Early clinical and radiographic outcomes of an augmented baseplate in reverse shoulder arthroplasty for glenohumeral arthritis with glenoid deformity

Background: Glenoid deformity is commonly encountered in patients undergoing reverse shoulder arthroplasty (RSA). Augmented baseplates can correct glenoid deformity while potentially avoiding certain complications encountered with structural bone graft. Limited evidence exists to support the use of metallic augmented baseplates in RSA.

Methods: We performed a retrospective review to identify all patients treated with an augmented baseplate during primary RSA with a minimum of 1 year of clinical and radiographic follow-up. Preoperative radiographs and advanced imaging were used to determine glenoid morphology and deformity. Postoperative radiographs were used to evaluate for deformity correction, radiographic complications, and early baseplate loosening or failure. Prospectively collected clinical data and patient-reported outcome scores were determined.

Results: Primary RSA was performed with an augmented baseplate in 44 patients (mean age, 72 ± 6 years; 15 half-wedge and 29 full-wedge augmentations). Glenoid retroversion was significantly improved for the entire cohort (P = .001). Among the 22 patients with either Walch type B2, B3, or C glenoid morphology, glenoid version improved from 28° ± 8° to 16° ± 8° (P = .001). Glenoid inclination, as determined by the β angle, was significantly improved for the entire cohort (P < .001). Among the 18 patients with Favard type E2 or E3 glenoid morphology, glenoid inclination improved from 67° ± 7° to 81° ± 8° (P < .001). Postoperative range of motion and functional outcome scores including the American Shoulder and Elbow Surgeons score, Simple Shoulder Test score, Single Assessment Numeric Evaluation score, and visual analog scale score for pain significantly improved within the entire cohort (P < .05). No patients had evidence of baseplate loosening or failure of the glenoid component. Acromial stress fractures developed in 5 patients (11.4%), and 2 patients (4.5%) underwent a reoperation unrelated to the glenoid component.

Discussion and conclusion: Primary RSA with an augmented baseplate results in excellent short-term clinical outcomes and significant deformity correction in patients with advanced glenoid deformity. There were no complications related to the augmented baseplate or glenoid component. The rate of acromial stress fractures appears higher than typically reported and warrants further investigation.