Reverse total shoulder arthroplasty demonstrates improved functional outcomes and equivocal mid-term survival compared to hemiarthroplasty following oncologic reconstruction in proximal humerus replacement.

Abstract

Oncologic proximal humerus replacement (PHR) poses challenges due to disruption of the rotator cuff and capsule. We evaluated functional outcomes, implant survivorship, resection length, and stem-to-resection length ratio in patients undergoing hemiarthroplasty or reverse total shoulder arthroplasty (rTSA) with either endoprosthesis or allograft-prosthesis composite (APC) reconstruction. This is a retrospective cohort study of 173 patients undergoing oncologic PHR between 1981-2024 (146 hemiarthroplasty; 27 rTSA). Mean follow-up was 59.3 ± 81.9 months (hemiarthroplasty) and 24.9 ± 26.6 months (rTSA). Implant failures were classified using the Henderson system. Shoulder range of motion (ROM)-abduction, forward flexion (FF), and external rotation (ER)-was assessed at most recent follow-up. Independent t-tests compared ROM between groups. Pearson correlation evaluated relationships between resection length and ROM. Stem-to-resection length ratios were analyzed for impact on implant survival. Kaplan-Meier analysis assessed implant survivorship. RTSA showed significantly greater ROM than hemiarthroplasty: abduction (109° vs. 32°), FF (110° vs. 34°), ER (38° vs. 17°) (p < 0.001; p < 0.001; p=0.002, respectively). In rTSA, abduction, FF, and ER did not correlate with resection length (p=.710; p=0.910; p=0.710, respectively), and stem-to-resection length ratio did not predict survival. In resections below the deltoid tuberosity, APC reconstructions had worse FF (56° vs. 121°, p = 0.040). Time to failure was shorter in rTSA (2.1 vs. 55.2 months, p < 0.001), though overall survival did not differ (p = 0.710) CONCLUSION: RTSA yields superior ROM compared to hemiarthroplasty without compromising implant longevity. APC use below the deltoid tuberosity may reduce functional outcomes. Early rTSA failures warrant improved follow-up and multicenter analysis. Level III; Retrospective Cohort Comparison; Treatment Study.