The purpose of this study was to use detailed medical information to evaluate lower extremity fractures of obese patients in real world frontal crashes. In this study, we used analytic morphomics to understand the effect of abdominal and hip body shape on lower extremity fracture for occupants in frontal crashes. Analytic morphomics extracts body features from computed tomography (CT) scans of patients. Lower extremity fractures were examined in front row occupants involved in frontal crashes from the International Center for Automotive Medicine (ICAM) database. Among these occupants, two BMI groups (BMI < 30 kg/m 2 [Nonobese] and BMI ≥ 30 kg/m 2 [Obese]) who suffered from severe lower extremity fractures (AIS2+) were analyzed. The severity of lower extremity fracture was compared between the groups. Regression analyses were conducted to investigate fracture outcomes considering variables including those for vehicle, demographics, and morphomics.

Compared to the nonobese group, the obese group sustained more lower extremity fractures. Logistic regression models were fitted with different configurations of variables predictive of the summation of injury severity score of lower extremity fractures AIS (LEXAIS). The model developed based solely on vehicle data (Scenario 1) had an area under the receiver operating characteristic curve (AUC) of 0.72. When demographic data was combined with vehicle data (Scenario 2), the model prediction improved to an AUC of 0.75. The AUC associated with vehicle and morphomics data (Scenario 3) was increased to 0.78 and increased to 0.79 when combining vehicle, demographic, and morphomics variables (Scenario 4). The important morphomics variable was vertebra-to-front skin which represents fat thickness in the anterior trunk. BMI was important when combined with the vehicle and demographic variables as well. However, morphomics variables such as fat distribution can be precisely adjusted in a finite element human body model or anthropomorphic testing device to represent occupants of different body shapes and sizes and are thus more valuable in assessing injury during vehicle crashes. The current results for fat distribution can highlight the importance of considering these morphomic characteristics when assessing lower extremity injury and creating obese models.

Morphomic data, specifically vertebra-to-front skin, showed a strong association in the severity of lower extremity fractures among obese patients in frontal crashes. These data are useful measurement that can be provided in human models to assess occupant response.