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October 21, 2009

Dynamic degenerative lumbar disc bulging

Filed under: Back Pain, Disc Problems, Posture — Administrator @ 1:25 pm

Dynamic Bulging of Intervertebral Discs in the Degenerative Lumbar Spine

From: Spine (Phila Pa 1976). 2009 Oct 16

The effect of postural change on degenerative lumbar discs was quantified using novel kinematic magnetic resonance imaging. The purpose is to describe the bulging of degenerative intervertebral lumbar discs in vivo subjected to different postural loads using a novel kinematic magnetic resonance imaging.

Symptomatic lumbar disc degeneration is a leading cause of pain and disability throughout the world. Over 70% of US citizens will experience a debilitating episode of low back pain. Earlier reports of degenerative disc changes are cadaver studies or are performed with recumbent MRI that eliminates the functional effects of gravity and muscle power. Little data are available on the behavior of degenerative intervertebral discs in vivo under physiologic loads.

A total of 513 patients obtained kMRI. Disc bulging beyond the intervertebral space was quantified during upright neutral, flexion, and extension imaging. The degree of intervertebral disc degeneration was correlated using the Pfirrmann Classification. Moderately degenerated intervertebral discs (grade III and IV) demonstrated greater bulging than mildly degenerated discs (grade II). Severely degenerated discs (grade V) also showed a trend toward greater bulging, but this was not significant. Grade I discs at all levels moved posteriorly in flexion and anteriorly in extension when compared to neutral posture. However, mild to severe (grade II-V) degenerative discs behaved differently in response to postural loads. Extension resulted in significant posterior bulging, while flexion did not demonstrate obvious anterior derangement.

Disc bulging increases with the severity of disc degeneration. Grade I discs demonstrate the expected sagittal migration in response to postural load. However, more degenerative discs behave less predictably, and spine extension may result in significant posterior disc bulging. Degenerative changes in the intervertebral disc significantly affect the kinematic patterns under postural load in vivo. Kinematic magnetic resonance imaging is a useful tool to quantify the kinematic behavior of degenerative intervertertebral discs.

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October 5, 2009

Cigarette smoking and chronic low back pain in the adult population

Filed under: Back Pain, Chronic Pain, General Health — Administrator @ 2:42 pm

Cigarette smoking and chronic low back pain in the adult population

From: Clin Invest Med. 2009 Oct 1;32(5):E360-7

Chronic low back pain is one of the main causes of disability in the community. Although there have been studies suggesting an association between smoking and chronic low back pain, these studies were limited by the small numbers of patients, and they did not control for confounders. The objective of this study was to determine whether cigarette smoking is associated with an increased risk of chronic low back pain among adults.

Using Canadian Community Health Survey (cycle 3.1) data, 73,507 Canadians aged 20 to 59 yr were identified. Self-reported chronic low back pain status, smoking habits, sex, age, height, weight, level of activity and level of education were identified as well. Back pain secondary to fibromyalgia was excluded. Multivariate logistic regression analysis was used to detect effect modification and to adjust for covariates. Design effects associated with complex survey design were taken into consideration.

The prevalence of chronic low back pain was 23.3% in daily smokers and only 15.7% in non smokers. Age and sex were found to be effect modifiers, and the relationship between smoking and chronic low back pain risk was dependent on sex and age. The association between daily smoking and the risk of chronic low back pain was stronger among younger individuals. Occasional smoking slightly increased the odds of having chronic low back pain.

Daily smoking increases the risk of chronic low back pain among young adults, and this effect seems to be dose dependent. Back pain treatment programs may benefit from integrating smoking habit modification. Further research is required to develop effective prevention strategies.

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September 17, 2009

Sustained mechanical loading and disc diffusion

Filed under: Back Pain, Disc Problems, Posture — Administrator @ 3:53 pm

2009 ISSLS Prize Winner: What Influence Does Sustained Mechanical Load Have on Diffusion in the Human Intervertebral Disc?: An In Vivo Study Using Serial Postcontrast Magnetic Resonance

From: Spine (Phila Pa 1976). 2009 Sep 14

An in vivo study of the effects of mechanical loading on transport of small solutes into normal human lumbar intervertebral discs using serial postcontrast magnetic resonance imaging (MRI) to investigate the influence of a sustained mechanical load on diffusion of small solutes in and out of the normal intervertebral disc.

