Early Outcome Trends of Unicompartmental Knee Arthroplasty in Patients With Morbid Obesity: A Potential for Outpatient Surgery

BackgroundElevated body mass index (BMI) was previously considered a contraindication to unicompartmental knee arthroplasty (UKA). This study sought to determine if outcomes following UKA in patients with elevated BMI have improved over the years. We hypothesized that operative times and length of stay (LOS) following UKA would significantly decrease, while discharge to home rates would increase across all BMI cohorts, especially those with a BMI > 40.MethodsUsing the National Surgical Quality Improvement Program registry, surgical cases categorized using the Current Procedural Terminology code 27446 for UKA with a recorded height and weight were included. Three BMI cohorts were created: BMI I (BMI < 30), BMI II (30 ≤ BMI ≤ 40), and BMI III (BMI > 40). Each BMI group was subclassified temporally by year of operation: Years A (2006-2009), Years B (2010-2014), and Years C (2015-2019).ResultsA total of 14,114 patients were included. For BMI III, both operative time (P < .001) and LOS (P < .001) significantly decreased over the Years cohorts. Discharge home rates increased from 88.3% to 94.4% in BMI III (P = .001). All BMI cohorts saw similar changes in discharge patterns, 30-day readmissions, and reoperations within 30 days in recent years.ConclusionThis study found that operative times and LOS have decreased significantly in patients with morbid obesity over the past 14 years, while more patients are being discharged home without being readmitted or reoperated on in the first month. As surgeons continue to improve their operative and reconstructive techniques, this study suggests that patients with elevated BMI should be considered candidates to undergo UKA procedures in ambulatory surgery centers or in hospitals with a rapid recovery unit.