title: Evaluation of Titanium-Coated Pedicle Screws: In Vivo Porcine Lumbar Spine Model.
abstract: OBJECTIVE
  Many studies have addressed the problem of loosening pedicle screws in spinal surgery, which is a serious concern. Titanium coating of medical implants (arthroplasty) is common, but few studies involving in vivo spine models have been reported. We evaluated the radiological, mechanical, and histological characteristics of titanium-coated pedicle screws compared with uncoated or hydroxyapatite-coated pedicle screws.
  
  
  METHODS
  Three different types of pedicle screws, i.e., uncoated, hydroxyapatite-coated, and titanium-coated, were implanted into the lumbar 3-4-5 levels of 9 mature miniature pigs. Radiological evaluation of loosening of pedicle screws was performed. Peak torsional extraction torque was tested in the 42 screws from 7 miniature pigs at 12 weeks postoperatively. The implant-bone interface of the remaining 12 pedicle screws from 2 miniature pigs in each group was assessed by micro-computed tomography and histologic studies.
  
  
  RESULTS
  The incidence of loosening at 12 weeks postoperatively was not significantly different between the titanium-coated pedicle screw group and the other groups. The titanium-coated pedicle screw group exhibited the greatest mean extraction torsional peak torque at 12 weeks postoperatively (P < 0.05). Quantitative micro-computed tomography data were greatest in the titanium-coated pedicle screw group (P < 0.05). Histologic findings showed osteointegration with densely packed new bone formation at the screw coating-bone interface in the titanium-coated pedicle screw group.
  
  
  CONCLUSIONS
  Fixation strength was greatest in the titanium-coated pedicle screw group. Osteointegration at the interface between the titanium-coated implant and bone produced prominent and firm bonding. The titanium-coated pedicle screw is a promising device for application in spinal surgery.
authors.affiliation: Department of Orthopedic Surgery, The Himchan Hospital, Jeonju, Korea.
authors.forename: Do-Yeon
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Department of Orthopedic Surgery, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Jung-Ryul
authors.initials: JR
authors.lastname: Kim
authors.affiliation: Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Korea.
authors.forename: Kyu Yun
authors.initials: KY
authors.lastname: Jang
authors.affiliation: Student.
authors.forename: Min Gu
authors.initials: MG
authors.lastname: Kim
authors.affiliation: Department of Orthopedic Surgery, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University, Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Korea. Electronic address: osdr2815@naver.com.
authors.forename: Kwang-Bok
authors.initials: KB
authors.lastname: Lee
mesh_terms: D000818:Animals; D001178:Arthroplasty; D020099:Coated Materials, Biocompatible / Q000592:standards*; D004195:Disease Models, Animal; D017886:Durapatite; D005260:Female; D008159:Lumbar Vertebrae / Q000601:surgery*; D019637:Orthopedic Procedures / Q000592:standards*; D065289:Pedicle Screws / Q000592:standards*; D013552:Swine; D014025:Titanium
chemical_list: D020099:Coated Materials, Biocompatible; D017886:Durapatite; D014025:Titanium
keywords: HA-coated pedicle screw; Osteointegration; Titanium-coated pedicle screw