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At least 775 records · Page 43Linked to original sources
PubMed1983

Relocation of the bending axis during flexion-extension of lumbar intervertebral discs and its implications for prolapse.

All the lumbar discs were dissected from three freshly killed, adult rabbits. Ligaments and facet joints were removed but each disc remained attached to bone. The discs were securely mounted in specially constructed bending apparatus. Ventral disc height and bending angle were measured simultaneously allowing the bending axis position to be calculated. Except for lumbosacral discs, the axis shifted ventrally during the transition from flexion to extension. The existence of separate flexion and extension axes has been reported for human lumbar discs; it is argued that similarity of disc structure leads to similar mechanical behaviour in rabbit and human discs. The positions of the two bending axes are such that flexion, but not extension, could damage the annulus fibrosus of the intervertebral disc.

Animals↗
PubMed1986

The relationship of degeneration of the intervertebral disc to mechanical loading conditions on lumbar vertebrae.

Degeneration of lumbar intervertebral discs is typical for the aging process and contributes to common low-back problems. It is likely to influence vertebrae by changing the mechanical interaction within each motion segment. This study focuses on the influence of disc degeneration on the mechanism of load transmission through the lumbar vertebral body. Effective stresses, ways of load transmission and failure modes of vertebral body were examined in cases of healthy and degenerated discs. The stress analysis was performed using the Finite Element Method. For healthy discs, the highest effective stresses were found in the center of bony end-plates. For degenerated discs, they were found in the lateral aspects of the end-plates, in the cortical wall, and also in the vertebral body rims. However, regardless of the disc condition, the highest effective stresses do not occupy the whole thickness of the endplate and/or the cortical wall, but are concentrated near the spongy core. Ways of load transmission through the lumbar vertebral body and modes of eventual damage to it are also strongly influenced by the disc condition.

Aging↗
PubMed1993

Multipoint determination of pressure-volume curves in human intervertebral discs.

To gain further insight into the biomechanics of the human intervertebral disc and to determine a potential mechanism for causation and relief of symptoms related to a herniated disc, the pressure-volume relation was determined within the nucleus pulposus. Pressure was measured continuously within the nucleus pulposus in 17 intact lumbar discs from human cadavers by means of a miniature strain gauge at the tip of a size 4 French (1.3 mm) catheter inserted into the nucleus pulposus. The volume of the nucleus pulposus was increased at the slow, continuous rate of 0.034 ml/min by the pump regulated infusion of saline coloured with methylene blue. In 12 unloaded discs, nucleus pulposus pressure rose in a linear fashion (linear r = 0.96) from an initial mean pressure of 174 (SD 81) kPa. The mean rate of pressure rise was 327 (SD 109) kPa/ml volume increase. The peak pressure measured was 550 kPa; this was slightly higher than the capability of the transducer. Similar linear relations were obtained during infusion of saline into five vertically loaded discs fixed at the deformation produced by a 9.1 kg weight. The data define the pressure-volume relation within the disc and show that the nucleus pulposus, surrounded by the relatively inelastic annulus and the solid vertebral end plates, has the properties of a tight hydraulic space in which a large pressure rise will regularly result from a small increase in volume. Presumably the opposite is also true. The data may provide a biomechanical basis for the physiological variation in symptoms related to the disc, and for any benefits obtained from interventions designed to remove disc tissue.

Biomechanical Phenomena↗
PubMed2004

Changes in nuclear composition following cyclic compression of the intervertebral disc in an in vivo rat-tail model.

While in vitro studies have shown that mechanical loading can result in changes in the composition of intervertebral disc matrix, the effects of cyclic loading in vivo have not been considered. The objective of this study was to assess the effect of static and cyclic compression of different frequencies on the nuclear composition of the intervertebral disc. Thirty-six Sprague-Dawley rats were randomly divided into a control group (no pin insertion, no loading), a sham group (pins inserted in sixth and seventh caudal vertebrae, no loading), a static loading group (compression applied via pins) and cyclic loading groups (loading at 0.5, 1.5 or 2.5 Hz). Loading was applied for 1 h each day from the third to 17th day following pin insertion, and the caudal 5-6, 6-7 and 7-8 discs harvested to quantify proteoglycan content, collagen content and chondrocyte density in the nucleus pulposus. Static compression resulted in a significant reduction in total proteoglycan content as compared with the adjacent control disc, but this effect was not seen in any of the cyclic loading groups. However, comparison with the sham group appears to indicate an overall decrease in total proteoglycan content at the targeted and adjacent levels following cyclic loading. The 0.5 Hz loading group showed a significantly greater total proteoglycan content than all other compression groups, and also showed a lower total collagen content than the sham group. Results suggest that frequency dependent changes in composition occur in response to cyclic loading, but are not limited to the directly loaded disc alone. Further studies are required to verify this, but the choice of control appears to need careful consideration in all studies of this nature.

