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Published on: May 31, 2017
Biomechanical study of the funnel technique applied in thoracic pedicle screw replacement
Yi-Jiang Huang1, Mao-Xiu Peng1, Shao-Qi He1
1Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical College, Wenzhou 325200, Zhejiang, China.
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.
