Comparison of Unicompartmental Versus Total Knee Arthroplasty in Morbidly Obese Patients: A Database Analysis From...

Patients who have a body mass index (BMI) over 40 face unique risks when undergoing joint arthroplasty. Although unicompartmental knee arthroplasty (UKA) may offer benefits such as reduced recovery time, its safety profile in morbidly obese populations remains unclear. This study compared postoperative complication rates between UKA and total knee arthroplasty (TKA) in patients who had a BMI above 40.

A retrospective cross-sectional analysis was performed utilizing a large national database. Patients who had a BMI greater than 40 undergoing UKA or TKA were identified with Current Procedural Terminology (CPT) codes. A total of 76,766 patients met the inclusion criteria (UKA: 1,341 [1.7%], TKA: 75,245 [98.3%]), who had a mean age of 62 years (range, 18 to 89); a mean BMI of 44.5 (range, 40.0 to 99.3); and 28.2% women. A composite outcome of "Any Complication" was created, including superficial infection, deep incisional, organ/space surgical site infection (SSI), wound disruption, sepsis, pulmonary embolism (PE), deep vein thrombosis (DVT), 30-day readmission, and 30-day reoperation. Multivariable logistic regressions evaluated associations between procedure type and outcomes, adjusting for age, sex, BMI, hypertension, diabetes, congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), and renal failure.

Adjusted odds of composite complications were higher after TKA compared with UKA (odds ratio (OR) = 1.33, 95% confidence interval (CI): 1.02 to 1.77, P = 0.042). TKA was associated with higher odds of 30-day readmission (OR: 1.48, 95% confidence interval (CI): 1.05 to 2.18, P = 0.034). In per-type analyses, venous thromboembolism (VTE, composite DVT/PE) was more frequent after a TKA (OR: 3.21, 95% CI: 1.37 to 10.36, P = 0.020); while infectious complications, wound disruption, and reoperation were similar; sepsis was rare. Independent predictors of higher complication risk included older age, men, higher BMI, hypertension, diabetes, CHF, and COPD.

Total knee arthroplasty is associated with higher 30-day readmission and composite complication risk than a UKA on multivariable analyses, although residual confounding and selection bias may affect this association.