Obesity Is Associated with Significant Morbidity after Multiligament Knee Surgery

The objective was to report the effect of obesity, utilizing a body mass index (BMI) threshold of 35 kg/m², on outcomes and complications of multiple ligament knee injury (MLKI). It was hypothesized that obese patients would have longer intraoperative times and hospital length of stay, greater estimated blood loss, and higher rates of wound infection requiring irrigation and debridement (I&D) and revision ligament surgery. A retrospective review was performed on 143 individuals who underwent surgery for an MLKI between 2011 and 2018 at a single academic center. Patients were included if there was a plan for potential surgical repair/reconstruction of two or more ligaments. Patients with prior surgery to the affected knee or intra-articular fracture requiring reduction and fixation were excluded. Comparisons between obese and nonobese patients were made using two-sample t-test and either chi-square or Fisher's exact test for continuous and categorical variables, respectively. Significance was set at p < 0.05. Of 108 patients meeting inclusion criteria, 83 had BMI < 35 kg/m² and 25 had BMI ≥ 35 kg/m². Obese patients sustained higher rates of MLKI due to ultralow velocity mechanisms (28.0 vs. 1.2%; p = 0.0001) and higher rates of concomitant lateral meniscus injury (48.0 vs. 25.3%; p = 0.04). Among patients undergoing single-staged surgery, obese patients had significantly longer duration of surgery (219.8 vs. 178.6 minutes; p = 0.02) and more wound infections requiring I&D (20.0 vs. 4.8%; p = 0.03). In contrast, nonobese patients had higher rates of arthrofibrosis requiring manipulation under anesthesia and/or arthrolysis (25.3 vs. 0%; p = 0.003). Obese patients undergoing surgery of an MLKI have longer operative times, greater rates of wound infection requiring I&D, and lower rates of arthrofibrosis. Surgeons may consider these results when counseling patients on their postoperative course and risk for complications. Future research might focus on strategies to reduce complication rates in obese patients with MLKI. This is a Level III, retrospective comparative study.