title: [A biomechanical evaluation of odontoid screw plate fixation system].
abstract: OBJECTIVE
  To evaluate the biomechanical stability of anterior odontoid screw plate (AOSP).
  
  
  METHODS
  Eight fresh-frozen cadaveric cervical spine specimens were subjected to stepwise destabilization of the C1-C3 complex, simulating a type Ⅰ Hangman fracture, type Ⅱ odontoid fracture, and the C2-3 disc injury. Intact specimens, fractured specimens, and fractured specimens with posterior, anterior fixation techniques were divided into six groups: control group (intact), injury group of type Ⅱ odontoid fracture and type Ⅰ Hangman fracture combined with C2-3 disk injury, after anterior cervical plate+ odontoid screw+ cage (ACP+ OS+ cage) group, after anterior odontoid screw plate (AOSP) fixation system group, after affixing rods from pedicle screws in C2 to lateral mass screws in C3+ odontoid screw (C2PS+ C3LMS+ OS) group, after affixing rods from pedicle screws in C1 to pedicle screws in C2 and lateral mass screws in C3 (C1PS+ C2PS+ C3LMS) group. The range of motion (ROM) and neutral zone of C1-C2 and C2-C3 segment was tested.
  
  
  RESULTS
  There was statistically significant difference between the C1PS+ C2PS+ C3LMS fixation group and the AOSP fixation group of ROMC1-C2(P<0.05). During all loading modes, AOSP+ Bone graft fixation significantly outperformed the ACP+ OS+ cage fixation in limiting ROMC2-C3. During flexion and extension, AOSP fixation significantly outperformed the C1PS+ C2PS+ C3LMS fixation and C2PS+ C3LMS+ OS fixation in limiting ROMC2-C3.
  
  
  CONCLUSIONS
  The AOSP fixation system has excellent biomechanical performance when dealing with type Ⅰ Hangman fracture, type Ⅱ odontoid fracture, and the C2-3 disc injury, and appear to be a safe and effective technique for dealing with the combined injury.
authors.affiliation: Department of Spinal Surgery, Ningbo No.6 Hospital, Ningbo 315040, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
authors.forename: W X
authors.initials: WX
authors.lastname: Dong
authors.forename: X Y
authors.initials: XY
authors.lastname: Sun
authors.forename: Z S
authors.initials: ZS
authors.lastname: Yuan
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Xie
authors.forename: C H
authors.initials: CH
authors.lastname: Wu
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D002574:Cervical Vertebrae / Q000473:pathology; D006801:Humans; D009809:Odontoid Process / Q000601:surgery*; D019637:Orthopedic Procedures; D016059:Range of Motion, Articular; D016103:Spinal Fractures / Q000601:surgery*