Effect Of Disc Degeneration Research Articles

Effect of disc degeneration on the mechanical behavior of the human lumbar spine: a probabilistic finite element study

BACKGROUND CONTEXTIntervertebral disc degeneration has been subject to numerous in vivo and in vitro investigations and numerical studies during recent decades, reporting partially contradictory findings. However, most of the previous studies were limited in the number of specimens investigated and, therefore, could not consider the vast variety of the specimen geometries, which are likely to strongly influence the mechanical behavior of the spine. PURPOSETo complement the understanding of the mechanical consequences of disc degeneration, whereas considering natural variations in the major spinal geometrical parameters. DESIGN/SETTINGA probabilistic finite element study. METHODSA parametric finite element model of a human L4–L5 motion segment considering 40 geometrical parameters was developed. One thousand individual geometries comprising four degeneration grades were generated in a probabilistic manner, and the influence of the severity of disc degeneration on the mechanical response of the motion segment to different loading conditions was statistically evaluated. RESULTSVariations in the individual structural parameters resulted in marked variations in all evaluated parameters within each degeneration grade. Nevertheless, the effect of degeneration in almost all evaluated response values was statistically significant. With degeneration, the intradiscal pressure progressively decreased. At the same time, the facet loads increased and the ligament tension was reduced. The initially nonlinear load-deformation relationships became linear whereas the segment stiffness increased. CONCLUSIONSResults indicate significant stiffening of the motion segment with progressing degeneration and gradually increasing loading of the facets from nondegenerated to moderately degenerated conditions along with a significant reduction of the ligament tension in flexion.

Radiologic Analysis of Kinematic Characteristics of Modic Changes Based on Lumbar Disc Degeneration Grade.

The kinematic characteristics of Modic changes (MCs) in the lumbar spine have rarely been reported; furthermore, the effect of disc degeneration (DD) on segmental motion has not been considered in analyzing the motion characteristics of MCs. Therefore, this study was designed to evaluate the kinematic characteristics of MCs based on different DD grades. 894 patients with 4470 lumbar segments were reviewed, and those with MCs were selected for segmental motion evaluation. MC type was defined as 0, I, II, and III, and DD grade was classified into 5 groups from grade A to grade E. Segmental angular and translational motion were calculated from X-ray images in positions of flexion and extension, and the absolute values of the differences were recorded. MCs were observed in 308 segments from 260 patients. No MC was found in DD grade A, and MC III was not observed in DD grade B. MC I was found to significantly increase angular motion in the DD grade E group, and MC II could enlarge translational motion in the DD grade D group (all P < 0.05); MC III had the lowest segmental motion in both angular and translational motion; There was no statistical difference in angular and translational motion between MC I and II in all DD grade groups (all P > 0.05). MC III indicates the final stable phase of segmental motion. MC I might increase angular motion, and MC II would increase certain translational motions in the segments that were believed to be stable.

The effect of disc degeneration on anterior shear translation in the lumbar spine: Still more problems lie ahead

