title: Evaluation of calcium dihydroxide- and silver-coated implants in the rat tibia.
abstract: BACKGROUND
  Silver ions (Ag+) have strong antibacterial effects, and silver-coated materials are in widespread clinical use. However, the application of silver-coated medical devices is not without concerns: its use with direct bone contact is not established, and systemic toxic side effects of released Ag+ have been described. Therefore, alternative bactericidal coatings with a more localized way of acting - e.g., calcium dihydroxide, Ca(OH)2 (CH) - would be advantageous.
  
  
  METHODS
  A new rat model of the animal's tibial metaphysis was developed. In the left proximal tibiae of 36 male Wistar rats, titanium screws were implanted. The screws were coated with hydroxyapatite (HA; 12 animals: group I), low-dosed HA silver (HA-Ag; 12 animals: group II) and CH (12 animals: group III). After 6 weeks, all rats were sacrificed. The implants were evaluated for morphological changes on their surfaces, by light microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy; for osteointegration, by measurement of resistance to removal; and for bacterial colonization, by quantitative culture analysis. Additionally, the tibial bone was investigated histologically for signs of osteomyelitis and sonicated to detect bacterial loads.
  
  
  RESULTS
  (i) No microbiological or histological signs of infection could be determined on any of the screws or the surrounding bone. (ii) The bone-implant interface analysis revealed extensive bone formation and direct bone-implant contact on all HA, HA-Ag and HA-CH coated screws. (iii) HA and HA-Ag were partially, and CH was fully, degraded on the screw coating, allowing host bone to osteointegrate.
authors.affiliation: Clinic of Orthopedics and Sports Orthopedics, Klinikum rechts der Isar, Technical University of Munich, Munich - Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Harrasser
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland (FHNW), School of Life Sciences, Muttenz - Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: de Wild
authors.affiliation: Clinic of Orthopedics and Sports Orthopedics, Klinikum rechts der Isar, Technical University of Munich, Munich - Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Gorkotte
authors.affiliation: Clinic of Orthopedics and Sports Orthopedics, Klinikum rechts der Isar, Technical University of Munich, Munich - Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Obermeier
authors.affiliation: Institute for Medical Microbiology, Immunology and Hygiene, Technical University of Munich, Munich - Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Feihl
authors.affiliation: Institute of Pathology, Klinikum rechts der Isar, Technical University of Munich, Munich - Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Straub
authors.affiliation: Clinic of Orthopedics and Sports Orthopedics, Klinikum rechts der Isar, Technical University of Munich, Munich - Germany.
authors.forename: Ruediger
authors.initials: R
authors.lastname: von Eisenhart-Rothe
authors.affiliation: Clinic of Orthopedics and Sports Orthopedics, Klinikum rechts der Isar, Technical University of Munich, Munich - Germany.|ATOS Clinic, Munich - Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Gollwitzer
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland (FHNW), School of Life Sciences, Muttenz - Switzerland.
authors.forename: Jasmine
authors.initials: J
authors.lastname: Rüegg
authors.affiliation: Atesos Medical AG, Aarau - Switzerland.
authors.forename: Walter
authors.initials: W
authors.lastname: Moser
authors.affiliation: Medicoat AG, Maegenwil - Switzerland.
authors.forename: Philipp
authors.initials: P
authors.lastname: Gruner
authors.affiliation: Clinic of Orthopedics and Sports Orthopedics, Klinikum rechts der Isar, Technical University of Munich, Munich - Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Burgkart
mesh_terms: D000818:Animals; D001863:Bone Screws; D002126:Calcium Hydroxide / Q000494:pharmacology*; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012834:Silver / Q000494:pharmacology*; D013977:Tibia / Q000378:metabolism* / Q000473:pathology
chemical_list: D020099:Coated Materials, Biocompatible; D012834:Silver; D002126:Calcium Hydroxide