Diffusion is an important source of disc nutrition and the in vivo effects of load on diffusion in human intervertebral disc remains unknown. Forty normal lumbar discs (on MRI) in 8 healthy volunteers were subjected to serial post contrast (Gadoteridol) 3 Tesla MRI in 2 phases. In phase 1 (control), volunteers were scanned at different time points – precontrast and 1.5, 3, 4.5, 6, and 7.5 hours postcontrast injection. In phase 2, 1 month later, the same volunteers were subjected to sustained supine loading for 4.5 hours. MRI scans were performed precontrast (preload) and postcontrast (postloading) at 1.5, 3, and 4.5 hours. Their spines were then unloaded and recovery scans performed at 6 and 7.5 hours postcontrast. In house software was used to analyze images.

Repeated-measures ANOVA and pairwise comparisons at different time points in the central region of the loaded disc compared to the unloaded discs revealed significantly lower signal intensity ratios indicating reduction in transport rates for the loaded discs. Signal intensity ratioscontinued to rise in loaded disc for 3 hours into recovery phase, whereas unloaded discs at the same time point showed a decrease.

Sustained supine creep loading (50% body weight) for 4.5 hours retards transport of small solutes into the center of human IVD and it required 3 hours of accelerated diffusion in recovery state for loaded disc to catch-up with diffusion in unloaded discs. The study supports the theory that sustained mechanical loading impairs diffusion of nutrients entering the disc and quite possibly accelerates disc degeneration.

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September 15, 2009

Lumbopelvic extensor muscle endurance and age

Filed under: Back Pain, Chronic Pain — Administrator @ 8:58 pm

Comparison between elderly and young males’ lumbopelvic extensor muscle endurance assessed during a clinical isometric back extension test.

From: J Manipulative Physiol Ther. 2009 Sep;32(7):521-6

Low back pain is one of the leading causes of disability, contributing to 40% of all workdays lost in the United States of America. Because of the cost associated with work-related low back pain disabilities, most published studies have focused on the working-aged population. However, back pain and neck pain are also common musculoskeletal disorders affecting, each month, approximately one third of adults older than 70 years. The annual prevalence of chronic low back pain ranges from 44% to 84% in adults older than 65 years. In Canada, chronic low back pain is the third and fourth most important chronic health problem in women and men, respectively, older than 65 years. Women with severe chronic low back pain are 3 to 4 times more likely than other women to have difficulty with light housework tasks and 2 times more likely to encounter problems with mobility tasks, such as climbing stairs, walking, or lifting. In Canada, it is estimated that approximately 25% of the population will be older than 65 years by 2031. Anticipating the growing impact of the ageing population, a better understanding of chronic low back pain’s impact on physical capabilities in elderly people is important.

In working aged adults, chronic low back pain has been associated with increased fatigability of the lumbopelvic extensor muscles, as demonstrated by shorter back endurance test duration. In all back endurance protocols reported in the literature, isometric testing procedures with the trunk positioned in a weight-dependent position, such as the Sorensen test, may be most suitable in clinical settings. Weight dependent position tests of muscle endurance are cost-effective, easy to perform in a clinical context, and require no special equipment. The Sorensen test is conducted with subjects lying prone, the upper body unsupported in a horizontal position relative to the ground, and the lower limbs fixed by straps. This procedure has been found to be a reliable measure of position-holding time and can discriminate between subjects with and without low back pain.

Ageing has been related to changes in the neuromuscular system. Among these changes, loss of muscle force generation capacity, a slower firing rate of motor units, and a reduction in motor unit and muscle fiber number have been observed. Together with the loss of muscle fibers, a selective decrease in fast twitch fibers has been demonstrated with advancing age, leading to alteration of muscle fiber type proportion. This shift in fiber-type proportion appears to contribute to changes in muscle fatigability in healthy elderly individuals.

Very few studies have assessed back muscle endurance in elderly subjects. The current investigation aims to evaluate back extensor muscle fatigability in healthy elderly adults by quantifying endurance time during a clinical isometric back endurance test and the posttest decrease of lumbopelvic extensor maximal force. We hypothesized that elderly subjects will experience greater fatigability of lumbopelvic extensor muscles than young subjects.

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September 12, 2009

gluteus medius weakness low back pain during pregnancy

Filed under: Back Pain, Posture — Administrator @ 10:15 am

Association between gluteus medius weakness and low back pain during pregnancy

From: Iowa Orthop J. 2009;29:97-9

This cross-sectional study examines whether there is an association between gluteus medius weakness in the presence of low back pain in pregnant women at any stage of gestation. Prevalence of low back pain during pregnancy is high, and identifying potential etiologies and targeted interventions is lacking. Thus, identification of an association between specific muscle weakness and pain would have clinical relevance. Initial pilot data suggests that weakness of the gluteus medius is strongly associated with the presence of low back pain during pregnancy.

