Arthritis « Neck Solutions Blog

November 8, 2010

Biomechanical Influence of Disk Properties on the Load Transfer of Healthy and Degenerated Discs Using a Poroelastic Finite Element Model

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Biomechanical Influence of Disk Properties on the Load Transfer of Healthy and Degenerated Discs Using a Poroelastic Finite Element Model

J Biomech Eng. 2010 Nov;132(11):111006

Spine degeneration is a pathology that will affect 80% of the population. Since the intervertebral discs play an important role in transmitting loads through the spine, the aim of this study was to evaluate the biomechanical impact of disc properties on the load carried by healthy (Thompson grade I) and degenerated (Thompson grades III and IV) discs. A three-dimensional parametric poroelastic finite element model of the L4/L5 motion segment was developed. Grade I, grade II, and grade IV discs were modeled by altering the biomechanical properties of both the annulus and nucleus. Models were validated using published creep experiments, in which a constant compressive axial stress of 0.35 MPa was applied for 4 h. Pore pressure and effective stress were analyzed as a function of time following loading application (1 min, 5 min, 45 min, 125 min, and 245 min) and discal region along the midsagittal profile for each disc grade. A design of experiments was further implemented to analyze the influence of six disc parameters disc height, fiber proportion, drained Young’s modulus, and initial permeability of both the annulus and nucleus) on load-sharing for disc grades I and IV. Simulations of grade I, grade III, and grade IV discs agreed well with the available published experimental data. Disc height had a significant influence on the pore pressure and effective stress during the entire loading history for both healthy and degenerated disc models.

Young’s modulus of the annulus significantly affected not only effective stress in the annular region for both disc grades in the initial creep response but also effective stress in the nucleus zone for degenerated discs with further creep response. The nucleus and annulus permeabilities had a significant influence on the pore pressure distribution for both disc grades, but this effect occurred at earlier stages of loading for degenerated than for healthy disc models. This is the first study that investigates the biomechanical influence of both geometrical and material disc properties on the load transfer of healthy and degenerated discs. Disc height is a significant parameter for both healthy and degenerated discs during the entire loading. Changes in the annulus stiffness, as well as in the annulus and nucleus permeability, control load-sharing in different ways for healthy and degenerated discs.

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October 29, 2010

Human intervertebral disc internal strain in compression: The effect of disc region, loading position, and degeneration

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Human intervertebral disc internal strain in compression: The effect of disc region, loading position, and degeneration

From: J Orthop Res. 2010 Oct 26. [Epub ahead of print]

The primary function of the disc is mechanical; therefore, degenerative changes in disc mechanics and the interactions between the annulus fibrosus and nucleus pulposus in nondegenerate and degenerate discs are important to functional evaluation. The disc experiences complex loading conditions, including mechanical interactions between the pressurized nucleus pulposus and the surrounding fiber-reinforced annulus fibrosus. Our objective was to noninvasively evaluate the internal deformations of nondegenerate and degenerate human discs under axial compression with flexion, neutral, and extension positions using magnetic resonance imaging and image correlation. The side of applied bending (e.g., anterior annulus fibrosus in flexion) had higher tensile radial and compressive axial strains, and the opposite side of bending exhibited tensile axial strains even though the disc was loaded under axial compression. Degenerated discs exhibited higher compressive axial and tensile radial strains, which suggest that load distribution through the disc subcomponents are altered with degeneration, likely due to the depressurized nucleus pulposus placing more of the applied load directly on the annulus fibrosus. The posterior annulus fibrosus exhibited higher compressive axial and higher tensile radial strains than the other annulus fibrosus regions, and the strains were not correlated with degeneration, suggesting this region undergoes high strains throughout life, which may predispose it to failure and tears. In addition to understanding internal disc mechanics, this study provides important new data into the changes in internal strain with degeneration, data for validation of finite element models, and provides a technique and baseline data for evaluating surgical treatments.

