Inferior glenosphere placement reduces scapular notching in reverse total shoulder arthroplasty.

Abstract

Scapular notching is a common complication after reverse shoulder arthroplasty and has been associated with poor clinical outcomes. Factors associated with notching include neck shaft angle and glenosphere position. The goal of this study was to evaluate the incidence of notching with an eccentric glenosphere that allows for inferior offset as well as its effect on clinical outcome. The charts of 82 patients who underwent reverse shoulder arthroplasty with this eccentric glenosphere were retrospectively reviewed. Scapular notching was assessed with standard anteroposterior radiographs of the glenohumeral joint according to the Nerot-Sirveaux classification system. Two experienced observers evaluated all radiographs. The presence of radiolucent lines was also evaluated. Both range of motion (ROM) and Constant-Murley scores were obtained. Average age was 74 years (range, 61-91 years), and follow-up was 26.3 months (range, 19-39 months). According to the Nerot-Sirveaux classification, 73 (89%) had no notching, 5 (6%) had grade I notching, 2 (2.5%) had grade II notching, and 2 (2.5%) had grade III notching. The overall presence of notching was 11% and correlated to the amount of inferior offset. No radiolucent lines were seen around the prosthesis. Both ROM and Constant-Murley scores (from 31.3 to 74.2) improved significantly in all patients from preoperative evaluation to final follow-up (P<.05). No significant differences in ROM and functional outcome were seen between the groups with and without notching. The inferior offset glenosphere created with this glenosphere base plate design reduced the incidence of scapular notching in reverse shoulder arthroplasty. This was particularly true when the glenosphere was maximally offset inferiorly. In the short term, notching does not affect ROM or functional outcome.