Epidemiology and natural history of acute patellar dislocation

Background: The goals of this study were to (1) define the epidemiology of acute patellar dislocation, (2) determine the risk of subsequent patellar instability episodes (subluxation and/or redislocation) during the study period, and (3) identify risk factors for subsequent instability episodes. Study Design: Prospective cohort study. Methods: The authors prospectively followed 189 patients for a period of 2 to 5 years. Historical data, injury mechanisms, and physical and radiographic measurements were recorded to identify potential risk factors for poor outcomes. Results: Risk was highest among females 10 to 17 years old. Patients presenting with a prior history of instability were more likely to be female (P