Clinical predictors of lateral meniscal hypermobility and development of the Hypermobile Lateral Meniscus Syndrome Score

PURPOSE: To identify independent preoperative predictors of arthroscopically confirmed lateral meniscal hypermobility and to develop and internally validate the Hypermobile Lateral Meniscus Syndrome Score (HLMSS). METHODS: A retrospective diagnostic prediction model study included 482 patients undergoing knee arthroscopy: 156 with lateral meniscal hypermobility, 171 with structural lateral meniscal tears without hypermobility and 155 arthroscopic controls. Lateral meniscal hypermobility was defined arthroscopically as reproducible anterior translation of the posterior horn beyond the midpoint (>50%) of the lateral tibial plateau. Preoperative clinical and magnetic resonance imaging (MRI) variables were evaluated as candidate predictors. Independent predictors were identified using multivariable logistic regression, and the HLMSS was derived from regression coefficients. Internal validation was performed using 1000 bootstrap resamples. Discrimination, calibration and clinical utility were assessed. RESULTS: The cohort included 482 patients (mean age, 31.8 ± 9.4 years; 62.4% male). Mean age was 28.9 ± 8.1 years in the hypermobility group, 34.7 ± 10.2 years in the structural tear group, and 31.8 ± 8.7 years in controls; 64.7%, 60.8% and 61.9% were male, respectively. Independent predictors of lateral meniscal hypermobility were intermittent locking (adjusted odds ratio [aOR], 4.78), hyperflexion pain (aOR, 4.21), rotational instability sensation (aOR, 3.74), posterolateral pain (aOR, 3.12) and popliteomeniscal fascicle abnormality on MRI (aOR, 2.68). The HLMSS demonstrated an area under the curve (AUC) of 0.91 (95% confidence interval [CI], 0.88-0.94) and an optimism-corrected AUC of 0.89. At ≥7 points, sensitivity was 86.5% and specificity was 84.8%. In the restricted comparison with structural lateral meniscal tears, the AUC was 0.84 (95% CI, 0.80-0.88). CONCLUSION: The HLMSS demonstrated good to excellent discrimination for identifying arthroscopically confirmed lateral meniscal hypermobility using preoperative clinical and MRI findings. External validation in consecutive symptomatic populations is required before routine clinical implementation. LEVEL OF EVIDENCE: Level III, retrospective diagnostic cohort study.