Investigating reverse butterfly fractures: An experimental approach and application of fractography

• Published in: Forensic science international Vol. 325; p. 110899
• Main Authors: Isa, Mariyam I., Fenton, Todd W., Antonelli, Lillian S., Vaughan, Patrick E., Wei, Feng
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-08-2021; Elsevier Limited
• Subjects: Bending; Bones; Butterfly fracture; Compression; Compression tests; Crack propagation; Evaluation; Experiments; Forensic anthropology; Forensic biomechanics; Forensic science; Forensic sciences; Fractography; Fracture mechanics; Fracture surfaces; Fractures; Human performance; Propagation; Research methodology; Shear strength; Tension; Trauma analysis; Visualization; Forensic anthropology; Forensic science; Trauma analysis; Butterfly fracture; Fractography; Forensic biomechanics
• ISSN: 0379-0738; 1872-6283
• DOI: 10.1016/j.forsciint.2021.110899

•Butterfly fractures initiated in tension regardless of wedge orientation.•Incomplete cracks branched from the tensile initiation site.•Small, irregularly shaped fragments contained useful fractography features.•High-speed videos confirmed interpretations made using fractography.•Fractography can be used to interpret complex fracture propagation sequences.
Butterfly fractures are expected to form with the transverse portion on the tension side and the wedge portion on the compression side of a bent bone, however wedges have also been observed in the reverse orientation and are reported to be frequent in concentrated 4-point bending. To investigate how these fractures form, concentrated 4-point bending experiments were performed on nine human femora and documented using high-speed video. Videos showed the wedge portion formed as fracture initiated in tension, branched obliquely, then curved to terminate on the tension face. The transverse portion formed as a crack traveled between the curved fracture branch and the compression face. Fractography was also applied to evaluate fracture surfaces. At least one fractography feature was present in all femora and 32/35 bone fragments examined. Fracture propagation sequences interpreted using fractography matched those observed on video, demonstrating the utility of this method for evaluating complex fracture patterns.