Primary versus conversion reverse total shoulder arthroplasty for complex proximal humeral fractures in elderly patients: a retrospective comparative study

The purpose of this study was to compare clinical, implant-related, and patient-reported outcomes of shoulders undergoing conversion to reverse total shoulder arthroplasty (rTSA) following previous open reduction–internal fixation vs. shoulders undergoing rTSA as a primary treatment modality for acute proximal humeral fractures (PHFs) in patients aged ≥65 years. We performed a retrospective analysis of a prospectively collected cohort of patients who underwent primary rTSA for PHFs vs. a cohort who underwent conversion arthroplasty with rTSA following fracture repair between 2009 and 2020. Outcomes were assessed preoperatively and at latest follow-up. Demographic characteristics and outcomes were analyzed between cohorts using conventional statistics, as well as stratification by minimal clinically important difference and substantial clinical benefit thresholds where applicable. In total, 406 patients met the study criteria, of whom 322 underwent primary rTSA for PHF and 84 underwent conversion rTSA after failed PHF open reduction–internal fixation. The conversion rTSA cohort was, on average, 7 years younger than the primary rTSA cohort (65 ± 10 years vs. 72 ± 9 years, P .99). The primary rTSA cohort achieved higher forward elevation, external rotation, and patient-reported outcome measurements including Simple Shoulder Test, American Shoulder and Elbow Surgeons, University of California–Los Angeles, Constant, Shoulder Arthroplasty Smart, and Shoulder Pain and Disability Index scores at a minimum of 24 months postoperatively (P