An examination of skeletal fracture patterns in car occupants following fatal motor vehicle incidents.

Hundreds of thousands of car drivers and passengers die each year in motor vehicle incidents globally. In addition to determining cause of death, forensic practitioners may be asked to infer the circumstances of the incident from associated injury patterns. At present however, evidence of the skeletal fracture patterns of deceased car occupants and associated mechanisms is sparse. Therefore, this research aimed to examine whole-body fracture patterns in occupants of four-wheeled passenger vehicles (i.e., cars) who died after motor vehicle incidents in the context of the intrinsic and extrinsic variables that influence fracturing. The sample comprised 200 adults admitted to the Victorian Institute of Forensic Medicine, Australia, and the East Midlands Forensic Pathology Unit, United Kingdom, between 2012 and 2020. Contextual data was collected from medico-legal reports, and the skeletal trauma was examined from full-body post-mortem computed tomography scans. Fracture patterning, and the influence of intrinsic and extrinsic variables on fracturing, was analysed using descriptive statistics and modified Poisson regression. Almost all occupants (99 %) sustained fractures, with 96 % exhibiting multi-regional trauma. The thorax (92 %) and skull (72 %) were the most frequently fractured regions and exhibited the highest fragmentation. Older occupants and males were associated with a decreased fracture risk to the skull and thorax, respectively. Furthermore, seating position, impact type and impact object influenced fracture risk across the skull, cervical and lumbar vertebrae, limbs and pelvic girdle. This study augments current understandings of the complexity and patterning of skeletal fractures in fatal motor vehicle incidents, and the circumstances that produce them.