title: Osseointegration and biocompatibility of different metal implants--a comparative experimental investigation in sheep.
abstract: BACKGROUND
  In the present study, 4 different metallic implant materials, either partly coated or polished, were tested for their osseointegration and biocompatibility in a pelvic implantation model in sheep.
  
  
  METHODS
  Materials to be evaluated were: Cobalt-Chrome (CC), Cobalt-Chrome/Titanium coating (CCTC), Cobalt-Chrome/Zirconium/Titanium coating (CCZTC), Pure Titanium Standard (PTST), Steel, TAN Standard (TANST) and TAN new finish (TANNEW). Surgery was performed on 7 sheep, with 18 implants per sheep, for a total of 63 implants. After 8 weeks, the specimens were harvested and evaluated macroscopically, radiologically, biomechanically (removal torque), histomorphometrically and histologically.
  
  
  RESULTS
  Cobalt-Chrome screws showed significantly (p = 0.031) lower removal torque values than pure titanium screws and also a tendency towards lower values compared to the other materials, except for steel. Steel screws showed no significant differences, in comparison to cobalt-chrome and TANST, however also a trend towards lower torque values than the remaining materials. The results of the fluorescence sections agreed with those of the biomechanical test. Histomorphometrically, there were no significant differences of bone area between the groups. The BIC (bone-to-implant-contact), used for the assessment of the osseointegration, was significantly lower for cobalt-chrome, compared to steel (p = 0.001). Steel again showed a lower ratio (p = 0.0001) compared to the other materials.
  
  
  CONCLUSIONS
  This study demonstrated that cobalt-chrome and steel show less osseointegration than the other metals and metal-alloys. However, osseointegration of cobalt-chrome was improved by zirconium and/or titanium based coatings (CCTC, TANST, TAN, TANNEW) being similar as pure titanium in their osseointegrative behavior.
authors.affiliation: Trauma Hospital, Goestingerstr. 24, Graz A-8021, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Plecko
authors.forename: Christine
authors.initials: C
authors.lastname: Sievert
authors.forename: Daniel
authors.initials: D
authors.lastname: Andermatt
authors.forename: Robert
authors.initials: R
authors.lastname: Frigg
authors.forename: Peter
authors.initials: P
authors.lastname: Kronen
authors.forename: Karina
authors.initials: K
authors.lastname: Klein
authors.forename: Stefan
authors.initials: S
authors.lastname: Stübinger
authors.forename: Katja
authors.initials: K
authors.lastname: Nuss
authors.forename: Alexander
authors.initials: A
authors.lastname: Bürki
authors.forename: Stephen
authors.initials: S
authors.lastname: Ferguson
authors.forename: Ulrich
authors.initials: U
authors.lastname: Stoeckle
authors.forename: Brigitte
authors.initials: B
authors.lastname: von Rechenberg
mesh_terms: D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods; D001863:Bone Screws / Q000592:standards*; D020099:Coated Materials, Biocompatible / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D008422:Materials Testing / Q000379:methods*; D008670:Metals / Q000494:pharmacology* / Q000627:therapeutic use; D023421:Models, Animal; D016348:Osseointegration / Q000502:physiology*; D019919:Prosthesis Implantation / Q000379:methods*; D034561:Sheep, Domestic
chemical_list: D020099:Coated Materials, Biocompatible; D008670:Metals