Evaluation of the patient with patellar instability

Patellofemoral instability is a result of medial retinacular deficiency in combination with insufficient bony constraint. It is a multifactorial entity that must be critically evaluated prior to undergoing operative intervention. We advocate evaluating patients based on whether they have experienced a first dislocation event, recurrent dislocations, or have recurrent dislocations after failed surgical management. Evaluation of all the above groups of patients involves evaluating all potential contributors (patella alta, trochlear dysplasia, generalize laxity). As with most orthopaedic diagnoses, history and physical exam provide much of the information needed to make a treatment decision. Imaging modalities can be used to assess factors contributing to instability and determine which interventions might be most beneficial.