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Posted By: Richard S. Pope, PA-C, MPAS
December 28, 2020
In November 2020, the American College of Rheumatology (ACR) hosted a virtual poster presentation. Abstract 1651, "Knee OA outcomes in patients with severe obesity following bariatric surgery or total knee arthroplasty," asked two questions: whether weight loss helps osteoarthritis (OA) of the knee, and whether total knee replacement (TKA) or gastric bypass is a better surgical option for those with body mass index (BMI) >40 kg/m2. All clinical guidelines regarding knee OA target weight reduction as a key to preventing and managing this painful condition. In the scenario of morbid obesity (>40 kg/m2), if your patient were given the choice between gastric surgery for weight loss or TKA, what would you say and how should you counsel them?
The abstract presented at ACR was an interim analysis for a trial titled Surgical Weight-loss to Improve Functional Status Trajectories following arthroplasty for painful knee osteoarthritis (SWIFT). At this point, SWIFT includes data for 25 patients who had bariatric surgery (BAR) compared with 28 who had undergone total knee arthroplasty (TKA). Thus far, the study has followed these patients for 6 months. At baseline and follow-up visits, data were collected on the Knee injury and Osteoarthritis Outcome Score, visual analog pain scales, and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Patients also performed functional assessments (ie, Timed-Up and Go, 30-second chair stand, and 40-meter fast-paced walk test) at baseline and follow-up visits. Data currently suggest that patients who underwent BAR had comparable improvement for all tests, aside from the WOMAC, to those in the TKA group.
Average BMI in the gastric bypass group was 47 kg/m2 and 41.6 kg/m2 in the TKA group. Mean age for the BAR group was 52 compared with 60 for the TKA group. There were no significant differences in the sex distribution of either group. The abstract did not the document the mean weight loss for those in the BAR group.
Two barriers to caring for patients with morbid obesity are often the inability to lose weight and painful knee OA. The abstract suggests BAR produced improvement in all parameters evaluated, and may delay the need for TKA in patients with knee OA. It is evident to me that a younger, more obese patient should have BAR prior to TKA. This is not to diminish the seriousness of either surgery or the potential of post-operative complications; however, there are so many comorbidities associated with obesity (eg, sleep apnea, type 2 diabetes, and hypertension) that BAR could be a very important factor in the patient’s overall health trajectory. This interim analysis provides real outcome data to guide decisions around BAR and TKA. I, for one, will watch for the long-term outcomes of the SWIFT study, as it has the goal of enrolling 150 patients in each arm.
- Samuels J, et al. Knee OA outcomes in patients with severe obesity following bariatric surgery or total knee arthroplasty. acrabstracts.org/abstract/knee-oa-outcomes-in-patients-with-severe-obesity-following-bariatric-surgery-or-total-knee-arthroplasty/. Accessed Dec 23, 2020.