Fatigue failure of materials for medical devices

Abstract

Medical devices such as joint prostheses are subjected to high stresses and high cycle loading. Coupled with the aggressive body environment, fatigue failure is common. A fatigue wear process causes the generation of wear debris, which invokes acute host-tissue reactions. This chapter reviews some fundamental concepts from mechanics to the methods of evaluation for biomaterials which would include wear debris morphology characterisation so as to understand the host-tissue reaction to wear debris. Case studies on hip and knee prostheses and dental restoratives are also presented. The development of fatigue fracture resistant and wear resistant biomaterials geared towards biocomposite systems with different phases to cope with the conflicting properties of fatigue fracture resistance and hard, but brittle, phases required for wear resistance and a good lubrication phase seems to provide some future direction. The ability to engineer biomaterials that have the capability to trap/isolate wear debris and promote easy removal of such wear debris remains a challenge.