Posture « necksolutions.com Blog

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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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 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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September 4, 2009

Postural responses in healthy seated individuals

Filed under: Neck Pain, Posture — Administrator @ 7:22 pm

A paradigm to assess postural responses triggered by anteroposterior translations in healthy seated individuals

From: Gait Posture. 2009 Aug 31.

Postural adjustments following mechanical perturbations have been studied in healthy seated humans. However, little is known on the minimal intensity that should be used to provoke a reaction. This knowledge could be essential to assess seated postural deficits in some pathological populations. The goal of the present study was to identify a low-intensity perturbation that could elicit postural reactions in healthy seated individuals.

Six healthy participants sat on an adapted ergonomic chair fixed on a moveable support surface that was submitted to forward and backward translations. The head and trunk kinematics as well as the activity of sixteen neck and trunk muscles were recorded. The head, arm and trunk center of mass was computed using kinematics and standard anthropometric tables. The authors found that ramp displacements with an acceleration profile reaching a maximal value of 1.17m/s(2) elicited reliable kinematic and electromyographic reactions across participants. Head and trunk segments initially responded opposite to the direction of translation, then reversed direction. Median peak-to-peak angular displacements in the neck, head and trunk, respectively, reached 3.6 degrees , 7.0 degrees and 7.1 degrees for forward translations, and 4.0 degrees , 8.2 degrees and 7.0 degrees for backward translations.

For forward translations, neck and trunk flexor muscles were activated first, followed by the extensor muscles, whereas for backward translations, extensor muscles were activated first, followed by flexors. Although this perturbation is of low-intensity compared to those typically used previously to evoke postural reactions, this stimulus is sufficient to elicit a reliable response. We suggest that such a perturbation could be used to assess the physical condition of individuals with neck injuries.

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July 9, 2009

Postural changes in women with chronic pelvic pain

Filed under: Chronic Pain, Posture — Administrator @ 10:22 pm

Postural changes in women with chronic pelvic pain

From: BMC Musculoskelet Disord. 2009 Jul 7;10(1):82. [Epub ahead of print]

Among women, chronic pelvic pain is a highly prevalent (2% to 25%) clinical problem, with substantial costs as well as social and marital repercussions. Chronic pelvic pain is defined as continuous or recurrent pain in the lower abdomen or pelvis lasting at least six months, not related to pregnancy, and sufficiently severe to interfere with the habitual activities of the patient. Chronic pelvic pain excludes pain occurring exclusively in association with menstruation (dysmenorrhea) or during sexual intercourse (dyspareunia).

Although the etiology is often unknown, it may result from complex interactions among the gastrointestinal, urinary, gynecologic, musculoskeletal, neurologic and endocrine systems, as well as being influenced by psychological and sociocultural factors. To date, few therapeutic modalities have been effective in relieving the symptoms of chronic pelvic pain, particularly over the long term. An interdisciplinary approach has therefore been recommended, both to diagnose the presumed primary etiology, and to diagnose and control all the secondary factors associated with chronic pelvic pain.

In clinical practice, postural changes are frequently observed among women with chronic pelvic pain. Although this disease has been associated with musculoskeletal changes and particular postures, to date there have been no studies of the detailed postural evaluation of women with chronic pelvic pain, which can be performed by attending physicians, especially primary care physicians and gynecologists. Postural assessment can lead to early detection of uneven positions, shortenings, antalgic postures and tensions. Although these changes may not be the primary cause of the clinical condition, they can contribute significantly to the worsening of pain and tension. The authors therefore determined the frequency of postural changes in women with chronic pelvic pain, as assessed only by clinical examinations.

The authors observed statistically significant differences in the cervical spine and scapulae between women with chronic pelvic pain and control women. The authors believe that the changes observed in women with chronic pelvic pain resulted from a vicious cycle of pain and antalgic postures acquired over time. The mean duration of symptoms among women with chronic pelvic pain was about five years, and postural impairments over time can contribute significantly to the maintenance or worsening of pain. Nevertheless, the authors cannot conclude that women with chronic pelvic pain always show the same postural pattern. First, although the authors observed an association between chronic pelvic pain and postural changes, the control group, consisting of women who did not report any type of pain, also presented with several postural changes.

