Influence of glenosphere size on the development of scapular notching: a prospective randomized study

Abstract

The objective of the study was to evaluate the development of scapular notching in reverse shoulder arthroplasty by comparing larger glenospheres (42 mm) with smaller glenospheres (38 mm). This was a prospective randomized study of 81 patients who had undergone reverse shoulder arthroplasty with a 2-year follow-up. Patients were randomized to receive either a 42-mm glenosphere (38 patients) or a 38-mm glenosphere (43 patients). Scapular notching development was assessed with an anteroposterior radiograph at the end of the follow-up. Functional outcome was assessed with the Constant score before surgery and at the end of follow-up. An independent blinded observer carried out radiologic and clinical assessments. Scapular notching was present in 48.8% of the patients receiving a 38-mm glenosphere and in 12.1% of the patients receiving one of 42 mm, with significant differences between both (P < .001). No significant differences were noted between the 2 glenosphere size groups in terms of the total Constant score. Patients with a 42-mm glenosphere had a mean glenoid-glenosphere overhang of 6.1 mm, whereas patients with a 38-mm glenosphere had one of 4.2 mm, with significant differences between them (P < .001). No significant differences in the total Constant score were found between the patients whether they had scapular notching or not. Bigger glenospheres (42 mm) significantly reduce development of scapular notching compared with smaller glenospheres (38 mm). Glenosphere size has no significant influence on functional outcomes measured with the Constant score.