Cone cracking in human bone: A CT case review series

Skeletal trauma analysis often involves the assessment of the types and patterns of fractures, followed by categorizing the trauma into one of several broad “mechanisms.” Trauma analysis ideally also involves understanding the underlying mechanistic basis for the bone's failure. Beveling in bone is one example of a fracture pattern that is often cited as evidence of a high-velocity projectile impact, but appears to be poorly understood in terms of both the mechanism for bevel production as well as the loading conditions responsible for its formation. It has recently been demonstrated that bone beveling results from a failure mechanism called cone cracking, which is also associated with lower velocity impacts. Many case reviews and instructional texts include imagery of beveled bone in association with projectile impacts, but present various other explanations (or no explanation) for the fracture mechanism responsible. Five cases are presented here involving cone cracking in human forensic cases. For each case, the associated fracture patterns are discussed, photographic and micro-CT imagery are shown, and a review of the cone crack is presented in cross-section. The diagnostic utility of CT examination of ambiguous perforations is also highlighted.