Surface bound bisphosphonate for implant fixation in bone Rat experiments with a novel coating technique

.................................................................................................................. 1 LIST OF PAPERS ........................................................................................................ 3 INTRODUCTION......................................................................................................... 5 Implant fixation, clinical aspects .......................................................................... 5 Why does fixation of implants in bone need to be improved? .......................... 5 Why do orthopaedic prostheses and dental fixtures come loose? ..................... 5 Implant fixation, biological aspects ...................................................................... 6 What happens initially at the cellular level around the implant? ...................... 6 Implant screws in the cortex, in animals ........................................................... 7 Are there critical phases for fixation of implants in bone?................................ 7 What constitutes the bone to implant interface?................................................ 8 What influence does micromotion have on endosseous implant fixation? ....... 9 Bisphosphonates................................................................................................... 10 What is the bisphosphonate mechanism of action? ......................................... 10 Do bisphosphonates influence other cells than osteoclasts? ........................... 11 Are bisphosphonates used in orthopaedics to improve implant fixation?....... 12 What is osteonecrosis of the jaw?.................................................................... 12 What has been done on bisphosphonate coated implants? .............................. 12 A novel coating technique ............................................................................... 16 MATERIALS AND METHODS ............................................................................... 17 Screws.................................................................................................................... 17 Screw coating........................................................................................................ 17 Measurements of coating thicknesses ................................................................ 17 Mechanical measurements .................................................................................. 18 Pullout measurements ...................................................................................... 18 Removal torque measurements........................................................................ 18 Histology ............................................................................................................... 18 RESULTS .................................................................................................................... 21 Paper I. Surface-bound bisphosphonates enhance screw fixation in rats increasing effect up to 8 weeks after insertion. ................................................. 21