Pathological Association of Coracoacromial Arch Tendons in Shoulder Impingement

Background: Pathology of the supraspinatus, subscapularis, and long head of biceps (LHB) can occur concurrently with shoulder impingement syndrome. Our study investigated the incidence and association of structurally significant pathology in these three tendons in subacromial impingement. Methods: A retrospective cohort of 250 shoulders of 240 patients with subacromial impingement syndrome that underwent arthroscopic subacromial decompression after failing three to six months of conservative management between November 2008 and December 2011 was included. Results: Structurally significant pathology was present in the supraspinatus tendon in 124 (49.6%) shoulders, the LHB tendon in 42 (16.8%) shoulders, and the subscapularis tendon in 45 (18%) shoulders. Of those with supraspinatus pathology, 24.2% had LHB pathology, and 27.4% had subscapularis pathology. Structurally significant supraspinatus pathology was associated with LHB and/or subscapularis pathology in 39.5% of shoulders. Patients with structural pathology of all three tendons were significantly older (57.2 ± 7.8, P = 0.004), more likely to be male (P = 0.006), and have the dominant arm affected (P = 0.037). Conclusion: Pathology of supraspinatus, LHB, and subscapularis tendons often occurs concomitantly in subacromial impingement. This study highlights this intimate relationship and serves as a clinical reminder for thorough evaluation of all three tendons to ensure complete diagnosis and treatment.