Continuous clinical and radiological follow-up of isainlay reverse shoulder prostheses: results from the isa registry with a minimum of 1-year follow-up.

BACKGROUND: Reverse total shoulder arthroplasty (rTSA) has been the subject of numerous studies reporting promising clinical outcomes which has led to its widespread use as the most common implant in shoulder arthroplasty today. However, few mid-term studies have reported outcomes of newer stem designs. This study evaluates the clinical and radiographic outcomes of a reverse shoulder prosthesis with an inlay stem design, through a multicenter, retrospective cohort analysis.

METHODS: This retrospective study included 856 patients who underwent primary implantation of the isainlay, a reverse total shoulder prosthesis with an inlay stem design, between March 2019 and October 2024. Data were collected at pre-operative and post-operative time points (1 year, 3 years, and 5 years). The clinical outcomes were assessed using: Constant-Murley Score, American Shoulder and Elbow Surgeons score, Simple Shoulder Test, Subjective Shoulder Value, and visual analog scale for pain. Radiological assessments, including the presence of osteolysis around the humeral stems of the prostheses, were also performed at the key follow-up visits.

RESULTS: At each follow-up, patients implanted with the isainlay stem design prosthesis demonstrated significant improvements in both pain and shoulder function (P < .0001) across all evaluated clinical scores. The primary outcome measure, the Constant-Murley Score, improved from 28 pre-operatively to 72 at 5 years. Radiographic analysis showed a low incidence of osteolysis, with no cases involving all stem zones.

CONCLUSION: Over the 5-year results, this reverse prosthesis design demonstrated favorable clinical and radiographic outcomes, comparable to those of other rTSA implants.