Evolution of mechanical fields during the gait cycle in healthy and implanted femoral bones

International audienceThe hip is considered as the most loaded joint in the human body, it can support up to 4 times the weight of the body. Diseases of this joint have become very widespread and are increasingly affecting younger populations. At their advanced stage, prosthesis remains the best medical solution to repair the damaged joint. To predict early deterioration and increase the lifespan of the prosthetic solutions, it is necessary to study the biomechanical behaviour of the femoral bone tissue. Bone is a tissue, which has capacity for continuous remodelling under the mechanical stimulus. This process plays central role in the context of implants and prostheses placed in it. Possibility of foreseeing the consequences of implant placement on the mechanical fields, and consequently on the process of bone remodelling, is crucial for implant designers. Insertion of non-natural parts with different mechanical properties into the bone leads to a change in stress distribution, and thus can generate the disruption of homeostasis, in which the healthy bone is. Moreover, the repetitive or cyclic loading of bone with evolving properties can yield the fatigue and fracture of the bone tissue surrounding implant. The final aim of this work is to compare the mechanical states of healthy and implanted human femur in order to design the appropriate fatigue testing device and bone sample geometry. Numerous studies of the stress distribution in the femur during human walking can be found in literature (Polgar et al. 2003; Abdellatif and Benaoumeur 2016). However in our knowledge, the risk of cortical bone fatigue in vicinity of the implant was neither considered. In this paper, the first results concerning the stress distribution in healthy and implanted femurs are presented. The bone geometry, loading, boundary conditions and mechanical properties have been deduced from OpenSIM simulations of gait cycle and µCT scanning of the human femur