Functional strontium phosphate coated magnesium alloys for orthopaedic use

Fractures are common in Australia and of particular concern with the aging demographic with fractures associated with osteoporosis. The incidence of hip fractures has been projected to increase by 15% every 5 years an estimated 150,000 fractures by 2026 and over 200,000 by 2050. Fracture management frequently requires the implantation of internal fixation devices such as plates, rods and screws in order to stabilise the injury. Traditionally, such implants are made of materials such as stainless steel, titanium or cobalt-chromium alloys. These materials differ substantially to mechanical properties of bone. In particular these materials have a significantly higher tensile properties than bone, producing stress shielding around implants. In addition, concerns have arisen over the release of toxic elements of the existing internal fixation devices and the low bone-tissue-growth rate over their surface. As such, addressing these issues in implant design should consider the development of techniques and materials to promote bone growth for more assured recovery.

This project aims to:

  1. Develop a functional strontium (Sr)-release surface upon magnesium-based orthopaedic implants to suppress the rapid degradation rate of Mg;
  2. Facilitate new bone formation and ultimately shorten healing process. The project will increase our understanding of the formation mechanisms in Sr-releasing coatings, and determine the critical release rate of Sr to activate bone cell responses.

This project addresses two key issues:

  1. The inherent high degradation rate of magnesium-based biomaterials for orthopaedic uses; and
  2. The low bone growth rate at bone-implant interface.

The knowledge will form a scientific basis to engineer more advanced biomedical materials from the ‘bottom up”, provide the necessary demonstrations, and establish a commercial product protocol. The project is significant for the development of practical, bone-favourable and degradation-inhibiting surfaces for magnesium implants, which are in demand and can bring significant patient benefits.