion, beam from top

- patella should be well engaged

- central ridge should lie at or medial to bisector of the trochlea groove


Congruence angle

- draw sulcus angle

- bisector of sulcus angle

- line to central ridge of patella

- should be - 10o (i.e. medial)

- lateral direction is positive




Patella non SubluxedPatella Medial Congruence Angle




Patella Lateral SubluxationPatella Lateral Congruence AnglePatella Subluxation


4.  Trochlea dysplasia




Patella Normal TrochleaPFJ Normal Sulcus Angle


Sulcus angle

- > 140o flattened


Trochlea Dysplasia


5. Excessive Lateral Pressure Syndrome


Ficat and Hungerford


A.  Indirect signs of excessive lateral pressure

- thickened subchondral plate

- increased density lateral facet

- lateralisation of trochlea

- medial facet osteoporosis

- hypoplasia lateral condyle


Patella Excessive Lateral Pressure 1Patella Excessive Lateral Pressure 2


B.  Indirect signs of excessive lateral ligament tension

- fibrosis lateral retinaculum

- calcification lateral retinaculum

- lateral osteophyte

- bipartite patella

- lateral facet hypoplasia

- medial compartment hypoplasia


Patella Excessive Lateral TensionPatella Excessive Lateral Pressure




1.  Skyline View


Assess for

- lateral tilt

- subluxation

- trochlea dysplasia


PFJ Axial CT


2.  Lateralisation of tibial tuberosity




Jones et al Skeletal Radiology


Superimpose 2 axial slices


A.  Axial slice of trochlea

- line of posterior condyles

- line perpendicular through trochlea


Axial CT PFJ


B.  Slice through tibial tuberosity

- perpendicular line through TT


CT Axial Tibial Tuberosity


Calculate Distance between two points / TTTG


10 - 15 mm normal, > 15 abnormal


Pandit et al Int Orthop 2011

- normal 10 +/-1 on MRI




Articular Cartilage Damage

MPFL integrity


Loose Bodies




Assess chondral surfaces

Removal of Loose Bodies


- not particularly valid

- patient is relaxed / knee filled with fluid


Non-operativePatella Instability MPFL and TTT AP




90% respond 

- very important

- 6 - 12 months minimum before offering surgery




1.  Stretches

- quads stretches


- lateral retinaculum


2.  Quads strengthening

- avoid pain

- PFJ contact pressures lowest from 0-30o

- short arc quads extension

- closed chain VMO exercises


3.  Taping / bracing

- patella cut out brace

- little hard evidence

- may provide proprioceptive feedback






For failure of non-operative treatment 

- patella tilt with lateral patella pain

- recurrent instability




Depends on pathology

- assessment and investigation critical for deciding treatment


1.  Isolated Patella tilt



- clinical and xray patella tilt

- no instability / malalignment

- excessive lateral pressure syndrome




1.  Arthroscopic lateral release

- knee in extension

- camera in AM portal

- hook diathermy in AL portal

- 5mm lateral to patella / 1cm superior to patella / down to anterolateral portal

- release retinaculum under vision

- must ensure SLGA coagulated / can visualise

- let down tourniquet at end of procedure

- ensure can evert patella 90o at end


2.  Smiley knife release

- arthroscopy

- insert in AL portal

- divide retinaculum by feel


Post op

- drain 24 hours

- protect for 1 week




McGinty et al Clin Orthop 1981

- 32/39 G/E results




A.  Haemarthrosis

- can be major / problematic

- insert drain, splint and minimise activities first few weeks

- manage via early washout / insertion drain


B. Medial subluxation

- extending release too far into VL

- performing lateral release when have ligamentous laxity and instability


Patella subluxation / recurrent dislocation



- must have had long non operative period

- treatment depends on cause

- different treatment options in skeletally immature


Treatment algorithm


1.  Recurrent subluxation + normal alignment (TTTG < 15 - 20)

- lateral release (only do if patella tilt / tight laterally or will dislocate medially)