Low back pain during pregnancy is considered a significant public health issue due to its high prevalence and associated health care costs. Prevalence ranges between 49-68.5% with up to one third of these women having pain that limits their ability to perform basic activities of daily living. Ten percent of women with chronic low back pain link the onset of their pain to pregnancy. Physical therapy literature and physical therapy clinical practice relating to low back pain in pregnancy has historically involved discussion of postural dysfunction, sacroiliac joint dysfunction, and “sciatica.” The authors of this proposal offer another possible correlation explaining back pain during pregnancy relating to gluteus medius performance.

It is the experience of the authors of this proposal that pregnant women routinely present to their physical therapy clinic with “radiculopathy” or “sciatica.” In fact, the incidence of herniated disc in pregnancy is actually quite rare (1%). Often, the physical exam does not reveal any neurologic findings indicative of radiculopathy, but instead reveals weakness and/or strain of the gluteus medius. Gluteus medius strain can present as low back pain either due to facet joint irritation relating to Trendelenburg gait, or can be referred pain from the gluteus medius itself. If a true neurologic weakness were present, one would expect to find both tensor fascia lata and posterior gluteus medius weak as they are commonly innervated (L5). Rather, in the authors experience weakness is specific to the gluteus medius. Foti et al. performed 3-dimensional gait analysis on 15 pregnant women during the second half of their pregnancy and again one year post-partum. Gait analysis includes both kinetic and kinematic parameters. The authors found significant changes in kinetic gait parameters during pregnancy, and offer this as an explanation for how
gait motion overall remains relatively unchanged. They found increased demand on the ankle plantar flexors, hip abductors, and hip extensors. Atrophied tissues, or weak muscles, are less tolerant of physical stresses applied. Pregnant women with weakness of the gluteus medius are therefore vulnerable for tissue injury—both because of the increased magnitude of stress applied (weight gain), and a decrease in stress tolerated before injury/strain.

Thus, the primary aim of this pilot study was to determine the association between weakness of the gluteus medius and the presence of low back pain during pregnancy.

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August 28, 2009

Musculoskeletal pain in Chinese elderly

Filed under: Arthritis, Back Pain, General Health, Neck Pain — Administrator @ 7:58 pm

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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August 22, 2009

Painful degenerate intervertebral disc

Filed under: Arthritis, Back Pain, Disc Problems — Administrator @ 7:25 pm

Increased expression of matrix metalloproteinase-10, nerve growth factor and substance P in the painful degenerate intervertebral disc

From: Arthritis Res Ther. 2009 Aug 20;11(4):R126. [Epub ahead of print]

The human intervertebral disc is an avascular and aneural tissue comprising a central gelatinous region (the nucleus pulposus), surrounded by a fibrous ring of highly organised collagen fibres (the annulus fibrosus). The extracellular matrix of the nucleus pulposus is rich in type II collagen and proteoglycans, predominantly aggrecan, which produces a highly hydrated matrix capable of withstanding the loads experienced within the spine. This extracellular matrix is constantly being remodelled in a process driven by the constituent nucleus pulposus cells.

During intervertebral disc degeneration there is an imbalance in the normal homeostatic mechanisms, which favours matrix catabolism and leads to a loss of disc height,
coupled with ingrowth of both nerves and blood vessels into both the annulus fibrosus and nucleus pulposus. The authors have previously demonstrated that this ingrowth of nerves into the degenerate intervertebral disc is associated with low back pain. While low back pain is multifactorial, studies have shown that this debilitating condition affecting around 80% of adults at some stage of life is associated with intervertebral disc degeneration in approximately 40% of cases. Indeed in a recent study by Cheung et al (2009) it has been shown that there is a significant association of lumber disc degeneration imaged by MRI with low back pain.

The nucleus pulposus of the normal human intervertebral disc is an avascular and aneural environment, comprising of chondrocyte like cells embedded within an extracellular matrix rich in proteoglycans and collagens. This matrix is continuously remodelled in a process controlled by the nucleus pulposus cells and closely regulated by anabolic growth factors and catabolic cytokines. In intervertebral disc degeneration there is disregulation in this finely balanced homeostatic matrix turnover mechanism, leading to an increase in catabolic processes over anabolic matrix formation. Over time this results in breakdown of matrix, until the disc loses both height and function and in a large proportion of cases there is innervation and initiation of the pain response which leads to low back pain.