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October 22, 2010

A longitudinal study of low back pain and daily vibration exposure in professional drivers

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A longitudinal study of low back pain and daily vibration exposure in professional drivers

From: Ind Health. 2010;48(5):584-95

Long-term exposure to whole body vibration in professional drivers of machines and/or vehicles used in industry, agriculture/forestry, and public utilities is associated with an excess risk for back symptoms and disorders of the lumbar tract of the spine. Epidemiological studies and reviews have reported a higher occurrence of low back pain, herniated disc and early degeneration of the spine in the exposed drivers than in either worker groups unexposed to whole body vibration or the general population. Driving of vehicles involves not only exposure to harmful whole body vibration but also to several ergonomic risk factors which can affect the spinal system, such as prolonged sitting and awkward postures. Moreover, some driving occupations involve heavy lifting and manual handling activities (e.g. drivers of delivery trucks), which are known to strain the lower part of the back. Individual characteristics (e.g. age, body mass, and smoking) and psychosocial factors are also suggested as potential predictors for low back pain. It follows that injuries in the lower back of professional drivers may be considered a complex of health disorders of multifactorial origin involving both occupational and non-occupational stressors.

The European (EU) Directive on mechanical vibration provides qualitative and quantitative guidance to protect workers against the risks arising from exposure to vibration at work. In the EU Directive, whole body vibration is defined as ‘the mechanical vibration that, when transmitted to the whole body, entails risks to the health and safety of workers, in particular lower back morbidity and trauma of the spine.

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October 4, 2010

Effect of TENS on pain relief in patients with degenerative disc disease in lumbosacral spine

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Effect of TENS on pain relief in patients with degenerative disc disease in lumbosacral spine

From: Ortop Traumatol Rehabil. 2010 Jul-Aug;12(4):289-300

The study sought to evaluate the impact of long-term TENS therapy on pain relief in patients with degenerative disc disease in the lumbosacral spine.

The study involved 39 patients with lumbosacral pain who were receiving treatment in the Regional Hospital No 2 in Rzeszów and in Winsen Hospital. The experimental group consisted of 16 patients who were fitted with L-S orthoses with a built-in Tens plus mini-device for long-term application (3 times a day, for 20 minutes) of TENS currents with a frequency of 35 Hz and impulse duration of 150µsec. The control group consisted of 23 patients who received conventional TENS therapy once a day for 20 minutes, with a frequency of 35 Hz and impulse duration of 150 µsec. The results were assessed with the Oswestry Questionnaire, a visual analogue scale, as well as Schober’s Test. Tests were performed before and on completion of the therapy.

All participants reported pain relief and improved spinal function and mobility. Statistically significant differences were obtained in the group of patients treated with low frequency pulsed TENS currents administered via the orthosis.

TENS therapy contributed to pain relief and improvement of function and mobility of the lumbosacral spine representing an appropriate and effective technique. TENS stimulation via an orthosis should be more commonly prescribed.

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September 21, 2010

Diagnosis and management of degenerative neck pain

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Diagnosis and management of degenerative neck pain.

From: Br J Hosp Med (Lond). 2010 Sep;71(9):M137-41.

Neck pain is a common presenting complaint, but the precise patho-aetiology is often unclear. Broadly speaking, the cause of neck pain can be considered as degenerative or non-degenerative. While detailing the important non-degenerative causes the clinician should not miss, this article reviews the diagnosis and management of the common degenerative orthopaedic causes of neck pain. Spondylosis refers to the age-related degenerative changes within the spinal column involving bone and soft tissue structures. It is analogous to osteoarthritis except that it relates to the degenerative changes within intervertebral discs rather than at synovial joints and is very common, frequently presenting late with subtle clinical symptoms and signs. The posterior facet joints do develop osteoarthritis with age, as these are synovial joints, but for practical purposes, both of these conditions can be treated as degenerative joint disease.

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May 26, 2010

The association between lumbar disc degeneration and low back pain: the influence of age, gender, and individual radiographic features

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The association between lumbar disc degeneration and low back pain: the influence of age, gender, and individual radiographic features.

From: Spine (Phila Pa 1976). 2010 Mar 1;35(5):531-6.