- MPFL reconstruction / VMO advancement / medial reefing


2.  Recurrent subluxation + malalignment (TTTG > 20)

- above + add TTT (tibial tuberosity transfer)

- Roux-Goldthwaite instead of TTT if physis open


3.  Above + Excessive femoral anteversion

- consider DRFO (derotation femoral osteotomy)


4. Above + Excessive external tibial torsion (> 45 degrees)

- consider tibial derotation osteotomy


5.  Trochlea dysplasia

- trochleoplasty


5.  Patella alta

- distalise TT


Surgical Algorithm


1.  Perform lateral release

- rarely needed

- most patients are ligamentous lax / hypermobile patella

- may be needed in chronic setting or if congenital


2.  Perform TTT (if TTTG > 20)

- incision over TTT

- medialise at least 1 cm

- ensure some element of Fulkerson / anteriorise

- can distalise if patella alta

- secure with screws (2 x small fragment usually sufficient)

- reassess stability


3.  MPFL reconstruction (with TTT, or if TTTG < 20)

- acts as checkrein to lateral displacement

- usually harvest hamstring autograft

- medial incision

- beware overtightening (will give pain) / patella fracture (drill holes in patella)

- reassess for stability


4.  Lateral Trochlea Elevation

- still unstable after above operations

- small lateral incision

- beware fracturing lateral femoral condyle

- need to be able to take bone graft from iliac crest


Tibial Tuberosity Transfer




Open Physis




A. Medial displacement corrects Q angle

- must correct Q angle < 10o

- at least 1 cm


B. Anterior displacement unloads PJF


C. Distal displacement corrects patella alta




Hauser distalisation

- for patella alta

- operation in isolation had disappointing results

- get posteriorisation tubercle and increased forces across PFJ



- anteromedial transfer

- osteotomy lateral to medial

- direct osteotomy anteriorly

- unloads PJF


Fulkerson Osteotomy APFulkerson Osteotomy LateralFulkerson Osteotomy Skyline



- medialisation

- no posterisation


Surgical Technique of TTT


Technique 1

- direct osteotomy with oscillating saw lateral to medial

- initial incision slightly lateral of midline over Tibial tuberosity

- lateral incision in periosteum

- osteotomy 1.5 cm deep, 6 cm long

- angle osteotomy 45 degrees / use k wires to guide

- attempt to leave medial and distal periosteum intact for stability

- minimum medial transfer is 1 cm, usually 18 - 20 mm

- fix with two screws

- if want to distalise for patella alta, performing distal step cut, and distalise 6 mm

