Phosphate Glass Fibre Composites for Bone Repair

We investigate high-modulus degradable materials intended to replace metals in biomedical applications. These are typically composites comprising a polylactide (PLA) matrix reinforced with phosphate glass fibres, which provide reinforcement similar to E-glass but are entirely degradable in water to produce, principally, calcium phosphate. We have made composites using a variety of fibre architectures, from non-woven random mats to unidirectional fibre tapes. Flexural properties in the region of 30 GPa modulus and 350 MPa strength have been achieved - directly comparable to quoted values for human cortical bone. In collaboration with other groups we have begun to consider the development of foamed systems with structures mimicking cancellous bone and this has shown significant promise. The fibres in these foamed structures provide improved creep resistance and reinforcement of the pore walls. To date the materials have exhibited excellent cellular responses in vitro and further studies are due to include consideration of the surface character of the materials and the influence of this on cell interaction, both with the composites and the glass fibres themselves, which show promise as a standalone porous scaffold.