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

Abstract

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<.001). The follow-up periods were similar between the cohorts, with an average of 47.1 months (range, 24-138 months). The percentages of Neer 3-part (41.9% vs. 45.2%) and 4-part (49.1% vs. 46.4%) PHFs were similar (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<.05 for all). Patient satisfaction was higher in the primary rTSA group than in the conversion rTSA cohort (P=.002). Patient-reported outcome measures uniformly favored the primary rTSA cohort, rising to the level of statistical significance for forward elevation, American Shoulder and Elbow Surgeons score, and Shoulder Pain and Disability Index score (P<.05) relative to substantial clinical benefit. The adverse event rate and revision rate in the conversion rTSA cohort were higher than those in the primary rTSA cohort (26.2% vs. 2.5% [P<.001] and 8.3% vs. 1.6% [P=.001], respectively). At 10 years postoperatively, the revision-free implant survival rate was significantly lower in the conversion cohort compared with the primary cohort (66% vs. 94%, P=.012). Finally, the hazard ratio of revision was 3.69 in the conversion rTSA cohort compared with only 1.0 in the primary rTSA cohort. This study demonstrates that elderly patients who undergo rTSA as a conversion procedure following previous osteosynthesis do not fare as well as those treated with rTSA for acute displaced PHFs. Conversion rTSA patients report lower patient satisfaction and have significantly restricted range of shoulder motion, a higher risk of complications, a higher risk of revision, poorer patient-reported outcomes, and a shorter implant survival rate at 10 years compared with patients undergoing acute rTSA.