Press-fit vs. cemented humeral stem fixation for reverse shoulder arthroplasty: functional outcomes at a mean follow-up of 9.5 years

Background: Reverse shoulder arthroplasty (RSA) is a reliable, long-term treatment option for degenerative shoulder pathology. However, the functional outcomes degrade around the fifth year postoperation, particularly for internal and external rotation. Long-term radiographic changes have been reported around the humeral stem, depending on the fixation method. Objectives: The primary objective was to compare the clinical outcomes of RSAs by fixation method-cemented vs. press-fit-after a minimum follow-up of 5 years. We hypothesized that proximal humeral osteolysis impacts the functional outcomes. Design and Methods: Our study compared 2 matched cohorts: 56 RSAs with cemented stems and 56 RSAs with press-fit stems. We evaluated all the patients using the Constant-Murley score (CMS) and range of motion (ROM), which we measured preoperatively and at the final follow-up visit. We evaluated radiographs from the final follow-up visit to look for proximal humeral osteolysis with tuberosity resorption, signs of stress shielding, periprosthetic radiolucent lines, and scapular notching. Results: At a mean follow-up of 9.5 years (5-21), regardless of the fixation method, the RSA procedure helped to improve the CMS and active joint ROM postoperatively, except for internal and external rotation with elbow at side in the press-fit group. Shoulder ROM was significantly better in the group with cemented stems for anterior elevation (P<.001), abduction (P=.006), and external (P=.02) and internal rotation with elbow at side (P=.02). The CMS did not differ between groups. The presence of tuberosity resorption or scapular notching had no effect on the CMS and active ROM in either group. Osteopenia, which was more prevalent in the press-fit group, had no impact on the functional outcome. Conclusion: There was no significant difference between groups in the CMS, although the active shoulder ROM was significantly worse in the press-fit group. This difference could be attributed to more frequent tuberosity resorption in this group. (C) 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.