Trends of Obese and Morbidly Obese Patients in Same-Day Bilateral Total Knee Arthroplasty from 2009 to 2016.

As obesity in the United States increases, the proportion of obese and morbidly obese patients undergoing same-day bilateral total knee arthroplasty (sd-BTKA) remains unknown. Therefore, this study analyzed: (1) incidence, (2) patient demographics, (3) patient course, and (4) patient outcomes in obese and morbidly obese patients undergoing sd-BTKA in the United States from 2009 to 2016. The National Inpatient Sample was queried for all sd-BTKA patients from 2009 to 2016, yielding 39,901 obese and 20,394 morbidly obese patients. Analyzed variables included overall incidence, age, length of stay (LOS), sex, race, payer, Charlson comorbidity index (CCI) status, disposition, complications, location/teaching status, region of hospital, costs, and charges. Categorical variables were evaluated with chi-square analysis, while continuous variables were analyzed by Student's t-tests. Overall, the number of sd-BTKAs decreased over the study period, although the proportion of both obese and morbidly obese patients increased (p < 0.001 for all). The most common CCI status, 3 + , decreased in proportion for both groups (p < 0.001 for all). Hospital costs decreased and charges increased for both groups (p < 0.001 for all). Mean LOS decreased and patients were most commonly discharged to skilled nursing facilities, although these proportions decreased (p < 0.001 for all). Respiratory failures (p < 0.001 for all) increased for both groups, while proportion of deep vein thromboses and hematomas/seromas (p < 0.001 for all) increased for obese patients and proportion of pulmonary emboli (p < 0.001) increased for morbidly obese patients. The results of this study appear to portray improving optimization and patient selection of higher body mass index (BMI) individuals undergoing this procedure. More information is needed comparing the safety of the sd-BTKA across patients of all BMI groups.