High rate of clinical improvement following anatomical total shoulder arthroplasty for glenohumeral osteoarthritis

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. Thus, an improvement that exceeds the MCID can be used to define a successful treatment for the individual patient.
Aim: The aim of this study was to quantify the rate of clinical improvement following anatomical total shoulder arthroplasty for glenohumeral osteoarthritis.
Materials and Methods: Patients were treated with the Global Unite total shoulder platform arthroplasty between March 2017 and February 2019 at Herlev and Gentofte Hospital, Denmark. The patients were evaluated preoperatively and 3, 6, 12 and 24 months postoperatively using the Western Ontario Osteoarthritis of the Shoulder index (WOOS), Oxford Shoulder Score (OSS) and onstant- Murley Score (CMS). The rate of clinically relevant improvement was defined as the proportion of patients who had an improvement 24 months postoperatively that exceeded the MCID. Based on previous literature, MCID for WOOS, OSS and CMS was defined as 12.3, 4.3 and 12.8 respectively.
Results: 49 patients were included for the final analysis. One patient was revised within the two years follow-up. The rate of clinically relevant improvement was 87% using WOOS, 94% using OSS and 88% using CMS.
Interpretation / Conclusion: Based on three shoulder-specific outcome measures we found that 87% to 94% of patients had a clinically relevant improvement following anatomical total shoulder arthroplasty for glenohumeral osteoarthritis. This is a clear and distinct message that together with information about implant
survival can be used to inform patients about their prognosis.