Tibial spino-meniscal clearance: A reproducible MRI-derived measurement associated with hypermobile lateral meniscus.

Purpose: To evaluate whether tibial spino-meniscal clearance (TSMC), a magnetic resonance imaging (MRI)-derived imaging measurement, is associated with arthroscopically confirmed hypermobile lateral meniscus (HML), and to assess the reproducibility of this measurement. Methods: A combined retrospective-prospective diagnostic accuracy study was conducted including 164 patients who underwent knee MRI followed by arthroscopy within six months. TSMC was measured on sagittal MRI as the shortest distance between the apex of the lateral tibial spine and the inner margin of the posterior horn of the lateral meniscus. Three blinded observers independently performed measurements to assess intra- and interobserver reliability using intraclass correlation coefficients (ICCs). Diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis, and multivariable logistic regression was used to examine the association between TSMC and HML. Results: Mean TSMC values were lower in patients with arthroscopically confirmed HML compared with controls. The measurement demonstrated excellent intra- and interobserver reliability. ROC analysis showed good discriminatory performance for identifying HML, and TSMC remained independently associated with hypermobility after adjustment for demographic and anatomical variables. Conclusion: TSMC is a reproducible MRI-derived imaging measurement associated with HML. While these findings suggest that TSMC may assist in preoperative suspicion of lateral meniscal instability, further external validation is required before routine clinical application. Level of Evidence: Level III.