BONE-BONDING BEHAVIOR OF POLY(ETHYLENE OXIDE)-POLYBUTYLENE TEREPHTHALATE COPOLYMER COATINGS AND BULK IMPLANTS - A COMPARATIVE-STUDY

A range of poly(ethylene oxide)-polybutylene terephthalate (PEO-PBT) c opolymers (70-30% PEO), both as coating on titanium alloy as well as b ulk cylinders, was press-fit implanted in the diaphyseal femur of 16 g oats. At early survival times (4 wk), a high degree of cortical bone c ontact was observed for bulk implants using light microscopy and this was confirmed by backscatter electron microscopy. This was attributed to the swelling behaviour of PEO-PBT copolymers. At this stage, bone c ontact was also revealed for coated implants, but to a lesser extent. At a later stage (12 wk), bone bonding was demonstrated both morpholog ically and by X-ray microanalysis, at the interface of 70:30 PEO-PBT b ulk as well as 70:30 PEO-PBT-coated implants. Bone bonding increased w ith time (26 and 52 wk) for this PEO-PBT proportion and was also obser ved for 60:40 and 55:45 implants, although less frequently. For 40:60 and 30:70 PEO-PBT proportions, bone bonding was not shown. Based on th ese qualitative data, it was not possible to differentiate between coa ted and bulk implants with respect to bone bonding. This study demonst rated that the application of PEO-PBT elastomers as coatings does not alter the bone-bonding properties. It was therefore concluded that PEO -PBT coatings are beneficial over the bone-bonding but brittle ceramic coatings, due to their flexibility. In addition, the bone-bonding cap acities of these PEO-PBT coatings surpass the non-bonding behaviour of currently available flexible coatings.