Effect of an internal fixator and a bone graft on intersegmental spinal motion and intradiscal pressure in the adjacent regions

Rohlmann, A.; Neller, S.; Bergmann, G.; Graichen, F.; Claes, Lutz; Wilke, Hans–Joachim

doi:10.1007/s005860100295

Cited by 88 publications

(35 citation statements)

References 33 publications

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“…The intradiscal pressures calculated for pure moment loads were in good agreement with values previously measured in vitro [17,18]. For these nonphysiological loading situations, however, the intradiscal pressure was much lower than that measured in vivo [23,24], since no axial preload was applied in these studies.…”

Section: Discussionsupporting

confidence: 86%

“…The validity of the intact computer model has been previously demonstrated [17,18]. To validate the modified models for the different degrees of resection, the intersegmental angle between the L4 and L5 vertebral body was compared to that measured in vitro by Quint et al [16].…”

Section: Discussionmentioning

confidence: 99%

“…The highly non-linear computer model allows large deformations and is able to simulate contact behaviour at the facet joints. The intact model was validated on the basis of experimental data from in vitro measurements [17,18] and a high degree of conformity was found.…”

Section: Finite Element Modelmentioning

confidence: 99%

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Influence of graded facetectomy and laminectomy on spinal biomechanics

Zander

Rohlmann

Klöckner

et al. 2003

European Spine Journal

Self Cite

143

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Facetectomy and laminectomy are techniques for decompressing lumbosacral spinal stenosis. Resections of posterior bony or ligamentous parts normally lead to a decrease in stability. The degree of instability depends on the extent of resection, the loading situation and the condition of the intervertebral discs. The correlation between these parameters is not well understood. In order to investigate how these parameters relate to one another, a three-dimensional, non-linear finite element model of the lumbosacral spine was created. Intersegmental rotations, intradiscal pressures, stresses, strains and forces in the facet joints were calculated while simulating an intact spine as well as different extents of resection (left and bilateral hemifacetectomy, hemilaminectomy and bilateral laminectomy, two-level laminectomy), disc conditions (intact and degenerated) and loading situations (pure moment loads, standing and forward bending). The results of the modelling showed that a unilateral hemifacetectomy increases intersegmental rotation for the loading situation of axial rotation. Expanding the resection to bilateral hemifacetectomy increases intersegmental rotation even more, while further resection up to a bilateral laminectomy has only a minor additional effect. Hemilaminectomy and laminectomy only differ in their effect for ventriflexion and muscle-supported forward bending. Two-level laminectomy increases the intersegmental rotation only for standing. Degenerated discs result in smaller intersegmental rotations and higher disc stresses at the respective levels. Decompression procedures affect the examined biomechanical parameters less markedly in degenerated than in intact discs. Resection of posterior bony or ligamentous elements has a stronger influence on the amount than on the distribution of stresses and deformations in a disc. It has only a minor effect on the biomechanical behaviour of the adjacent region. Spinal stability is decreased after a laminectomy for forward bending, and after a two-level laminectomy for standing. For axial rotation, spinal stability is decreased even after a hemifacetectomy. Patients should therefore avoid excessive axial rotation after such a treatment.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of graded facetectomy and laminectomy on spinal biomechanics

Zander

Rohlmann

Klöckner

et al. 2003

European Spine Journal

Self Cite

143

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“…Therefore, the results for the adjacent segments show only trends, and the absolute values should be handled with caution. A predetermined load instead of a predetermined deformation would probably have shown that the implant had only a minor influence on the adjacent segments [9]. In a patient, spinal deformation is often predetermined by the aimed activity.…”

Section: Discussionmentioning

confidence: 99%

“…The capsule of the facet joints and the six ligaments of the lumbar spine were (Tables 1 and 2) were taken from the literature [4,5,13]. The intact model was validated on the basis of experimental data from in vitro measurements [9,10], and a high degree of conformity was found. It is described in detail elsewhere [19,21].…”

Section: Methodsmentioning

confidence: 99%

Comparison of the biomechanical effects of posterior and anterior spine-stabilizing implants

2005

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Review of postcontrast MRI studies on diffusion of human lumbar discs

Rajasekaran

Naresh‐Babu

Murugan³

2007

Magnetic Resonance Imaging

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Diffusion is the only source of nutrition to the intervertebral discs, and alteration of diffusion is considered to be the final common pathway for disc degeneration. Yet diffusion remains poorly understood due to the paucity of reliable methods to study diffusion noninvasively in humans in vivo. In recent years, postcontrast MRI has emerged as a powerful and reliable tool for analyzing diffusion in lumbar discs. Since it is noninvasive and safe, it can be used to document the process of diffusion temporally over a period of 24 hours. Well-designed studies have shown that diffusion is a very slow process, and that the endplate is the main structure that controls the process of diffusion. Contrast MRI studies have also made it possible to identify endplate breaks in vivo. In the future this technique may be applied to study the influence of smoking, mechanical loading of the discs, abnormal posture, and atherosclerosis of the lumbar arteries on diffusion. These conditions have all been implicated in disc degeneration through a final common pathway of altered diffusion and decreased nutrition. This review article focuses on the current knowledge, methodology, various factors that influence the diffusion properties of the discs, and future applications of this promising technique.

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Effect of an internal fixator and a bone graft on intersegmental spinal motion and intradiscal pressure in the adjacent regions

Cited by 88 publications

References 33 publications

Influence of graded facetectomy and laminectomy on spinal biomechanics

Influence of graded facetectomy and laminectomy on spinal biomechanics

Comparison of the biomechanical effects of posterior and anterior spine-stabilizing implants

Review of postcontrast MRI studies on diffusion of human lumbar discs

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