title: Bioactive ceramic coating of cancellous screws improves the osseointegration in the cancellous bone.
abstract: BACKGROUND
  A number of methods for coating implants with bioactive ceramics have been reported to improve osseointegration in bone, but the effects of bioactive ceramic coatings on the osseointegration of cancellous screws are not known. Accordingly, biomechanical and histomorphometric analyses of the bone-screw interface of uncoated cancellous screws and cancellous screws coated with four different bioactive ceramics were performed.
  
  
  METHODS
  After coating titanium alloy cancellous screws with calcium pyrophosphate (CPP), CaO-SiO(2)-B(2)O(3) glass-ceramics (CSG), apatite-wollastonite 1:3 glass-ceramics (W3G), and CaO-SiO(2)-P(2)O(5)-B(2)O(3) glass-ceramics (BGS-7) using an enameling method, the coated and the uncoated screws were inserted into the proximal tibia and distal femur metaphysis of seven male mongrel dogs. The torque values of the screws were measured at the time of insertion and at removal after 8 weeks. The bone-screw contact ratio was analyzed by histomorphometry.
  
  
  RESULTS
  There was no significant difference in the insertion torque between the uncoated and coated screws. The torque values of the CPP and BGS-7 groups measured at removal after 8 weeks were significantly higher than those of the uncoated group. Moreover, the values of the CPP and BGS-7 groups were significantly higher than the insertion torques. The fraction of bone-screw interface measured from the undecalcified histological slide showed that the CPP, W3G, and BGS-7 groups had significantly higher torque values in the cortical bone area than the uncoated group, and the CPP and BGS-7 groups had significantly higher torque values in the cancellous bone area than the uncoated group.
  
  
  CONCLUSIONS
  In conclusion, a cancellous screw coated with CPP and BGS-7 ceramic bonds directly to cancellous bone to improve the bone-implant osseointegration. This may broaden the indications for cancellous screws by clarifying their contribution to improving osseointegration, even in the cancellous bone area.
authors: Department of Orthopedic Surgery, Seoul National University, College of Medicine, SMG-SNU Boramae Medical Center, 425 Shindaebang 2-dong, Dongjak-gu, Seoul 156-707, Korea. spinelee@snu.ac.kr
authors: Jae Hyup
authors: JH
authors: Lee
authors: Hwa
authors: H
authors: Nam
authors: Hyun-Seung
authors: HS
authors: Ryu
authors: Jun-Hyuk
authors: JH
authors: Seo
authors: Bong-Soon
authors: BS
authors: Chang
authors: Choon-Ki
authors: CK
authors: Lee
mesh_terms: D000818:Animals; D001863:Bone Screws; D002516:Ceramics / Q000494:pharmacology*; D020099:Coated Materials, Biocompatible; D004195:Disease Models, Animal; D004285:Dogs; D005264:Femoral Fractures / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D017102:Fracture Healing; D008297:Male; D008422:Materials Testing; D016348:Osseointegration / Q000502:physiology*; D013499:Surface Properties; D013978:Tibial Fractures / Q000601:surgery*; D016896:Treatment Outcome
chemical_list: D020099:Coated Materials, Biocompatible; C023506:Glass ceramics