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July 30, 2009

Modic changes and lumbar intervertebral disc degeneration

Filed under: Back Pain, Disc Problems — Administrator @ 9:26 am

Modic changes, possible causes and promotion to lumbar intervertebral disc degeneration

From: Med Hypotheses. 2009 Jul 23. [Epub ahead of print]

Modic changes are bone marrow and endplate lesions visible in magnetic resonance imaging (MRI). They are regarded as a part of degenerative disc disease and associated with low back pain. And severe disc degeneration was occurred more in the patients with Modic changes. But there is still no study to analyze the relationship between Modic changes and intervertebral disc degeneration. The authors hypothesize that Modic changes are the possible causes and promotion of lumbar intervertebral disc degeneration. And there are three possible mechanisms for this hypothesis:

A structural cause: Modic changes make cartilaginous material easier in extruded disc herniations, to destroy the structure of intervertebral disc and inhibit the absorption of the disc.

A biomechanical cause: Modic changes alter the mechanical loading distribution on disc, to initiate a series of disc disruption and inhibit the self-recovery of the disc.

A nutritional cause: Modic changes destroy the vascular architecture in vertebral endplate and block the most important metabolism pathway between vertebrae and disc.

Perspectives:

(1) Find out procedures to cure Modic changes may be an important breakthrough for disc degenerative disease.

(2) Treatment of Modic changes may be a critical step of biotherapy for disc degeneration disease.

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July 28, 2009

Whiplash associated disorder and low back pain

Filed under: Back Pain, Neck Pain, Whiplash — Administrator @ 8:59 am

Can patients with low energy whiplash associated disorder develop low back pain

From: Injury. 2009 Jul 20. [Epub ahead of print]

800 consecutive claimant generated medicolegal reports were analysed for symptomatology of whiplash associated disorder including the presence of mid and low back pain. The authors aimed to establish whether the two were linked and if so if there were correlations between accident vector and severity. The authors also aimed to establish if a low back injury could result from a vehicular accident in the absence of a neck injury. In addition we examined if occupant bracing and occupant neutral position at the time of the accident affected symptom patterns.

The authors found that a claimed back injury following whiplash associated disorder was independent of both accident severity and accident vectors, approximately 40% claiming injury in low, medium and high violence groups and with rear, frontal and side impact. The authors established that it was unusual to have a back injury in the absence of a neck injury (18 out of 325, 5.5%) without a past medical history of back pain (72.2% of this group having previous back pain). Occupant bracing was not protective. The authors also showed that occupant neutral position was not protective against a back injury. The authors were surprised that patients with next to no car damage had the same incidence of back pain as those involved in more violent crashes when biomechanically unlikely. The complex biopsychosocial response and the relationship to constitutional factors are discussed. The literature concerning forces across the lumbar spine and possibilities of injury is reviewed.

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July 15, 2009

Intervertebral disc and articular cartilage matrix

Filed under: Back Pain, Disc Problems — Administrator @ 10:19 pm

The internal mechanical functioning of intervertebral discs and articular cartilage, and its relevance to matrix biology

From: Matrix Biol. 2009 Jul 5. [Epub ahead of print]

Degeneration of intervertebral discs and articular cartilage can cause pain and disability. Risk factors include genetic inheritance and age, but mechanical loading also is important. Its influence has been investigated using miniature pressure transducers to measure the distribution of compressive stress (force per unit area) within loaded tissue. The technique quantifies stress concentrations, and detects regions that behave in a fluid-like manner.

Intervertebral discs demonstrate a central fluid-like region which normally extends beyond the anatomical nucleus pulposus so that the whole disc functions like a “water bed”. With increasing age, the fluid region shrinks and pressure within it falls. Stress concentrations appear in the surrounding anulus fibrosus, with location depending on posture. Stress concentrations become large in degenerated discs, and are intensified by sustained loading or injury. Articular cartilage never exhibits an internal fluid pressure: stress gradients and concentrations normally occur within it, and are intensified by sustained loading.

Excessive matrix stresses can cause pain and progressive damage. They also inhibit matrix synthesis and stimulate production of matrix degrading enzymes. In this way, injury to chondroid tissues can initiate a ‘vicious circle’ of abnormal matrix stresses, abnormal metabolism, weakened matrix, and further injury, which explains many features of their degeneration.

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