In vivo studies on flexion and extension of the lumbar spine after stabilisation with a non-fusion pedicle screw system

Klauß, Jörg Rainer; Richter, MJ; Bergert, H.; Braunschweig, R.; Roehl, Klaus F.

doi:10.1590/s1808-18512012000300001

Cited by 1 publication

(2 citation statements)

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“…Recently, FE studies have focused on the hypothesis that lumbar pedicle fixation and interbody fusion cause an increase in ASD due to the increment of FJ force and the ROM at adjacent segments [18][19][20][21]. Furthermore, different alternative non-fusion methods have been developed to eliminate the possible drawbacks of fusion formed with PS fixation, such as ASD, screw loosening, and rod and screw breakage [21][22][23][24]. However, the new alternative methods also have some drawbacks [11,25,26].…”

Section: Discussionmentioning

confidence: 99%

“…However, no certain conclusions have been reached regarding the biomechanics or risk factors at play in the relationship between ASD and lumbar fusion surgery [18][19][20][21]. Non-fusion dynamic methods of PS fixation were developed to eliminate the possible disadvantages of fusion achieved with PS fixation [22][23][24]. Although these approaches provided some advantages such as reducing surgical morbidity and cases of ASD, they also introduced some problems of screw loosening due to the dynamic structure [11,25,26].…”

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confidence: 99%

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Influence of posterior pedicle screw fixation at L4–L5 level on biomechanics of the lumbar spine with and without fusion: a finite element method

et al. 2021

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Background Posterior pedicle screw (PS) fixation, a common treatment method for widespread low-back pain problems, has many uncertain aspects including stress concentration levels, effects on adjacent segments, and relationships with physiological motions. A better understanding of how posterior PS fixation affects the biomechanics of the lumbar spine is needed. For this purpose, a finite element (FE) model of a lumbar spine with posterior PS fixation at the L4–L5 segment level was developed by partially removing facet joints (FJs) to imitate an actual surgical procedure. This FE study aimed to investigate the influence of the posterior PS fixation system on the biomechanics of the lumbar spine before and after fusion by determining which physiological motions have the most increase in posterior instrumentation (PI) stresses and FJ loading. Results It was determined that posterior PS fixation increased FJ loading by approximately 35% and 23% at the L3–L4 adjacent level with extension and lateral bending motion, respectively. This increase in FJ loading at the adjacent level could point to the possibility that adjacent segment disease has developed or progressed after posterior lumbar interbody fusion. Furthermore, analyses of peak von Mises stresses on PI showed that the maximum PI stresses of 272.1 MPa and 263.7 MPa occurred in lateral bending and flexion motion before fusion, respectively. Conclusions The effects of a posterior PS fixation system on the biomechanics of the lumbar spine before and after fusion were investigated for all physiological motions. This model could be used as a fundamental tool for further studies, providing a better understanding of the effects of posterior PS fixation by clearing up uncertain aspects.

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