Weight Loss Before Total Hip Arthroplasty Was Not Associated with Decreased Postoperative Risks.

Abstract

Background: Many surgeons use body mass index (BMI) cutoffs when offering total hip arthroplasty (THA). However, little is known about who loses weight before THA, and if weight loss improves outcomes. This study determined how many patients lost weight before primary THA, identified predictors of preoperative weight loss, and evaluated whether preoperative weight loss was associated with improved outcomes.

Methods: Among 53,038 primary THAs that were performed between 2002 and 2019, we identified 2,463 patients who had a BMI of ≥30 kg/m2 (measured 1 to 24 months before surgery) and had their weight measured at the time of surgery. The mean age was 66 years; 47% were women. The mean BMI was 35 kg/m2. Nonparametric models evaluated potential associations with weight loss. Univariable and multivariable logistic regression and Cox proportional hazards models evaluated the impact of preoperative weight change on hospital length of stay, discharge disposition, operative time, periprosthetic joint infection (PJI), complications, revision, and reoperation. The mean follow-up was 5 years.

Results: Overall, 17% of the patients gained >5 pounds (2.27 kg), 38% maintained their weight, 16% lost 5 to <10 pounds (4.54 kg), 17% lost 10 to <20 pounds (9.07 kg), and 12% lost ≥20 pounds before THA. Only 28% of patients with a preoperative BMI of ≥40 kg/m2 achieved a BMI of <40 kg/m2 by the time of surgery; those who did required a mean of 1.3 years to lose the weight. In multivariable analyses, there were no significant improvements in operative time, length of stay, and discharge disposition, or survivorship free of PJI, complication, revision, or reoperation for any weight-loss category when compared with those who maintained their weight.

Conclusions: Only 12% of patients lost ≥20 pounds, and only 28% of patients with a BMI of ≥40 kg/m2 achieved a BMI of <40 kg/m2 before primary THA. There was no decrease in complications, revisions, or reoperations for any preoperative weight-loss category when compared with those who maintained their weight. While weight loss benefits overall health, the results of this study call into question whether preoperative weight loss alone is enough to reduce postoperative complications for most patients.

Level of evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.