Improved osseointegration and periprosthetic bone volume around cementless metal implants under bisphosphonate treatment

Aim: The effects of a systemic treatment with the bisphosphonate ibandronate on osseointegration of uncoated and hydroxyapatite-coated titanium implants and on periprosthetic bone volume have been evaluated and the dosage of medication had to be defined. Method: We used an animal model of the rat, the animals were assigned to three treatment groups receiving 1 mu g, 5 mu g and 25 mu g/kg body weight and one control group receiving NaCl 0.9%. An uncoated and a hydroxyapatite-coated titanium rod were inserted into the medullary canal of the femur. After 28 days the specimens were harvested and histomorphometric evaluation revealed extend of osseointegrated implant surface and changes of periprosthetic bone volume. Results: Treatment groups receiving 5 mu g and 25 mu g ibandronate showed significant improvement of osseointegrated implant surface compared to the control group. Enhancement of periprosthetic bone volume was revealed in all treatment groups but only application of 25 mu g ibandronate was significantly improved compared to the control group. Conclusion: A minor dose of 1 mu g ibandronate is not effective to improve osseointegration. A high dosed bisphosphonate treatment with 5 mu g or 25 mu g ibandronate is potent to improve osseointegrated implant surface significantly compared to an untreated control in both uncoated and hydroxyapatite-coated titanium implants and to enhance periprosthetic bone volume. By that, improved secondary stability and prolonged survival time of cementless metal implants can be expected.