Targeted Local Delivery of Bisphosphonate from Orthopaedic Implants

Abstract

Two methods of loading bisphosphonate (BP) into hydroxylapatite (HA) coatings on crystalline TiO2 surfaces were investigated to improve bone ingrowth to implant surfaces. In the study the BP pamidronate was used. Ti-plates coated with crystalline TiO2 were soaked in phosphate buffer saline (PBS) for 7 days at 40° C and thereafter soaked in solutions of BP, 0.5 mg/ml for 15 or 60 minutes (fast loading method). In the second method BP was dissolved into PBS in different concentrations before immersion of the discs for 7 days (co-precipitation method). Surface and bulk were analysed using electron spectroscopy for chemical analysis, scanning electron microscope and x-ray diffraction. Release of BP was studied using alternating ionic current method. It was shown that fast loading by soaking in a BP solution for 15 minutes was sufficient to load BP into a HA coating. Co-precipitation showed that a thin layer of calcium phosphate crystals containing BP can be deposited directly onto a crystalline TiO2 surface.