title: Investigating injury mechanism and occupant bmi for malleolar fractures in frontal motor vehicle collisions - biomed 2010.
abstract: Injury statistics show that lower extremity injuries follow second to head trauma in motor vehicle crashes. Fractures to the ankle/foot make up approximately 35% of all lower extremity injuries in motor vehicle crashes. Previous studies have shown that toe pan intrusion is one of the main causes of foot and ankle fractures in motor vehicle crashes (MVC). This study investigates injury mechanisms of malleolar fractures involving occupants enrolled in the Wake Forest University Crash Injury Research and Engineering Network (WFU CIREN) center. By narrowing cases to frontal impacts (+/- 20 degrees principal direction of force) with the case occupant as the driver with lower leg fractures, 16 cases are identified and investigated for trends in lower leg injury. Of these fractures, 81% of the occupants have a body mass index (BMI) greater than 25 kg/m2, with an average BMI of 32 kg/m2, which is obese. For occupants with malleolar fractures the average delta V is 44.1 kph (27.4 mph) and the average intrusion is 9.6 cm. Using radiology images of each ankle fracture in conjunction with interior vehicle evidence, injury mechanisms for malleolar fracture types are identified using the Lauge-Hansen and Weber classifications. The most common malleolar fracture type was supination-exorotation with a Weber B fibular fracture (4 cases). There were also four drivers that sustained trimalleolar fractures. Drivers sustaining lower leg fractures other than malleolar fractures had an average BMI of 30 kg/m2, an average delta V of 39.6 kph (24.6 mph), and average toe pan intrusion of 12.0 cm. Results show that the malleolar fracture and other lower leg fracture datasets have similar average delta Vs and toe pan intrusions, but the average BMI is slightly higher in the malleolar fracture group. These preliminary data suggest that occupants with increased BMI may be more susceptible to ankle fractures in frontal crashes, particularly malleolar fractures. The trends presented in this research will be used for the development of future studies for the enhancement of vehicle safety.
authors.affiliation: Virginia Tech - Wake Forest University Center for Injury Biomechanics, Winston Salem, NC.
authors.forename: Jillian E
authors.initials: JE
authors.lastname: Urban
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Loftis
authors.forename: Joel D
authors.initials: JD
authors.lastname: Stitzel