In vivo measurement of intradiscal pressure changes related to thrust and non-thrust spinal manipulation in an animal model: a pilot study.

BACKGROUND: The intervertebral disc is a known back pain generator and is frequently the focus of spinal manipulative therapy evaluation and treatment. The majority of our current knowledge regarding intradiscal pressure (IDP) changes related to spinal manual therapy involves cadaveric studies with their inherent limitations. Additional in vivo animal models are needed to investigate intervertebral disc physiological and molecular mechanisms related to spinal manipulation and spinal mobilization treatment for low back disorders. METHODS: Miniature pressure catheters (Millar SPR-1000) were inserted into either the L4-L5 or L5-L6 intervertebral disc of 3 deeply anesthetized adult cats (Oct 2012-May 2013). Changes in IDP were recorded during delivery of instrument-assisted spinal manipulation (Activator V® and Pulstar®) and motorized spinal flexion with/without manual spinous process contact. RESULTS: Motorized flexion of 30° without spinous contact decreased IDP of the L4-L5 disc by ~ 2.9 kPa, while physical contact of the L4 spinous process decreased IDP an additional ~ 1.4 kPa. Motorized flexion of 25° with L5 physical contact in a separate animal decreased IDP of the L5-L6 disc by ~ 1.0 kPa. Pulstar® impulses (setting 1-3) increased IDP of L4-L5 and L5-L6 intervertebral discs by ~ 2.5 to 3.0 kPa. Activator V® (setting 1-4) impulses increased L4-L5 IDP to a similar degree. Net changes in IDP amplitudes remained fairly consistent across settings on both devices regardless of device setting suggesting that viscoelastic properties of in vivo spinal tissues greatly dampen superficially applied manipulative forces prior to reaching deep back structures such as the intervertebral disc. CONCLUSIONS: This study marks the first time that feline in vivo changes in IDP have been reported using clinically available instrument-assisted spinal manipulation devices and/or spinal mobilization procedures. The results of this pilot study indicate that a feline model can be used to investigate IDP changes related to spinal manual therapy mechanisms as well as the diminution of these spinal manipulative forces due to viscoelastic properties of the surrounding spinal tissues. Additional investigation of IDP changes is warranted in this and/or other in vivo animal models to provide better insights into the physiological effects and mechanisms of spinal manual therapy at the intervertebral disc level.

Three-Dimensional Spinal Position With and Without Manual Distraction Load Increases Spinal Height.

OBJECTIVE: The purpose of this study was to investigate if spinal height increases using 3-dimensional (3-D) spinal position with and without manual distraction load and to assess the correlation between spine height changes and degrees of trunk rotation. METHODS: Fifty-six participants were randomly placed in one of two groups: (1) 3-D spinal position with manual distraction load, and (2) without manual distraction load. Spinal height was measured before and after the interventions using a stadiometer. For the statistical analysis, we used a 2 (Loading status: pre- versus post-intervention height) X 2 (3-D spinal position: with versus without manual distraction load) repeated measures Analysis of Variance (ANOVA) was used to identify significant interaction and main effects. Paired t-tests were used to calculate differences in spinal height changes between the two interventions. Pearson correlation coefficient was used to measure correlations between changes in spinal heights and degrees of trunk rotation. RESULTS: Mean spinal height increase with 3-D spinal position with and without manual distraction load was 6.30 mm (±6.22) and 5.69 mm (±4.13), respectively. No significant interaction effect was present between loading status and 3-D spinal position but a significant main effect in loading status was. Paired t-tests revealed significant differences in spinal heights between pre-and post-3-D spinal position with and without manual distraction load. No significant correlation was measured between trunk rotation and spinal height changes. CONCLUSION: 3-D spinal position with or without distraction load increased spinal height. This suggests that 3-D spinal positioning without manual distraction could be used in home settings to help maintain intervertebral disc (IVD) health.

Growing a backbone - functional biomaterials and structures for intervertebral disc (IVD) repair and regeneration: challenges, innovations, and future directions.

