2017 ISAKOS Biennial Congress ePoster #1728

 

What is the Natural History of Patellar Dislocation in Skeletally Immature Patients? A Long-Term Population-Based Study

Thomas Lee Sanders, MD, Rochester, MN UNITED STATES
Ayoosh Pareek, BS, 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

Skeletally immature patients have a high rate of recurrent patellar instability that is associated with structural abnormalities such as patella alta and trochlear dysplasia but low rates of contralateral dislocation and overall incidence of end-stage arthritis at 12-year follow-up.

Abstract

Background

Patellar dislocation can occur in isolation or be associated with chronic instability. The goals of this study are to describe the rate and factors associated with additional patellar instability events (ipsilateral recurrence and contralateral dislocation), as well as the incidence of patellofemoral arthritis among skeletally immature patients following patellar dislocation.
Hypothesis/Purpose: Skeletally immature patients likely have a high rate of recurrence and low rate of arthritis after patellar dislocation.
Study Design: Retrospective Case Series

Methods

The study included a population-based cohort of 232 skeletally immature patients who experience a first-time lateral patellar dislocation between 1990 and 2010. A chart review was performed to collect information related to the initial injury, treatment, and outcomes. Subjects were followed for a mean of 12.1 years to determine the rate of subsequent patellar dislocation (ipsilateral recurrence or contralateral dislocation) as well as clinically significant patellofemoral arthritis.

Results

104 patients had ipsilateral recurrent patellar dislocation. The cumulative incidence of recurrent dislocation was 11% at 1 year, 21.1% at 2 years, 37.0% at 5 years, 45.1% at 10 years, 54.0 % at 15 years, and 54.0% at 20 years. Patella alta (HR: 10.6, 95% CI: 3.6, 36.1), increasing TT-TG distance (HR 18.7, 95% CI: 1.7, 228.2), and trochlear dysplasia (HR 23.7, 95% CI: 1.0, 105.2) were associated with recurrence. Similarly, 18 patients had contralateral patellar dislocation. The cumulative incidence of patellofemoral arthritis was 0% at 2 years, 1.0% at 5 years, 2.0% at 10 years, 10.1% at 15 years, 17%% at 20 years, and 39.0% at 25 years. Osteochondral injury was associated with arthritis (HR 25.7, 95% CI: 6.2, 143.8).

Conclusion

Skeletally immature patients have a high rate of recurrent patellar instability that is associated with structural abnormalities such as patella alta and trochlear dysplasia. In contrast, the rate of subsequent contralateral dislocation is low. Osteochondral injury is associated with arthritis after patellar dislocation, but the overall incidence of end-stage arthritis in pediatric patients is low at 12-year follow-up.