Prediction of Subsequent Contralateral Patellar Dislocation after First-Time Dislocation Based on Patellofemoral...

Area of Science:

• Orthopedics and Sports Medicine
• Biomechanical Engineering
• Radiology

Background:

• First-time lateral patellar dislocation (LPD) can lead to contralateral LPD.
• Anatomic risk factors for subsequent contralateral LPD are not well understood.
• Identifying these factors is crucial for predicting and preventing recurrent patellofemoral instability.

Purpose of the Study:

• To identify specific contralateral patellofemoral anatomic parameters associated with subsequent LPD.
• To establish predictors for contralateral LPD following an initial event.
• To elucidate the role of abnormal patellar positioning in recurrent LPD.

Main Methods:

• Retrospective analysis of 17 patients with contralateral LPD and 34 controls with unilateral LPD.
• Measurement of contralateral patellofemoral parameters using CT scans and radiographs.
• Statistical analysis including Wilcoxon rank-sum test, binary regression, and ROC curve analysis.

Main Results:

• Significantly increased tibial tubercle-Roman arch (TT-RA) distance in patients with contralateral LPD (24.1 mm vs. 19.5 mm).
• Elevated hip-knee-ankle (HKA) angle, patellar tilt, congruence angle, and patellar displacement in the contralateral LPD group.
• TT-RA distance (AUC 0.727) and HKA angle (AUC 0.797) were significant predictors of contralateral LPD.

Conclusions:

• Contralateral patellofemoral anatomy differs significantly between patients with and without subsequent LPD.
• Increased TT-RA distance and excessive valgus deformity are identified risk factors for contralateral LPD.
• Abnormal patellar positioning relative to the trochlea at the time of first dislocation may contribute to subsequent LPD.