Epidemiology and natural history of acute patellar dislocation

Am J Sports Med. 2004 Jul-Aug;32(5):1114-21. doi: 10.1177/0363546503260788. Epub 2004 May 18.


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 < .05) and were older than first-time dislocation patients (P < .05). Fewer first-time dislocators (17%) had episodes of instability during follow-up than patients with a previous history of instability (49%) (P < .01). After adjusting for demographics, patients with a prior history had 7 times higher odds of subsequent instability episodes during follow-up than first time dislocators (adjusted odds ratio = 6.6, P < .001).

Conclusions: Patellar dislocators who present with a history of patellofemoral instability are more likely to be female, are older, and have greater risk of subsequent patellar instability episodes than first-time patellar dislocators. Risk of recurrent patellar instability episodes in either knee is much higher in this group than in first-time dislocators.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Adolescent
  • Adult
  • Age Distribution
  • Age Factors
  • Aged
  • Athletic Injuries / complications
  • Child
  • Female
  • Follow-Up Studies
  • Hip Dislocation, Congenital / complications
  • Humans
  • Joint Instability / complications
  • Joint Instability / physiopathology
  • Knee Joint / pathology
  • Knee Joint / physiopathology
  • Male
  • Middle Aged
  • Patellar Dislocation / epidemiology*
  • Patellar Dislocation / etiology*
  • Patellar Dislocation / physiopathology
  • Prospective Studies
  • Recurrence
  • Risk Factors
  • Sex Distribution
  • Sex Factors
  • United States / epidemiology