Natural history of patellofemoral dislocations

Abstract

The natural history of patellar dislocation depends on whether the patient is presenting after his/her first (primary) dislocation or after a recurrent episode of instability. Risk of recurrence is only about 20% after the first dislocation, whereas risk of recurrence is around 50% for patients presenting with a history of prior instability. In treating first-time dislocators, the clinician should look for significant osteochondral fractures and should try to identify the location of the medial retinacular injury. MRI is helpful in addressing both of these concerns. Surgical treatment is not recommended for first-time dislocators unless there is a specific reason such as a large articular fragment needing fixation. Recurrent dislocators, i.e., patients presenting with a prior history of patellar instability, are more likely to be female than those with primary dislocation, and they are more likely to present predisposing factors such as trochlear dysplasia, patella alta, and malalignment in addition to medial retinacular laxity. © 2010 Springer-Verlag Berlin Heidelberg.