The mechanical behavior of the human femur subjected to impact loading

The objective of this thesis was to perform a definitive study of the mechanical behavior of the human femur subjected to loading conditions similar to those experienced by a motorcyclist whose leg is impacted by an automobile. The results of this report will then be used in the development of artificial bones for crash dummies. To meet this objective, nearly one hundred femurs and other long bones have been broken in a specially designed laboratory. The principle component of this laboratory is a machine which simulates an automobile/motorcycle collision. The testing was divided into four sections: (a) bending strength of the femur, (b) femurs under torsional loads, (c) femurs under axial loads, and (d) fresh tissue testing. Given the number of different types of test performed in compiling this thesis, there are many results and conclusions. The femur appears stronger when impacted in the anterior-posterior direction than in the lateral-medial. In addition, the fractures produced by these a-p impacts provide interesting clinical information. It was found that even very small torsional preloads can greatly diminish the femur's breaking strength. Axially loading the femur allowed the mapping of the stress along the femur to accurately predict fracture locations. Fresh bones tend to be stronger than embalmed bones, and impacted bones are stronger than slowly loaded bones.