Obesity, morbid obesity and their related medical comorbidities are associated with increased complications and revision rates after unicompartmental knee arthroplasty.

Recent studies have demonstrated clinical success in expanding the indications for unicompartmental knee arthroplasty (UKA) to patients with increased body mass index (BMI). This study utilized national databases to identify 15,770 unique patients who underwent UKA between 2005 and 2011. 18.7% of patients undergoing a UKA were obese or morbidly obese. Univariate analysis demonstrated that obesity and morbid obesity were associated with significantly higher complication rates within 90 days postoperatively compared to non-obese patients. The overall short-term revision rate in obese and morbidly obese patients undergoing UKA was almost twice as high as the revision rate in non-obese patients. Obese and morbidly obese patients being considered for UKA should be counseled preoperatively regarding their increased risk of postoperative complications and revision surgery.