Body mass index as a predictor of complications after operative treatment of acetabular fractures

Background: Obesity, a growing public health concern, is often thought to be an important risk factor for postoperative complications. We hypothesized that body mass index is predictive of complications after operative treatment of acetabular fractures. Methods: A retrospective chart review identified 169 consecutive patients in whom an acetabular fracture had been treated with open reduction and internal fixation at a level-1 trauma center. The patients were stratified into four classes according to their body mass index: normal (< 25), overweight (>= 25 but < 30), obese (>= 30 but < 40), and morbidly obese (>= 40). The perioperative outcomes that were evaluated included estimated blood loss, wound infection, nerve palsy, deep venous thrombosis, pulmonary embolism, and heterotopic ossification. Multivariate general linear models were used to test for the relationship between body mass index and perioperative outcomes while controlling for potential intervening variables (including surgical approach, fracture type, and surgeon experience). Odds ratios were calculated as well. Results: When body mass index was measured as a continuous variable, it was found to have a significant relationship with estimated blood loss (p = 0.003), prevalence of wound infection (p = 0.002), and prevalence of deep venous thrombosis (p = 0.03). Odds ratio analysis revealed that obese subjects (body mass index of >= 30) were 2.1 times more likely than patients of normal weight (body mass index of < 25) to have an estimated blood loss of > 750 mL and 2.6 times more likely to have a deep venous thrombosis. Morbidly obese patients (body mass index of >= 40) were five times more likely to have a wound infection. Conclusions: Body mass index is predictive of complications after operative treatment of acetabular fractures.