RECURRENT PATELLA DISLOCATION

2. ANATOMY

3. ANATOMY

4. ANATOMY

5. ANATOMY

6. ANATOMY

7. EPIDEMIOLOGY & RISK FACTOR
Most commonly occurs in 2nd-3rd decades of life
Risk factors
• previous patellar instability event
• increased Q angle
• femoral anteversion
• genu valgum
• external tibial torsion / pronated feet

11. Anatomical factors
BONE :
• Patella alta --> not
articulate with sulcus,
losing its constraint effects
• Trochlear dysplasia
• Excessive lateral patellar
tilt
• Lateral femoral condyle
hypoplasia

14. Trochlear dysplasia

15. Anatomical factors
MUSCLE
• Dysplastic vastus medialis
oblique (VMO) muscle
• overpull of lateral
structures
• Iliotibial band
• Vastus lateralis

16. Passive stability
• Medial patellofemoral ligament (MPFL)--> avulsion of MPFL
• femoral origin-insertion is between medial epicondyle and adductor tubercle
• patellar-femoral bony structures account for stability in deeper knee flexion
• Trochlear groove morphology, patella height, patellar tracking
Dynamic stability
• Provided by vastus medialis (attaches to MPFL)

17. SYMPTOMS and EXAMINATION
Symptoms
• Complaints of instability
• Anterior knee pain
PE
• Acute dislocation usually
associated with a large
hemarthrosis
• Medial sided tenderness (over
MPFL)
• Patellar apprehension (+)
• Increased Q angle
• J sign

18. IMAGING
• X-RAY :
– AP views
• best to evaluate overall lower
extremity alignment and version
– Lateral views
• best to assess for trochlear
dysplasia
• Evaluate for patellar height (patella alta vs.
baja)
• Sunrise/Merchant views
– best to assess for lateral patellar tilt
CT scan
MRI

19. Treatment
• No study addresses specifically recurrent patellar
dislocation in the young child
• Conservative
– Physical therapy
– Knee bracing
• Surgical

20. Surgical Treatment
Patellar Tendon
Hemitransfer

21. PATELLAR INSTABILITY TREATMENT
Faktor soft tissue
• Medial longgar :
1. Mpfl defisiensi : Mpfl Reconstruction
2. VMO weakness : VMO Strenghtening
3. Medial kapsul/retinakulum laxity : Medial Patellar Retinaculum
Plasty
• Lateral tightness:
1. ITB kontaktur : lateral release
2. Lateral kapsul/retinakulum : lateral release

23. PATELLAR INSTABILITY TREATMENT
• Fibrosis/kontrakturbony factor
1. Valgus knee : DFO (Distal Femur Osteotomy)
2. External rotasi tibia : Derotation Tibial Osteotomy
3. Internal rotasi femur : Derotation Femoral Osteotomy
4. Patellar facet displacia : Patellar osteotomy
5. Trochlear displacia : Trocheoplasty
6. Patella alta : Tibial tubercle distalization

24. DFO

25. DFO

26. DFO

28. Trochlear Dysplasia Surgery Procedure
Crossing sign :
radiographic line of
trochlear groove cross the
projection of femoral
condyle
Trochlear bump :
Trochlear line extend to
anterior femoral cortex

29. Sulcus Deepening Tracheoplasty (Lyon/Dejour)