Risk Factors Associated With Osteochondral Fractures After Lateral Patellar Dislocation Based on Individual Factors.

Background: Individual risk factors for osteochondral fractures (OCFs) have been discussed separately; nonetheless, there is a lack of established systematic assessment models to predict the risk of OCFs after lateral patellar dislocation (LPD). Timely diagnosis, appropriate treatment, and rehabilitation can help optimize outcomes for affected patients.

Purpose: To develop a comprehensive and effective personalized scoring system based on demographic and clinical characteristics to help understand the factors associated with OCFs after LPD and compare the anatomic differences of OCFs in different locations.

Study design: Case-control study; Level of evidence, 3.

Methods: From 2016 to 2023, a total of 369 patients with LPD who were admitted to our hospital were enrolled in this study; OCFs were considered positive events, and patient characteristics and imaging data were collected. Backward stepwise regression identified independent risk factors associated with the incidence of OCFs after LPD. A predictive nomogram was constructed based on the analysis results. The predictive performance was assessed using receiver operating characteristic curves (ROCs), calibration plots, and decision curve analysis.

Results: After regression analysis, skeletal immaturity, higher body mass index (BMI), shorter tibial tuberosity-trochlear groove distances, knee valgus, and smaller patellar tilt angles were identified as independent risk factors and incorporated into the predictive model. The ROC curve, calibration plot, Hosmer-Lemeshow test, and decision curve analysis all demonstrated good performance in both the training and validation cohorts. The area under the curve was 0.769 and 0.794 in the training and validation cohorts, respectively.

Conclusion: This study developed a comprehensive and effective personalized nomogram with 5 predictors (skeletal maturity, BMI, tibial tubercle-trochlear groove distance, mechanical axis deviation, and patellar tilt). This tool quantifies the risk factors for OCFs and provides a more detailed understanding of how these factors interact with one another.