title: Odontoid plate fixation without C1-C2 arthrodesis: biomechanical testing of a novel surgical technique and comparison to the conventional screw fixation procedure.
abstract: BACKGROUND
  Odontoid plate fixation without C1-C2 arthrodesis appears to be a practicable option for the management of odontoid fractures that are not amenable for conventional screw fixation. The purpose of this study was to measure the mechanical stability of odontoid plate fixation using a specially designed plate construct, and to compare the results to those after conventional screw fixation.
  
  
  METHODS
  The second cervical vertebra was removed from twenty fresh human spinal columns. Stiffness and failure load of the intact odontoid were measured, and type II odontoid fractures were created. Afterward, the specimens were randomly assigned to one of the following four groups: Group I: plate-fixation; Group II: 2-AO-screw-fixation; Group III: 1-AO-screw-fixation; Group IV: Herbert-screw-fixation. In a second series, stiffness and failure load of the stabilized odontoid fractures were assessed for comparison and statistical analysis.
  
  
  RESULTS
  Group I showed a significantly higher mean failure load than the other groups. The mean failure load of Group I after fixation of the odontoid fracture was 86% of the mean failure load of the intact odontoid. Comparing Groups II, III and IV, there was no significant difference regarding the failure load. In these three groups the mean failure load after odontoid fixation was approximately 50% of the mean failure load of the intact odontoid.
  
  
  CONCLUSIONS
  Odontoid plate fixation as an alternative procedure in certain fracture patterns provided a significantly higher biomechanical stability than the technique of odontoid screw fixation. Using a specially designed plate construct, 86% of the original stability of the intact odontoid was restored.
authors.affiliation: Medical University of Vienna, Department of Trauma Surgery, Waehringer Guertel 18-20, Vienna, Austria. patrick.platzer@gmx.at
authors.forename: Patrick
authors.initials: P
authors.lastname: Platzer
authors.forename: Stefan
authors.initials: S
authors.lastname: Eipeldauer
authors.forename: Vilmos
authors.initials: V
authors.lastname: Vécsei
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001174:Arthrodesis; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D019245:Compressive Strength; D055119:Elastic Modulus; D019544:Equipment Failure Analysis / Q000379:methods; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D017276:Friction; D006801:Humans; D066298:In Vitro Techniques; D009809:Odontoid Process / Q000293:injuries* / Q000503:physiopathology* / Q000601:surgery; D016103:Spinal Fractures / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome