Many surgeons recommend weight loss for patients with obesity before total joint arthroplasty (TJA), but few studies have evaluated weight loss interventions. This study compared weight loss using a remote dietitian and a mobile application (app) with weight loss using standard care for patients with severe obesity before TJA.

This multicenter randomized controlled trial included 60 subjects with a body mass index (BMI) of 40 to 47 kg/m 2 who had been scheduled for primary total hip or knee arthroplasty from September 2019 to January 2023. The mean age was 61 years, 67% were women, and the mean BMI was 44 kg/m 2 . The control subjects (n = 29) received standard care; the intervention subjects (n = 31) completed video calls with dietitians and used a mobile app for 12 weeks preoperatively. Weights and surveys were collected at baseline and 12 weeks, with 87% follow-up. Weight loss, patient-reported outcomes, complications, revisions, and reoperations were compared. The mean follow-up was 1.8 years.

The intervention subjects lost more weight (-4.1 versus -2.1 kg, p = 0.22) and had larger decreases in BMI (-1.4 versus -0.9 kg/m 2 , p = 0.36 than the controls, but not significantly so. The intervention subjects had higher odds of achieving a BMI of <40 kg/m 2 (odds ratio = 1.9, p = 0.44), but not significantly so. There were no significant differences in the mean change in the Hip disability and Osteoarthritis Outcome Score, the Knee injury and Osteoarthritis Outcome Score, or the Lower Extremity Activity Scale score. At baseline, only 11% had seen a dietitian in the last 3 months. Most subjects (83%) felt that video calls were helpful. There were no differences in complications between the groups; there was a patellar fracture in the control group and a deep venous thromboembolism in the intervention group.

A preoperative weight loss intervention using a dietitian and a mobile app was feasible and viewed favorably among patients. Remote dietitians and mobile apps may address gaps in access to obesity treatment before TJA. While the intervention subjects lost more weight and were more likely to achieve a BMI of <40 kg/m 2 , the differences were not significant. More intensive interventions may be needed to achieve enough weight loss for clinically important improvements in TJA.

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

We explore the incidence of periprosthetic infections post-total knee arthroplasty (TKA) in morbidly obese patients who achieved weight loss. Current American Academy of Orthopaedic Surgeons guidelines suggest a preoperative body mass index (BMI) below 40 for TKA. This study assesses infection risks in patients initially who had a BMI of 40-50 who reduced their BMI to under 35 at varying intervals prior to surgery.

We reviewed a national, all-payer database, PearlDiver, for patients undergoing primary TKA. Patients were stratified based on initial BMI of 40 to 50 and reduction of BMI to less than 35 at 3 months (n = 1,932), 3 to 6 months (n = 794), 6 to 9 months (n = 2,233), and 9 to 12 months (n = 1,194) prior to TKA, as well as patients who had a BMI between 40 to 50 (n = 41,632) on the day of surgery. The nonobese group comprised of patients who had a BMI between 20 and 30 (n = 33,294). Multivariate analyses were performed at one-year follow-up.

We found an increased risk of PJI for patients who had achieved BMI reduction less than nine months prior to TKA, compared to the BMI 20 to 30 cohort at the one-year follow-up (P < .001). Patients who achieved BMI reduction nine to twelve months prior to TKA showed no significant difference in PJI risk compared to the matching nonobese cohort at one-year follow-up (P = .400).

In conclusion, our results suggest that weight loss should be achieved at least nine months before TKA to decrease infection risks. These findings have significant implications for surgical considerations in obese patients undergoing TKA.

An upcoming total joint arthroplasty (TJA) may motivate patients with severe obesity (body mass index [BMI] > 40 kg/m²) to lose weight. Weight loss can optimize outcomes following TJA, and many surgeons use a 40 kg/m² cut-off for undergoing TJA to reduce the risk of complications. However, few patients who are denied TJA for severe obesity successfully lose weight. This is the first systematic review of nonsurgical weight loss interventions before TJA.

Five electronic databases were searched for articles on January 11, 2021. Studies that utilized preoperative nonsurgical weight loss interventions for patients with obesity (BMI ≥ 30 kg/m²) scheduled for or awaiting TJA of the hip or knee were included. Two reviewers independently screened articles, assessed methodological quality, and extracted data.

We retrieved 1943 unique records, of which 7 met inclusion criteria including 2 randomized clinical trials and 5 single-arm case series. Overall, weight loss ranged from 5.0 to 32.5 kg. Four interventions reduced BMI by 3 kg/m² at 3-5 months, while 1 reduced BMI by 12.7 kg/m². Other weight outcomes and those related to pain, function, complications, and adverse events were inconsistently reported.

Although larger trials are needed, particularly randomized controlled trials that measure preoperative weight loss in a control group, nutritional status, and postoperative complications, the available evidence indicates that short-term, nonsurgical, preoperative weight loss interventions before TJA produce both statistically significant weight loss and reduced BMI before surgery. It remains unknown if the amount of weight loss from these interventions is clinically significant and sufficient to improve outcomes after TJA.