title: Extracellular matrix-coating pedicle screws conduct and induce osteogenesis.
abstract: BACKGROUND
  The purpose of the present study was to study the effects of the extracellular matrix-coating pedicle screws on the conduction and induction of bone formation in young sheep.
  
  
  METHODS
  Pedicle screws [coated with collagen/chondroitin sulfate (coll/CS), hydroxyapatite (HA), and coll/CS/HA or uncoated] were randomly implanted into the L2-L5 pedicles of sheep. In the first stage, a static experiment was performed. In the second stage, a loading test was performed by implanting connecting rods. After 3 months, the lumbar vertebrae with the screws were removed and examined by micro-CT, histological, and biomechanical analyses.
  
  
  RESULTS
  Under non-loading conditions, there is bone formation around the surfaces of coated screws. Bone formation on the surface of the coll/CS/HA coating of pedicle screws was the highest. In terms of the trabecular bone morphology parameters of the region of interest around the surface of the pedicle screws, those associated with coll/CS/HA coatings were highest under non-loading conditions, the pullout strength of the coll-/CS-/HA-coated screws was the highest and that of the uncoated screws was minimal. Under loading conditions, the maximum pullout strength of each group of pedicle screws was less than that of the pedicle screws in the non-loading state.
  
  
  CONCLUSIONS
  Under non-loading conditions, the organic and inorganic components of the titanium pedicle screw coatings can conduct or induce bone formation around the surface of the screws. The ability of the coll/CS/HA coating to induce bone formation was the strongest. Under loading conditions, a large amount of connective tissue formed around the surface of the screws in each group.
authors.affiliation: Department of Orthopedics, The Second Hospital, Jilin University, Changchun, 130041, China.
authors.forename: Guo-Min
authors.initials: GM
authors.lastname: Liu
authors.forename: Ning
authors.initials: N
authors.lastname: Kong
authors.forename: Xing-Yi
authors.initials: XY
authors.lastname: Zhang
authors.forename: Hao-Tian
authors.initials: HT
authors.lastname: Bai
authors.forename: Yan
authors.initials: Y
authors.lastname: Yao
authors.forename: Hong-Zhi
authors.initials: HZ
authors.lastname: Han
authors.forename: Yun-Gang
authors.initials: YG
authors.lastname: Luo
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage / Q000494:pharmacology; D001696:Biomechanical Phenomena; D002809:Chondroitin Sulfates / Q000008:administration & dosage / Q000494:pharmacology; D003094:Collagen / Q000008:administration & dosage / Q000494:pharmacology; D004338:Drug Combinations; D017886:Durapatite / Q000008:administration & dosage / Q000494:pharmacology; D005109:Extracellular Matrix / Q000502:physiology*; D008159:Lumbar Vertebrae / Q000601:surgery; D010012:Osteogenesis / Q000502:physiology*; D065289:Pedicle Screws; D011897:Random Allocation; D012756:Sheep
chemical_list: D001672:Biocompatible Materials; D004338:Drug Combinations; D002809:Chondroitin Sulfates; D003094:Collagen; D017886:Durapatite