title: Surface immobilized bisphosphonate improves stainless-steel screw fixation in rats.
abstract: An increase in the mechanical fixation in bone of metallic biomaterials is considered advantageous in joint replacement and fracture surgery. Different approaches to improve fixation may be e.g. surface roughening, Ca-mineral coating or surface immobilization of growth factors or drugs. In the present work, bisphosphonate, a class of drugs that inhibit bone resorption, was immobilized onto stainless-steel screws. The screws were first roughened and coated with immobilized and cross-linked fibrinogen. Subsequently, an N-bisphosphonate, pamidronate, was immobilized onto fibrinogen, and another N-bisphosphonate, ibandronate, adsorbed on top of this. The so coated screws were inserted into the tibiae of eight male Sprague-Dawley rats. Another eight rats received screws prepared in the same way, but without the bisphosphonate coating. Pullout strength tests were performed after 2 weeks of implantation. The results showed a 28% (p=0.0009) higher pullout force and 90% increased pullout energy for the bisphosphonate coated screws, and support the idea that surface immobilized bisphosphonates can be used to improve biomaterials fixation in bone.
authors.affiliation: Department of Physics and Measurement Technology, Biology and Chemistry, Linköping University, SE-581 83, Linköping, Sweden. pet@ifm.liu.se
authors.forename: P
authors.initials: P
authors.lastname: Tengvall
authors.forename: B
authors.initials: B
authors.lastname: Skoglund
authors.forename: A
authors.initials: A
authors.lastname: Askendal
authors.forename: P
authors.initials: P
authors.lastname: Aspenberg
mesh_terms: D000327:Adsorption; D000818:Animals; D001862:Bone Resorption / Q000503:physiopathology / Q000517:prevention & control; D001863:Bone Screws; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004164:Diphosphonates / Q000737:chemistry / Q000494:pharmacology*; D019544:Equipment Failure Analysis / Q000379:methods*; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D008297:Male; D008422:Materials Testing; D051381:Rats; D017207:Rats, Sprague-Dawley; D013193:Stainless Steel / Q000737:chemistry; D013718:Tensile Strength; D013978:Tibial Fractures / Q000503:physiopathology* / Q000601:surgery*
chemical_list: D020099:Coated Materials, Biocompatible; D004164:Diphosphonates; D013193:Stainless Steel