Study finds morbid obesity has little impact on postoperative outcome of THR

McCalden RW, et al. JBJS (Br). 2011. doi: 10.1302/0301-620X.93B3.25876.

In this study, researchers found morbid obesity does not affect postoperative outcome after primary total hip replacement – with the possible exception of a “marginally increased” rate of infection. They reason, therefore, that withholding surgery based on body mass index is not justified.

The researchers evaluated the outcome of primary total hip replacement in 3,290 patients with a primary diagnosis of osteoarthritis at a minimum follow-up of 2 years. Patients were stratified into categories of body mass index (BMI) based on the World Health Organization classification of obesity. They then performed statistical analysis to determine if there was a BMI-based difference in postoperative Western Ontario and McMaster Universities osteoarthritis index, Harris hip score and Short-Form-12 outcome.

The authors found that while preoperative and postoperative scores were lower for the group classified as morbidly obese, overall change in outcome scores suggested an equal – if not greater – improvement when compared with patients who were not morbidly obese. Overall survivorship and rate of complications were similar between the BMI groups, but the authors noted a slightly higher rate of revision for sepsis in the morbidly obese group.

“While efforts to decrease the prevalence of obesity remain important from the position of the patient’s general health, and also as a means of decreasing the incidence of osteoarthritis and the need for joint replacement surgery, delaying surgery on the basis of obesity is clearly not justified,” the authors wrote.