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
Case Reports
. 2020 Jun 15:26:e922050.
doi: 10.12659/MSM.922050.

Comparative Three-Dimensional Finite Element Analysis of 4 Kinds of Pedicle Screw Schemes for Treatment of Adult Degenerative Scoliosis

Yang Zhou  1 , Daqi Xin  2 , Zhuoting Lei  3 , Yuan Zuo  4 , Yan Zhao  4
Affiliations
Case Reports

Comparative Three-Dimensional Finite Element Analysis of 4 Kinds of Pedicle Screw Schemes for Treatment of Adult Degenerative Scoliosis

Yang Zhou et al. Med Sci Monit. .

Abstract

BACKGROUND This study aimed to evaluate the biomechanical stress of the internal fixation screws and vertebral bodies after the full-segment, interval, key vertebral, and strategy pedicle screw fixations under 7 work conditions in a patient with adult degenerative scoliosis (ADS) using finite elements (FE) analysis. MATERIAL AND METHODS A patient with ADS underwent internal fixation by pedicle screws after posterior incision in combination with subtotal laminectomy decompression and bone graft fusion, and received thin-layer computed tomography (CT) spine scanning at T12-L5. The CT data were used to constitute three-dimensional FE full-segment, interval, key vertebral, and strategic pedicle screw models. The stress of each screw-rod system under different working conditions was evaluated. RESULTS Forward flexion, backward extension, lateral flexion, and rotation greatly increased the force of the pedicle screw systems. The maximum stress of the screw-rods was the lowest in the full-segment model under almost all the working conditions except for the upright situation. The maximum stress of the vertebral bodies was the minimum in the strategic model under all the 7 working conditions, followed by that in the key vertebra and full-segment models. CONCLUSIONS Collectively, the strategic and key vertebra pedicle screw schemes can decrease the biomechanical stress of screw-rod systems and vertebral bodies, which is close to the full-segment scheme. Our results may help explore the optimal surgical means for pedicle screw fixation for ADS patients, which can maximally reduce the risk of screws-related postoperative complications and simultaneously maintain a reasonable 3D orthopedic effect.

PubMed Disclaimer

Conflict of interest statement

Conflict of interest

None.

Figures

Figure 1
Figure 1
Reconstruction of postoperative spinal model of ADS patient with Mimics17.0. (A) Primary 3D vertebral body model by Mimics17.0 software. (B) Final 3D vertebral body model by the Mimics’ Remesh function. (C) Establishment of 3D screw-rod system. (D) Establishment of a 3D model of lumbar intervertebral discs. (E–H). Primary full-segment (E), interval (F), key vertebra (G) and strategic (H) screw models.
Figure 2
Figure 2
Establishment of 3D FE models of the full-segment, interval, key vertebra and strategic screw. (A–D) The full-segment (A), interval (B), key vertebra (C), and strategic (D) screw models were further polished and optimized by Geomagic Studio software. (E–H) Complete 3D FE models of the full-segment (E), interval (F), key vertebra (G), and strategic (H) screw by the Ansys software.
Figure 3
Figure 3
The X-ray images of spine (T12–L5) before (A) and after (B) operation.
Figure 4
Figure 4
Typical biomechanical characteristics of the screw-rod systems of the full-segment (A), interval (B), key vertebra (C), and strategic (D) screw systems under left lateral flexion condition.
Figure 5
Figure 5
Typical biomechanical characteristics of the intervertebral discs of the full-segment (A, L2), interval (B, L2), key vertebra (C, L2), and strategic (D, L5) screw systems under left lateral flexion condition.
See this image and copyright information in PMC

References

    1. Silva FE, Lenke LG. Adult degenerative scoliosis: evaluation and management. Neurosurg Focus. 2010;28(3):E1. - PubMed
    1. Hong JY, Suh SW, Modi HN, et al. The prevalence and radiological findings in 1347 elderly patients with scoliosis. J Bone Joint Surg Br. 2010;92(7):980–83. - PubMed
    1. Schwab F, Dubey A, Gamez L, et al. Adult scoliosis: prevalence, SF-36, and nutritional parameters in an elderly volunteer population. Spine (Phila Pa 1976) 2005;30(9):1082–85. - PubMed
    1. Faldini C, Di Martino A, Borghi R, et al. Long vs. short fusions for adult lumbar degenerative scoliosis: Does balance matters? Eur Spine J. 2015;24(Suppl 7):887–92. - PubMed
    1. Kleinstueck FS, Fekete TF, Jeszenszky D, et al. Adult degenerative scoliosis: Comparison of patient-rated outcome after three different surgical treatments. Eur Spine J. 2016;25(8):2649–56. - PubMed