Tailoring Biomineralization and Biodegradation of Magnesium Calcium Alloy for Orthopaedic Applications

Abstract

Orthopaedic implants are designed to support or replace bones and joints. Temporary newlineorthopaedic implants, such as screws, nails, plates, wires, etc., will remain inside the body newlinefor a short duration. Once the tissue is healed, the implant needs to be removed from the newlineimplant site. This removal can be accomplished either by a second surgery or by the newlinedegradation/resorption of the implant in the physiological environment. The latter is newlineexpected to happen during the healing process, and the implant is expected to disintegrate newlinein the physiological environment with the growing tissue replacing it. Currently, there newlineare many biodegradable and biocompatible polymeric and ceramic biomaterials. newlineHowever, the inherent low mechanical properties of these polymers and ceramics limit newlinetheir use for load bearing orthopaedic implant applications. On the other hand, metallic newlineimplants made of stainless steel, titanium, and cobalt chromium-based alloys were newlinesuperior to polymers and ceramics due to their superior mechanical properties. However, newlinethese materials are non-biodegradable, cause stress shielding, and necessitate a second newlinesurgery. This prompted the researchers to think about a viable alternative from the newlinemetallic class that can degrade at a controlled rate in the physiological environment. newlineAmong the metals, magnesium (Mg) is a biodegradable, biocompatible, and lightweight newlinemetal with density and elastic modulus values much closer to those of human bone. newlineNevertheless, when exposed to physiological environment that contains corrosive ions newlinelike chlorides, the degradation process of Mg becomes more rapid and complex. Hence, newlineafter implantation, Mg alloys degrade rapidly, leading to loss of mechanical integrity and newlinesubcutaneous hydrogen gas cavity formation at the implant site. Surface modifications newlinecombined with suitable metallurgical modifications need to be explored for controlling newlinedegradation and enhancing the bioactivity of Mg-based materials in the physiological newlineenvironment. newline newline