To evaluate whether stemless shoulder implants in rheumatoid arthritis (RA) patients provide comparable functional outcomes to patients with osteoarthritis or post-traumatic arthritis. In addition, the study assessed for differences in incidence of radiolucent lines or proximal humeral bone loss during radiographic follow-up.
Consecutive stemless shoulder arthroplasties performed in RA patients and a matched control group were retrospectively identified between February 2012 and 2018. Thirty-five patients were included in each group: 24 total shoulder arthroplasty (TSA) and 11 hemiarthroplasty (HA). Patients were evaluated annually using the Oxford Shoulder Score (OSS) and radiographically.
The mean OSS significantly improved in all groups until 24 months. The mean improvement for RA TSA and HA patients at 24 months was 19.86 (95% CI 10.66-29.05, p = 0.0004) and 19.71 (95% CI 7.33-32.31, p = 0.0084), respectively. The mean improvement in the control TSA and HA patients at 24 months was 20.86 (95% CI 17-24.71, p = 0.0001) and 17.86 (95% CI 1.36-34.35, p = 0.0381), respectively. During the study period, two patients in the RA TSA group (8%), one patient in the control TSA group (4%) and one patient in the control HA group (9%) required revision. The proportion of progressive proximal humeral bone loss after TSA was 33% in the RA group and 13% in the control group.
Stemless shoulder implants can provide significant improvement in functional scores in RA patients in the short term. However, early bone loss around the humeral implant is a concern and the authors recommend long-term clinical and radiological follow-up.