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At least 1,099 records · Page 61Linked to original sources
PubMed1981

Suggestions for a total elasto-dynamic intervertebral disc prosthesis.

The essential considerations to be taken for the design of a composite elasto-dynamic intervertebral disc prosthesis (IDP) are discussed, and a disc implant, supposedly satisfying the demands for surgical and biomechanical applicability and biocompatibility, are outlined. The suggested IDP implant is composed of an elastic kernel, covered in a two-components telescoping shell, situated in a polymer slit-tube fundament, after preparation fixed to the respective vertebral bodies of the respective motion segment with bone cement. The approach to a lumbar motion segment is suggested to be by way of an abdominal and retroperitoneal incision and exploration.

Biocompatible Materials↗
PubMedDate not supplied

Magnetic motor evoked potentials for assessing spinal cord integrity in dogs with intervertebral disc disease.

Magnetically elicited transcranial motor evoked potentials (MEPs) were studied in 37 dogs with type 1 intervertebral disc (IVD) disease. The waveforms were recorded from both cranial tibial muscles before and after surgery. The latencies and amplitudes obtained were compared to those of a control population (n = 14). MEPs were recordable in all dogs with mild or no neurologic deficits, but they were recordable in only 50% of ambulatory dogs that were severely ataxic. MEPs could not be elicited from nonambulatory dogs. There was a significant attenuation of the amplitudes in all clinical cases, even if the dogs demonstrated back pain alone. Significantly prolonged latencies were associated with neurologic deficits. MEPs were not good predictors of neurologic recovery. The responses obtained from the side where the disc material was found were not different from those recorded from the opposite side. MEPs were very sensitive to lesions of the spinal cord, as indicated by the significant changes in the waves in patients with mild or no neurologic deficits and in the loss of response in dogs that still demonstrated purposeful movement. Neurologic exams provided more accurate diagnoses and prognoses than did MEPs in dogs with IVD disease.

Animals↗
PubMed1985

The proteoglycans of the canine intervertebral disc.

The high-buoyant-density proteoglycans of the nucleus pulposus and annulus fibrosus of the beagle intervertebral disc have been isolated by CsCl density gradient ultracentrifugation. The sulphated proteoglycans were labelled in vivo with 35SO4, 24 h and 60 days prior to killing. The hydrodynamic size and aggregation of the 24 h, 60 day and resident (from hexuronic acid and hexosamine analysis) proteoglycan subunit populations were determined by Sepharose CL-2B chromatography in the presence or absence of excess hyaluronic acid. The hydrodynamic size of the keratan sulphate-proteoglycan core protein complexes were also determined by Sepharose CL-2B chromatography after chondroitinase ABC digestion of proteoglycans. When initially synthesised (24 h) or after 60 days, the percentage aggregation and hydrodynamic size of the proteoglycans derived from the annulus fibrosus were larger than those present in the nucleus pulposus. Hexosamine, hexuronic and protein determination of the high-buoyant-density fractions showed that the proteoglycans of the nucleus pulposus were richer in chondroitin sulphate than those in the annulus. However there was no difference in Mr of the chondroitin sulphate and keratan sulphate attached to the proteoglycans of the two disc regions, nor were differences detected by HPLC between the proportions of chondroitin 4-sulphate and chondroitin 6-sulphate present in these high-density fractions. In contrast, the low-buoyant-density (1.54 greater than p greater than 1.45) proteoglycan fractions and tissue residues remaining after 4 M GuHCl extraction were found to contain dermatan sulphate, suggesting the presence of a third proteoglycan species possibly associated with the collagen of the fibrocartilagenous matrix.

Animals↗
PubMedDate not supplied

The effect of intervertebral disc space narrowing on the contact force between the nerve root and a simulated disc protrusion.

