Macroscopic and microscopic assessments of the glenohumeral and subacromial synovitis in rotator cuff disease

BACKGROUND Whereas synovitis is one of most common findings during arthroscopic surgery in patients with rotator cuff diseases, no study has investigated its characteristics. We propose a macroscopic assessment system for investigating the characteristics of synovitis. METHODS Fifty-four patients with a full-thickness rotator cuff tear undergoing arthroscopic rotator cuff repair with an average age of 62.5 ± 7.0 years were included. For the macroscopic assessment, 3 parameters, villous hypertrophy, hyperemia, and density, were measured and translated into grades in 3 regions-of-interest (ROI) in the glenohumeral joint and 4 ROIs in the subacromial space. For the microscopic assessments, 4 commonly used microscopic assessment systems were used. The reliability and association between the macroscopic and microscopic assessments were investigated. RESULTS The inter- and intra-observer reliability of all of the macroscopic and microscopic assessments were excellent. The severity of synovitis was significantly greater in the glenohumeral joint than that in the subacromial space, 1.54 ± 0.61 versus 0.94 ± 0.56 (p < 0.001). Synovitis varied with respect to location, and was generally more severe near the tear with the macroscopic assessment system. Meanwhile, none of the microscopic assessment systems demonstrated differences between different ROIs in both the glenohumeral joint and the subacromial space. CONCLUSIONS The macroscopic assessment system for synovitis in rotator cuff disease in this study showed excellent reliability. It critically described characteristics of synovitis that microscopic assessment systems could not. Therefore, this system could be a useful tool for investigating synovitis in rotator cuff disease.