title: The development and evaluation of individualized templates to assist transoral C2 articular mass or transpedicular screw placement in TARP-IV procedures: adult cadaver specimen study.
abstract: OBJECTIVE
  The transoral atlantoaxial reduction plate system treats irreducible atlantoaxial dislocation from transoral atlantoaxial reduction plate-I to transoral atlantoaxial reduction plate-III. However, this system has demonstrated problems associated with screw loosening, atlantoaxial fixation and concealed or manifest neurovascular injuries. This study sought to design a set of individualized templates to improve the accuracy of anterior C2 screw placement in the transoral atlantoaxial reduction plate-IV procedure.
  
  
  METHODS
  A set of individualized templates was designed according to thin-slice computed tomography data obtained from 10 human cadavers. The templates contained cubic modules and drill guides to facilitate transoral atlantoaxial reduction plate positioning and anterior C2 screw placement. We performed 2 stages of cadaveric experiments with 2 cadavers in stage one and 8 in stage two. Finally, guided C2 screw placement was evaluated by reading postoperative computed tomography images and comparing the planned and inserted screw trajectories.
  
  
  RESULTS
  There were two cortical breaching screws in stage one and three in stage two, but only the cortical breaching screws in stage one were ranked critical. In stage two, the planned entry points and the transverse angles of the anterior C2 screws could be simulated, whereas the declination angles could not be simulated due to intraoperative blockage of the drill bit and screwdriver by the upper teeth.
  
  
  CONCLUSIONS
  It was feasible to use individualized templates to guide transoral C2 screw placement. Thus, these drill templates combined with transoral atlantoaxial reduction plate-IV, may improve the accuracy of transoral C2 screw placement and reduce related neurovascular complications.
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Xue-Shi
authors.initials: XS
authors.lastname: Li
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Zeng-Hui
authors.initials: ZH
authors.lastname: Wu
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Xia
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Ma
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Fu-Zhi
authors.initials: FZ
authors.lastname: Ai
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Wang
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Mai
authors.affiliation: Department of Orthopedics, Key Laboratory of Orthopaedic Tecnology and Implant Materials of Guangdong Province, Institute of Traumatic Orthopaedics of People's Liberation Army, Guangzhou General Hospital of Guangzhou Military Command (Liuhuaqiao Hospital), Guangzhou, People's Republic of China.
authors.forename: Qing-Shui
authors.initials: QS
authors.lastname: Yin
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000293:injuries*; D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D002574:Cervical Vertebrae / Q000601:surgery*; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D016268:Internal Fixators; D004204:Joint Dislocations / Q000601:surgery*; D008488:Medical Illustration; D019637:Orthopedic Procedures / Q000295:instrumentation* / Q000379:methods; D012016:Reference Values; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed