Clinical and radiologic outcomes of eccentric glenosphere versus concentric glenosphere in reverse shoulder arthroplasty.

Abstract

The use of an eccentric glenosphere (EG) has been proposed as a way to prevent scapular notching in reverse shoulder arthroplasty (RSA). The purpose of this study was to investigate whether the use of an EG decreases scapular notching compared with matched standard concentric glenosphere (CG) controls. A retrospective analysis was performed. This study included 49 RSAs with an EG and 49 paired RSAs with a CG with a minimum 60 months of both clinical and radiographic follow-up. Clinical and radiologic outcomes of the EG and CG groups were compared at inclusion and at the last follow-up using the paired Student t test for quantitative data and the χ² test for qualitative data. Scapular notching was graded according to the Sirveaux classification. Statistical significance was set at P < .05. Notching was observed 2.7 times (95% confidence interval, 1.0-6.8 times) more often in the CG group (P = .037). The difference in notching severity between the groups was not statistically relevant; however, there was a trend toward more severe notching in the CG group (P = .059). Compared with a CG, an EG did not increase the percentage of radiolucent lines around the screws (3% vs. 1.5%, P = .62), around the post (3% vs. 1.5%, P = .62), or below the baseplate (15% vs. 7.5%, P = .18). EGs are associated with less notching than CGs. This finding confirms that RSA with an EG is an effective procedure without specific complications at a minimum follow-up of 5 years.