Extent of nucleus pulposus migration in the annulus of porcine intervertebral discs exposed to cyclic flexion only versus cyclic flexion and extension

Balkovec, Christian; McGill, Stuart M.

doi:10.1016/j.clinbiomech.2012.05.006

Cited by 15 publications

(11 citation statements)

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“…Compressive strain on the anterior side of the discs (Figure , cycles 10 005 and 20 000) in the most neutral position image relative to cycle 5 is indicative of wedging of the discs, implying that the anatomical neutral position of the motion segment changes as the number of cycles increases . This modified anatomical neutral state deforms the nucleus pulposus posteriorly relative to the first cycle of loading, and is consistent with existing literature reports that showed similar deformation at 10 000 or fewer cycles . This deformation alters the center of rotation between the adjacent two vertebrae and also increases lumbar disc herniation risk, and may explain the observed changes in intervertebral kinematics (Figure ).…”

Section: Discussionsupporting

confidence: 84%

“…22,23 This modified anatomical neutral state deforms 24 the nucleus pulposus posteriorly relative to the first cycle of loading, and is consistent with existing literature reports that showed similar deformation at 10 000 or fewer cycles. 25,26 This deformation alters the center of rotation between the adjacent two vertebrae and also increases lumbar disc herniation risk, and may Intervertebral Angles FIGURE 5 Intervertebral angles for a representative cervine specimen. Note the change in inflection of the later cycles compared to the earlier cycles explain the observed changes in intervertebral kinematics ( Figure 5).…”

Section: Resultsmentioning

confidence: 99%

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Increased lumbar spinal column laxity due to low‐angle, low‐load cyclic flexion may predispose to acute injury

et al. 2018

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Lumbar spinal column laxity contributes to instability, increasing the risk of low back injury and pain. Until the laxity increase due to the cyclic loads of daily living can be quantified, the associated injury risk cannot be predicted clinically. This work cyclically loaded 5‐vertebra lumbar motion segments (7 skeletally‐mature cervine specimens, 5 osteoporotic human cadaver specimens) for 20 000 cycles of low‐load low‐angle (15°) flexion. The normalized neutral zone lengths and slopes of the load‐displacement hysteresis loops showed a similar increase in spinal column laxity across species. The intervertebral kinematics also changes with cyclic loading. Differences in the location and magnitude of surface strain on the vertebral bodies (0.34% ± 0.11% in the cervine specimens, and 3.13% ± 1.69% in the human cadaver specimens) are consistent with expected fracture modes in these populations. Together, these results provide biomechanical evidence of spinal column damage during high‐cycle low‐load low‐angle loading.

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Section: Discussionsupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Increased lumbar spinal column laxity due to low‐angle, low‐load cyclic flexion may predispose to acute injury

et al. 2018

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“… 12 14 15 The results agree with findings from Tanaka and colleagues, 13 who found evidence of cartilaginous end plate separation in degenerated cadaveric specimens. Intervertebral disk herniation can occur under both acute 16 17 and repetitive 18 19 20 21 flexion and extension motions with varying degrees of compressive load. Unlike the annulus and nucleus tissues, the hyaline cartilage does not swell greatly in tissue fluid, even when physically disrupted.…”

Section: Discussionmentioning

confidence: 99%

Annulus Fibrosus Can Strip Hyaline Cartilage End Plate from Subchondral Bone: A Study of the Intervertebral Disk in Tension

Balkovec

Adams

Dolan

et al. 2015

Global Spine Journal

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Study Design Biomechanical study on cadaveric spines. Objective Spinal bending causes the annulus to pull vertically (axially) on the end plate, but failure mechanisms in response to this type of loading are poorly understood. Therefore, the objective of this study was to identify the weak point of the intervertebral disk in tension. Methods Cadaveric motion segments (aged 79 to 88 years) were dissected to create midsagittal blocks of tissue, with ∼10 mm of bone superior and inferior to the disk. From these blocks, 14 bone–disk–bone slices (average 4.8 mm thick) were cut in the frontal plane. Each slice was gripped by its bony ends and stretched to failure at 1 mm/s. Mode of failure was recorded using a digital camera. Results Of the 14 slices, 10 failed by the hyaline cartilage being peeled off the subchondral bone, with the failure starting opposite the lateral annulus and proceeding medially. Two slices failed by rupturing of the trabecular bone, and a further two failed in the annulus. Conclusions The hyaline cartilage–bone junction is the disk's weak link in tension. These findings provide a plausible mechanism for the appearance of bone and cartilage fragments in herniated material. Stripping cartilage from the bony end plate would result in the herniated mass containing relatively stiff cartilage that does not easily resorb.

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“…[8][9][10][11][12][13][14][15][16][17] The inelastic behaviour that assures a more even distribution of local stresses is a fundamental characteristic of the healthy IVD provided by its two main subcomponents, that is, inner nucleus pulposus (NP) and outer annulus fibrosus (AF). The respective role of NP and AF during motion of the functional spine unit (FSU) has to be understood through their interactions and their specificities, for example, NP migration [18][19][20][21] and AF micro-structure. 16,22,23 Cyclically loaded FSUs exhibit a hysteretic response manifested by a difference between loading and unloading paths.…”

Section: Introductionmentioning

confidence: 99%

Osmo-inelastic response of the intervertebral disc

Derrouiche

Zaouali

Zaïri

et al. 2019

Proc Inst Mech Eng H

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The intervertebral disc exhibits a complex inelastic response characterized by relaxation, hysteresis during cyclic loading and rate dependency. All these inelastic phenomena depend on osmotic interactions between disc tissues and their surrounding chemical environment. Coupling between osmotic and inelastic effects is not fully understood, so this article aimed to study the influence of chemical conditions on the inelastic behaviour of the intervertebral disc in response to different modes of loading. A total of 18 non-frozen 'motion segments' (two vertebrae and the intervening soft tissues) were dissected from the cervical spines of mature sheep. The motion segments were loaded in tension, compression and torsion at various loading rates and saline concentrations. Analysis of variance showed that saline concentration significantly influenced inelastic effects in tension and especially in compression (p \ 0.05), but not in torsion. Opposite effects were seen in tension and compression. An interpretation of the underlying osmo-inelastic mechanisms is proposed in which two sources of inelastic effects are identified, that is, extracellular matrix rearrangements and fluid exchange created by osmosis.

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Extent of nucleus pulposus migration in the annulus of porcine intervertebral discs exposed to cyclic flexion only versus cyclic flexion and extension

Cited by 15 publications

References 11 publications

Increased lumbar spinal column laxity due to low‐angle, low‐load cyclic flexion may predispose to acute injury

Increased lumbar spinal column laxity due to low‐angle, low‐load cyclic flexion may predispose to acute injury

Annulus Fibrosus Can Strip Hyaline Cartilage End Plate from Subchondral Bone: A Study of the Intervertebral Disk in Tension

Osmo-inelastic response of the intervertebral disc

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