Comparison of arthroscopic coracoacromial ligament degeneration between traumatic and non-traumatic rotator cuff tears: a retrospective, observational study

Abstract Background Distinguishing between traumatic and non-traumatic rotator cuff tears (RCTs) remains challenging in clinical practice. The coracoacromial ligament (CAL), an important component of the subacromial space, may undergo morphological changes associated with RCT progression. We investigated whether arthroscopically assessed CAL degeneration differed by tear etiology (traumatic or non-traumatic RCT) and whether this association persisted after adjustment for age, tear area, and critical shoulder angle (CSA). Methods We retrospectively included patients who underwent arthroscopic rotator cuff repair at a single center between July 2023 and December 2025. Tears were classified as traumatic or non-traumatic based on the patient’s clinical history and preoperative magnetic resonance imaging findings. CAL degeneration was graded intraoperatively using the Copeland–Levy classification and categorized as mild (grades 0–1) or severe (grades 2–3). Tear etiology, age, CSA, and tear area were compared between the groups, and a forced-entry multivariable logistic regression model was used to identify factors independently associated with severe CAL degeneration. Results A total of 138 cases were included, comprising 58 with mild and 80 with severe CAL degeneration. Severe CAL degeneration was present in 56 of 80 non-traumatic tears (70.0%) and 24 of 58 traumatic tears (41.4%; p < 0.001). In the forced-entry multivariable analysis, non-traumatic tear etiology (odds ratio [OR], 2.318; 95% confidence interval [CI], 1.033–5.203; p = 0.041), higher CSA (OR, 1.175; 95% CI, 1.035–1.334; p = 0.013), and larger tear area (OR per 100-mm² increase, 1.158; 95% CI, 1.046–1.283; p = 0.005) were independently associated with severe CAL degeneration. Conclusions Severe arthroscopic CAL degeneration was more frequently observed in non-traumatic than in traumatic RCTs and was independently associated with non-traumatic tear etiology, larger tear area, and higher CSA. These findings suggest that arthroscopic CAL findings may provide complementary information regarding tear etiology; however, CAL degeneration should not be interpreted as a stand-alone diagnostic criterion for distinguishing traumatic from non-traumatic RCTs or as evidence of a causal relationship.