- never make transfer posterior


Tibial Tuberosity Transfer


Technique 2

- use reciprocating saw

- cut down from the top, behind the PT

- 4 cm long

- leave intact distally

- use 3.5 mm drill to perforate distal attachment laterally

- can then swing the TT medially on distal / medial pivot

- secure with singe 4.5 mm bi-cortical lag screw


Consider patella cartilage

- combine with cartilage procedure

- microfracture / MACI / de novo


Patella instability cartilage loss




Caton and Dejour Int Orthop 2010

- TTT in 61 knees

- 76.8% stability


Cossey et al Knee 2005

- 19 patients with TTT / MPFL reconstruction

- no redislocations


Skeletally Immature





- skeletally immature with malalignment



- lateral half PT rerouted

- under medial PT

- stitched to MCL / sartorius


Technique Modification


Take medial half patella tendon

- suture to MCL


PT transfer + MPFL

- incision midway between PT and MCL

- identify patella tendon

- divide in two

- sharp dissection of medial half off bone

- dissect medially

- divide fascia and retinaculum to expose MCL

- suture to MCL with 2.0 non absorbable sutures

- through same incision can harvest hamstrings for MPFL reconstruction




Fondren et al JBJS Am 1985

- 43/47 G/E results


Medial Operations


1.  MPFL reconstruction



- patient with history initial traumatic dislocation

- also indicated in patient with laxity to act as a check rein




1.  Y Graft

- double ST autograft into Y


2.  Single limb free semitendinosus autograft

- limb to patella via endobutton


MPFL Reconstruction 1MPFL Reconstruction 2


Schottle's Point


Schottle AJSM 2007

- cadaveric study

- 1 mm anterior posterior cortex

- 2 mm distal to MFC origin

- above blumensaats


Schottles Point




A. Patella fixation

- incision along medial patella

- 2 drill holes in patella

- attach ends of graft, pass into patella, secure with anchor of choice

- pass graft superficial to capsule


B. Femoral fixaiton

- best to use II to find point

- stem between medial epicondyle and adductor tubercle

- Schottle's Point

- drill wire across femur, drill hole for fixation screw

- pass doubled graft into tunnel

- set at 30o flexion

- ensure doesn't dislocation laterallly

- don't overtighten

- secure with screw


Xrays 1


Tunnel too anterior / tight in flexion


Patella Instability MPFL and TTTPatella Instability MPFL and TTT Lateral


Xray 2


Finding Schottles Point


Schottles pointFemoral Fixaiton MPFL




Nomura et al J Arthroscopy 2006

- recurrent dislocation, no malalignment

- 83% G/E results

- no redislocation at  2 year follow up


Howells JBJB Br 2012

- 211 procedures in 193 knees

- all TTTG < 18

- most moderate trochlea dysplasia

- no redislocations at 16 months


Shah et al AJSM 2012

- Systematic review MPFL

- 26% complication rate

- 4/629 (0.6%) fractures

- 26/629 (4%) stiffness

- 23/629 (3.7%) failure rate


2.  Medial imbrication



- MPFL needs to be intact or won't work

- laxity / stretched / attenuated structures




Insall procedure

- medial flap sutured 1 cm over lateral flap




Scuderi et al JBJS Am 1988

- combined with lateral release

- normal and abnormal Q angle

- 42/52 G/E 81%


Barber et al Arthroscopy 2008

- TTT + medical plication in 34 knees

- 91.4% stability


Zhao AJSM 2012

- RCT MPFL v medial plicaiton

- 100 patients

- recurrent instability 7% v 16%

- better Kujala scores in MPFL


3.  VMO advancement


Madigan procedure

- VMO detached and advanced laterally and distally

- sutured to fascia on patella





- trochlea dysplasia

- if after MPFL and TTT the patella still unstable at end of case




1. Dejour Trochleoplasty

- lift up anterior aspect femoral condyles

- deepening of trochlea

- replacement of LFC

- risk of chondral fracture / AVN / non union / displacement


Utting et al JBJS Br 2008

- 50/54 92% 

- combined with other procedures as required


2.  Elevate lateral edge of lateral femoral condyle

- insert osteotome

- gently elevate without fracturing chondral surface

- insert 2 - 3 mm of iliac crest bone graft

- no need for stabilisation




Nelitz et al AJSM 2013

- trochleoplasty + MPFL in 26 knees

- no redislocation, no complications

- 96% statisfied


Tibial Derotation Osteotomy



- excessive external tibial torsion > 45 degrees

- 1 / 5000 people


Tibial Derotation Osteotomy


Tibial Derotation OsteotomyTibial Derotation Osteotomy Lateral




Drexler et al KSSTA 2013

- good outcome for 15/17 knees


Chronic Dislocation


Chronic Patella Dislocation 1Chronic Patella Dislocation 2Chronic Patella Dislocation


Chronic / congenital

- patella subluxed out of joint

- patella alta

- treat with identical principles

- lateral release / TTT / MPFL reconstruction


Chronic Patella DislocationChronic Patella DislocationChronic Patella Dislocation 5

