Is Morbid Obesity a Modifiable Risk Factor In Patients who have Severe Knee Osteoarthritis and do not have a Formal Perioperative Optimization Program?

BACKGROUND: Obesity is considered a modifiable risk factor prior to total knee arthroplasty (TKA), however, little data supports this hypothesis. Our purpose was to evaluate patients who have a body mass index (BMI) > 40 presenting for TKA to determine the incidence of : 1) patients who achieved successful weight loss through nutritional modification or bariatric surgery and 2) patients who underwent TKA over the study period without the presence of a formal optimization program.

METHODS: This was a retrospective, single-center analysis. Inclusion criteria included: Kellgren and Lawrence (KL) grade 3 or 4 knee osteoarthritis, BMI>40 at presentation, and minimum 1-year follow-up (mean 45 months) (N=624 patients).Demographics, weight loss interventions, pursuit of TKA, maximum BMI change, and Patient Reported Outcomes Measurement Information System (PROMIS) scores were collected. Multivariable logistic and linear regressions evaluated associations of underlying demographic and treatment characteristics with outcomes.

RESULTS: There were 11% of patients ended up pursuing TKA over the study period. Bariatric surgery was 3.7 times more likely to decrease BMI by minimum 10 compared to non-surgical intervention (95% Confidence Interval (CI) [1.7,8.1];P=.001). Bariatric surgery resulted in mean BMI change of -3.3 [range, 0-22] compared to non-surgical interventions (-2.6 [range, 0-12]) and no intervention (0.4[range, 0-15];(P<.0001).Bariatric surgery patients were 3.1 times more likely to undergo TKA (95% CI [1.3,7.1];P=0.008), and non-surgical interventions were 2.4 times more likely to undergo TKA(95% CI [1.3, 4.5];P=.006) compared to no intervention. Non-white patients across all interventions were less likely to experience loss >5 BMI compared to White patients (95% CI [0.2,0.9];P=.018).

CONCLUSION: Most patients were unable to reduce BMI greater than 5 to 10 over mean four-year period without a formal weight optimization program. Utilization of bariatric surgery was most successful compared to non-surgical interventions although ultimate pursuit of TKA remained low in all cohorts.