title: Surface immobilized zoledronate improves screw fixation in rat bone: a new method for the coating of metal implants.
abstract: Previous studies show that surface immobilized bisphosphonates improve the fixation of stainless steel screws in rat tibia after 2-8 weeks of implantation. We report here about the immobilization of a potent bisphosphonate, zoledronate, to crosslinked fibrinogen by the use of another technique, i.e. ethyl-dimethyl-aminopropylcarbodiimide (EDC)/imidazole immobilization. Bone fixation of zoledronate-coated screws was compared to screws coated with crosslinked fibrinogen only and ditto with EDC/N-hydroxy-succinimide immobilized pamidronate. Fixation in rat tibia was evaluated by a pull-out test at either 2 or 6 weeks after implantation. Both bisphosphonate coatings increased the pull-out force at both time points, and zoledronate showed a significantly higher pull-out force than pamidronate. To further evaluate the new coating technique we also performed a morphometric study, focusing on the area surrounding the implant. The zoledronate coating resulted in an increased bone density around the screws compared to controls. No pronounced increase was seen around the pamidronate coated screws. Together, the results demonstrate the possibility of obtaining a significant local therapeutic effect with minute amounts of surface immobilized zoledronate.
authors.affiliation: Experimental Orthopaedics, Department of Clinical and Experimental Medicine, Faculty of Medicine, Linköping University, 58183 Linköping, Sweden. therese.andersson@liu.se
authors.forename: Therese
authors.initials: T
authors.lastname: Andersson
authors.forename: Fredrik
authors.initials: F
authors.lastname: Agholme
authors.forename: Per
authors.initials: P
authors.lastname: Aspenberg
authors.forename: Pentti
authors.initials: P
authors.lastname: Tengvall
mesh_terms: D000465:Algorithms; D000818:Animals; D050071:Bone Density Conservation Agents / Q000737:chemistry / Q000494:pharmacology; D001863:Bone Screws; D001842:Bone and Bones / Q000737:chemistry / Q000187:drug effects*; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D004164:Diphosphonates / Q000737:chemistry / Q000494:pharmacology*; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D008422:Materials Testing; D008670:Metals / Q000737:chemistry; D019736:Prostheses and Implants; D019919:Prosthesis Implantation / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013193:Stainless Steel / Q000494:pharmacology; D013499:Surface Properties / Q000187:drug effects; D013977:Tibia / Q000187:drug effects; D000077211:Zoledronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D020099:Coated Materials, Biocompatible; D004164:Diphosphonates; D007093:Imidazoles; D008670:Metals; D013193:Stainless Steel; D000077211:Zoledronic Acid