Patella Tendon Rupture



Usually occurs in young people

- often previous history of tendonitis ± steroid injections




Usually at level of inferior pole of patella

- less common at tibial tubercle

- mid-substance ruptures rare




Severe pain

Palpable defect

Extensor deficit / unable to SLR




Patella alta / high riding patella


Patella Tendon Rupture


Distal Pole Patella Fracture


Patella Tendon Bony Avulsion




In chronic cases may only detect that tendon not attaching to distal pole patella


Patella Tendon Tear MRI


Acute Management


Requires operative repair





- avoid baja caused by overtightening patella tendon

- drape patient in such a way so as to palpate other PT

- compare patella heights at end of case


Multiple Bunnell / Krackow Sutures to Patella Tendon

- 2 non absorbable

- drill holes through patella ( 3 - 4)

- pass sutures and tie 

- can augment with box fibrewire


Patella Tendon Rupture Post Repair Intraosseous Sutures and Box suturePatella Tendon Rupture MRI Post Repair


Can reinforce with box wire loop

- large gauge wire 18G

- drill hole in tibial tuberosity

- transverse drill hole in patella

- pass in square and tie

- protects patella tendon

- problem is will break / irritate / need removal

- only do if concerned re repair


Patella Box Wire APPatella Box Wire LateralPatella Box Wire Broken APPatella Box Wire Broken Lateral


Test repair at end of case

- should be able to do some limited ROM


Patella Tendon AvulsionPatella Tendon ORIF




1. Semitendinosus autograft

- leave semitendinosus attached distally

- pass through distal pole patella

- reattach to tibia on lateral side


2.  Patella tendon Allograft


3.  Lars Ligament


Chronic Rupture




Case: Reconstruction with tendoachilles allograft, bone block in tibia


Chronic Patella Tendon Rupture XrayChronic Patella Tendon Rupture MRIPatella Tendon Graft


Chronic Patella Tendon Rupture 1Chronic Patella Tendon Rupture 2Chronic Patella Tendon Rupture 3


Chronic Patella Tendon Rupture 4Chronic Patella Tendon Rupture 5


Chronic Patella Tendon Rupture Post Op LateralChronic Patella Tendon Rupture Post OP AP


Case: Reconstruction with Hamstring Autograft


Chronic patella tendon ruptureChronic patella tendon rupture Hamstring ReconChronic patella tendon rupture Hamstring Recon


Chronic patella tendon rupture Hamstring ReconChronic patella tendon rupture Hamstring ReconChronic patella tendon rupture Hamstring Recon


Chronic patella tendon rupture Hamstring ReconChronic patella tendon rupture Hamstring Recon


Patellar tendonitis



Patellar Tendinitis




Most common in athletes

- especially if involved in running, jumping and kicking

- over use injury


Basketball players




Chronic overload v inferior patella impingement


Schmidt et al Am J Sports Med

- dynamic MRI in patients with jumper's knee v controls

- no evidence of impingemnt

- concluded that chronic overload main cause


Incidence of inferior patella spurs

- likely part of pathology


Clinical Features


Insidious onset of pain at inferior pole of patella

- initially after activity only, worse as cools down

- localised tenderness at inferior pole

- may progress to rupture




Usually normal


May see

- traction spurs

- calcification of patella tendon


Patella Tendon CalcificationPatella Spur




Cyst / Degeneration


Jumpers Knee MRI


Traction spurs / calcification / ossicles


Patella Tendonitis Calcification MRIPatella Tendon Calcification MRIPatella Spur MRI




