Prior metabolic and bariatric surgery and outcomes after open reduction and internal fixation of proximal humerus fractures: a nationwide retrospective cohort study

Background Metabolic and bariatric surgery (MBS) can have lasting nutritional and skeletal effects, but outcomes after proximal humerus fracture (PHF) fixation are poorly characterized. Objective To compare unplanned readmission and complications after PHF open reduction and internal fixation in patients with prior MBS versus documented severe obesity without MBS. Methods This retrospective cohort study used the Nationwide Readmissions Database (2016-2022). Adults undergoing inpatient PHF open reduction and internal fixation were grouped by prior MBS, documented severe obesity without MBS, or neither. The primary outcome was unplanned readmission at 30, 90, and 180 days. Survey-weighted logistic regression was used. Results Among 28,035 index hospitalizations, 461 involved prior MBS and 2,528 involved documented severe obesity without MBS. Readmission was higher after prior MBS at 90 days (13.4% vs 10.8%; adjusted odds ratio [aOR], 1.52; 95% confidence interval [CI], 1.03-2.26) and 180 days (20.3% vs 15.3%; aOR, 1.75; 95% CI, 1.15-2.64), but not at 30 days. The adjusted 180-day absolute difference was 7.1 percentage points (95% CI, 1.2-13.0). Major medical complications at 180 days were more frequent after MBS (12.7% vs 9.5%; aOR, 1.73; 95% CI, 1.04-2.88), although several sensitivity estimates included 1. A broad gastrointestinal, nutritional, or metabolic category accounted for 25.9% versus 6.8% of first 90-day readmissions and represented 13 readmissions in the prior-MBS group. Fracture-specific complications were uncommon, with no clear between-group difference. The 180-day readmission association persisted across all 13 sensitivity analyses, whereas the 90-day estimates were attenuated in the propensity-based analyses. Conclusion Prior MBS was associated with higher unplanned readmission after inpatient PHF open reduction and internal fixation, most consistently at 180 days. Bariatric history may identify patients who warrant closer attention to nutritional and metabolic concerns during perioperative care and follow-up.