Long-term clinical and radiographic outcomes after inverted-bearing reverse total shoulder arthroplasty: a multicenter study with the Affinis Inverse prosthesis.

Abstract

Inverted-bearing reverse total shoulder arthroplasty (IB-rTSA) prostheses feature a polyethylene glenosphere and a metallic or ceramic humeral liner. Although midterm clinical results are promising, long-term clinical data with IB-rTSA are limited. Therefore, we evaluated the long-term clinical and radiographic outcomes of IB-rTSA in a variety of shoulder pathologies. Additionally, we reported the type and rate of scapular notching and assessed its effect on clinical results. Finally, we recorded implant survival and complication rates. In this prospective, multicenter, observational study, patients with different shoulder pathologies underwent IB-rTSA with the Affinis Inverse prosthesis. We recorded clinical and functional scores, active range of motion, pain, radiolucent lines, and the type and rate of scapular notching. All complications were documented, and prosthesis survival rates were calculated. We included 318 patients (335 shoulders) with IB-rTSA. The final clinical and radiographic analysis involved 175 patients (183 shoulders), examined at a median of 120.7 months (range, 84.1-172.4 months). At final follow-up, clinical and functional scores, active range of motion, and pain improved significantly from preoperative values (P < .001). Additionally, improvements at the final follow-up in clinical scores and pain substantially exceeded the corresponding minimal clinically important difference determined for rTSA. The type of scapular notching was strikingly different from that observed with conventional rTSA prostheses, and no grade 4 scapular notching was seen. We found scapular notching in 63 (35.8%) shoulders, and the presence of scapular notching did not affect long-term clinical outcomes as well as complication and prosthesis survival rates. The overall prosthesis survival for any revision was 95.7% at 14 years. IB-rTSA with the Affinis Inverse prosthesis resulted in excellent long-term clinical scores and radiographic outcomes, low scapular notching rates, and high prosthesis survival rates in patients with a range of shoulder pathologies. Overall, patients undergoing IB-rTSA can expect good and stable long-term clinical outcomes with low complication and revision rates, making it a viable choice for different shoulder pathologies.