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

Paediatric Orthopaedics Fellow Sydney 2006-2007 Consultant Manchester 2007 -2012

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

Patellofemoral Instability Patellofemoral pain Patellofemoral subluxation Patellofemoral Dislocation

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

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

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

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

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

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

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

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

Radiology Insall index < than o.8 suggests patella alta

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

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

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

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

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. 2009 ; 91: 139-45. Nietosvaara Y, Paukku R, Palmu S, Donell ST. “The slaying of a beautiful hypothesis by an ugly fact” – T H Huxley

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):463-470 62 patients younger than 16 who sustained acute patellar dislocation with an osteochondral fragment of 15mm. 36 0peratively 28 non-operatively: 1. 7 only lateral release 2. 29 repair medial structures

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):463-470 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

Non randomised prospective study- 37 adolescent knees Acute patellar dilsocation in adlescents: operative versus non-operative treatment. Int orthopaedics. Apostolovic 2011;35(10):1483-1487. 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

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

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

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

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.

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.

Predictors of recurrent instability after acute patellofemoral dislocation in paediatric and adolescent patients. Am J Sports Med 2013;41(3):575-581. 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

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):65-71. USA Recurrent dislocation 7% Subjective opinion of knee function was less than expected 5 years post-op.

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):1033-1037. 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.

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

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

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

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

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

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