Location of medial collateral ligament tears: introduction to a magnetic resonance imaging-based classification.

Purpose: Despite established tear grade classifications, there is currently no radiological classification for sMCL tear locations. This study aims to establish a magnetic resonance imaging (MRI) tear location classification system for sMCL tears, to enhance understanding and guide treatment decisions by categorizing tear types.
Methods: A retrospective search in a single institution's MRI database identified patients with acute, Grade III sMCL tears (< 30 days between injury and MRI) from January to December 2022. Non-acute and partial tears were excluded, and three observers assessed tear types based on the proposed sMCL MRI tear location system: type I (proximal 25%), Ib (proximal femoral bony avulsion), II (midsubstance, 25-75%), III (distal 25%), IIIb (distal tibial bony avulsion), IIIs (Stener-like lesion). The interclass correlation coefficient (ICC) was used to assess interrater and intrarater reliability for continuous data; Fleiss and Cohen's kappa assessed interrater and intrarater reliability for categorical data.
Results: MRI scans of thirty patients with diagnosed sMCL injuries (53% female, mean age 37 ± 13 years, range 16-68 years) were included based on inclusion/exclusion criteria. Interrater reliability was excellent (ICC: 0.968, 95% CI, 0.933-0.985), and intrarater reliability was excellent (ICC: 0.938, 95% CI: 0.874-0.970 & 0.900, 95% CI, 0.789-0.952). Type I injuries were most common (60%), followed by type III (33.3%), type II (3.3%), type Ib (3.3%), type IIIb (0.0%), and type IIIs (0.0%).
Conclusion: The presented MRI-based sMCL tear location classification provides a reproducible system for grading high-grade sMCL injuries. We propose that this framework will significantly unify tear location understanding and support more informed treatment decisions.
Competing Interests: Declarations. Ethical approval was waived by the institutional review board (No. 2022–0943) in view of the retrospective nature of the study and all the procedures being performed were part of the routine care. Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Consent to participate: Informed consent was obtained from all individual participants included in the study. Conflict of interest: G.S.D. receives royalties and owns stock for Zimmer Biomet. G.S.D. receives royalties from Arthrex. All other authors declare no competing interests.
(© 2024. The Author(s), under exclusive licence to International Skeletal Society (ISS).)