Comparable outcomes of reverse shoulder arthroplasty for proximal humerus fractures and for rotator cuff arthropathy in a predominantly asian population.

Background: Reverse shoulder arthroplasty (RSA) was initially developed for rotator cuff arthropathy but has been expanded to treat comminuted proximal humerus fractures. Few studies have compared RSA for traumatic and degenerative indications. We present the first report of mid-term outcomes of RSA comparing both indications in an Asian population. Methods: 113 degenerative and 20 fracture patients underwent RSA from 2010 to 2019. Patients with degenerative indications were 4:1 propensity-score matched to fractures and adjusted for age and sex. Patients were assessed for range of motion (ROM), strength, pain, Constant-Murley score (CMS), University of California Los Angeles Shoulder Score (UCLA) and Oxford shoulder score (OSS) preoperatively, at 6-months and 1-year. Patients' satisfaction, expectation fulfilment and minimal clinically important difference (MCID) were analysed. Results: Degenerative patients had better ROM, isometric strength and CMS at 6-months, although at 1-year only abduction was superior (104.8  ±  17.3° vs 86.7  ±  19.8°). No significant differences in pain, UCLA and OSS were observed. Most improvements occurred within 6 months. Similar proportions of patients were satisfied (83.3% vs 73.3%, p = 0.460) and attained MCID (85.0% vs 86.7%, p = 1.000) at 1-year. Discussion: Although initially exhibiting slower recovery, patients with proximal humerus fractures can expect similar functional recovery and satisfaction at 1-year compared to those who received RSA for degenerative indications.