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Assessing Impact Direction in 3-point Bending of Human Femora: Incomplete Butterfly Fractures and Fracture Surfaces,
Mariyam I Isa1, Todd W Fenton1, Trevor Deland2
1Department of Anthropology, Michigan State University, 354 Baker Hall, East Lansing, MI, 48824.
Journal of Forensic Sciences
|April 25, 2017
Summary
Butterfly fractures in bone bending failure can be unreliable for determining impact direction. New research shows fracture surface characteristics, not just fragment shape, accurately reconstruct impact direction in human femora.
Area of Science:
- Forensic anthropology
- Biomechanics
- Orthopedic research
Background:
- Butterfly fractures are commonly associated with bone bending failure.
- Fracture fragment orientation is traditionally used to infer impact direction.
- Previous studies show inconsistent fracture patterns, limiting diagnostic reliability.
Purpose of the Study:
- To investigate the reliability of butterfly fractures in determining bone impact direction.
- To identify reliable fracture characteristics for impact direction reconstruction.
- To analyze fracture patterns in human femora under experimental bending stress.
Main Methods:
- Experimental three-point bending tests were performed on thirteen unembalmed human femora.
- Fracture patterns, including complete and incomplete fractures, were analyzed.
- Fracture surface characteristics (tension vs. compression) were documented.
Main Results:
- Complete fracture patterns varied, but incomplete fractures and distinct surface characteristics were consistently observed.
- Tension surfaces exhibited flat, billowy features, while compression surfaces showed jagged, angular peaks.
- Impact direction was accurately reconstructed in all specimens using incomplete fractures and surface criteria.
Conclusions:
- Bone fracture surface characteristics are reliable indicators of impact direction.
- Incomplete butterfly fractures and tension/compression surface morphology provide accurate directional information.
- This study refines the interpretation of bone fracture mechanics in forensic and clinical contexts.
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