Overweight and premorbid obesity status correlates with thromboembolism risk but not infection after total shoulder arthroplasty

Background: Total shoulder arthroplasty (TSA) is an effective treatment for shoulder arthritis. Although obesity is associated with complications after hip and knee arthroplasty, its association with TSA outcomes remains less defined. This study evaluated TSA outcomes stratified by body mass index (BMI). Methods: The TriNetX Research Network was queried for adults who underwent TSA between January 1, 2000 and April 6, 2023. Patients were stratified into normal weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), obese (30-39.9 kg/m²), and morbidly obese (≥40 kg/m²) cohorts. Outcomes included infection, wound disruption, sepsis, deep vein thrombosis (DVT), pulmonary embolism (PE), mechanical complications, revision surgery, and hardware removal within 2 years. Propensity score matching controlled for age, sex, comorbidities, and smoking status. Risk ratios (RRs), 95% confidence intervals (CIs), and P values were reported. Benjamini-Hochberg correction was performed as a sensitivity analysis. Results: Matched cohorts included 8,642 overweight vs. normal BMI patients, 14,714 obese vs. overweight patients, and 4,996 morbidly obese vs. obese patients per group. Compared with normal BMI patients, overweight patients had higher DVT risk (RR: 1.48, 95% CI: 1.12-1.96; P = .006). Compared with overweight patients, obese patients had higher risks of DVT (RR: 1.36, 95% CI: 1.12-1.65; P = .002) and PE (RR: 1.25, 95% CI: 1.01-1.55; P = .037). In sensitivity analysis, only DVT among obese vs. overweight patients remained significant. No significant differences were observed for infection, wound disruption, sepsis, mechanical complications, revision surgery, or hardware removal. Conclusion: Elevated BMI was associated with weak-to-moderate increases in thromboembolic risk after TSA but not infection or revision surgery. These findings support individualized thromboembolic risk assessment while suggesting TSA remains relatively safe in patients with elevated BMI.