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July 1, 2009

Car driving and back support

Filed under: Back Pain, Posture — Administrator @ 9:43 am

Car driving with and without a movable back support: Effect on transmission of vibration through the trunk and on its consequences for muscle activation and spinal shrinkage

From: Ergonomics. 2009 Jul;52(7):830-9

The aim of this study was to test the effect of a movable backrest on vibration transmission through the trunk during driving and on the physiological consequences thereof. Eleven healthy male subjects drove for about 1 h on normal roads with a movable and with a fixed backrest (back support) while surface electromyography (EMG) was measured at the level of the fifth lumbar vertebra (L5) and vertical accelerations were measured at the seat, backrest and at the spine at the levels of the second sacral vertebra (S2) and seventh cervical vertebra (C7). The movable backrest significantly reduced accelerations at C7 by up to 11.9% at the 5 Hz frequency band. The movable back support also significantly reduced the coherence and transmission between S2 and C7 accelerations, but not the differential motion between these sensors. EMG at both sides of L5 was on average 28% lower when using the movable backrest. Spinal shrinkage was unaffected by backrest type. It is concluded that a movable backrest reduces the transmission of vibration through the trunk and that it reduces low back EMG. Car driving is associated with the risk of developing low back pain and this may be related to exposure to whole body vibration. This study found an effect of a simple ergonomics measure on the transmission of vibration through the trunk as well as on back muscle activation.

Interestingly, according to Ind Health. 2005 Jul;43(3):421-35

The addition of a back support causes stiffening of the body to limit the low frequency rocking motion of the upper body under x-axis motion, while considerable dynamic interactions with the backrest occur. The mean apparent mass (APMS) responses measured at the seat pan and the backrest suggest strong contributions due to the back support condition, and the direction and magnitude of horizontal vibration, while the role of seat height is important only in the vicinity of the resonant frequencies. In the absence of a back support, the seat pan responses predominate at a lower frequency (near 0.7 Hz) under both directions of motion, while two secondary peaks in the magnitude also occur at relatively higher frequencies. The addition of back support causes the seat pan response to converge mostly to a single primary peak, resulting in a single-degree-of-freedom like behavior, with peak occurring in the 2.7-5.4 Hz range under x-axis, and 0.9-2.1 Hz range under y-axis motions, depending upon the excitation magnitude and the back support condition. This can be attributed to the stiffening of the body in the presence of the constraints imposed by the backrest. A relaxed posture with an inclined backrest, however, causes a softening effect, when compared to an erect posture with a vertical backrest. The backrest, however, serves as another source of vibration to the seated occupant, which tends to cause considerably higher magnitude responses. The considerable magnitudes of the apparent mass response measured at the seat back under fore-aft motions suggest strong interactions with the backrest. Such interactions along the side-to-side motions, however, are relatively small. The results suggest that the biodynamic characterization of seated occupants exposed to horizontal vibration requires appropriate considerations of the interactions with the backrest.

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June 27, 2009

Neck pain, sleep quality and pillow comfort in side sleepers

Filed under: Neck Pain, Posture — Administrator @ 9:02 pm

Pillow use: The behaviour of cervical pain, sleep quality and pillow comfort in side sleepers

From: Man Ther. 2009 May 6. [Epub ahead of print]

Pillow performance research has largely involved testing pillows of novel shape and design, comparing contour and noncontour shaped pillows and comparing contour pillows with the participants’ usual pillow. Shields et al. who undertook a systematic review regarding the effect of contour or cervical pillow use on neck pain, highlighted the methodological flaws in these studies and concluded that there was insufficient evidence to support the use of contour pillows in the management of chronic neck pain. Helewa et al. reported that contour pillows were ineffective in the management of chronic neck pain unless combined with active neck exercises.