Letter to Dr. Linda Sandell: Low back pain is the single most common cause for disability in individuals aged 45 years or younger and as a result carries tremendous weight in socioeconomic considerations. Undoubtedly, numerous factors are contributed to low back pain; mechanical causes of low back pain include degenerative spinal pathologies such as spondylolisthesis, disc herniation, discogenic pain, and so on. Although the study by Melnyk et al.1 has dramatically improved our knowledge about the effect of disc degeneration on anterior translation of the lumbar spine under shear loading, we do not completely agree with the conclusion indicating that disc degeneration, as classified with the Pfirrmann scale, does not predict lumbar spinal motion in shear. First, recent biomechanical studies have revealed distinct behavior at the different lumbar levels2; and the study of lumbar intervertebral disc morphology using MR images has shown segment-dependent geometric features.3 Moreover, different clinical outcomes following surgical treatment at the different lumbar levels have been reported.4 Various factors could influence segment-dependent function of the lumbar spine, such as the surrounding ligaments and muscles, vertebral geometries, the orientation of facet joints, and so on. Notably, the segment-dependent discrepancy may be an inherent factor on the effect of disc degeneration on anterior translation of the lumbar spine under shear loading, which specifically compared at different segment levels are necessary. Further, lumbar disc degeneration is found most often at the L5-S1 level.5 We believe that the study by Melnyk et al.1 has some important limitations. For example, the study only investigated the L3-4 and L4-5 levels that they did not take the other lumbar levels into account, especially the L5-S1 level. Finally, the in-vitro study applied shear loading conditions could be quite different from in-vivo shear loading conditions, which the surrounding ligaments and muscles are not considered. In addition, the in-vivo studies have reported that different abnormal vertebral motions are closely associated with different lumbar disc degenerations graded by Pfirrmann's criteria.6 The conclusion of Melnyk et al.1 may mislead the surgeons on the operative treatment options of lumbar disc degeneration. In the end, we unanimously applaud Melnyk et al. for their significant work and the diligence with which they handled this controversial topic. Currently, it is still more problems waiting to be solved. Therefore, substantial work to determine the effect of disc degeneration on anterior translation of the lumbar spine under shear loading is essential in the near future. YS made substantial contributions to manuscript drafting and approval. DP made substantial contributions to revising the manuscript critically for important intellectual content and approval. ZD made substantial contributions to manuscript revision and approval. WZ made substantial contributions to Conception and design of the manuscript; manuscript revision and approval for the final version submitted. Yi Shen, Dan Peng, Zhihui Dai, Weiye Zhong Department of Orthopaedic Surgery Second Xiangya Hospital and Central South University 139 Middle Renmin Road, Changsha, Hunan 410011, P.R. China

Effect of disc degeneration on lumbar segmental mobility analyzed by kinetic magnetic resonance imaging.

Retrospective radiographical study. To define the relationship between the grade of disc degeneration and the motion of the lumbar spine by using kinetic magnetic resonance imaging. Disc degeneration is common after middle age. Lumbar instability has generally been recognized as a potential risk factor of low back pain. However, correlations between the grade of disc degeneration and the motion of the lumbar spine need more investigation. Kinetic magnetic resonance imaging was performed in 162 patients with symptomatic low back pain without prior history of surgery. The lumbar intervertebral discs were graded by spine surgeons according to the degenerative grading system (grades I-V). Translational motion and angular variation were measured at each segment from L1-L2 through L5-S1. The relationship between the degree of lumbar disc degeneration and extent of lumbar spine mobility was analyzed. The translational motion in discs with grade I through IV increased gradually, but decreased with grade V. Compared with other less degenerative grades, grade V discs had significantly decreased total intervertebral translational motion (P < 0.05). The angular variation in discs with grade I through IV was fairly constant, but decreased with grade V. Compared with other degenerative grades (I-IV), grade V discs had significantly decreased total intervertebral translational motion (P < 0.05). For less degenerative grades I and II discs, the L2-L3 and L3-L4 segmental units contributed the majority of total angular mobility of the spine. However, for the severely degenerated segments, grade V discs, the contributions of the L2-L3 and L3-L4 significantly decreased (P < 0.01). As disc degeneration developed from the normal to an increasingly severe stage, the motion of lumbar spine progressed from the normal stage to an unstable phase with higher mobility and finally to an ankylosed stage where stability was increased. 3.

Effect of disc degeneration on the muscle recruitment pattern in upright posture: a computational analysis

Based on the sensor driving control mechanism model, the effect of disc degeneration on the trunk muscle recruitment (TMR) pattern was analysed in erect standing posture. A previously developed computational model was used for this analysis, with modifications incorporating the T12-L1 motion segment and additional muscle fascicles. To generate disc degeneration at three different levels (L3–L4, L4–L5, or L5–S1), the material properties of the ground matrix of the annulus and bulk modulus of the nucleus were reduced. The finite element method combined with an optimization technique was applied to calculate the muscle forces. Minimization of deviations in the averaged tensile stress in the annulus fibres at the outermost layer in the five discs was selected for muscle force calculations. The results indicated that the disc degeneration noticeably increased the activation of the superficial muscle (IT and R) even though there was no clear change in the longissimus thoracis. Unlike some of the superficial muscles, activation in the deep muscles (multifidus (ML, MS, MT), LL and Q) was decreased. The change in TMR pattern generated an intervertebral disc angle difference and nucleus pressure increased in the upper level. These differences are expected to be functional in that they reduce the stress at the degenerated disc by changing the muscle activation, which slows down the progress of disc degeneration.

