Modern implants provide improved recovery times and lower implant rejection rates. Early implants were expensive, and often failed because the bonding between the implant and the bone, a process known as osteo-integration, was poor. Several designs have been formulated to date but many failed to achieve a strong enough bond. A solution involves coating the metal with a layer of hydroxyapatite (HA). Hydroxyapatite forms almost three-quarters of natural bone. Coating the metal first with HA gives a stronger metal-bone bond. Even with this improvement, one in five implants can still fail. One of the main reasons of failure is the residual stress developed at the metal-HA interface. Neutrons offer significant advantages to analyse this critical interface, enabling measurements to be made in-depth and non-destructively. This unique capability enables us to improve our understanding of how HA bonds to the metal and bone.
R Ahmed (Heriot-Watt University), AM Paradowska (STFC), M Fitzpatrick (Open University)
Research date: January 2010
Contact: Dr R Ahmed, R.Ahmed@hw.ac.uk
Further reading: R Ahmed et al., Mater Sci Forum 652 (2010) 309