Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
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.

PubMed Disclaimer

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)
None
126x99mm (72 x 72 DPI)
None
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)
None
210x156mm (72 x 72 DPI)
See this image and copyright information in PMC

References

    1. Yingsakmonkol W, Karaikovic E, Gaines RW. The accuracy of pedicle screw placement in the thoracic spine using the “Funnel Technique”: part 1. A cadaveric study. Journal of spinal disorders & techniques. 2002;15(6):445–449. - PubMed
    1. Hirano T, Hasegawa K, Takahashi HE, et al. Structural characteristics of the pedicle and its role in screw stability. Spine. 1997;22(21):2504–2510. - PubMed
    1. Brantley AG, Mayfield JK, Koeneman JB, Clark KR. The effects of pedicle screw fit: an in vitro study. Spine. 1994;19(15):1752–1758. - PubMed
    1. Okuyama K, Abe E, Suzuki T, et al. Influence of bone mineral density on pedicle screw fixation: a study of pedicle screw fixation augmenting posterior lumbar interbody fusion in elderly patients. The Spine Journal. 2001;1(6):402–407. - PubMed
    1. Karaikovic EE, Yingsakmongkol W, Gaines RW., Jr Accuracy of cervical pedicle screw placement using the funnel technique. Spine. 2001;26(22):2456–2462. - PubMed

Publication types