Finite Element and Experimental Investigation of Human Femur Cortical Bone Microdamage during Radial Fretting

Abstract

Accumulation of microdamage can result in increased bone fragility and osteoporotic fracture in human bone.Microcracks in bone have been implicated in the development of stress fractures.The goal of this study was to investigate the human femur cortical bone microdamage during radial fretting and its stress and strain distribution. Modeling and analysis were taken for Haversian system using FEM soft. Analytical results indicated that stress concentration which occurred in the haversian canal and around circumferential lamellas and through the circumferential lamellas and the interstitial tissues could lead to microcrack initiation of multi-areas. In addition, microcrack could occur as a result of a rather large plastic area which crossed interstitial bone and connected adjacent osteon under high load condition. In the meantime, radial fretting behaviors of the fresh human axial femur compact bone were investigated under a flat-on-ball configuration in high accuracy hydraulic servo fretting experimental machine. The kinetics behaviors of the compact bone were revealed by the F-D curves. The surface damage was analyzed combined with the examinations by laser confocal scanning microscopy (LCSM) and scanning electron microscopy (SEM) . The morphologies showed that the microcracks were the primary damage form.The results showed that three typical types of cracks-radial microcrackannular microcrack and linking microcrack were observed. The test results and the FEM analysis results were of good consistency, and brought forth that most of microcracks run between the surrounding interstitial bone and the cement line.