Short-term evaluation of humeral stress shielding following reverse shoulder arthroplasty using press-fit fixation compared with cemented fixation

Background: The purpose of this study was to compare the functional outcomes and humeral stress shielding of a reverse shoulder arthroplasty (RSA) placed with either cement or press-fit fixation. The hypothesis was that there would be no difference in functional outcomes or stress shielding. Methods: We performed a multicenter retrospective review of primary RSAs performed with standard-length stems. The stems were identical in geometry and coating with the only variable being whether the stems were secured with cement or by a press-fit technique. The functional outcomes and radiographs of 93 press-fit stems and 26 cemented stems were reviewed at a minimum of 2 years postoperatively. Results: Significant improvements were noted in all ranges of motion and functional outcomes from baseline (P < .001), but no difference was found between the groups (P > .05). Calcar osteolysis was seen in 43% of press-fit and 58% of cemented stems (P = .266). Proximal lateral stress shielding was more common in the press-fit group (68%) than in the cemented group (25%) (P = .045). Adaptive changes were considered low in 97% of press-fit stems, and there were no cases of tuberosity resorption. No evidence of loosening or humeral component shift was noted in either group. Conclusion: At short-term follow-up, no differences in functional outcomes or stem loosening were found between press-fit fixation and cemented fixation of an RSA humeral stem. Proximal stress shielding was more common with press-fit fixation with the stem in this study, but the overall changes were considered low in 97% of cases. Further study is needed to evaluate the mid- to long-term differences regarding stress shielding. (C) 2019 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.