title: Biomechanical comparison of occiput-C1-C2 fixation techniques: C0-C1 transarticular screw and direct occiput condyle screw.
abstract: METHODS
  In vitro human cadaveric biomechanical study.
  
  
  OBJECTIVE
  The objective was to evaluate and compare the construct stability of occiput-C1-C2 fixation provided by C0-C1 transarticular screws or occipital condyle screws.
  
  
  BACKGROUND
  The placement of an occipital plate is commonly recommended in occipitocervical fixation surgery. However, there are unique clinical situations in which the placement of the occipital plate may not be possible or may have already failed. For these situations, 2 novel techniques that use the occipital condyle have been recently introduced: (1) C0-C1 transarticular screws fixation and (2) direct occipital condyle screws and C1 lateral mass screws fixation. However, there is a lack of thorough biomechanics studies of these techniques.
  
  
  METHODS
  Nondestructive kinematic tests and destructive tests were conducted in 16 fresh frozen cadaveric spines. As a nondestructive kinematic test, a pure moment of up to 2.0 N·m was applied in smooth continuous flexion/extension, lateral bending, and axial rotation motions. In addition to an intact-state case, a total of 5 different constructs (standard occipital plate, C0-C1 transarticular screws with/without occipital plate, and occipital condyle screws with/without occipital plate) were tested after destabilization of C0-C1 and C1-C2. All constructs had C2 pedicle screws fixation, and occipital condyle screws were incorporated with C1 lateral screws.
  
  
  RESULTS
  All fixation techniques significantly reduced ranges of motion compared with the intact state. In comparison with the standard occipital plate construct, the 2 novel techniques showed higher stability in axial rotation and lower stability in lateral bending. In both nondestructive and destructive tests, there were no statistical differences between C0-C1 transarticular screw construct and occipital condyle screw construct.
  
  
  CONCLUSIONS
  The C0-C1 transarticular screw technique and direct occipital condyle screw with C1 lateral mass screw technique can be salvage fixation methods when occipital plate fixation is not feasible.
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Takigawa
authors.forename: Peter
authors.initials: P
authors.lastname: Simon
authors.forename: Alejandro A
authors.initials: AA
authors.lastname: Espinoza Orías
authors.forename: Jae Taek
authors.initials: JT
authors.lastname: Hong
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ito
authors.forename: Nozomu
authors.initials: N
authors.lastname: Inoue
authors.forename: Howard S
authors.initials: HS
authors.lastname: An
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D002574:Cervical Vertebrae / Q000601:surgery*; D005260:Female; D006801:Humans; D016268:Internal Fixators; D007593:Joint Instability / Q000517:prevention & control / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009777:Occipital Bone / Q000601:surgery*; D016059:Range of Motion, Articular; D012399:Rotation; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*