Impact of Coracoacromial Ligament Thickness on Shoulder Impingement Syndrome: A Cross‐Sectional Magnetic Resonance Imaging Study

Background and Aims Shoulder impingement syndrome (SIS) is a common cause of shoulder pain and dysfunction. This study explored the association between coracoacromial ligament (CAL) thickness and SIS using magnetic resonance imaging (MRI). Methods This cross‐sectional MRI‐based observational study involved 47 patients aged 18–70 years with shoulder pain. T2 fat‐saturated sagittal MRI views were used to measure CAL thickness at proximal and distal portions by two radiologists. Statistical analyses included t ‐tests, χ 2 tests, and Pearson's correlation, with significance set at p < 0.05. Results Mean proximal CAL thickness was 1.24 mm (SD = 0.44 mm), and distal thickness was 1.50 mm (SD = 0.72 mm). Patients with SIS had significantly greater thickness at proximal (1.36 mm vs. 1.05 mm, p = 0.002, d = 0.82) and distal (1.78 mm vs. 1.12 mm, p = 0.001, d = 0.92, 95% CI: 0.39–0.93). Males showed greater distal thickness (1.62 mm) than females (1.34 mm, p = 0.04, d = 0.45). Age did not correlate with thickness ( p > 0.71). Subacromial bursitis (70.21%, p < 0.001) and acromioclavicular (AC) joint osteophytes (68.09%, p = 0.003) were prevalent and associated with SIS. Conclusion CAL thickness, particularly at the distal portion, was strongly associated with SIS, independent of age but varying by gender. Measuring CAL thickness may aid SIS diagnosis.