Can small glenospheres with eccentricity reduce scapular notching as effectively as large glenospheres without eccentricity? A prospective randomized study

Background: The objective of this study was to analyze whether small glenospheres with eccentricity were comparable to large glenospheres in scapular notch development.

Methods: This prospective randomized study included 82 patients who had undergone a reverse shoulder arthroplasty with a 2-year follow-up period. After randomization, 43 patients were allocated to receive a 42-mm glenosphere and 39 patients were allocated to receive a 38-mm glenosphere with 2 mm of eccentricity. Scapular notch development was defined after examination of an anteroposterior radiograph at the end of follow-up. Functional outcomes were recorded using the Constant score before surgery and at the end of follow-up.

Results: Scapular notch development was present in 16.6% of patients who received a 42-mm glenosphere and 34.2% of patients who received a 38-mm eccentric glenosphere. No significant difference was found between the groups with the number of cases available (P = .07). Functional outcomes significantly increased from preoperatively to postoperatively in both groups, with no significant difference found between them (P = .77). The mean glenosphere overhang measure was 6.3 mm in patients with a 42-mm glenosphere and 6.0 mm in those with a 38-mm eccentric glenosphere (P = .68). No significant differences were noted between patients with a scapular notch and patients without a scapular notch in terms of functional outcomes.

Discussion: Small glenospheres with eccentricity fared slightly worse than large glenospheres regarding scapular notch development, even though no significant differences were noted. Functional outcomes were comparable between the 2 designs.