A new concept for producing graded bio-functionalized materials for orthopaedic implants

Abstract

Aseptic loosening (bone resorption) and infection are some of the main causes leading to the failure of orthopaedic implants. Between other causes, aseptic loosening is attributed to stress shielding and/or to the over-activation of osteoclasts (bone resorbing cells) induced by the release of wear debris by the implant. Infection is due to the colonization of the surface of the implant by microorganisms. While, stress shielding is dependent on the bulk elastic properties of the material, mechanical wear, osseointegration and colonization by microorganisms are dependent on the surface characteristics of the implant. Another serious clinical problem is associated with the accelerated degradation by wear and corrosion that occurs at the head-neck junction (connection between the stem and the head) of hip implants.This project will focus on the development of a new concept for the fabrication of b type titanium alloys (with low elastic modulus, thus more appropriate to minimize stress shielding) with graded properties aimed to contribute to the minimization of those problems. The project will focus on alloys from the Ti-Zr-Mo and Ti-Nb systems. The concepts of functionally graded materials (FGMs) and functionally graded surfaces (FGSs) will be applied to:-Produce the b type alloys with a graded distribution of ceramic particles (from the surface to the bulk) in order to combine low global elastic modulus with high wear resistance at the surface. With this approach, it is expected to minimize problems occurring at the head-neck junctions;-Bio-functionalize the surface of the materials with graded films, in order to provide bio-selectivity (improved osseointegration, minimizing the possibilities of colonization by microorganisms) and degradation resistance. (AU)