Activity modification


Rest 6/52

- warm up & stretching

- ice & NSAIDS


Sport rehabilitation protocol


Concentration on eccentric exercises

- decline squats on a 25o decline board


Jonsson et al B J Sports Med 2005

- RCT of concentric v eccentric quads exercises

- superior results with eccentric


Engebretsen et al JBJS Am 2206

- RCT of eccentric rehab v surgery

- no advantage surgery

- recommended minimum 12 weeks non operative treatment in all cases






Platelet Rich Plasma


Fillardo et al Int Orthop 2010

- compared three injections PRP 2 weeks apart in 15 chronic patients

- compared wth 16 patients treated with physiotherapy alone

- significant improvements in PRP group


Charousset AJSM 2014

- 3 consecutive US guided PRP into tendon defect

- sucess in 21 / 28 athletes




Vulpiani et al J Sports Med Phys Fitness 2007

- 4 sessions every 2 days

- 73% successful in all patients

- 87.5% successful in athletes with return to sport at 6 weeks






Fails to resolve & interferes with activity






1.  Resection fat pad

2.  Resection posterior inflammed portion of tendon

3.  Careful burr resection of inferior pole patella

- 1 - 2 mm

- does't affect patella tendon insertion

- removes source of impingement

- likely stimulates healing process




Lorbach et al Arthroscopy 2008

- arthroscopic debridement inferior pole patella in 20 patients

- 18/20 good or excellent results


Pascarella AJSM 2011

- arthroscopic debridement undersurface of tendon / tendinopathy

- excise distal pole

- success in 66 / 73 knees

- RTS by 3 months





Quadriceps Rupture



Usually occurs in patients over 60

- due to decreased vascularity & collagen weakness


Younger patient on steroids / growth hormone


Occasionally occurs in young athlete with excessive contracture




Often preceded by quadriceps tendinosis


Quadriceps Tendinosis MRIQuadriceps Tendinosis 2




1.  Avulsion of quadriceps tendon from superior patella

2.  Rupture of belly of rectus femoris

3.  Rupture at musclulotendinous junction in athletes




Quadriceps Tendon RuptureQuads Tear


Palpable gap in tendon



Extensor lag

- function usually good if tear incomplete


Extensor Lag


Diagnosis can be missed once acute features settle




Patella Baja


Quadriceps Rupture




MRI Chronic Quadriceps RuptureQuads rupture MRI







- immobilise for 4/52 in extension

- then rehabilitate


Rectus Femoris Avulsion 1Rectus Femoris Tear 2



- surgical repair



- surgical repair


Surgical Technique



- patient supine


Midline incision

- expose quadriceps

- mobilise tendon / release from subcutaneous tissue

- debride insertion on patella


Quads Repair 1Quads Repair 2Quads Repair 3


Drill holes in patella

- pass sutures with houston suture passer

- pass large non absorbable suture

- multiple times through tendon


Quads Repair 4Quads Repair 5Quads Repair 6


Other option

- suture anchors in distal patella


Post operative rehab

- keep in extension 6 - 8/52


Late presentations / Rerupture



- quadriceps turndown

- quadriceps VY advancement

- fascia lata graft

- Lars graft reinforcement


Note: Patella Baja with chronic rupture

- patient may develop patella baja

- with chronic injuries / failed injuries

- may need to perform tibial tuberosity osteotomy


Failed Quadriceps Repair


Tibial Tuberosity OsteotomyTibial Tuberosity Osteotomy 2



Quads Repair Tibial OsteotomyQuads Repair Tibial Osteotomy 2


Revision Quadriceps Repair with Tibial Tuberosity Osteotomy


Allograft Reconstruction


Chronic Quads TearQuads Recon 1Quads Recon 2


Quads Recon 3Quads Recon 5


Quads Allograft Final 1Quads Allograft reconstruction 2



- flat portion oversewn proximally

- two limbs passed through drill holes in patella

- sewn onto themselves



Sinding - Larson - Johanssen



Active pre teen boy

- activity related pain

- common in high jumpers




Fragmentation / calcification of inferior pole

- repetitive traction injury where PT inserts

- tender at this point




I     Normal

II    Ca inferior pole irregularity

III   Coalesce Ca inferior pole

IV    Incorporation of Ca




Patella stress fracture

Sleeve fracture

Type 1 bipartite patella

Jumper's knee in older patient




Self- limiting 

- symptomatic treatment

- can use cast immobilisation


Rarely surgical excision