First-Time Patellofemoral Dislocation: Risk Factors for Recurrent Instability.

Area of Science:

• Orthopedics
• Sports Medicine
• Biomechanical Engineering

Background:

• Patellofemoral instability presents a complex management challenge.
• Understanding demographics and risk factors for recurrent patellar instability is crucial for effective treatment strategies.

Purpose of the Study:

• To describe the patient demographics of first-time patellofemoral dislocations.
• To identify specific risk factors associated with recurrent patellofemoral instability.

Main Methods:

• Retrospective review of over 2,000 patients with patellar dislocation (1998-2010).
• Inclusion criteria: first-time dislocation, recent X-rays, and confirmed dislocation.
• Radiographic assessment included Caton-Deschamps, Insall-Salvati indices (patella alta), and Dejour classification (trochlear dysplasia). Skeletal maturity was graded.

Main Results:

• 326 knees (312 patients) met criteria; average age 19.6 years (9-62).
• 30.6% of nonoperatively managed patients experienced recurrent instability; 49.4% of these eventually required surgery.
• Identified risk factors for recurrence: younger age, immature physes, sports injuries, patella alta, and trochlear dysplasia.

Conclusions:

• While 69% of first-time dislocations stabilize with conservative care, specific patient groups face higher recurrence risks.
• Patients under 25 with trochlear dysplasia have a 60-70% 5-year recurrence risk.
• Demographic and radiographic findings are vital for patient counseling and tailoring treatment plans for patellofemoral instability.