DO PATIENTS WITH AN ANATOMICAL TOTAL SHOULDER ARTHROPLASTY FOR GLENOHUMERAL OSTEOARTHRITIS ACHIEVE A CLINICALLY RELEVANT IMPROVEMENT?

Background: The minimal clinically important difference (MCID) is defined as the smallest meaningful change in a health domain that a patient would identify as important. The primary aim of this study was to determine the proportion of patients achieving a clinically important improvement among patients with glenohumeral osteoarthritis treated with an anatomical platform total shoulder arthroplasty. As a secondary endpoint we compared the platform shoulder arthroplasty system with a non-platform system.
Methods: Between March 2017 and February 2019 patients with symptomatic glenohumeral osteoarthritis indicating an anatomical total shoulder arthroplasty at Herlev/Gentofte University Hospital, Denmark were evaluated. The included patients received a Global Unite Anatomical Shoulder Arthroplasty. Patients were clinically evaluated preoperatively and 3, 6, 12 and 24 months postoperatively using the Western Ontario Osteoarthritis of the Shoulder index (WOOS), the Oxford Shoulder Score (OSS) and the Constant-Murley Score (CMS). The MCID for WOOS, OSS and CMS are reported to be 12.3, 4.3 and 9.8 respectively. As a reference group, we included the 44 most recently operated patients with a Global Advantage prosthesis. These patients were followed up minimum 2 years postoperatively with completion of WOOS, OSS and CMS.
Results: For WOOS, OSS and CMS 89%, 96% and 91% had an improvement above the MCID value respectively. The difference
between the Global Unite system and the Global Advantage system was 2.4 (P=0.575) for WOOS, 0.8 (P=0.617) for OSS and
3.1 (P=0.411) for CMS.
Conclusions: In patients with glenohumeral osteoarthritis treated with an anatomical total shoulder arthroplasty, we found approximately 90 % of the patients to achieve a clinically relevant improvement. This is a clear and distinct message for the surgeon to explain to the patients preoperatively. We found no difference between the Global Unite platform shoulder system and the Global Advantage non-platform shoulder system.