Correlation of body mass index and blood loss during total knee and total hip arthroplasty.

Almost one-third of Americans older than 20 years are considered obese. Excessive weight has been linked to faster destruction of weight-bearing joints, which may then need to be replaced. Joint replacement surgeons disagree about an association between obesity and increased blood loss during hip or knee joint replacement. In this retrospective study, we examined the effect of body mass index (BMI), operative time (length of procedure), and anesthesia time on total blood loss during primary total knee arthroplasty (TKA) and primary total hip arthroplasty (THA). Intraoperative data from 94 primary TKAs and 78 primary THAs were reviewed, and divided into obese and nonobese groups on the basis of calculated BMI. Regression analysis was used to compare intraoperative blood loss amounts to patient characteristics. TKA and THA groups were analyzed separately. Obesity did not correlate with increased intraoperative blood loss in the TKA or THA group. However, operative time correlated with increased intraoperative blood loss. A 1-minute increase in anesthesia time resulted in total blood loss increases of 3.167 mL during TKA and 1.552 mL during THA.