In Patients with Knee OA and Severe Obesity, Bariatric Surgery and Weight Loss Before TKA Reduced Complications Versus TKA Alone

Dowsey MM, Brown WA, Cochrane A, Burton PR, Liew D, Choong PF. Effect of bariatric surgery on risk of complications after total knee arthroplasty: a randomized clinical trial. JAMA Netw Open. 2022 Apr 1;5(4):e226722. Question: In patients with advanced osteoarthritis (OA) of the knee and severe obesity, what is the effect of bariatric surgery before total knee arthroplasty (TKA) versus TKA alone on post-TKA complications? Design: Randomized (unclear allocation concealment), blinded (outcome assessor, outcome validation panel, and data analysts), controlled trial with 12 months of follow-up. The trial was stopped early because patients in the bariatric surgery group were declining TKA due to improvement in OA symptoms. Setting: Orthopaedic clinic and bariatric centers in Victoria, Australia. Patients: 82 patients ≤65 years of age (mean age, 58 years; 81% women; mean body mass index [BMI], 44 kg/m2) who were on the surgical wait list for primary TKA due to advanced OA, had BMI ≥35 kg/m2, and were willing to follow a long-term weight management program. Exclusion criteria were revision surgery, surgery for neoplastic disease, a medical condition negating participation, or previous esophagogastric surgery. 100% of patients were assessed for the primary outcome at a median 24 to 27 months and included in the intention-to-treat analysis. Intervention: Patients were allocated to bariatric surgery with laparoscopic adjustable gastric banding, followed by TKA after 20% loss of baseline body weight or 1 year (n = 41); or TKA with usual follow-up and general weight management advice (n = 41). Main outcome measures: The primary outcome was a composite of death from any cause, perioperative or postoperative complications that delayed discharge, wound complications, periprosthetic infection, or unplanned procedures and/or readmission after TKA. Secondary outcomes included BMI, weight, pain, function, and quality of life. Main results: Median time to TKA was 17 versus 4 months in the bariatric surgery and TKA groups, respectively. In the bariatric surgery group, 12 patients declined TKA after weight loss due to improvement in symptoms. The primary composite outcome of complications after TKA was reduced in the bariatric surgery group versus the TKA group, as were BMI and weight at 12 months (Table I). Groups did not differ for pain, function, stiffness, or quality of life (Table I). TABLE I - Bariatric surgery before TKA versus TKA in patients with advanced knee OA and severe obesity* Outcomes Event rates at a median 24 to 27 months Risk difference (95% CI)† NNT (CI)† TKA Bariatric surgery before TKA Primary composite outcome‡ 36.6% 14.6% 22%% (4% to 40%) 5 (3 to 33) Mean at 12 Months after TKA Mean difference between groups (CI) P value BMI (kg/m 2 ) 42.5 36.5 −6.32 (−7.90 to −4.50) <0.001 Weight (kg) 111.5 96.6 −16.5 (−21.0 to −12.0) <0.001 WOMAC-pain§ 23.4 21.2 0.6 (–9.6 to 10.9) NS WOMAC-function§ 27.5 20.8 –4.7 (–12.6 to 3.1) NS WOMAC-stiffness§ 34.5 27.4 −6.5 (–16.1 to 3.1) NS WOMAC-global§ 27.3 21.4 −5.0 (–13.1 to 3.1) NS Quality of life-physical# 37.0 40.3 3.8 (−0.8 to 8.6) NS Quality of life-mental# 48.8 53.2 4.0 (−1.4 to 9.4) NS *The values shown in this table are based on the values reported in the original article. CI = confidence interval, NNT = number needed to treat, WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index, NS = not significant.†NNT and CI calculated from event rates in article.‡Composite of death from any cause, perioperative or postoperative complications that delayed discharge, wound complications, periprosthetic infection, or unplanned procedures and/or readmission.§WOMAC score range, 0 (no pain or disability) to 100 (higher score = worse pain and greater disability).#Veterans RAND 12-Item Health Questionnaire score, population average 50.0; higher score = better health-related quality of life. Conclusion: In patients with advanced knee OA and severe obesity, bariatric surgery before TKA reduced perioperative complications compared with TKA alone. Sources of funding: National Health and Medical Research Council Project Grant. The LAP-BAND device was provided at a reduced price by Allergan. For correspondence: Dr. Peter F. Choong, Department of Surgery, St Vincent’s Hospital Melbourne, The University of Melbourne, Fitzroy, Victoria, Australia. E-mail address: [email protected] Commentary The results of the randomized controlled trial by Dowsey and colleagues enhance our understanding of the effects of surgical weight loss in patients seeking TKA for treatment of advanced OA. There is conflicting evidence about the need for and timing of bariatric surgery in relation to arthroplasty surgery. Studies comparing bariatric surgery versus no surgery in patients with obesity and lower (<40 kg/m2) or higher (≥40 kg/m2) BMI have shown reduced implant stability and survivorship1,2, whereas others have reported lower medical and surgical complication rates in patients who had previous bariatric surgery3. However, these studies relied on retrospective cohorts and large administrative data sets. In contrast, the trial by Dowsey and colleagues is unique in randomizing patients to surgical lap band versus standard-of-care weight-loss management. While a lap band is not the most common bariatric technique4, it resulted in an unexpected 30.8% of patients in the treatment group not proceeding to TKA due to symptom relief, which altered the intended analysis. This finding is as important as the primary outcome assessment because it led to lower TKA rates, potentially driving down unnecessary spending. With the evolving health-care climate in the U.S., this has potential ramifications. The trial also allowed for measuring secondary effects of bariatric surgery. Two participants developed infections related to the lap band and required additional intervention. Not surprisingly, these patients both experienced postoperative complications that were included in the primary composite outcome. This reinforces that additional surgery is not without risk. Further analysis of primary outcomes may find that a more nuanced complication grading system, like the modified Clavien-Dindo classification5, would parse out clinical meaningful acquired conditions that necessitate a change in management versus those that could be managed expectantly. Dowsey and colleagues should be congratulated for completing this long-term trial, but questions remain about the optimal management and intervention timing for patients with obesity who have advanced knee OA.

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