title: Biomechanical study of the funnel technique applied in thoracic pedicle screw replacement.
abstract: BACKGROUND
  Funnel technique is a method used for the insertion of screw into thoracic pedicle.
  
  
  OBJECTIVE
  To evaluate the biomechanical characteristics of thoracic pedicle screw placement using the Funnel technique, trying to provide biomechanical basis for clinical application of this technology.
  
  
  METHODS
  14 functional spinal units (T6 to T10) were selected from thoracic spine specimens of 14 fresh adult cadavers, and randomly divided into two groups, including Funnel technique group (n = 7) and Magerl technique group (n = 7). The displacement-stiffness and pull-out strength in all kinds of position were tested and compared.
  
  
  RESULTS
  Two fixed groups were significantly higher than that of the intact state (P < 0.05) in the spinal central axial direction, compression, anterior flexion, posterior bending, lateral bending, axial torsion, but there were no significant differences between two fixed groups (P > 0.05). The mean pull-out strength in Funnel technique group (789.09 ± 27.33) was lower than that in Magerl technique group (P < 0.05).
  
  
  CONCLUSIONS
  The Funnel technique for the insertion point of posterior bone is a safe and accurate technique for pedicle screw placement. It exhibited no effects on the stiffness of spinal column, but decreased the pull-out strength of pedicle screw. Therefore, the funnel technique in the thoracic spine affords an alternative for the standard screw placement.
authors.affiliation: Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical College, Wenzhou 325200, Zhejiang, China.
authors.forename: Yi-Jiang
authors.initials: YJ
authors.lastname: Huang
authors.affiliation: Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical College, Wenzhou 325200, Zhejiang, China.
authors.forename: Mao-Xiu
authors.initials: MX
authors.lastname: Peng
authors.affiliation: Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical College, Wenzhou 325200, Zhejiang, China.
authors.forename: Shao-Qi
authors.initials: SQ
authors.lastname: He
authors.affiliation: Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical College, Wenzhou 325200, Zhejiang, China.
authors.forename: Liang-Le
authors.initials: LL
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical College, Wenzhou 325200, Zhejiang, China.
authors.forename: Ming-Hai
authors.initials: MH
authors.lastname: Dai
authors.affiliation: Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical College, Wenzhou 325200, Zhejiang, China.
authors.forename: Chenxuan
authors.initials: C
authors.lastname: Tang
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D011859:Radiography; D013122:Spinal Diseases / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*
keywords: Biomechanics; Funnel technique; Pedicle screws; Thoracic