Synovitis as a concomitant disease in shoulder pathologies

Shoulder pathologies are often accompanied by rotator interval synovitis. This phenomenon is poorly described in the literature so far. The aim of the study was to analyze the occurrence of macroscopically visible synovial reaction in the rotator interval in patients with chronic shoulder pathologies and to perform a histopathological evaluation.

In this prospective cohort study, 167 consecutive patients undergoing arthroscopic shoulder surgery for chronic shoulder pathology were included (♀ = 45, ♂ = 122; [Formula: see text]54.5 years ± 12.8). Included patients were divided into subgroups according to the encountered chronic shoulder pathology: (1) impingement syndrome with or without bursal sided partial rotator cuff tear (RCT); (2) articular sided partial RCT; (3) full-thickness RCT; (4) RCT that involves at least two tendons; (5) shoulder instability; and (6) cartilage damage. Standardized soft tissue biopsies from the rotator interval were taken. The synovitis score of Krenn/Morawietz was used for histopathological examination.

Extraarticular pathology (group 1) showed significantly decreased synovitis scores compared to all the other groups. Increased size of rotator cuff tears (group 4), as well as cartilage damage (group 6) showed significantly higher synovitis scores than group 3 (p < 0.05). Moreover, the synovitis score was significantly increased in patients with concomitant pathologies of the long head of the biceps (p = 0.001).

This study suggests that chronic intra- and extraarticular shoulder diseases are very often accompanied by a histopathologically verifiable low-grade synovitis. Intraarticular pathologies seem to induce increased levels of synovitis. Furthermore, the increased size of rotator cuff tears is accompanied by a higher degree of synovitis.

Cohort study, level of evidence, 2b.