Effect of Bariatric Surgery on Risk of Complications after Total Knee Arthroplasty: A Randomized Clinical Trial

Abstract

Importance: People with severe obesity who undergo a total knee arthroplasty (TKA) for osteoarthritis (OA) are at higher risk of short-term and long-term complications compared with people with reference (<30) body mass index (BMI; weight in kilograms divided by height in meters squared). It is not known whether weight loss before TKA modifies this risk. Objective: To determine whether outcomes are improved by undergoing bariatric surgery before TKA in people with BMI greater than or equal to 35 and end-stage OA. Design, Setting, and Participants: This parallel-group, assessor-blinded, randomized clinical trial was conducted between May 2012 and June 2020 with a minimum follow-up of 12 months after TKA. TKA was performed at a tertiary referral university-affiliated public hospital, and bariatric surgery was performed at a private hospital facility and a university-affiliated private practice. Data analysis was performed from February to July 2021. Interventions: Bariatric surgery compared with usual weight management advice (treatment as usual [TAU]) in people scheduled for TKA. Main Outcomes and Measures: The primary outcome was complications of TKA measured by a composite of death from any cause, perioperative or postoperative complications resulting in a discharge delay, unplanned procedure, or readmission for at least 12 months after TKA. Secondary outcomes included hospital bed day utilization, anthropomorphic measures, and patient-reported outcomes. Results: Eighty-two patients waiting for TKA were randomized to undergo bariatric surgery (41 patients) or TAU (41 patients). Of the 82 participants, 66 (80.5%) were women, the mean (SD) age was 57.8 (4.9) years, and the mean (SD) BMI was 43.8 (5.5). Thirty-nine participants (95.1%) in the intervention group underwent laparoscopic adjustable gastric banding, and 29 (70.7%) subsequently underwent TKA. Thirty-nine patients (95.1%) in the TAU group underwent TKA. Six patients (14.6%) in the intervention group incurred the primary outcome (median follow-up, 24 months), compared with 15 (36.6%) in the TAU group (median follow-up, 27 months) (difference, 22.0%; 95% CI, 3.7% to 40.3%; P =.02). The between-group difference in BMI at 12 months was -6.32 (95% CI, -7.90 to -4.50; P