Mg-Zn-Ca glasses show considerable promise for use as medical implants. Magnesium, zinc and calcium are all elements found within the human body, and the biocompatibility of these glasses has been shown both in vitro and in vivo. Glasses in the Mg-Zn-Ca system have elastic moduli comparable to that of human bone, which minimises stress mismatch for orthopaedic applications. In order to model and predict the behaviour of these materials and potentially optimise these glasses for implantation it is important to have a good understanding of the local structure. We therefore propose to undertake a detailed study of these materials using a combination of neutron and X-ray diffraction and computer modelling including principal component analysis and classical molecular dynamics.