Defining the Biomechanical Parameters of Kinematics of Lumbar Spine and Effect of Disc Degeneration: A Biomechanical Study of Cadaver Lumbar Spine

Defining the Biomechanical Parameters of Kinematics of Lumbar Spine and Effect of Disc Degeneration: A Biomechanical Study of Cadaver Lumbar Spine

Defining the Biomechanical Parameters of Kinematics of Lumbar Spine and Effect of Disc Degeneration: A Biomechanical Study on Cadaver Lumbar Spine

Defining the Biomechanical Parameters of Kinematics of Lumbar Spine and Effect of Disc Degeneration: A Biomechanical Study on Cadaver Lumbar Spine

Behavioral Signs of Chronic Back Pain in the SPARC-Null Mouse

Secreted Protein, Acidic, and Rich in Cysteine (SPARC)-null mice were examined for behavioral signs of chronic low back and/or radicular pain. to assess SPARC-null mice as an animal model of chronic low back and/or radicular pain caused by degenerative disc disease. degeneration of intervertebral discs is a major cause of chronic low back and adicular pain in humans. Inactivation of the SPARC gene in mice results in premature intervertebral disc degeneration. The effect of disc degeneration on behavioral measures of chronic pain has not been evaluated in this model. cohorts of young and old (3 and 6-12 months, respectively) SPARC-null and wild-type control mice were screened for behavioral indices of low back and/or radiating pain. Sensitivity to mechanical, cold and heat stimuli, locomotor impairment, and movement-evoked hypersensitivity were determined. Animals were challenged with 3 analgesic agents with different mechanisms: morphine, dexamethasone, and gabapentin. SPARC-null mice showed signs of movement-evoked discomfort as early as 3 months of age. Hypersensitivity to cold stimuli on both the lower back and hindpaws developed with increasing age. SPARC-null mice had normal sensitivity to tactile and heat stimuli, and locomotor skills were not impaired. The hypersensitivity to cold was reversed by morphine, but not by dexamethasone or gabapentin. SPARC-null mice display behavioral signs consistent with chronic low back and radicular pain that we attribute to intervertebral disc degeneration. We hypothesize that the SPARC-null mouse is useful as a model of chronic back pain due to degenerative disc disease.

P120. The Effect of Disc Degeneration on the Morphologic Changes of Intervertebral Discs in the Cervical Spine using Kinetic MRI

BACKGROUND CONTEXT: The degenerative change of intervertebral discs occurs as an age-related physiological process and it is affected by a decrease in proteoglycan and water concentration. Disc degeneration induces morphologic changes (disc height and disc endplate contour) of intervertebral discs. MRI is the most effective method for evaluating these changes. Thus far, no quantitative in vivo MRI data has been available regarding disc morphologic changes following cervical disc degeneration.

P172. The Effect of Disc Degeneration on the Adjacent Motion Segments of the Lumbar Spine: A Kinetic MRI Study

P172. The Effect of Disc Degeneration on the Adjacent Motion Segments of the Lumbar Spine: A Kinetic MRI Study

70. The Relationship Between Disc Degeneration and the Lumbar Segmental Axial Motion in Asymptomatic and Chronic Low Back Pain Subjects

