The biomechanical effect of pedicle screws' insertion angle and position on the superior adjacent segment in 1 segment lumbar fusion

Ho Joong Kim, Heoung Jae Chun, Kyoung Tak Kang, Seong Hwan Moon, Hak Sun Kim, Jin Oh Park, Eun Su Moon, Bo Ram Kim, Joon Seok Sohn, Yu Na Ko, Hwan Mo Lee

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

STUDY DESIGN.: A finite element analysis. OBJECTIVE.: To investigate the association between the position of an inserted pedicle screw and the corresponding facet contact force or intradiscal pressure. SUMMARY OF BACKGROUND DATA.: Although superior facet joint violation by pedicle screws is not an uncommon occurrence in instrumented lumbar fusion surgery, its actual biomechanical significance is not well understood. Furthermore, the association between the position of the pedicle screw and the stress on the corresponding disc/facet joint has yet to be investigated. METHODS.: According to the positions of pedicle screws in L4 of the L4-L5 lumbar fusion, 4 L4-L5 fusion models were simulated. These models included the violation of both L3-L4 superior facet joints by pedicle screws (facet joint violation [FV] model), the nonencroachment of both L3-L4 superior facet joints by pedicle screws (facet joint preservation [FP] model), and the removal state of pedicle screws in the FV model (removal of violated pedicle screws [rFV] model). The facet joint contact [FC] model represented the scenario in which the pedicle screws did not encroach upon either facet joint but were inserted close to the L3-L4 facet joint surface. Moreover, the uninstrumented fusion [UF] model represented the uninstrumented L4-L5 fusion. In each scenario, the intradiscal pressures and facet contact forces at the L2-L3 and L3-L4 segments were analyzed under extension and torsion moments. RESULTS.: The FV model yielded the greatest increases in facet contact force and intradiscal pressure at the L3-L4 segment under extension and torsion moments. Following the FV model, the increases in intradiscal pressure and facet contact force were the second highest in the FC model followed by the FP model. Furthermore, the rFV model represented prominent reductions of previously increased facet contact force and intradiscal pressure at the L3-L4 segment. CONCLUSION.: In models of 1-segment lumbar fusion surgery, the positions of pedicle screws were closely linked with corresponding disc stresses and facet contact forces. However, even in cases of facet violation by pedicle screws, removal of the pedicle screw after fusion completion can reduce facet contract forces and disc stresses under both extension and torsional moments.

Original languageEnglish
Pages (from-to)1637-1644
Number of pages8
JournalSpine
Volume37
Issue number19
DOIs
Publication statusPublished - 2012 Sep 1
Externally publishedYes

Fingerprint

Zygapophyseal Joint
Pressure
Pedicle Screws
Finite Element Analysis
Contracts

Keywords

  • facet joint violation
  • finite element model
  • lumbar fusion surgery
  • pedicle screws

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Clinical Neurology

Cite this

Kim, H. J., Chun, H. J., Kang, K. T., Moon, S. H., Kim, H. S., Park, J. O., ... Lee, H. M. (2012). The biomechanical effect of pedicle screws' insertion angle and position on the superior adjacent segment in 1 segment lumbar fusion. Spine, 37(19), 1637-1644. https://doi.org/10.1097/BRS.0b013e31823f2115

The biomechanical effect of pedicle screws' insertion angle and position on the superior adjacent segment in 1 segment lumbar fusion. / Kim, Ho Joong; Chun, Heoung Jae; Kang, Kyoung Tak; Moon, Seong Hwan; Kim, Hak Sun; Park, Jin Oh; Moon, Eun Su; Kim, Bo Ram; Sohn, Joon Seok; Ko, Yu Na; Lee, Hwan Mo.

In: Spine, Vol. 37, No. 19, 01.09.2012, p. 1637-1644.

Research output: Contribution to journalArticle

Kim, HJ, Chun, HJ, Kang, KT, Moon, SH, Kim, HS, Park, JO, Moon, ES, Kim, BR, Sohn, JS, Ko, YN & Lee, HM 2012, 'The biomechanical effect of pedicle screws' insertion angle and position on the superior adjacent segment in 1 segment lumbar fusion', Spine, vol. 37, no. 19, pp. 1637-1644. https://doi.org/10.1097/BRS.0b013e31823f2115
Kim, Ho Joong ; Chun, Heoung Jae ; Kang, Kyoung Tak ; Moon, Seong Hwan ; Kim, Hak Sun ; Park, Jin Oh ; Moon, Eun Su ; Kim, Bo Ram ; Sohn, Joon Seok ; Ko, Yu Na ; Lee, Hwan Mo. / The biomechanical effect of pedicle screws' insertion angle and position on the superior adjacent segment in 1 segment lumbar fusion. In: Spine. 2012 ; Vol. 37, No. 19. pp. 1637-1644.
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AU - Moon, Seong Hwan

AU - Kim, Hak Sun

AU - Park, Jin Oh

AU - Moon, Eun Su

AU - Kim, Bo Ram

AU - Sohn, Joon Seok

AU - Ko, Yu Na

AU - Lee, Hwan Mo

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N2 - STUDY DESIGN.: A finite element analysis. OBJECTIVE.: To investigate the association between the position of an inserted pedicle screw and the corresponding facet contact force or intradiscal pressure. SUMMARY OF BACKGROUND DATA.: Although superior facet joint violation by pedicle screws is not an uncommon occurrence in instrumented lumbar fusion surgery, its actual biomechanical significance is not well understood. Furthermore, the association between the position of the pedicle screw and the stress on the corresponding disc/facet joint has yet to be investigated. METHODS.: According to the positions of pedicle screws in L4 of the L4-L5 lumbar fusion, 4 L4-L5 fusion models were simulated. These models included the violation of both L3-L4 superior facet joints by pedicle screws (facet joint violation [FV] model), the nonencroachment of both L3-L4 superior facet joints by pedicle screws (facet joint preservation [FP] model), and the removal state of pedicle screws in the FV model (removal of violated pedicle screws [rFV] model). The facet joint contact [FC] model represented the scenario in which the pedicle screws did not encroach upon either facet joint but were inserted close to the L3-L4 facet joint surface. Moreover, the uninstrumented fusion [UF] model represented the uninstrumented L4-L5 fusion. In each scenario, the intradiscal pressures and facet contact forces at the L2-L3 and L3-L4 segments were analyzed under extension and torsion moments. RESULTS.: The FV model yielded the greatest increases in facet contact force and intradiscal pressure at the L3-L4 segment under extension and torsion moments. Following the FV model, the increases in intradiscal pressure and facet contact force were the second highest in the FC model followed by the FP model. Furthermore, the rFV model represented prominent reductions of previously increased facet contact force and intradiscal pressure at the L3-L4 segment. CONCLUSION.: In models of 1-segment lumbar fusion surgery, the positions of pedicle screws were closely linked with corresponding disc stresses and facet contact forces. However, even in cases of facet violation by pedicle screws, removal of the pedicle screw after fusion completion can reduce facet contract forces and disc stresses under both extension and torsional moments.

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