1. Patellar dislocation in adolescents
Mr Michalis Zenios
Consultant Paediatric Orthopaedic Surgeon
MBChB (Hons), MRCS (Eng), MSc, FRCS (Orth)

2. Paediatric Orthopaedics
Fellow Sydney
Consultant Manchester

3. Aims Aetiology of patellar instability/subluxation Assessment
Treatment (Evidence based)
Congenital patellar dislocation

4. Patellofemoral Instability
Patellofemoral pain
Patellofemoral subluxation
Patellofemoral Dislocation

5. Patellofemoral Instability
Bony Causes (local)
Femoral Trochlea
Patella Shape
Patella Height

6. Patellofemoral Instability
Bony Causes (Lower Limb)
Genu Valgum
Femoral Torsion
Tibial Torsion

7. Patellofemoral Instability
Soft tissue restraints
Medial
Medial patellofemoral (60%)
Medial Retinaculum
VMO
Lateral
Vastus Lateralis
Lateral Retinaculum

8. Pathology Lateral hypermobility of the patella
Dysplastic distal one third of VMO
High or lateral position of the patella
Previous history of patellar subluxation

9. Patellar dislocations
Rare in a child. Common in adolescents.
Twisting injury or direct trauma
Lateral
Acute vs recurrent
Osteochondral fractures of patella or femur

10. Patellofemoral Instability
Assessment
History
Acute or spontaneous
Duration
Number of episodes
Circumstances of injury
Previous treatment
Beware ACL injury (Pop)
Syndromes

11. Patellofemoral Instability
Assessment
Examination
Full knee examination
Patella Tracking
J-sign
Medial or lateral tenderness
Tilt or lateral tightness
Apprehension Test (most reliable)
Q-angle
Torsional profile
General Laxity

12. Patellofemoral Instability
Investigation
Plain X Rays
AP (? Osteochondral lesion)
Lateral view
30 deg flexion (Koshino Index)
Merchant View
30 deg flexion

13. Radiology
Insall index
< than o.8 suggests patella alta

14. Patellofemoral Instability
Sulcus Angle
140 degrees
Congruence angle
-6 +/- 11degrees

15. Patellofemoral Instability
CT Scans
Fulkerson views
Vary knee flexion
MRI Scans
Medial restraints
EUA & Arthroscopy
Acute (MPFL)
Check tracking

16. Radiological measurements
Tibial tubercle trochlear groove distance
Lateralisation of the patella
Abnormal when above 20 mm

17. Patellofemoral Instability
Conservative Treatment:
RICE
SLR/ Isometric Quadriceps
Open and closed chain kinetic exercises
Gradual return to activities
No casts or immobilization
Patellar stabilizing orthosis
Time

18. Patellofemoral Instability ? Role for acute surgery
Treatment:
No place for acute operative stabilization in children and adolescents
Acute patellar dislocation in children and adolescents. Surgical technique.
J Bone Joint Surg Am ; 91:
Nietosvaara Y, Paukku R, Palmu S, Donell ST.
“The slaying of a beautiful hypothesis by an ugly fact” – T H Huxley

19. 36 0peratively 28 non-operatively: 1. 7 only lateral release
Acute patellar dislocation in children and adolescents: a RCT. J Bone Joint Surg (Am) 2008;90(3):
62 patients younger than 16 who sustained acute patellar dislocation with an osteochondral fragment of 15mm.
36 0peratively non-operatively:
1. 7 only lateral release
2. 29 repair medial structures

20. Positive family history was a significant risk factor for recurrence
Acute patellar dislocation in children and adolescents: a RCT. J Bone Joint Surg (Am) 2008;90(3):
14 year follow up
Initial operative repair did not improve the long-term outcome. 70 % re-dislocation rates
Positive family history was a significant risk factor for recurrence

