Higher body mass index is not a risk factor for in-hospital adverse outcomes following total knee arthroplasty.

Abstract

To investigate the association between body mass index (BMI) and perioperative complications until hospital discharge, following primary total knee arthroplasty (TKA). This retrospective study reviewed 1665 cases of elective primary unilateral TKA performed between 2006 and 2010, from a prospective secure electronic database. Types of complications, length of operating time, and duration of hospital stay were analyzed in both adjusted (for known confounders) and unadjusted analyses. A further matched analysis was also performed. In terms of overall complications, there was no statistically significant difference between the BMI categories. When individual obesity category was considered, obese 2 had the lowest odds of developing complications, both with unadjusted (odds ratio (OR): 0.61, 95% confidence interval (CI) 0.41-0.91, p < 0.015) and adjusted regression analysis (OR: 0.65, 95% CI: 0.43-0.99, p = 0.044). Compared to normal weight category, obese class 3 (≥40 kg/m²) individuals were at 66% (OR: 0.34, 95% CI: 0.21-0.55) lower (unadjusted) odds of developing cardiac complications (overall p < 0.001). With the matched analysis, compared to normal weight category, obese class 3 (≥40 kg/m²) individuals were at a 60% (OR: 0.40, 95% CI: 0.23-0.68) lower (unadjusted) odds of developing cardiac complications (overall p = 0.004). Obese 3 patients had significantly higher operating time compared with other groups ( p < 0.001). This study did not find a significant association between BMI and increased overall in-hospital medical or surgical complications following primary TKA. Obesity significantly increased the length of operating time.