title: Biomechanical Evaluation of a Novel Integrated C1 Laminar Hook Combined with C1-C2 Transarticular Screws for Atlantoaxial Fusion: An In Vitro Human Cadaveric Study.
abstract: OBJECTIVE
  To evaluate the acute stability of a novel integrated C1 laminar hook (H) combined with a C1-C2 transarticular screw (TAS) with established techniques.
  
  
  METHODS
  A novel integrated C1 laminar hook was tested. Seven human cadaveric cervical spines (C0-C3) were used. The range of motion (ROM) of C1-C2 during flexion-extension, lateral bending, and axial rotation were recorded. The specimens were tested under the following conditions: intact, destabilized (using a type II odontoid fracture model), and destabilized but with internal fixation. The following screw systems were used: bilateral C1-C2 TAS combined with the Gallie (G) technique (TAS+G), C1-C2 TAS combined with a novel integrated C1 laminar hook (TAS+H), C1 lateral mass screw and C2 pedicle screws (C2PS+C1LMS), and novel integrated C1 laminar hook combined with C2 pedicle screws (C2PS+H). The TASs were always inserted after the C2PSs. The C2PS+C1LMS and C2PS+H tests were performed alternatively, as were the TAS+G and TAS+H tests.
  
  
  RESULTS
  All fixation constructs greatly improved acute atlantoaxial stability, with no significant difference among TAS+H, TAS+G, and C2PS+C1LMS (all P > 0.05). C2PS+H showed the greatest C1-C2 ROM in axial rotation, significantly different from TAS+G, C2PS+C1LMS, and TAS+H fixation models (all P < 0.05). However, there were no significant differences between C2PS+H and the other 3 models in flexion-extension and lateral bending (all P > 0.05).
  
  
  CONCLUSIONS
  The TAS+H technique can achieve acute stability comparable to that with the TAS+G technique for treating C1-C2 instability. The C2PS+H is a promising alternative, although it provides less stability in axial rotation than TAS+G, TAS+H, or C2PS+C1LMS.
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China; Department of Orthopedics, No. 455 Hospital, The Chinese People's Liberation Army, Shanghai, People's Republic of China.
authors.forename: Tianming
authors.initials: T
authors.lastname: Xu
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Qunfeng
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Lu
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Xuhua
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China. Electronic address: nibin99@sohu.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Ni
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000002:abnormalities* / Q000503:physiopathology / Q000601:surgery; D001696:Biomechanical Phenomena; D002102:Cadaver; D002574:Cervical Vertebrae / Q000601:surgery; D000013:Congenital Abnormalities / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D065289:Pedicle Screws; D016059:Range of Motion, Articular / Q000502:physiology; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D013525:Surgical Instruments; D055815:Young Adult
keywords: Atlantoaxial instability; Biomechanics; Fixation; Laminar hook; Range of motion; Transarticular screw