Animals↗
PubMed1984

Surgery of the lumbar intervertebral disc. Results of a personal minimal technique.

Surgery of the intervertebral disc, despite its relative simplicity, has a high failure rate at the functional level. There is often severe residual pain which is a real problem because it is so difficult to treat either the symptom or its cause. We report the results of 122 procedures in 100 patients, some of whom had multiple lesions, using a technique (already described in a preliminary paper) consisting of an interlaminar approach modified to provide greater preservations of neural, bony and joint structures. The results were very good, both soon after operation and at later follow-up (between six months and five years). There were no cases of recurrence or pseudo-recurrence, one case of contralateral recurrence (cured by further operation) and a very low incidence of residual backache. These results confirm that, provided the patients have been well selected so that not every patient with lumbar backache is operated on but only those with proven disc lesions, operation does fundamentally influence the quality of the results.

Humans↗
PubMed1996

Radiological prevalence of lumbar intervertebral disc calcification in the elderly: an autopsy study.

OBJECTIVE: The objective of this study was to investigate the in vitro radiological prevalence of lumbar intervertebral disc calcification (IDC) in the elderly and its relation to osteoarthritis (OA). MATERIALS AND METHODS: Lumbar spine segments comprising L2-4 were resected from 60 cadavers (30 males, 30 females; average age 67 years) and investigated with high-contrast radiography and computed tomography (CT). RESULTS AND CONCLUSIONS: IDC was found in 58.3% of the patients using high-contrast radiography and in 46.7% of the patients using CT. IDC prevalence and OA grades in the lumbar spine and right hand were found to increase with age. IDC prevalence and OA grades for L2-3 were not significantly different from those for L3-4. No significant sex difference was found for IDC prevalence and OA grades. The results indicate that IDC is significantly underestimated in vivo by conventional radiography and the intervertebral disc calcification may be a common phenomenon in aging. The exact relation IDC to OA remains undetermined.

Adult↗
PubMedDate not supplied

Molecular therapy of the intervertebral disc.

BACKGROUND CONTEXT: Currently, no biologic treatment is available for disc degeneration. However, many different molecules of potential therapeutic benefit are being investigated. PURPOSE: Review and categorize the molecules under investigation for potential therapy in preventing or reversing disc degeneration. STUDY DESIGN: Review article. METHODS: Review of published articles on molecules that may be useful in biologic therapy of the intervertebral disc. RESULTS: The list of molecules under investigation for potential benefit in biologic therapy of the intervertebral disc repair continues to grow. These molecules are so diverse that they no longer all fall into the classic terminology of "growth factor." Some of these molecules are not growth factors at all and some are not even cytokines. At least four different classes of molecules may be effective in disc repair. These include anticatabolics (eg, tissue inhibitors of metalloproteinase [TIMPs]), mitogens (eg, insulin-like growth factor-1 [IGF-1], platelet-derived growth factor [PDGF]), chondrogenic morphogens (transforming growth factor beta [TGF-beta] and bone morphogenetic proteins [BMPs]), and intracellular regulators (LIM mineralization protein-1 [LMP-1] and Sox9). Although some in vitro data are available on all of these molecules, few of these molecules have been tested in vivo with an animal model of disc degeneration. CONCLUSIONS: As the current screening experiments are concluded, more definitive in vivo systems involving a more realistic degeneration model will be a necessary step before attempting human studies.

Biological Products↗
PubMed2005

Matrix-assisted cell transfer for intervertebral disc cell therapy.

Cell therapy seems to be a promising way to reconstitute degenerated discs. We elucidate the basic aspects of intervertebral disc (IVD) cell therapy to estimate its potential in disc regeneration. Cell transfer efficiency and survival was quantified by luciferase expression after injection of recombinant cells into healthy, nucleotomized or mechanically degenerated rabbit IVDs in vitro, in situ or in vivo. A two-component fibrin matrix was adapted to allow injection of a fluid cell suspension that quickly polymerizes in IVDs. Thirty-five to fifty percent of matrix injected cells remained in the nucleus and transition zone in contrast to a rapid loss of medium-injected cells. Nucleotomy, which reduces intradiscal pressure, was crucial to the survival of the transferred cells over 3 days and nutritional enrichment of the fibrin matrix with potent biomolecules from serum significantly enhanced cell viability. In conclusion, advanced matrix substitutes are needed for efficient transfer and improved cell survival in the low-nutrient intradiscal environment to further improve disc cell therapy.

Animals↗
PubMed2003

The micromechanical environment of intervertebral disc cells determined by a finite deformation, anisotropic, and biphasic finite element model.

Cellular response to mechanical loading varies between the anatomic zones of the intervertebral disc. This difference may be related to differences in the structure and mechanics of both cells and extracellular matrix, which are expected to cause differences in the physical stimuli (such as pressure, stress, and strain) in the cellular micromechanical environment. In this study, a finite element model was developed that was capable of describing the cell micromechanical environment in the intervertebral disc. The model was capable of describing a number of important mechanical phenomena: flow-dependent viscoelasticity using the biphasic theory for soft tissues; finite deformation effects using a hyperelastic constitutive law for the solid phase; and material anisotropy by including a fiber-reinforced continuum law in the hyperelastic strain energy function. To construct accurate finite element meshes, the in situ geometry of IVD cells were measured experimentally using laser scanning confocal microscopy and three-dimensional reconstruction techniques. The model predicted that the cellular micromechanical environment varies dramatically between the anatomic zones, with larger cellular strains predicted in the anisotropic anulus fibrosus and transition zone compared to the isotropic nucleus pulposus. These results suggest that deformation related stimuli may dominate for anulus fibrosus and transition zone cells, while hydrostatic pressurization may dominate in the nucleus pulposus. Furthermore, the model predicted that micromechanical environment is strongly influenced by cell geometry, suggesting that the geometry of IVD cells in situ may be an adaptation to reduce cellular strains during tissue loading.

Animals↗
PubMed2006

[Adenovirus-mediated human bone morphogenetic protein 2 gene transferred to rabbit intervertebral disc cells in vitro].

OBJECTIVE: To study the adenovirus-mediated human bone morphogenetic protein-2 gene (Ad-hBMP-2)transferred to the intervertebral disc cells of the New Zealand rabbit in vitro. METHODS: The cells of New Zealand white rabbits were isolated from their lumbar discs. The cells were grown in the monolayer and treated with an adenovirus encoding the LacZ gene (Ad-LacZ) and Ad-hBMP-2 (50, 100, 150 MOI, multiplicity of infection) in the Dulbecco's Modified Eagle Medium and the Ham's F-12 Medium in vitro. Three days after the Ad-hBMP-2 treatment, the expression of hBMP-2 in the cells that had been infected by different doses of MCI was determined by immunofluorescence and the Western blot analysis, and the expression was determined in the cells with the Ad-LacZ treatment in a dose of 150 MDI. Six days after the Ad-hBMP-2 treatment, mRNA was extracted fur the reverse transcription polymerase chain reaction (RT-PCR) and the difference was detected between the control group and the culture group that was treated with Ad-hBMP-2 in doses of 50, 100 and 150 MCI so that the expressions of aggrecan and collagen II mRNA could be observed. RESULTS: The expression of hBMP-2 in the cells was gradually increased after the transfection in an increasing dose, which was observed by immunofluorescence and the Western blot analysis. At 6 days the aggrecan and collagen type II mRNA expressions were up-regulated by Ad-hBMP-2 after the transfection at an increasing viral concentration in the dose-dependent manner. CONCLUSION: The results show that Ad-hBMP-2 can transfect the rabbit intervertebral disc cells in vitro with a high efficiency rate and the expression of hBMP-2 after the infection is dose-dependent in the manner. Ad-hBMP-2 after transfection can up-regulate the expression of aggrecan and collagen IL mRNA at an increasing viral concentration.

