Patellofemoral Arthritis After Lateral Patellar Dislocation: A Matched Population-Based Analysis.

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Rheumatology

Background:

• The long-term incidence of patellofemoral arthritis following lateral patellar dislocation is not well-established.
• Understanding this risk is crucial for patient counseling and management strategies.

Purpose of the Study:

• To compare the incidence of patellofemoral arthritis and knee arthroplasty in patients with versus without a history of lateral patellar dislocation.
• To identify factors predicting arthritis development after lateral patellar dislocation.

Main Methods:

• A cohort study design (Level of evidence, 3) comparing 609 patients with lateral patellar dislocation to a matched control group.
• Review of medical records to assess initial injury, recurrence, treatment, and progression to clinically significant patellofemoral arthritis.
• Analysis of factors including age, sex, recurrence, osteochondral injury, and trochlear dysplasia.

Main Results:

• Patients with lateral patellar dislocation had a significantly higher risk of developing patellofemoral arthritis (HR, 7.8; P < .001) compared to controls.
• Cumulative incidence of arthritis reached 48.9% at 25 years post-dislocation versus 8.3% in controls.
• Risk of knee arthroplasty was similar between groups (HR, 2.8; P = .2).
• Recurrent dislocations (HR, 4.5), osteochondral injury (HR, 11.3), and trochlear dysplasia (HR, 3.6) were associated with arthritis development.

Conclusions:

• Lateral patellar dislocation is a significant risk factor for developing patellofemoral arthritis.
• Nearly 50% of patients experience arthritis 25 years after lateral patellar dislocation.
• Osteochondral injury, recurrent instability, and trochlear dysplasia are key predictors of post-dislocation arthritis.