The Effect of Body Mass Index on 30-day Complications After Revision Total Hip and Knee Arthroplasty

Background: We aimed to explore the effect of body mass index (BMI) on 30-day complications after aseptic revision total knee arthroplasty (rTKA) and aseptic revision total hip arthroplasty (rTHA), considering BMI as both a categorical and continuous variable. Methods: A total of 18,866 patients (9093 rTHA and 9773 rTKA) patients were included for analysis using the American College of Surgeons National Surgical Quality Improvement Project database. Thirty-day rates of readmissions, reoperations, and major and minor complications were compared between different weight categories (overweight: BMI >25 and <= 30 kg/m(2); obese: BMI >30 and <= 40 kg/m(2); morbidly obese: BMI >40 kg/m(2)) and the normal weight category (BMI >18.5 and <= 25 kg/m(2)) using multivariate regression models. Spline regression models were created to study BMI as a continuous variable. Results: Both readmission rates and reoperation rates increased for rTKA as BMI increased (P < .005). There was a linear relationship between BMI and readmission rates for rTKA. Morbid obesity was associated with an increased reoperation rate for rTHA on univariate analysis (P = .022); however, multivariate analysis showed no statistically significant increase in readmission or reoperation rates as BMI increased for rTHA. Conclusions: The relationship between BMI and complications after revision total joint arthroplasty is a J-shaped curve with the lowest rates of complications occurring around a BMI of 30 kg/m(2). The relationship between BMI and perioperative complications is stronger for revision TKA as opposed to revision THA. (c) 2019 Elsevier Inc. All rights reserved.