Thickening of the Middle Glenohumeral Ligament Is Associated with Subscapularis Tendon Tears: An Arthroscopic Analysis

Background The middle glenohumeral ligament (MGHL) demonstrates substantial anatomical variation, including absent, flat, cord-like, and thickened morphologies. Although a close anatomical relationship exists between the MGHL and subscapularis tendon, the clinical relationship between MGHL thickening and subscapularis tendon tears remains uncertain. This study evaluated the association between MGHL thickening and subscapularis tendon tears. Methods We conducted a retrospective cross-sectional analysis of prospectively collected arthroscopic data from 119 shoulders in 118 patients who underwent shoulder arthroscopy between 2021 and 2024. Shoulders were categorized as thick-MGHL or thin-MGHL according to arthroscopic morphology. Subscapularis tendon tears and other arthroscopic findings were recorded. Univariate and multivariable logistic regression analyses were performed. A sensitivity analysis added synovitis/capsulitis to the primary multivariable model. Results Thickened MGHL was identified in 56.3% (67/119) of shoulders. Subscapularis tendon tears were more frequent in the thick-MGHL group than in the thin-MGHL group (67.2% vs. 44.2%; P=.020; OR, 2.58; 95% CI, 1.22-5.45). In the primary multivariable model, thickened MGHL remained independently associated with subscapularis tendon tears (adjusted OR, 2.52; 95% CI, 1.00-6.32; P=.049). In a sensitivity model additionally including synovitis/capsulitis, the association remained significant (adjusted OR, 2.55; 95% CI, 1.01-6.44; P=.047). Conclusion Thickened MGHL was independently associated with subscapularis tendon tears in patients undergoing shoulder arthroscopy. Because of the cross-sectional design, the temporal and causal relationship between MGHL morphology and subscapularis tendon pathology cannot be determined. Prospective studies, including standardized preoperative imaging assessment, are needed to clarify the direction and clinical relevance of this association.