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Biomechanical study of the funnel technique applied in thoracic pedicle screw replacement


YJ Huang
MX Peng
SQ He
LL Liu
MH Dai
C Tang

Abstract

Background: Funnel technique is a method used for the insertion of screw into thoracic pedicle.
Aim: 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.

Keywords: Thoracic; Pedicle screws; Biomechanics; Funnel technique


Journal Identifiers


eISSN: 1729-0503
print ISSN: 1680-6905