BACKGROUND CONTEXT: Degenerative disc disease is believed to be one of the major causes of low back pain and maybe associated with segmental instability of the spine particularly in axial rotation. Our laboratory has developed a 3D, non-invasive, in vivo method for measuring segmental motion of the lumbar spine due to a passive external rotation. The current study explores the hypothesis that rotational hypermobility is greater in patients with Grade III or IV disc degeneration than in normal (Grade I or II) and advanced degeneration (Grade V) discs and it can be measured using the clinically available diagnostic equipment. PURPOSE: To investigate the effect of disc degeneration on lumbar segmental axial motion in asymptomatic (Healthy) and chronic low back pain (LBP) subjects using a validated in vivo 3-D segmental motion measurement technique. STUDY DESIGN/ SETTING: In vivo measurement of lumbar segmental axial motion in asymptomatic and chronic low back pain subjects. PATIENT SAMPLE: One hundred volunteers (63 Healthy: 35.069.8 yrs and 37 LBP: 39.969.8 yrs) were used for this study (IRB approved). OUTCOME MEASURES: Correlation between disc degeneration and lumbar axial segmental motion in asymptomatic and LBP subjects. METHODS: Each subject underwent CT scanning at neutral and rotated positions and segmental motions were calculated using custom volumemerging software. MRI was used to determine disc degeneration from Grade I (normal) to Grade V (advanced). Unpaired t-tests were used for comparison between Healthy and LBP subjects. One-way analysis of variance with Fisher’s post-hoc test was used to determine differences between spinal levels and age. RESULTS: Disc degeneration grades increased with age (p!0.0001). Male subjects have higher grades in 20s (p!0.0007), 30s (p!0.04) and 40s (p50.79) than those in female subjects, but there was no difference in 50s (p5 0.92). Disc degeneration grades in LBP subjects were higher than those in Healthy subjects (p!0.0001). Overall, disc degeneration grades at L5/S1 and L4/L5 were higher than those at higher levels (p!0.004 and p!0.02, respectively). In LBP subjects, axial rotation at L3/L4 and L4/L5 were higher (p!0.04 and p!0.02, respectively) but that at L5/S1 was lower in LBP subjects compared with Healthy subjects. In LBP subjects, axial rotation in the discs with Grade IV was higher than that with Grade III (p!0.04) and axial rotation in the discs with Grade V was lower than that with Grade IV (p!0.007). These differences were not shown in Healthy subjects. CONCLUSIONS: The present in vivo study has demonstrated that there is greater degree of disc degeneration at L4-5 and L5-S1 in the LBP patients than healthy subjects, and rotational segmental movement was associated with disc degeneration (up to Grade IV but not Grade V) in LBP subjects at the L3-4 and L4-5 levels but not at L5-S1 level. This finding is consistent with previous published in vitro studies. These results indicate that increased segmental movement is one of the causes of discogenic LBP in the patients with Grade III and IV disc degeneration. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.

Effect of aging and degeneration on disc volume and shape: A quantitative study in asymptomatic volunteers

Debate continues on the effect of disc degeneration and aging on disc volume and shape. So far, no quantitative in vivo MRI data is available on the factors influencing disc volume and shape. The objective of this MRI study was to quantitatively investigate changes in disc height, volume, and shape as a result of aging and/or degeneration omitting pathologic (i.e., painful) disc alterations. Seventy asymptomatic volunteers (20-78 years) were investigated with sagittal T1- and T2-weighted MR-images encompassing the whole lumbar spine. Disc height was determined by the Dabbs method and the Farfan index. Disc volume was calculated by the Cavalieri method. For the disc shape the "disc convexity index" was calculated by the ratio of central disc height and mean anterior/posterior disc height. Disc height, disc volume, and the disc convexity index measurements were corrected for disc level and the individuals age, weight, height, and sex in a multilevel regression analysis. Multilevel regression analysis showed that disc volume was negatively influenced by disc degeneration (p < 0.001) and positively correlated with body height (p < 0.001) and age (p < 0.01). Mean disc height and the disc convexity index were negatively influenced by disc degeneration but not by gender, weight, and height. Disc height was positively correlated with age (p < 0.01). From the results of this study, it can be concluded that disc degeneration generally results in a decrease of disc height and volume as well as a less convex disc shape. In the absence of disc degeneration, however, age tends to result in an inverse relationship on disc height, volume, and shape.