Back pain is one of the most common musculoskeletal complaints of the elderly, with a point prevalence of 26.9% in the Netherlands. Van Tulder et al performed a systematic review and reported that lumbar disc degeneration could be a possible risk factor for back pain in adults. However, the review reported that the methodologic quality of most of these studies was low and the studies were difficult to compare due to difference in gender frequencies, age groups, settings, radiographic grading systems, and definitions for lumbar disc degeneration.

Lumbar disc degeneration is characterized radiologic by the presence of osteophytes, endplate sclerosis, and disc space narrowing. In 1993, Lane et al presented a reliable grading system for these individual radiographic features. In a recent review, this grading system was recommended for use in epidemiologic studies. There have been a number of recent studies that have used the classification of the individual radiographic features of disc degeneration defined by Lane et al. One of these studies described the occurrence of these separate features and their relationship with back pain in the open population, but only in a limited sample.

However, it is still unknown how to combine the individual radiographic features and how to define a clinically relevant definition for lumbar disc degeneration. Currently there is no consensus about whether the lumbosacral disc should be scored. Some studies have included the lumbosacral level in their definition of lumbar disc degeneration, while others have not. Currently within the literature, there have been no studies that have explored different definitions of lumbar disc degeneration and their association with low back pain within one study sample.

The purpose of this study was to explore the association of the different individual radiographic features, including osteophytes and disc space narrowing, with self-reported low back pain. Different definitions of lumbar disc degeneration with self-reported low back pain and disability were considered in a large open population sample. Furthermore, in order to disentangle the discrepancies in reported strength of the associations, the authors characterized the frequency of the different individual radiographic features of lumbar disc degeneration and definitions of lumbar disc degeneration, as well as their association with low back pain status, by age, gender, and vertebral level.

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April 8, 2010

Association of the Polymorphisms of Vitamin D Receptor and Aggrecan Genes with Degenerative Disc Disease

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Association of the Polymorphisms of Vitamin D Receptor and Aggrecan Genes with Degenerative Disc Disease.

From: Genet Test Mol Biomarkers. 2010 Mar 31. [Epub ahead of print]

The aim of this study was to investigate the association between the polymorphisms of vitamin D receptor and aggrecan genes and degenerative disc disease in young Turkish patients. Aggrecan and vitamin D receptor proteins are the main components of bone and cartilage. In our study, the polymorphisms of vitamin D receptor and aggrecan genes were investigated in a total of 300 individuals regarding disc degeneration and herniation.

An association was found in the patients having vitamin D receptor gene TT, Tt, FF, and Ff genotypes with the protrusion type of disc herniation, whereas the patients having tt and ff genotypes were associated with extrusion/sequestration types of the disease. Also, an association was observed between TT and FF genotypes of vitamin D receptor gene and mild forms of disc degeneration; and tt, ff, and Ff genotypes and severe forms of the disease. There was also an association between shorter, normal, and longer alleles of the aggrecan gene and a protrusion type of disc herniation. An association was found between short alleles and multilevel and severe disc degeneration, as well as normal and long alleles and mild disc degeneration. This study revealed that the polymorphisms of vitamin D receptor and aggrecan genes are associated with disc degeneration and herniation.

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November 15, 2009

Facet tropism and degeneration

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Relationship of facet tropism with degeneration and stability of functional spinal unit

From: Yonsei Med J. 2009 Oct 31;50(5):624-9

Facet tropism is defined as asymmetry in both the facet joint angles of the lumbar and lumbosacral regions. For many years, the effect of facet tropism on the development of intervertebral disc degeneration has been debated. However, the specific details regarding the effects of facet tropism on the development of degenerative disc disease remains as the subject of debate. Most of the previous facet tropism studies have focused on the relationship between facet tropism and lumbar disc herniation.

The role of facet tropism in the pathogenesis of lumbar degenerative disc disease is not fully understood Currently, controversy exists surrounding the question of whether or not any significant relationship exists between facet tropism and the development of disc or facet joint degeneration. Additionally, the relationship between facet tropism and degenerative spondylolisthesis and translational segmental motion is highly controversial.

