A Magnetic Resonance Imaging-Based Clinical Prediction Model Accurately Identifies Patellar Instability Risk Using
Varun Nukala1, Alisha Sodhi1, Isha Wadhavkar1
1Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, U.S.A.
Arthroscopy, Sports Medicine, and Rehabilitation
|September 22, 2025
Summary
Machine learning accurately predicts patellar instability using MRI measurements. Key risk factors identified include Insall-Salvati ratio, tibial tubercle-trochlear groove distance, and trochlear depth, aiding personalized patient care.
Area of Science:
- Orthopedic imaging analysis
- Machine learning in medicine
- Biomechanical assessment of knee joints
Background:
- Patellar instability is a common orthopedic condition.
- Accurate diagnosis relies on identifying specific radiographic risk factors.
- Magnetic resonance imaging (MRI) offers detailed anatomical visualization.
Purpose of the Study:
- To develop a machine learning model for predicting patellar instability using MRI measurements.
- To identify and quantify the importance of radiographic risk factors associated with patellar instability.
Main Methods:
- Retrospective analysis of knee MRI scans from patients with and without patellar instability.
- Measurement of parameters related to patella alta, malalignment, and trochlear dysplasia.
- Application of logistic regression and machine learning models (e.g., random forest) with SHAP for variable importance analysis.
Main Results:
- Multivariable logistic regression identified lower patellotrochlear index, greater Insall-Salvati ratio, greater tibial tubercle-trochlear groove (TT-TG) distance, and lower trochlear depth as significant predictors.
- The random forest model achieved an area under the receiver operating characteristic curve of 0.85.
- Insall-Salvati ratio, TT-TG distance, and trochlear depth were the most important variables identified by the machine learning model.
Conclusions:
- A machine learning model can reliably predict MRI-based parameters associated with patellar instability.
- Key risk factors like Insall-Salvati ratio, TT-TG distance, and trochlear depth are crucial for both statistical and machine learning models.
- The developed model shows potential for improving diagnostic accuracy and personalizing patient care.