21. Non randomised prospective study- 37 adolescent knees
Acute patellar dilsocation in adlescents: operative versus non-operative treatment. Int orthopaedics. Apostolovic 2011;35(10):
Non randomised prospective study- 37 adolescent knees
Decision for surgery on the basis of clinical and arthroscopic findings. Not clear
No difference between operative and non-operative treatment in terms of re-dislocation rates and functional outcome

22. Surgical intervention
Recurrent instability with functional compromise
Osteochondral lesions. Repair if > 2cm

23. Patellofemoral Instability
Surgical Strategy (100 operations in 100 years!)
Proximal Re-alignment (TUBS)
Acute initial episode
Lax soft-tissue restraints
Restore anatomy (MPFL reconstruction/ Insall procedure)
Distal Re-alignment (AMBRI)
Predisposition to patellar subluxation
Anatomical factors (Increased Q Angle)
Reconstruct anatomy
Patellar tendon or Tibial Tubercle

24. Patellofemoral Instability
Surgical Strategy (100 operations in 100 years!)
Proximal Re-alignment (TUBS)
Acute initial episode
Lax soft-tissue restraints
Restore anatomy (MPFL reconstruction/ Insall procedure)
Distal Re-alignment (AMBRI)
Predisposition to patellar subluxation
Anatomical factors (Increased Q Angle)
Reconstruct anatomy
Patellar tendon or Tibial Tubercle

25. A Surgical algorithm for the treatment of patellar dislocation
A Surgical algorithm for the treatment of patellar dislocation. Results of 5 year follow up. Acta Orthop Belgica 2013.

26. A Surgical algorithm for the treatment of patellar dislocation
A Surgical algorithm for the treatment of patellar dislocation. Results of 5 year follow up. Acta Orthop Belgica 2013.
Higher re-dislocation rates in immature patients who underwent proximal re-alignment procedures.
Mature patients with combined proximal and distal procedures had the lowest re-dislocation rates but low functional scores.

27. Predictors of recurrent instability after acute patellofemoral dislocation in paediatric and adolescent patients. Am J Sports Med 2013;41(3): USA.
222 knees
Mean age 14.9 years
Patients with open physes and dysplastic trochlea had the highest dislocation rate at 69%
Age, sex, body mass index and patella alta were not associated with recurrent instability

28. Recurrent dislocation 7%
Outcomes after patellar re-alignment surgery for recurrent patellar instability dislocations: a minimum 3-year follow-up study of children and adolescents. JPO 2011;31(1): USA
Recurrent dislocation 7%
Subjective opinion of knee function was less than expected 5 years post-op.

29. 80 patients with acute patellar dislocation
Weight-bearing osteochondral lesions of the lateral femoral condyle following patellar dislocation in adolescents athletes. Orthopaedics 2012;35(7): USA
80 patients with acute patellar dislocation
27.5% had an osteochondral lesion of the wt bearing area of lateral femoral condyle and 60% required surgical intervention
Suggestion of performing an MRI if there is tenderness over the lateral femoral condyle.

30. Surgical treatment for instability -Summary
Do not operate acutely
Understand and try to correct your anatomy
No tibial tubercle transfer in skeletally immature patients

31. Congenital patella dislocation
First described by Singer 1856
Present at birth diagnosed then or within first decade
The patella should be permanently fixed to the lateral aspect of the femur

32. Congenital patella dislocation
Aetiology
Failure of the myotome containing the Quadriceps and Patella from internally rotating in the first trimester

33. Congenital patella dislocation
Pathology
Extensor mechanism inserted antero-laterally
Contracture of Iliotibial band, Vastus lateralis, and Lateral capsule
Loose and atrophic medial capsule & VMO
Hypoplastic femoral trochlea
External rotation of tibia and valgus deformity of knee

34. Congenital patella dislocation
Treatment
Initiated before 1st birthday
Extensive lateral release of whole of Vastus lateralis & knee capsule
Extensor mechanism is reduced and medial structures lateralised
+/- Roux Goldthwaite

35. What do we do?

40. What do I do?

43. Thank you