Weight and body mass index change after total joint arthroplasty.

Obesity has become a leading public health issue in the United States. The goal of this study was to examine whether patients experience a significant change in body mass index (BMI) or weight after total joint arthroplasty. Previous studies have not corrected for the natural, annual positive BMI change in North Americans aged 29 to 73 years. Our study takes this natural weight gain into consideration in examination of total hip arthroplasty (THA) and total knee arthroplasty (TKA) populations. Our study population trended toward weight loss and BMI loss when weight was corrected for natural gain. Clinically significant weight loss, as determined by US Food and Drug Administration parameters, occurred in 19.9% of the study population when weight was corrected for natural gain. The TKA population exhibited a statistically significant (P<.05) weight loss and a clinically significant weight loss in 21.5% of the population. Patients with an initial BMI >30 exhibited a trend toward weight loss. This study was a level II retrospective study.