Patellofemoral Dislocation Recurrence After a First Episode: A Case-Control Study

Area of Science:

• Orthopedic surgery
• Sports medicine
• Biomechanics

Background:

• Recurrent lateral patellar dislocation is a common complication after an initial episode.
• Identifying patients at high risk for redislocation is crucial for effective treatment planning.

Purpose of the Study:

• To determine clinical and radiological predictors of recurrent patellar dislocation following a first-time event.

Main Methods:

• A case-control study (Level of evidence, 3) included 130 patients (139 knees) with primary lateral patellar dislocation.
• Evaluated patient demographics, physical exam findings (e.g., patellar apprehension), and radiographic measurements (Caton-Deschamps, Insall-Salvati ratios).
• Defined high-grade trochlear dysplasia as Dejour types B, C, and D.

Main Results:

• Recurrent dislocation occurred in 59.71% of knees.
• Significant risk factors for redislocation included Caton-Deschamps ratio ≥1.15 (OR, 2.39), age <21 years (OR, 2.53), and high-grade trochlear dysplasia (OR, 4.17).
• The probability of redislocation increased additively with the presence of these factors, reaching 86.2% when all three were present.

Conclusions:

• Patella alta, high-grade trochlear dysplasia, and young age (<21 years) are independent risk factors for recurrent lateral patellar dislocation.
• The combined presence of these factors significantly increases the risk of redislocation.
• Findings can inform treatment strategies for patients following their first patellar dislocation.