Impact of Obesity on Orthopedic Injury and Fracture Patterns in Motor Vehicle Accidents

Obese trauma patients face a higher risk of mortality, prolonged ICU stays, and more complications than non-obese patients. However, some studies suggest that obesity might provide protective benefits in high-impact trauma situations through the "cushion effect". This study will examine whether obesity influences fracture occurrence, injury severity, and clinical outcomes in motor vehicle accidents (MVA).

A retrospective study of 555 adult patients who presented to a Level 1 Trauma Center following a MVA from 2010-2022. Patients with a Body Mass Index (BMI) greater than or equal to 30 kg/m² were categorized as obese (178 patients, 32.6%), and those with a BMI less than 30 kg/m² were classified as non-obese (377 patients, 67.4%). Incidence of bone fractures and injury severity were compared between both groups using injury severity score (ISS) and abbreviated injury scale (AIS). For variables significant on univariate analysis, binary logistic regression models were used to control age, gender, restraint use, and airbag deployment.

The mean number of fractures (0.62 vs 0.46, p=0.096) and ISS (4.55 vs 4.51, p=0.703) were similar between the obese and non-obese groups. However, obese patients were more likely to experience upper extremity fractures (7.3% vs 3.4%, p=0.045) and lower extremity fractures (7.3% vs 2.7%, p =0.01), particularly fractures of the tibia/fibula (5.6% vs 1.6%, p=0.008). No significant differences were found in the incidence of head, thoracolumbar, or pelvic fractures between the two groups. After controlling for age, gender, restraint use, and airbag deployment, obesity remained an independent predictor of lower extremity fracture (aOR) 2.62 (95% CI: 1.01-6.56), p = 0.04).

Obesity is an independent predictor of lower extremity fractures following a MVA. Clinicians should acknowledge potential differences in fracture occurrence and patterns between obese and non-obese patients during triage.