Patellar dislocation in adolecscents

Patellar dislocation in adolescentsMr Michalis ZeniosConsultant Paediatric Orthopaedic SurgeonMBChB (Hons), MRCS (Eng), MSc, FRCS (Orth)Paediatric OrthopaedicsFellow Sydney 2006-2007Consultant Manchester 2007 -2012

AimsAetiology of patellar instability/subluxation

Assessment

Treatment (Evidence based)

Congenital patellar dislocation

Patellofemoral InstabilityPatellofemoral pain

Patellofemoral subluxation

Patellofemoral Dislocation

Patellofemoral InstabilityBony Causes (local)

Femoral Trochlea

Patella Shape

Patella Height

Patellofemoral InstabilityBony Causes (Lower Limb)

Genu Valgum

Femoral Torsion

Tibial Torsion

Patellofemoral InstabilitySoft tissue restraints

MedialMedial patellofemoral (60%)Medial RetinaculumVMO

LateralVastus LateralisLateral Retinaculum

PathologyLateral hypermobility of the patellaDysplastic distal one third of VMOHigh or lateral position of the patellaPrevious history of patellar subluxation

Patellar dislocationsRare in a child. Common in adolescents.Twisting injury or direct traumaLateralAcute vs recurrentOsteochondral fractures of patella or femur

Patellofemoral InstabilityAssessment

HistoryAcute or spontaneousDurationNumber of episodesCircumstances of injuryPrevious treatmentBeware ACL injury (Pop)Syndromes

Patellofemoral InstabilityAssessmentExaminationFull knee examinationPatella TrackingJ-signMedial or lateral tendernessTilt or lateral tightnessApprehension Test (most reliable)Q-angleTorsional profileGeneral Laxity

Patellofemoral InstabilityInvestigation

Plain X RaysAP (? Osteochondral lesion)Lateral view30 deg flexion (Koshino Index)Merchant View30 deg flexion

RadiologyInsall index

< than o.8 suggests patella alta

Patellofemoral InstabilitySulcus Angle

140 degrees

Congruence angle-6 +/- 11degrees

Patellofemoral InstabilityCT ScansFulkerson viewsVary knee flexionMRI ScansMedial restraintsEUA & ArthroscopyAcute (MPFL)Check tracking

Radiological measurementsTibial tubercle trochlear groove distance

Lateralisation of the patella

Abnormal when above 20 mm

Patellofemoral InstabilityConservative Treatment:RICESLR/ Isometric QuadricepsOpen and closed chain kinetic exercisesGradual return to activitiesNo casts or immobilizationPatellar stabilizing orthosisTime

Patellofemoral Instability ? Role for acute surgeryTreatment:

No place for acute operative stabilization in children and adolescentsAcute 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

Acute patellar dislocation in children and adolescents: a RCT. J Bone Joint Surg (Am) 2008;90(3):463-47062 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 structuresAcute patellar dislocation in children and adolescents: a RCT. J Bone Joint Surg (Am) 2008;90(3):463-47014 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 recurrenceAcute patellar dilsocation in adlescents: operative versus non-operative treatment. Int orthopaedics. Apostolovic 2011;35(10):1483-1487.Non randomised prospective study- 37 adolescent kneesDecision for surgery on the basis of clinical and arthroscopic findings. Not clearNo difference between operative and non-operative treatment in terms of re-dislocation rates and functional outcomeSurgical interventionRecurrent instability with functional compromise

Osteochondral lesions. Repair if > 2cm

Patellofemoral InstabilitySurgical Strategy (100 operations in 100 years!)

Proximal Re-alignment (TUBS)Acute initial episodeLax soft-tissue restraintsRestore anatomy (MPFL reconstruction/ Insall procedure)

Distal Re-alignment (AMBRI)Predisposition to patellar subluxationAnatomical factors (Increased Q Angle)Reconstruct anatomyPatellar tendon or Tibial TuberclePatellofemoral InstabilitySurgical Strategy (100 operations in 100 years!)

Proximal Re-alignment (TUBS)Acute initial episodeLax soft-tissue restraintsRestore anatomy (MPFL reconstruction/ Insall procedure)

Distal Re-alignment (AMBRI)Predisposition to patellar subluxationAnatomical factors (Increased Q Angle)Reconstruct anatomyPatellar tendon or Tibial TubercleA 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. 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 yearsPatients 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 instabilityOutcomes 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. Weight-bearing osteochondral lesions of the lateral femoral condyle following patellar dislocation in adolescents athletes. Orthopaedics 2012;35(7):1033-1037. USA80 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 -SummaryDo not operate acutely

Understand and try to correct your anatomy

No tibial tubercle transfer in skeletally immature patientsCongenital patella dislocationFirst described by Singer 1856Present at birth diagnosed then or within first decadeThe patella should be permanently fixed to the lateral aspect of the femur

Congenital patella dislocationAetiology Failure of the myotome containing the Quadriceps and Patella from internally rotating in the first trimesterCongenital patella dislocationPathologyExtensor mechanism inserted antero-laterallyContracture of Iliotibial band, Vastus lateralis, and Lateral capsuleLoose and atrophic medial capsule & VMOHypoplastic femoral trochleaExternal rotation of tibia and valgus deformity of kneeCongenital patella dislocationTreatment

Initiated before 1st birthdayExtensive lateral release of whole of Vastus lateralis & knee capsuleExtensor mechanism is reduced and medial structures lateralised+/- Roux GoldthwaiteWhat do we do?

What do I do?

Thank you