Title

Fracture Biomechanics of the Human Skeleton

Date of Award

8-2007

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Anthropology

Major Professor

Murray K. Marks

Committee Members

Walter Klippel, Lyle Konigsberg, Mohamed Mahfouz

Abstract

Trauma analysis is a growing area of physical and forensic anthropology. The analysis of fracture patterns is useful in determining cause and manner of death, as well as making inferences about past populations. Traditionally, anthropologists have categorized bone trauma into the discrete categories of blunt, ballistic, and sharp trauma. While these descriptors provide a practical approach, anthropologists need to change the way that trauma is perceived and analysis of fractures is conducted. Bone trauma is best viewed as a continuum (rather than discrete independent categories), with the variables of force, acceleration/deceleration, and surface area of impacting interface governing the appearance of the resulting fractures. The application of this new way of thinking will allow anthropologists to better understand bone fracture and injury to the body as a relationship between the engineering inputs and the anatomical outputs.

This new way of thinking is applied to the human skeleton and tested through a series of experimental studies and injury data analyses. The studies include fracture propagation and patterning in the skull, the response of the thorax/upper body to propeller induced trauma, force tolerance for human phalanges, and mechanics of lower limb fractures. The results from these studies assist in reiterating the importance of variables (or “engineering inputs”), such as force, surface area of impacting interface, and acceleration/deceleration, on the resulting injury and fracture patterns (“anatomical outputs”) of the human body.

As expected, the magnitude of force clearly influences the severity of fractures. However, comparison of force magnitude is not a “one-to-one” comparison. Surface area between the impacting object and the bone is a crucial variable. It essentially explains differences between blunt and sharp trauma. An example of the surface area variable in this experimental testing involved the propeller impacts to the buttocks and upper body. Note, though, as failure occurs, surface area interfacing can change, resulting in sharp trauma wounds that could contain characteristics of blunt trauma, or vice versa. Intrinsic properties of the bone (such as geometry, location, quality of bone) and its anisotropic and viscoelastic nature should also be considered along with these other engineering variables.

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