Lewallen et al identified predictors for recurrent patellofemoral instability in a pediatric patient with a first-time acute patellofemoral dislocation. These can help to identify a patient who may benefit from more aggressive management. The authors are from the Mayo Clinic.
Patient selection: pediatric patient (<= 18 years); first episode of patellofemoral dislocation
Clinical features of patellofemoral dislocation:
(1) effusion/hemarthrosis
(2) tenderness along the medial parapatellar structures
(3) apprehension with lateral patellar translation
Outcome: recurrent instability
Factors associated with recurrent instability:
(1) trochlear dysplasia (using the Dejour classification)
(2) immature physes (distal femoral, proximal tibial plateau)
Trochlear dysplasia is associated with recurrent instability. The presence of both trochlear dysplasia and immature physes was associated with a 69% recurrence rate.
A nonoperative initial management strategy had a 62% success rate. In patients with recurrent instability half required surgery to gain knee stability.
