CAS-Croucher Joint Labs

The CAS-Croucher Funding Scheme for Joint Laboratories is the outcome of an agreement between The Chinese Academy of Sciences (CAS) and the Croucher Foundati...

Magnesium as a promising biodegradable metal for fixation of bone fracture

Serious bone fractures require prompt surgery to fix bone fragments and to prevent degeneration and further impairment and complications. However, a second round of surgery is required to remove the permanent implants after fractures heal. This project aims to develop a novel implantation material that will degrade slowly, at a controlled rate- negating the need for subsequent surgery.

The mismatch of mechanical properties between bone and traditional metals can cause re-fractures, so it is also important to ensure the biocompatibility of fixator implants and their by-products, as well as similar mechanical properties to human natural bone. As such, magnesium-based implants were developed due its presence in and importance to the human body, its degradation into non-toxic by-products, and the absence of adverse reactions in long-term implantation. 

In recent years, the development of magnesium processing technology significantly improved the corrosion resistance of pure magnesium by improving its purity and reducing its crystal defects, hence enabling its potential use as a biodegradable fixator material to repair bone fractures. Recent findings also support that magnesium could accelerate bone remodelling of fractures through stimuli of bone-related cells, stem cells and microvascular cells.

A current limitation for magnesium-based fixator implants is the lack of mechanic support, especially when it is to be used in the load-bearing regions of a bone fracture. Thus, another focus of the current project is on surface modification treatment of magnesium-based implants by microarc oxidation, a metal surface coating technology also known as plasma electrolytic oxidation.

Professor Qin has been an orthopaedic researcher and clinical scientist, and is currently the Director of Musculoskeletal Research Laboratory in the Department of Orthopaedics & Traumatology at the Chinese University of Hong Kong. Professor Yang has been a materials research scientist and is currently the Head of Specialised Materials and Devices Division at the Chinese Academy of Sciences, Institute of Metal Research. Over the past three years, they have been working collaboratively in the engineering of magnesium-based implant materials and their preclinical validation and clinical testing.

Currently, they are looking into bone fracture repair using biodegradable magnesium with or without surface treatment by microarc oxidation, as well as investigating the effects of the magnesium ions on bone formation and vascularisation. They aim to demonstrate the potential impact of microarc oxidation treatment of the magnesium implants and investigate the efficacy in animal models in vivo. Magnesium-based fixators will be employed to support fixation of ruptured bone fragments in rabbits with bone fractures, where the magnesium ions released are expected to promote new bone formation and shorten healing time while its biodegradable property would eliminate a second implant removal operation and relieve patient suffering. Such bio-resorbable implants for bone fixation are of major clinical relevance with promising potential to significantly improve patient treatment and recovery in orthopaedics and traumatology.

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