An instrumented probe mounted on the anterior surface of the lumbar spine over an excised lumbar intervertebral disc was used to stimulate a disc protrusion in 12 fresh cadavers. The contact force between probe and nerve root was measured as a function of two independent variables: probe protrusion depth and disc space height. The contact force on the nerve root was found to increase with increasing probe depth. Disc space widening increased the contact force while narrowing the disc space decreased it. A simple mechanical model analysis confirmed that the force exerted on the nerve root by the probe is the result of tension produced in the nerve root as it is deformed by the probe. The mechanical principle that disc narrowing can reduce the pressure on a nerve root produced by a disc protrusion may be an explanation of how chemonycleolysis relieves sciatic pain.

Adolescent↗
PubMed2006

Measurement of in vivo lumbar intervertebral disc pressure during spinal manipulation: a feasibility study.

This paper presents the first reported measurements of lumbar intervertebral disc pressure in vivo during spinal manipulation. A pressure transducer was inserted into the nucleus pulposus of one normal-appearing lumbar disc in an asymptomatic adult volunteer. Pressures were recorded during several body positions and maneuvers, then during spinal manipulation, and lastly during a repetition of the preintervention body positions. Baseline pressures in the prone and side-lying positions measured 110 kPa and 150 kPa, respectively. During the manipulation, pressure rose to a peak of 890 kPa over 250 ms. Immediately following, pressures in the prone and side-lying positions measured 150 kPa and 165 kPa, respectively. These data do not support the hypotheses that manipulation can reduce a herniation by decreasing intradiscal pressure, or cause a herniation by raising pressure to failure levels. Further work may lead to a better understanding of this treatment method.

Adult↗
PubMed1976

The anatomy of the lumbar intervertebral disc syndrome.

Four elements of the nervous system may be involved in the production of the lumbar intervertebral disc syndrome. These are the lumbosacral nerve roots, the spinal nerves, the dorsal rami and the sinuvertebral nerves. Each nerve is associated with a particular group of pathological conditions which may irritate the nerve and produce symptoms. The anatomy of each nerve determines which particular conditions may irritate it. Moreover, one or both of two mechanisms may be involved in symptom production. The type of nerve irritated determines which mechanism is involved. In the first mechanism, low back pain and referred lower limb symptoms are produced when afferent fibres from dorsal and ventral rami are stimulated where they pass in common through spinal nerves or nerve roots. In the second mechanism, dorsal rami or sinuvertebral nerves are stimulated. This directly produces low back pain, but referred pain is produced by reflex mechanisms in the spinal cord.

Back Pain↗
PubMed2002

Nerve growth factor expression and innervation of the painful intervertebral disc.

Following a previous description of nociceptive nerve fibre growth into usually aneural inner parts of painful intervertebral disc (IVD), this study has investigated whether nociceptive nerve ingrowth into painful IVD is stimulated by local production of neurotrophins. Immunohistochemistry and in situ hybridization have been used to investigate expression of the candidate neurotrophin, nerve growth factor (NGF), and its high- and low-affinity receptors trk-A and p75, respectively, in painful IVD excised for the management of low back pain. IVD from patients with back pain were of two types: those that when examined by discography reproduced the patient symptoms (pain level IVD) and those that did not (non-pain level IVD). Microvascular blood vessels accompanied nerve fibres growing into pain level IVD and these expressed NGF. The adjacent nerves expressed the high-affinity NGF receptor trk-A. These vessels entered the normally avascular IVD through the discal end plates. NGF expression was not identified in non-pain level or control IVD. Some non-pain level IVD had vessels within them, which entered through the annulus fibrosus. These did not express NGF nor did nerves accompany them. These findings show that nociceptive nerve ingrowth into painful IVD is causally linked with NGF production by blood vessels growing into the IVD, from adjacent vertebral bodies.

Adaptor Proteins, Signal Transducing↗
PubMed1986

Changes in mouse intervertebral-disc proteoglycan synthesis with age. Hereditary kyphoscoliosis is associated with elevated synthesis.