In the current study, the authors attempted to evaluate the effect of facet tropism on disc and facet joint degeneration. Additionally, the relationship between facet tropism and changes in translational segmental motion was investigated.

Facet tropism is defined as asymmetry between the left and right facet joint angles of the lumbar spine. Asymmetry in the orientation of the zygapophyseal joint surfaces is not uncommon, with estimates of its occurrence at 10-70.5% of the population. Our study revealed an incidence of facet tropism in 35% of the spinal units which were taken into consideration. Facet tropism is most common at L5-S1, followed by L4-L5.

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September 26, 2009

Muscone protects vertebral end plate degeneration

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Muscone Protects Vertebral End plate Degeneration by Antiinflammatory Property

From: Clin Orthop Relat Res. 2009 Sep 18

Neck pain is one of the most common chronic conditions affecting quality of life and sometimes causing disability in adults. Most chronic neck pain is the result of degeneration of the intervertebral discs in the cervical spine. An intact end plate cartilage is critical for normal disc functions, as the major nutrient supply of the discs is diffused through the end plates. Pathological changes in end plate cartilage are closely related to disc degeneration and thus to cervical spondylopathy. Prevention and reduction of lesions to the vertebral end plate are high research priorities.

IL-1beta may play an important role in intervertebral disc degeneration. This being the case, inhibiting IL-1beta could provide a therapeutic approach for reducing or preventing disc degeneration. Muscone reportedly relieves pain and suppresses inflammation. Therefore, the authors asked whether muscone, a potent antiinflammatory agent, could reduce proinflammatory cytokines in vitro (end-plate cartilage cultures) and end-plate degeneration in vivo (a rat model that induces intervertebral disc degeneration). In vitro, muscone reversed IL-1beta-induced upregulation of IL-1beta, tumor necrosis factor alpha, cyclooxygenase 2, inducible nitric oxide synthase, matrix metalloproteinase 13, aggrecanase 2, and nitric oxide and downregulation of Col2alpha1 and aggrecan. Pretreatment with muscone (6.25, 12.5, 25 mumol/L) inhibited the IL-1beta-induced phosphorylation of extracellular signal-regulated kinases 1/2 and c-Jun N-terminal kinase in a dose-dependent manner. In vivo, muscone inhibited the expression of prostaglandin E2, 6-keto-prostaglandin F1alpha, IL-1beta, and tumor necrosis factor alpha and recovered the structural distortion of the degenerative disc. The findings suggest muscone is a promising agent for treating intervertebral disc degeneration through its antiinflammatory effects.

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August 28, 2009

Musculoskeletal pain in Chinese elderly

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Prevalence and correlates of musculoskeletal pain in Chinese elderly and the impact on 4-year physical function and quality of life

From: Public Health. 2009 Aug 24

Examination of the prevalence, correlates and prospective impact of musculoskeletal pain on physical and psychological function in a population health survey of elderly Chinese men and women. Four thousand men and women, aged 65 years and over, living in the community in Hong Kong took part in this study. A questionnaire to determine demographics, socio-economic status, medical history, smoking, alcohol intake and level of physical activity was administered by an interviewer. Participants were asked about the presence of pain in the back, neck, hip and knee in the past 12 months. They were re-interviewed after 4 years of follow-up to document physical performance measures, psychological function and occurrence of falls, fractures and mortality.

Overall, back pain was most prevalent (48%), followed by knee (31%), neck (22.5%) and hip (8.9%) pain; the values was nearly twice as high in women compared with men for all sites. The presence of pain was not correlated with age, but was associated with various measures of socio-economic status as well as comorbidities. Baseline prevalence of pain was related to physical performance and quality-of-life measures, and fracture incidence after 4 years of follow-up.

Musculoskeletal pain is prevalent among elderly men and women, being much higher in the latter, giving rise to considerable functional and psychological impairments. Osteoporosis and osteoarthritis are likely to be the main underlying causes. The condition may be considered part of the frailty syndrome, and in this context, prevention and management represent major public health challenges.

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