2017 ISAKOS Biennial Congress ePoster #1722

 

Incidence Of Acute Lateral Patellar Dislocation: A 21-Year Population-Based Study

Thomas Lee Sanders, MD, Rochester, MN UNITED STATES
Tyson C Christensen, MD, Rochester, MN UNITED STATES
Rohith Mohan, BA, Rochester, MN UNITED STATES
Nick R. Johnson, BS, Rochester, MN UNITED STATES
Timothy E. Hewett, PhD, Rochester, MN UNITED STATES
Michael J. Stuart, MD, Rochester, MN UNITED STATES
Diane L. Dahm, MD, Rochester, MN UNITED STATES
Aaron J. Krych, MD, Rochester, MN UNITED STATES

Mayo Clinic, Rochester, MN, UNITED STATES

FDA Status Not Applicable

Summary

With an annual incidence of 23.2 per 100,000 person-years, lateral patellar dislocation is a frequently encountered orthopedic injury with a higher incidence in the adolescent population than previously reported.

Abstract

Background

Acute lateral patellar dislocation is a common orthopedic injury. The purpose of this study was to 1) evaluate the incidence of acute lateral patellar dislocation in a geographically determined population, 2) report trends over time in the incidence of dislocation, and 3) describe the rate of surgical treatment.
Hypothesis/Purpose: The rate of patellar dislocation is highest among adolescent patients.
Study Design: Cohort study; Level of evidence, 3

Methods

The study population included 609 individuals identified through a multi-disciplinary geographic cohort county database who were diagnosed with first episode lateral patellar dislocation between 1990 and 2010. The complete medical records were reviewed to confirm the diagnosis and to evaluate details of injury and treatment. Age- and sex -specific incidence rates were calculated and adjusted to the 2010 United States population. Poisson regression analyses were performed to examine incidence trends by age, sex, and calendar period.

Results

The overall age- and sex-adjusted annual incidence of patellar dislocation was 23.2 (95% CI: 21.2, 24.9) per 100,000 person-years. The annual incidence was similar between males and females and highest among adolescents aged 14-18 years (147.7 per 100,000 person-years). The mean age at dislocation was 21.4 (±9.9) years and 331 patients (54.4%) were female. During the study period, there was a significant decline in the incidence of patellar dislocation among males aged 19-25 years (p = 0.002) and females ages 14-18 years (p = 0.025). 80 patients received surgical treatment during the study period including 66 patients (10.8%) for recurrent instability and 14 patients (2.3%) for acute osteochondral injury.

Conclusion

With an annual incidence of 23.2 per 100,000 person-years, lateral patellar dislocation is a frequently encountered orthopedic injury. The incidence of dislocation among adolescent patients in this cohort is higher than previously reported. Despite a decrease in the annual incidence of dislocation in adolescent females, the overall incidence of patellar dislocation remained relatively constant over a 21-year observation period.