Short-term outcomes of reverse shoulder arthroplasty using a custom baseplate for severe glenoid deficiency

Abstract

Hypothesis and background: Complex glenoid bone loss and deformity present a challenge for the shoulder arthroplasty surgeon. Eccentric reaming, bone grafting, augmented glenoid components, and salvage hemiarthroplasty are common strategies for managing these patients. The glenoid vault reconstruction system (VRS; Zimmer-Biomet) is a novel solution for both primary and revision arthroplasty using a custom glenoid baseplate. We hypothesized that patients undergoing reverse shoulder arthroplasty (RSA) with VRS would have acceptable short-term outcomes and complication rates.

Methods: Patients who underwent RSA with VRS for severe glenoid deformity or bone loss by one of 4 board-certified, fellowship-trained shoulder and elbow surgeons at 3 academic tertiary referral centers between September 2015 and November 2018 were eligible for inclusion. Patient data were obtained via medical record review and telephone questionnaires. The Numeric Pain Rating Scale (NPRS), Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), Penn Shoulder Scores, and range of motion (ROM) measurements were obtained pre- and postoperatively. Radiographs were reviewed at final follow-up for evidence of component loosening or hardware failure. Any complication was documented. Outcomes were compared using Wilcoxon signed-rank tests with P <. 05 considered significant.

Results: Twelve shoulders (11 patients) were included with a mean age of 68 years; 7 were primary arthroplasties and 5 were revisions. At an average follow-up time of 30 months, median improvement in NPRS score was 7 points, SANE score 43%, ASES score 45 points, and Penn Shoulder Score 49 points. There were statistically significant improvements in median ROM measurements (forward elevation 20°, external rotation 40°, internal rotation 2 spinal levels). At final follow-up, all implants were radiographically stable without loosening. There were no complications.

Discussion and conclusion: This study demonstrates that RSA using the custom VRS glenoid implant is a safe and effective technique addressing complex glenoid deformity or bone loss in both primary and revision settings. At short-term follow-up, all patient-reported outcomes and ROM measures improved significantly, and there were no complications. Future work should determine mid- and long-term outcomes, preferably in a prospective manner with defined patient populations.

Keywords: CAD/CAM; Reverse shoulder arthroplasty; custom implant; glenoid deficiency; revision shoulder arthroplasty.