Anatomic shoulder replacement has superior functional outcomes with equivalent survivorship compared with reverse shoulder replacement in patients with inflammatory arthritis-New Zealand registry results

Reverse shoulder arthroplasty (rTSA) has become increasingly common for inflammatory arthritis (IA) due to concerns regarding rotator cuff failure and glenoid loosening in anatomic total shoulder arthroplasty (aTSA). Comparative data between these procedures in IA, however, remains limited. This study aims to compare functional outcomes and revision-free survival between aTSA and rTSA in IA using data from the New Zealand Joint Registry. All primary aTSA and rTSA procedures performed for IA between 2000 and 2022 were identified in the New Zealand Joint Registry. Demographic data, revision events, causes of revision, and Oxford Shoulder Scores were analyzed. Revision rates were expressed per 100 component-years. Cox regression models estimated the hazard of revision, adjusted for age, sex, and American Society of Anesthesiologist score. A total of 714 arthroplasties were included (433 rTSA and 281 aTSA) with mean follow-up of 6.0 years for rTSA and 9.8 years for aTSA. Patients with aTSA were younger (65.7 vs. 70.3 years, P < .001) and had higher body mass index (30.3 vs. 28.2, P = .018). aTSA demonstrated significantly higher Oxford Shoulder Scores at all time points: 38.7 vs. 36.4 at 6 months (P = .012), 41.9 vs. 38.0 at 5 years (P = .002), and 41.9 vs. 35.4 at 10 years (P = .021); however, this did not exceed the reported minimal clinically important difference. Revision rates were equivalent: 0.92 per 100 component-years for rTSA and 0.99 for aTSA (P = .529). Ten-year revision-free survival was 92.0% for rTSA and 90.8% for aTSA. Causes of revision differed, with infection more frequent in rTSA (33.3% vs. 7.4%, P = .02), whereas aTSA was more often revised for glenoid loosening and cuff failure. Compared with rTSA, aTSA was associated with statistically higher functional outcomes and equivalent revision-free survival. IA is not a contraindication to aTSA, with it being a viable option for appropriately selected patients, rTSA should be considered for those with rotator cuff deficiency or severe glenoid pathology.