Midterm clinical outcomes of reverse shoulder arthroplasty in Japanese patients with rheumatoid arthritis using patient-reported outcome measures (Shoulder36).

BACKGROUND: Reverse shoulder arthroplasty normally has adequate functional outcomes in patients with cuff tear arthropathy. The present study aimed to investigate the midterm clinical outcomes of reverse shoulder arthroplasty in Japanese patients with rheumatoid arthritis. METHODS: Between July 2014 and May 2016, reverse shoulder arthroplasty was performed in 14 rheumatic shoulders with joint destruction and rotator cuff tears. The range of motion, Constant score, and Shoulder36, which is a patient-reported outcome measure, were compared preoperatively and postoperatively. The prevalence of subscapular notching, subscapular osteophytes, postoperative fractures, and stress shielding of the humeral stem were evaluated by X-ray. RESULTS: Range of motion significantly improved from 77 to 122 degrees in flexion and from 67 to 111 degrees in abduction at four years. The Constant score significantly improved from 27 to 62, and each domain of Shoulder36 also significantly increased at four years. There was no dislocation, infection, or loosening of the prosthesis. Three shoulders presented scapular notching, and three cemented humeral stems showed stress shielding in the proximal humeral cortical bone. CONCLUSION: Reverse shoulder arthroplasty performed in Japanese patients with rheumatoid arthritis not only decreased the pain and improved the function of the shoulder joint but also significantly improved patients' health and activity of daily living in midterm results.