Adenoviridae↗
PubMed2007

Anti-catabolic effect of OP-1 in chronically compressed intervertebral discs.

Experimental animal models of disc degeneration have been used to assess the biomechanical behavior, biochemical composition, and biological changes in the intervertebral discs. The objective of our study was to evaluate the anabolic and anti-catabolic effects of intradiscal injection of Osteogenic Protein-1 (OP-1) by histology and immunohistochemistry in disc degeneration model. Thirty-four rats were divided into five groups: intact control; sham control; compressed nucleus pulposus (NP) injected with saline; and two OP-1 groups: COP-1 group (compression was continued after intradiscal OP-1 injection) and ROP-1 group (compression was released at the time of OP-1 injection). Anabolic and anti-catabolic effects of OP-1 were evaluated by histology and immunohistochemistry with the following antibodies: anti-pro- and anti-mature OP-1, anti-MMP-13, anti-aggrecanase, anti-substance P, anti-tumor necrosis factor-alpha (TNF-alpha), and anti-interleukin-1beta (IL-1beta). The OP-1 injection to the degenerative disc stimulated an anabolic response characterized by the restoration of the normal morphology of the disc, increased Safranin O staining in the NP, extention of the extracellular matrix, and stimulation of endogenous OP-1 synthesis in the NP, annulus fibrosis (AF), and end-plate. The anti-catabolic effect of OP-1 was documented by reduced immunostaining for aggrecanase, MMP-13, substance P, TNF-alpha, and IL-1beta. This study confirmed the anti-catabolic activity of OP-1 as demonstrated previously in human articular cartilage and provided critical evidence for the potential of OP-1 therapy in the treatment of disc degeneration. Because substance P is a neuropeptide linked with inflammation and pain, a reduction in the level of this protein may support our previously reported results on the effect of OP-1 on pain-related behavior.

Animals↗
PubMed2005

The elastic fiber network of the anulus fibrosus of the normal and scoliotic human intervertebral disc.

STUDY DESIGN: Immunohistochemical study of elastic fibers in human intervertebral discs (IVD) collected at surgery from patients with scoliosis. OBJECTIVES: To compare the elastic fiber network in scoliotic discs (idiopathic scoliosis or neuromuscular scoliosis) to that of control (normal) discs. To study whether the change in elastic fiber organization could contribute to the progression of spinal deformity. SUMMARY OF BACKGROUND DATA: Elastin and elastic fibers have been identified previously in human IVD but were believed to contribute little to the tissue's mechanical properties. However, a recent immunohistochemical study has revealed an abundant and organized elastic fiber network in bovine IVD, indicating that elastic fibers could play an important mechanical role. This article reports the organization of elastic fibers in human IVD and the changes of elastic fiber organization in scoliosis. METHODS: Intact wedges of IVD were obtained from patients undergoing surgery for scoliosis (aged 12-22 years). Control discs were obtained from a patient (aged 12 years) with a spinal tumor and a trauma patient (aged 17 years). The discs were dissected to give radial slices and were snap frozen. Frozen sections were cut and digested with hyaluronidase to remove glycosaminoglycans. Micrographs of the sections were examined by polarized light to visualize collagen organization. The elastic fiber network was visualized immunohistochemically or by histochemical staining with orcein. RESULTS: A highly organized elastic fiber network, similar to that described in bovine discs, was revealed in the control human discs. In the anulus fibrosus of control discs, dense elastic fibers were located between adjacent lamellae, with fibers also present within individual lamellae. Elastic fibers appeared to be long (>200 microm) and straight in outer anulus, whereas in inner anulus, they nearly ran parallel to each other and at an angle of approximately 60 degrees or 120 degrees to those in adjacent lamellae. However, in scoliotic discs, elastic fibers were sparse, and the collagen and elastic fiber networks were disorganized with loss of lamellar structure. Cell clusters, one of typical degenerative feature, were seen in scoliotic discs but not in age-matched control discs. CONCLUSIONS: Our results reveal an abundant and organized network of elastic fibers in the adolescent (12 and 17-year-olds) human IVD, and suggest that elastic fiber network plays a significant biomechanical role. This network is sparse and disrupted in scoliotic discs, and could be involved in the progression of the spinal deformity.

Adolescent↗