Hip Prostheses Computational Modeling: FEM simulations integrated with fatigue mechanical tests

Hip prosthetic implants represent a consolidated and successful solution to restore functional gait in patients affected by a wide range of disease including osteoarthritis degeneration processes, cancer effects, osteoporosis, traumatic injuries. While at the beginning of the worldwide dissemination of this joint replacement methodology the target patients were mainly part of a quite old population, characterized by moderate physical activity and only asking for restoring of an acceptable quality of life and of functional gait and standing, the scenario significantly changed along the years. Nowadays, hip implants are also used to treat young and active patients; moreover, the amount of expected life years is more and more increasing; and, last but not least, the average body mass of western populations is increasing as well. As an overall consequence of the above changes, hip implants need to be highly performing: they have to cope with many years of repetitive high stresses not only due to regular locomotor daily activities but also to sports, excessive loading, wear and ageing effects. It is thus of extremely relevance for Researchers, Industry, Health Authorities and Users, to gain deeper and deeper knowledge of mechanical properties and performance of hip prosthesis components, and behavior of the musculo-skeletal system which hosts the implant. Potentially dangerous conditions should be clearly identified and investigated so as to prevent implant structural failure, being implant revision highly demanding for patients and health structures in terms of worsening of health status and increase of overall assistance costs. The present chapter investigates the potentialities of research studies in the field of hip implants biomechanics which rely on a synergy between FE modeling and experimental mechanical fatigue tests and whose main goal is to infer about related risks. An example of the implemented methodology is described, and few practical applications are reported, analyzed and commented from clinical, biomechanical and regulatory point of view.