Short-term clinical and radiological outcome of the uncemented isoelastic monoblock Affinis Glenoid vitamys in stemless anatomic total shoulder arthroplasty: a multicenter study

Background: This study evaluated the short-term clinical and radiological outcomes of an uncemented isoelastic monoblock glenoid component in stemless anatomic total shoulder arthroplasty (aTSA). We hypothesized that the implant's design and biomechanical properties would offer sufficient fixation and good functional outcomes. Methods: In this prospective multicenter study, 75 patients received stemless aTSA for shoulder osteoarthritis using the Affinis Glenoid vitamys implant. We evaluated 64 patients at a mean follow-up of 25.2 ± 2.1 months. The Constant Score, Simple Shoulder Test, active range of motion, and complications were recorded. The radiological evaluation was based on the occurrence of radiolucent lines (RLLs) and periprosthetic bone adaptations using plain radiographs and scored according to Lazarus and Molé. The radiological evaluation revealed minor humeral periprosthetic bone adaptations without clinical consequences. RLLs on the glenoid side were detected in 31.5% of cases; most (62%) of them were < 2 mm. The mean adapted Molé score was 1.08 ± 2.34. Since the majority of observed RLLs were not located around the pegs, 95% of the investigated implants were classified 0 according to Lazarus. Finally, no revision surgery was necessary due to failed fixation or loosening of the glenoid component. Conclusion: Stemless aTSA with the uncemented isoelastic monoblock Affinis Glenoid vitamys yielded good and reliable short-term radiological and clinical results. Studies with a longer follow-up period are necessary to confirm these results.