The paucity of research has caused health professionals to provide patient advice regarding neck pillows based on the anecdotal suggestions of expert colleagues and professional associations. This advice has included the use of malleable pillows, a cervical roll, a contour pillow or a down or urethane pillow. Furthermore the range of marketing advice provided by pillow manufacturers is confusing for consumers, although details regarding this statement by the authors was not substantiated by evidence.

This paper reports the performance of commonly used type of pillows from specific manufacturers and their association with neck pain behavior. This pillow field trial was undertaken to:

Compare the frequency of waking cervical pain reported when subjects slept on their own pillow and on five trial pillows;

Examine temporal symptom reports, to determine if pillow content or shape was related to overnight abolition of retiring symptoms or overnight production of waking symptoms; and

Compare pillow comfort and sleep quality ratings for participants’
usual pillow and the trial pillows.

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June 23, 2009

Disc hydration following lumbar flexion and extension postures

Filed under: Back Pain, Disc Problems, Posture — Administrator @ 9:03 pm

Changes in Spinal Height Following Sustained Lumbar Flexion and Extension Postures: A Clinical Measure of Intervertebral Disc Hydration Using Stadiometry

From: J Manipulative Physiol Ther. 2009 Jun;32(5):352-7

Throughout the course of the day, the spinal intervertebral discs display viscoelastic creep properties that determine an individual’s overall stature. These properties were demonstrated by Tyrrell et al who used in vivo stadiometry measurements to detect 19.3 mm (1.1% of stature) variation in height between first arising and the end of the day.

Contributions to the total diurnal stature loss from structures other than the intervertebral disc are minimal. Kanlayanaphotporn et al used stadiometer measurements to assess the contribution of soft tissue structures below the sacrum and concluded that these structures accounted for 19% of the height change during the first 5 minutes of sitting. Based on these findings, stadiometry is considered to provide an accurate measure of spinal height changes after various loading conditions.

The 2 primary methods of measuring spine height changes are magnetic resonance imaging (MRI) and stadiometry. Stadiometry has been shown to be a valid and reliable tool to assess spinal height when compared to objectifiable measures made from MRI. Stadiometry assessment has advantages over MRI in terms of costs, use in clinical setting, as well as the ability to measure subjects that simultaneously sustain compressive loads of the trunk.

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April 18, 2009

Backback and computer use among children

Filed under: Back Pain, Neck Pain, Posture — Administrator @ 12:21 pm

Backback and computer use among children and related musculoskeletal disorders

These abstracts are from: Work. 2009;32(3)

Effect of backpack load placement on posture and spinal curvature in prepubescent children

From: Work. 2009;32(3):351-60

Parents, educators and researchers have expressed concern about the long term impacts of children carrying excessive loads in their backpacks on a daily basis. Although many researchers have investigated appropriate weight limits for children’s packs, little research has been conducted on the design of children’s backpacks. The purpose of this study was to evaluate the changes in children’s trunk forward lean, cranio-vertebral angle and spinal lordosis angle that occurred with high, medium and low load locations during standing and walking. Ten-year-old children (n = 15) completed a repeated measures designed study while carrying 15% of each child’s body weight in a typical backpack with only shoulder straps. A special instrumented backpack was designed that allowed the weight to be placed in the proper location and continuously measure changes in spinal curvature. Trunk forward lean and cranio-vertebral angle postures were captured on digital video at five intervals including: standing without a backpack prior to a 1000 m walk; standing with a backpack at the beginning and end of a 1000 m walk; and walking with a backpack at the beginning and end of a 1000 m walk. Results indicated that significant changes occurred in trunk forward lean and cranio-vertebral angle when the backpack was loaded to 15% body weight. The low load placement in the backpack produced fewer changes in cranio-vertebral angle from the initial standing baseline measure than the high and mid placements. When all measures were assessed collectively, there were fewer changes in spinal lordosis angle in the low load placement. These findings indicate that future backpack designs should place loads lower on the spine in order to minimize children’s postural adaptations.

