Increased Waist Circumference is Associated with Severe Postoperative Medical Complications Following Total Knee Arthroplasty: Understanding Waist Circumference and Relation to Body Mass Index.

Abstract

Background: Obesity is projected to affect nearly 42% of Americans nationwide by 2050. Waist circumference (WC), an estimate of central obesity/adiposity, has been shown to be a better predictor for cardiometabolic morbidity and mortality than body mass index (BMI), which does not consider body fat distribution. This study aimed to evaluate whether 1) WC correlates with increasing BMI cohorts and 2) WC is a predictor of severe Clavien-Dindo IV complications within 30 days following total knee arthroplasty (TKA).

Methods: A national dataset was retrospectively queried to identify patients who received primary TKA for knee osteoarthritis between 2010 and 2020 (N = 385,996). A validated model converted each patient's BMI to WC. The BMI cohorts were grouped into underweight, healthy weight, overweight, and obesity classes 1 to 3. Primary outcomes included comparing WC among different BMI cohorts undergoing TKA. The secondary outcome was to evaluate if waist circumference was associated with severe surgical complications within 30 days. Clavien-Dindo IV complications included cardiac arrests, myocardial infarctions, septic shock episodes, pulmonary emboli, acute renal failures, and cerebrovascular accidents. Multivariable logistic regressions adjusted for age, functional status, frailty, various comorbidities, and obesity to evaluate the odds ratios (ORs) between WC and postoperative complications following TKA, with P-values less than 0.001 as significant.

Results: The mean WC significantly correlated with increasing BMI cohorts (P < 0.001). The mean WC was significantly higher among patients who developed Clavien-Dindo IV complications (112.4 versus 110.5 centimeters, P < 0.001). For all TKA patients, each centimeter increase in WC was associated with developing a postoperative complication (OR: 1.11, P < 0.001). Sub-analysis of only obese patients showed WC to be a better predictor than BMI class (OR: 1.35, P < 0.001).

Conclusion: Central adiposity, measured by WC, was associated with severe complications following TKA, even when controlling for obesity. Screening interventions using waist measurements may assist joint arthroplasty surgeons in risk-stratifying patients who have higher BMIs. Further study is warranted on how to integrate WC into TKA practice.