Influence of glenosphere design and material on clinical outcomes of reverse total shoulder arthroplasty.

Abstract

The aim of this multicentre retrospective study was to compare reverse total shoulder arthroplasty clinical outcomes with glenospheres of different diameters, designs and materials. Between 2003 and 2008, 133 patients were divided into three groups: 60 (45%) with 36-mm standard CoCrMo (group A), 21 (16%) with 36-mm eccentric cobalt-chromium-molybdenum (CoCrMo) (group B) and 52 (39%) with 44-mm cross-linked ultra-high molecular weight polyethylene (X-UHMWPE) (group C) glenospheres. Mean (SD) follow-up was 38.7 (17.4) months. Clinical evaluation included Constant score and range of motion. Radiographic analysis included radiolucent lines, instability, loosening and assessment of scapular notching. Mean Constant score significantly increased for all groups (Wilcoxon test, p < 0.001). Group C allowed a higher and stable increase in range of motion. After 12 months and 24 months, groups C and B showed less pain than group A (Mann-Whitney U-test, p < 0.05). Group C had significantly lower scapular notching than group B (Mann-Whitney U-test, p = 0.001) and A (Mann-Whitney U-test, p = 0.009) at 12 months, 24 months and 36 months. Groups A and C presented 5 (8.3%) and 4 (7.6%) early complications, respectively. The present study reported good results for all groups, although groups C and A presented better clinical outcomes, significantly lower notching and instability. A 44-mm X-UHMWPE glenosphere allowed a faster and more stable functional recovery, despite poorest pre-operative conditions. Additional long-term studies are needed to evaluate survivorship.