Backpack load limit recommendation for middle school students based on physiological and psychophysical measurements

From: Work. 2009;32(3):339-50

The load of student’s backpacks has raised questions over the safety and health of schoolchildren everywhere. The purpose of this study is to use electromyography (EMG), posture evaluation, heart rate, and ratings of perceived exertion and perceptions of pain to find an acceptable backpack load limit for middle school students. Twenty middle school students aged 11 to 14 (10 female and 10 male) volunteered for the study. The subjects completed two tests, standing stationary and walking on a treadmill, where they carried 5% incremental loads from 0% body mass to 20% body mass. The study indicated that the Borg-CR10 ratings and trunk flexion angle for the walking trial indicated a possible load limit of 10% body mass due to the non-significant difference between 0 and 10% body mass and the significant difference between 10 and 15% body mass.

Computer use in school: Its effect on posture and discomfort in schoolchildren

From: Work. 2009;32(3):321-8

The aim of the study was to investigate the posture and musculoskeletal discomfort of secondary school students while working at computers in school. Students (n = 40) were observed while working at a computer during their designated computer class. The Rapid Upper Limb Assessment Tool was used to assess posture. A Body Discomfort Chart and Visual Analogue Scale were used to record the area(s) and intensity of musculoskeletal discomfort, if any, experienced by the students at the beginning and end of the computer class. None of the students’ posture was in the acceptable range (Action Level 1) according to Rapid Upper Limb Assessment Tool. The majority (65%) were in Action Level 2, 30% were in Action Level 3, and 5% were in Action Level 4. There was a statistically significant increase in reported discomfort from the beginning to the end of the computer class. Longer class length (80 minutes) did not result in greater reporting of discomfort than shorter class length (40 minutes).

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April 16, 2009

Cervical range of motion and changes in head and neck posture

Filed under: Neck Pain, Posture — Administrator @ 7:35 pm

The relationship between the active cervical range of motion and changes in head and neck posture after continuous computer screen work

From: Ind Health. 2009 Apr;47(2):183-8

Poor posture is a common finding in physical therapy evaluations of patients with musculoskeletal complaints. The upper spine has been of particular interest to physical therapists treating disorders of the cervical and thoracic spine, the shoulder, and the temporomandibular region. Many studies have attempted to identify head and neck postures that would reduce the risk of developing musculoskeletal pain of the neck and trunk.

The effects of the head and neck posture depend on the characteristics of a task. Visual display terminal (computer screen) work typically involves remaining for a long time in a fixed position. Sezto et al. found that individuals increase their forward head posture during computer screen work, which involves an excessive anterior position of the head in relation to the theoretical plumb line perpendicular to the body’s center of gravity, and can be considered similar to a protracted position of the cervical spine in which the lower cervical vertebrae are flexed in a forward glide and the upper cervical vertebrae are extended. This causes a shortening of the posterior cervical and suboccipital muscles, lengthening and weakness of the anterior neck muscles, weakness of the scapula retractor muscles, and increased stress on the ligaments. The imbalances created by this position decrease muscular efficiency, and extra muscular action is needed to hold the head and neck in a stable position. Fredriksson et al. reported that neck and shoulder pain was associated with computer screen work in both men and women.

The head and neck posture of an individual can influence soft-tissue relationships in the cervical region. Neck postural changes can lead to neck pain via associated changes in cervical movement patterns, so it is necessary to evaluate cervical spine kinematics in both normal subjects and in patients with neck pain. Reductions in the cervical range of motion (ROM) have implications for the safety and efficiency of functional activities and lead to a loss of corrective or protective reactions, which contribute to a loss of balance in the soft tissue extensibility around a joint. A study has also shown that a decreased cervical ROM is associated with poor sitting postures, such as forward head posture. ROM losses can occur from inactivity and structural changes of the tissues in the cervical spine, and result in an increase in connective-tissue density, shortening of collagen tissue, and muscle fibrosis.

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