Relationship between Body Mass Index and Complications during the First 45 Days after Primary Total Hip and Knee Replacement: A Single-Center Study from South America

BACKGROUND: The goal of this study was to evaluate the relationship between body mass index (BMI) and early complications of total hip replacement (THR) and total knee replacement (TKR). METHODS: This is a retrospective study of patients who underwent primary THR and TKR between January 2011 and December 2015. We included patients between 18 and 90 years of age with BMI less than 40 kg/m(2) with a minimal postoperative follow-up time of 45 days. The primary outcomes were the presence of infection, mechanical complications (dislocation, fractures, arthrofibrosis, or neuropraxia), and thromboembolic events. Overweight and obesity were defined as a BMI of 25–29.9 kg/m(2) and ≥ 30 kg/m(2), respectively. RESULTS: In total 750 patients were included (THR, 268; TKR, 482) with a mean age of 65.0 ± 12.4 years. The percentage of patients with normal weight, overweight, and obesity was 24.9% (n = 187), 41.7% (n = 313), and 33.4% (n = 250), respectively. The early complication rate was 8.9% (95% confidence interval [CI], 7.1% to 11.2%). Infection and mechanical complications were most prevalent. There was no statistically significant relationship between the incidence of complications and BMI (obesity vs. normal weight: hazard ratio [HR], 1.49; 95% CI, 0.72 to 3.06; p = 0.282); however, there was a tendency toward a greater risk of infectious complications in the patients with obesity (HR, 6.08; 95% CI, 0.75 to 49.16; p = 0.090). Patients with diabetes mellitus (DM) had more risk of infectious complications than those without DM (HR, 2.60; 95% CI, 1.00 to 6.79). CONCLUSIONS: There was no statistical relationship between BMI and early complications of THR and TKR. Nonetheless, there was a tendency toward a higher risk of infection in patients with some degree of obesity.