The Lateral Alignment Angle: A Novel Method for Evaluating Lateral Patellar Tilt With High Accuracy, Good...

Excessive lateral pressure syndrome (ELPS), a major cause of anterior knee pain, stems from axial lateral patellar tilt. Current diagnostic methods exhibit limited accuracy, poor reproducibility, and difficulty in cases with morphological abnormalities. This study introduces the Lateral Alignment Angle (LAA) as a novel measurement technique.

In this retrospective study (June 2021-March 2025), 150 patients were enrolled and matched 1:1 with controls (total n = 300). Two senior surgeons independently measured LAA, Lateral Patellofemoral Angle (LPFA), Patellar Tilt Angle (PTA), and Patellofemoral Index (PFI) at separate time points. Receiver operating characteristic (ROC) curves were constructed to evaluate diagnostic performance, with area under the curve (AUC) computed and optimal cut-off determined by maximum Youden index. Intraclass correlation coefficients (ICC) assessed interobserver reproducibility.

LAA demonstrated superior diagnostic accuracy with an AUC of 0.913, sensitivity of 89.3%, specificity of 88.0%, and overall accuracy of 88.7%, all significantly outperforming LPFA and PTA. LAA achieved higher positive (88.2%) and negative predictive values (89.2%), with a positive likelihood ratio of 7.44 and negative likelihood ratio of 0.12. The ICC for LAA was 0.782, indicating good interobserver reliability. The optimal diagnostic cut-off value was determined to be 5.35°.

The LAA is a stable, accurate measurement that minimizes morphological influence on patellofemoral joint assessment. An LAA greater than 5.35° reliably indicates lateral patellar tilt, providing enhanced diagnostic utility and improved clinical management of ELPS.