Short-term outcomes of bone grafting in conjunction with the comprehensive total shoulder system with a convertible metal-backed glenoid

Young patients with glenohumeral arthritis pose a substantial challenge to shoulder surgeons. Altered biomechanical forces place these patients at risk for early, aseptic glenoid loosening if a traditional cemented all-polyethylene component is used. Modern glenoid designs, including hybrid-post and metal-backed glenoids, have been developed to decrease the risk of glenoid loosening. To date, none of these options offer the ability to correct significant retroversion, posterior subluxation, or medialization of the glenohumeral joint. This study reports on the short-term radiographic and clinical outcomes of bone grafting in conjunction with the Zimmer-Biomet Comprehensive Total Shoulder system with a convertible metal-backed glenoid (BioTSA) to address significant glenoid deformities in young, active patients.

Patients undergoing total shoulder arthroplasty were followed prospectively at a single center with a single surgeon specializing in shoulder arthroplasty. Data regarding clinical, radiographic, and patient-reported outcome measures were collected as part of a shoulder registry and reviewed retrospectively. Patients who underwent BioTSA for primary glenohumeral arthritis with at least 2-year follow-up were identified for inclusion in the study.

Between 2016 and 2022, 20 patients (22 shoulders) underwent BioTSA with a modern metal-backed glenoid that met the inclusion criteria. The patients averaged 57.2 ± 8.7 years of age with an average follow-up of 2.1 years. The cohort was predominantly male (80%) and Caucasian (95%) with a Walch type B glenoid (81.8%). Radiographic parameters included preoperative glenoid retroversion (24.4°), humeral head subluxation (79.1%), glenoid inclination (-2.8°), lateral-humeral offset (13.9 mm), and acromiohumeral interval (11.2 mm). Postoperatively, glenohumeral recentering was seen with glenoid retroversion improved to 14.4° and humeral head subluxation to 60.2%, while lateral-humeral offset increased to 20.9 mm. Improvements were also seen in the average forward elevation, external rotation, and internal rotation from 125° to 167°, 22° to 46°, and back pocket to L4, respectively. Average preoperative patient-reported outcomes included American Shoulder and Elbow Surgeons score (34.8), single alpha-numeric evaluation (23.7), Shoulder Activity Scale (9.35), and visual analog scale (6.2). At the final follow-up, these improved to 82.4, 77.3, 12.3, and 1.0, respectively. Only one patient required a reoperation 3.5 years after their index procedure, a conversion to reverse shoulder arthroplasty for recurrent posterior subluxation.

Structural bone grafting with the BioTSA is a viable solution for young, active patients with good functional outcomes and a low complication rate. This information can be useful in counseling patients regarding this procedure's short-term to mid-term results. Long-term studies are needed to elucidate the efficacy and durability of the BioTSA procedure in young patients undergoing anatomic total shoulder arthroplasty.