Effect of body mass index on patients with multiligamentous knee injuries

Abstract

Purpose: Our goal was to evaluate the impact of body mass index (BMI) on complications and associated injuries in patients undergoing surgical treatment for multiligamentous knee injuries (MLKIs).

Methods: Over a period of 10 years, 126 MLKIs (123 patients) were included in the study. The inclusion criteria were (1) injury to 2 or more knee ligaments, (2) multiligament repair and/or reconstruction performed by 1 of 3 sports medicine orthopaedic surgeons at our institution, and (3) minimum of 1 year of follow-up. A chart review was performed to collect demographic data, mechanism of injury, ligaments involved, complications, and associated neurovascular injuries. Lastly, patients were divided by BMI into non-obese (<30 kg/m(2)) and obese (≥30 kg/m(2)) groups.

Results: Of the 126 MLKIs, 87 occurred in non-obese patients and 39 occurred in obese patients. Surgical complication rates for non-obese and obese patients were 8.05% and 15.4%, respectively (P = .21). Revisions were needed in 8.05% and 5.1% of patients in these groups, respectively (P = .72). Three wound complications were found in the obese group only. Vascular injuries were found in 2.3% and 7.7% of patients in the non-obese and obese groups, respectively (P = .17). The rates of nerve injuries were 11.49% and 20.51%, respectively (P = .18). Patients in the obese group were most likely to have an MLKI from low-energy mechanisms, disregarding sports-related injuries (51.28%, P = .02). Using a logistic model and BMI as a continuous variable, we found that a 1-unit increase in BMI increased the odds ratio of complications by 9.2%, with statistical significance (P = .0174). In addition, post hoc power analysis using previous literature showed that this study could produce satisfactory power.

Conclusions: Our results indicate that (1) obese individuals are significantly more likely to have an MLKI caused by low-energy mechanisms and (2) complication rates increase by 9.2% for every 1-unit increase in BMI.

Level of evidence: Level III, retrospective comparative study.