Clinical and Radiologic Outcomes after Anatomical Total Shoulder Replacement Using a Modular Metal-Backed Glenoid after a Mean Follow-Up of 5.7 Years

Background: Glenoid wear is a common complication of anatomical total shoulder arthroplasty (aTSA) with a metal-backed glenoid (MBG), and the clinical and radiological results of historical implants are poor. The aim of this work was to evaluate the clinical and radiological results of 25 participants as well as the longevity after implantation of an anatomic shoulder prosthesis with a recent, modular cementless flat metal-backed glenoid component after a mean follow-up of 5.7 years. Methods: Clinically, the Simple Shoulder Test (SST), UCLA Activity Score (UCLA), and Constant Murley Score (CMS) were evaluated. Radiographically, the radiolucent lines (RLs), humeral head migration (HHM), and lateral glenohumeral offset (LGHO) were assessed. Survival was calculated with Kaplan–Meier curves and life-table analysis. Results: The mean CMS at follow-up was 46.2 points (range: 14–77; SD: 19.5). In terms of the SST score, the average value was 6.5 points (range: 1–10; SD: 3.5). The UCLA activity score showed a mean value of 5.9 points (range: 1–9; SD: 2.1). There were 17 revisions after a mean follow-up of 68.2 months (range: 1.8–119.6; SD: 27.9). HHM occurred in every patient, with a mean measurement of 6.4 mm (range: 0.5–13.4; SD: 3.9; p < 0.0001). The mean LGHO between the initial postoperative and follow-up images was 2.6 mm (range: 0–4.0; SD: 1.5; p < 0.0001). RLs were found in 22 patients (88%) around the glenoid and in 21 patients (84%) around the humeral head prosthesis. Conclusion: The clinical and radiographic outcomes after metal-backed glenoids were poor at 2.2 to 8.4 years of follow-up. We determined devastating survival in the majority of cases (68%), with mostly inlay wear (71%) as the main reason that led to revision surgery. The use of metalback genoids cannot be recommended based on the data of this study.