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Randomized Controlled Trial
. 2014 Sep;14(3):716-24.
doi: 10.4314/ahs.v14i3.30.

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

Yi-Jiang Huang  1 , Mao-Xiu Peng  1 , Shao-Qi He  1 , Liang-Le Liu  1 , Ming-Hai Dai  1 , Chenxuan Tang  1
Affiliations
Randomized Controlled Trial

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

Yi-Jiang Huang et al. Afr Health Sci. 2014 Sep.

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: Biomechanics; Funnel technique; Pedicle screws; Thoracic.

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Figures

Fig. 1
Fig. 1
The representative figures for Biomechanical experiment. Universal material testing machine (2500 N, Zwick, Germany) was used in this study for loading exposure and the displacement of the middle vertebral segment was measured using KG-digital grating high precision micrometer. (A) displacement-stiffness test; (B) torsion test; (C)pullout strength test 126x116mm (72 x 72 DPI)
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126x99mm (72 x 72 DPI)
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127x128mm (72 x 72 DPI)
Fig. 2
Fig. 2
The representative figure of Funnel technique. 126x127mm (72 x 72 DPI)
Fig. 3
Fig. 3
Pullout strength curve for Magerl technique (A) and Funnel technique (B). 210x164mm (72 x 72 DPI)
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210x156mm (72 x 72 DPI)
See this image and copyright information in PMC

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References

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