Morphology and ultrastructure of the interface between hydroxyapatite-polyhydroxybutyrate composite implant and bone.

A composite of polyhydroxybutyrate (PHB) polymer, reinforced with synthetic hydroxyapatite (HA) particles, with potential as a bone-analogue material, was examined microscopically using scanning electron microscopy and transmission electron microscopy. These imaging techniques provide the means of understanding and monitoring the morphological and structural behaviour of retrieved implants. Scanning electron microscopy was used to assess the overall mechanism of new bone formation at the implant interface after up to 6 months implantation. This procedure was followed by a detailed ultrastructural examination at lattice plane resolution level, using high resolution electron microscopy and selected area diffraction of the regions showing bone apposition. Fine hydroxyapatite crystallites were found to form at the interface after in vivo implantation into cortical bone.