Bacterial adhesion behavior and bone formation effect of Zoledronic Acid (ZOL) immobilized sputtered hydroxyapatite implants

Abstract

Bisphosphonates are well known drugs that can inhibit bone resorption and normalize the high rate of bone turnover that characterizes osteoporosis. Recently, hydroxyapatite (HA) has been used in a bisphosphonates local delivery system to enhance peri-implant bone formation, and the results are generally encouraging. In the present study, a thin film HA coating prepared by radio frequency (RF) magnetron sputtering technique was used as a bisphosphonate carrier. The purpose of the present study is to evaluate whether a coating concentration of zoledronic acid (ZOL), a nitrogen containing bisphosphonate, can improve peri-implant bone formation and decrease bacterial adhesion. Custom made sputtered HA coated titanium cylinders with different amounts of ZOL were inserted into the femur of OVX rats. After 2 weeks healing, the animals were sacrificed and the samples were analyzed histologically and radiologically. The results indicated that the ZOL released from the sputtered HA coating stimulated peri-implant bone formation at relatively low doses (0.5 μg and 2 μg), which is even lower than previously reported using a ZOL administered plasma spray HA coating. Furthermore, the bacterial adhesion to the HA implant seemed unaffected by the application of ZOL. The results from this study demonstrate the effectiveness of a local delivery of ZOL from the sputtered HA coating in order to increase the peri-implant bone formation.