Interpreting impact direction: applying fractography to the analysis of butterfly fractures produced by blunt force trauma

ABSTRACT

Historically, bending impact to long bones has been thought to result in butterfly fragments with the apex opposite the side of impact. This theory is restrictive and may lead to erroneous reconstructions regarding impact events. The current study investigated the formation of butterfly fractures in dynamic three-point bending events and assessed the applicability and accuracy of methods for the inference of impact direction. Sixty ovine femora were subjected to drop tests of varying energy to either the anterior or posterior aspect. Butterfly type fractures were present in 73% of fractured specimens. The analysis demonstrated that the use of fracture surface morphology was superior to other methods, correctly reconstructing impact direction in all cases with complete butterfly fractures. Furthermore, this method could be applied to all cases displaying a degree of fracture with a 98.3% success rate. This study demonstrates the applicability of fractography to the inference of impact direction.

KEYWORDS:

• Blunt force trauma
• butterfly fractures
• 3-point bending
• fractography

Acknowledgments

The authors would like to thank the Faculty Research Committee of the Faculty of Health Sciences, University of Cape Town for funding.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Research supported by the postgraduate incentive fund supplied by the Faculty Research Committee of the Faculty of Health Sciences, University of Cape Town.