The effect of disc degeneration on the structural property distributions in the cervical vertebral endplates

To study the effect of disc degeneration on the structural property distributions in the cervical vertebral endplates. A 2 mm-diameter hemispherical indenter was used to perform indentation tests at 0.03 mm/s to the depth of 2 mm at 20 normalized locations in 50 bony endplates of intact human cervical vertebrae (C2 approximately C7). The resulting load-displacement curves were used to extract the failure load and stiffness of each test site. Grade of disc degeneration was determined using Nachemson's grading scale. One-way ANOVA, factorial analyses, SNK tests and correlate analyses were used to analyze the result data. Both the failure load and stiffness decreased with disc degeneration in the cervical endplates (P <0.001, both), and correlated significantly with the disc degeneration (rs=-0.429 and rs=-0.244, respectively). Only the distribution of superior cervical endplate changed with disc degeneration, but that of inferior cervical endplate changed little. The structural property distributions in the cervical vertebral endplates change significantly in the degenerated discs. It suggests that disc degeneration is an important factor to evaluate the intervertebral implant subsidence in anterior cervical fusion.

The effect of disc degeneration and facet joint osteoarthritis on the segmental flexibility of the lumbar spine.

A biomechanical and imaging study of human cadaveric spinal motion segments. To investigate the effect of both disc degeneration and facet joint osteoarthritis on lumbar segmental motion. Spinal degeneration includes the osteoarthritic changes of the facet joint as well as disc degeneration. Disc degeneration has been reported to be associated with spinal motion. The association of facet joint osteoarthritis with lumbar segmental motion characteristics and the combined influence of disc degeneration and facet osteoarthritis has not yet been investigated. A total of 110 lumbar motion segments (52 female, 58 male) from 44 human lumbar spines were studied (mean age = 69 years). Magnetic resonance images were used to assess the disc degeneration from Grade I (normal) to Grade V (advanced) and the osteoarthritic changes in the facet joints in terms of cartilage degeneration, subchondral sclerosis, and osteophytes. Disc height, endplate size, and facet joint orientation and width also were measured from the computed tomographic images. Rotational movements of the motion segment in response to the flexion, extension, lateral bending, and axial rotational moments were measured using a three-dimensional motion analysis system. Female motion segments showed significantly greater motion (lateral bending: P < 0. 001, flexion: P < 0.01, extension: P < 0.05) and smaller endplate size (P < 0.001) than male ones. The segmental motion increased with increasing severity of disc degeneration up to Grade IV, but decreased in both genders when the disc degeneration advanced to Grade V. In male segments, the disc degeneration-related motion changes were significant in axial rotation (P < 0.001), lateral bending (P < 0.05), and flexion (P < 0.05), whereas female segments showed significant changes only in axial rotation (P < 0.001). With cartilage degeneration of the facet joints, the axial rotational motion increased, whereas the lateral bending and flexion motion decreased in female segments. In male segments, however, motion in all directions increased with Grade 3 cartilage degeneration and decreased with Grade 4 cartilage degeneration. Subchondral sclerosis significantly decreased the motion (female: axial rotation, P < 0. 05; extension, P < 0.05 vs.- male:flexion,P < 0.05). Severity of osteophytes had no significant association with the segmental motion. Axial rotational motion was most affected by disc degeneration, and the effects of disc degeneration on the motion were similar between genders. Facet joint osteoarthritis also affected segmental motion, and the influence differed for male and female spines. Further studies are needed to clarify whether the degenerative process of facet joint osteoarthritis differs between genders and how facet joint osteoarthritis affects the stability of the spinal motion segment.

Load-displacement properties of lower cervical spine motion segments

The load-displacement behavior of 35 fresh adult cervical spine motion segments was measured in compression, shear, flexion, extension, lateral bending and axial torsion tests. Motion segments were tested both intact and with posterior elements removed. Applied forces ranged to 73.6 N in compression and to 39 N in shear, while applied moments ranged to 2.16 Nm. For each mode of loading, principal and coupled motions were measured and stiffnesses were calculated. The effect of disc degeneration on motion segment stiffnesses and the moments required for motion segment failure were also measured. In compression, the stiffnesses of the cervical motion segments were similar to those of thoracic and lumbar motion segments. In other modes of loading, cervical stiffnesses were considerably smaller than thoracic or lumbar stiffnesses. Removal of the posterior elements decreased cervical motion segment stiffnesses by as much as 50%. Degenerated cervical discs were less stiff in compression and stiffer in shear than less degenerated discs, but in bending or axial torsion, no statistically significant differences were evident. Bending moments causing failure were an order of magnitude lower than those for lumbar segments.