Mice with hereditary kyphoscoliosis (ky/ky) develop intervertebral-disc degeneration at the cervico-thoracic junction. Disc proteoglycans were investigated to determine whether changes in synthesis or structure were associated with this. Elevated 35S-proteoglycan synthesis was found in one or more cervico-thoracic discs in 80-day-old ky/ky mice. The hydrodynamic size and aggregation properties of ky/ky-mouse disc 35S-proteoglycans extracted with 4 M-guanidinium chloride were normal. Increased proportions of small 35S-proteoglycans were extracted with 0.5 M-guanidinium chloride from discs of normal and ky/ky mice with increasing age.

Age Factors↗
PubMed1989

Biochemical and structural properties of the cartilage end-plate and its relation to the intervertebral disc.

The cartilaginous end-plate is thought to play an important role in the nutrition of the intervertebral disc, and hence may be of significance in the etiology of back pain. The present study describes the biochemical and histologic properties of the end-plate and adjacent tissues in the young human adult lumbar spine. Thus, a datum is established in which to demonstrate variation with location and relationships between properties of different tissues. Results of the chemical analyses show a change in composition through the end-plate with that at the outer annulus and nearer the bone, having higher collagen but lower proteoglycan and water contents, than the end-plate nearest the disc at the nucleus. Histology demonstrated numerous disruptions along the end-plate, with Schmorl's nodes being present in several specimens. Where these occurred, the disc, and in some cases the end-plate, showed loss of proteoglycan compared with the surrounding tissue.

Adolescent↗
PubMed1994

The strength in anterior bending of lumbar intervertebral discs.

STUDY DESIGN: This was a motion segment experiment. OBJECTIVES: To determine the strength in bending of lumbar intervertebral discs. METHODS: Eighteen "motion segments" consisting of two vertebrae and the intervening disc and ligaments were loaded to simulate forward bending movements in life. The range of flexion and the resistance to bending of each specimen was compared before and after removal of the posterior elements. Nine of the discs were tested after the intradiscal pressure had been reduced by damaging the vertebral end plate in compression. RESULTS: The posterior elements restricted the disc to 80% of its full range of flexion. The strength in anterior bending of isolated discs decreased with age and was 33 Nm on average. Reducing intradiscal pressure did not affect the discs' strength in bending. CONCLUSIONS: Disc failure in bending occurs through overstretching of the outer anulus in the vertical direction. In life, the posterior elements may not adequately protect the posterior anulus from fatigue damage.

Adolescent↗
PubMed1990

Clinical aspects of lumbar intervertebral disc disease.

The diagnosis and management of lumbar disc disease has undergone significant changes in recent years. This is especially true for diagnostic imaging studies (MRI and CT). Currently, CT/myelography or unenhanced MRI may be used to confirm the diagnosis and the level of involvement of lumbar disc disease. The indications for lumbar disc surgery include patients with neurologic deficits and/or those in whom intractable pain does not respond to conservative measures. Conventional disc surgery and/or microdiscectomy are both good operative procedures for lumbar disc disease, and each yields excellent results when criteria for diagnosis and surgery are strictly followed.

Diagnosis, Differential↗
PubMed1994

Usefulness of computed tomography after myelography for surgery on dogs with cervical intervertebral disc protrusion.

Computed tomography after myelography (CTM) was performed pre- and postoperatively on four dogs diagnosed as having cervical intervertebral disc protrusion. The surgery was performed by ventral slot technique in all the cases. The direction of the ventral slot was precisely adjusted according to the location of the protruded discs as seen on CTM. Postoperative values for the transversal area of the spinal cord were greater than those measured preoperatively, suggesting effective decompression of the cord. The prognosis for these patients was excellent. In view of these results, it was considered that preoperative confirmation of the positional relationship between the spinal cord and the protruded disc by CTM was quite useful in planning the surgical technique for disc disease in the dog.

Animals↗