Back pain and associated maladies can account for an immense amount of healthcare cost and loss of productivity in the workplace. In particular, spine related injuries in the US affect upwards of 5.7 million people each year. The degenerative disc disease treatment almost always arises due to a clinical presentation of pain and/or discomfort. Preferred conservative treatment modalities include the use of non-steroidal anti-inflammatory medications, physical therapy, massage, acupuncture, chiropractic work, and dietary supplements like glucosamine and chondroitin. Artificial disc replacement, also known as total disc replacement, is a treatment alternative to spinal fusion. The goal of artificial disc prostheses is to replicate the normal biomechanics of the spine segment, thereby preventing further damage to neighboring sections. Artificial functional disc replacement through permanent metal and polymer-based components continues to evolve, but is far from recapitulating native disc structure and function, and suffers from the risk of unsuccessful tissue integration and device failure. Tissue engineering and regenerative medicine strategies combine novel material structures, bioactive factors and stem cells alone or in combination to repair and regenerate the IVD. These efforts are at very early stages and a more in-depth understanding of IVD metabolism and cellular environment will also lead to a clearer understanding of the native environment which the tissue engineering scaffold should mimic. The current review focusses on the strategies for a successful regenerative scaffold for IVD regeneration and the need for defining new materials, environments, and factors that are so finely tuned in the healthy human intervertebral disc in hopes of treating such a prevalent degenerative process.

Changes in Spinal Height After Manual Axial Traction or Side Lying: A Clinical Measure of Intervertebral Disc Hydration Using Stadiometry

OBJECTIVES: The purpose of this study was to determine the immediate effects of a manual therapy technique consisting of axial traction compared with side lying on increased spine height after sustained loading. METHODS: Twenty-one asymptomatic participants were included. Participants either received manual therapy technique consisting of manual axial traction force for 2 consecutive rounds of 3 minutes or sustained side lying for 10 minutes. Spine height was measured using a commercially available stadiometer. Spinal height change was determined from measurements taken after loaded walking and measurements taken after manual therapy. A paired t test was performed to determine if a manual therapy technique consisting of axial traction increased spinal height after a period of spinal loading. RESULTS: A significant increase in height was found after both manual therapy technique and sustained side lying (P < .0001). The mean height gain was 8.60 mm using 3-dimensional axial separation. CONCLUSION: This study is an initial attempt at evaluating the biomechanical effects of manual therapy technique consisting of axial traction. Both manual axial traction force and sustained side-lying position were equally effective for short-term change in spine height after a loaded walking protocol among healthy asymptomatic individuals. This study protocol may help to inform future studies that evaluate spine height after loading.

Evaluation of the Effect of Daptomycin, a Glycopeptide Agent, on Intact Intervertebral Disc Tissue.

AIM: To evaluate the effects of pre- and intra-operatively administered daptomycin (DAP) on the intact human primary intervertebral disc tissue cells. MATERIAL AND METHODS: Primary cell cultures were established using tissues obtained through decompressive laminectomy, traumatic intervertebral disc herniation excision, and posterior transpedicular stabilization. Non-drug-administered samples were used as a control group. The samples treated with DAP formed the study group. Molecular assays for proliferation and gene expression were performed. The obtained data were evaluated statistically, and results with a value of p < 0.05 were accepted as significant. RESULTS: While no reduction was observed in the proliferation, the gene expression of intact intervertebral disc tissue cells was time-dependently decreased compared to the control group, and these results were reported to be statistically significant. CONCLUSION: This study observed the effect that a pharmaceutical preparation, which was used on intervertebral disc tissue before and after the operation, had on normal, healthy, and intact tissue. It concludes that alterations in the expression of genes involved in the anabolic and/or catabolic process, even in adjacent healthy tissue, may slow down the healing process of the damaged tissue or cause undesired cell differentiation.

A Finite Element Analysis of Stress Distribution and Disk Displacement in Response to Lumbar Rotation Manipulation in the Sitting and Side-Lying Positions.

OBJECTIVE: This study aimed to investigate stress distribution and disk displacement in healthy and degenerated intervertebral disks during simulated lumbar rotation manipulation (LRM) in the sitting and side-lying positions. METHODS: Three-dimensional (3D) finite element models of healthy, mildly degenerated and moderately degenerated L4/5 spinal units were reconstructed. Lumbar rotation manipulation in the sitting and side-lying positions were simulated, and alterations in stress distribution and disk displacement in the lumbar disks were observed. RESULTS: The application of LRM in the sitting or side-lying position resulted in a similar stress distribution in healthy, mildly degenerated, and moderately degenerated disks. Stress was concentrated at the anterior right side of the annulus. In all disks, intradiskal pressure (IDP) and maximum von Mises stress were higher during LRM in the sitting position than during LRM in the side-lying position. During these manipulations, Intradiskal pressure and stress in the annulus of moderately degenerated disks were higher than in mildly degenerated disks. Displacement was most obvious in healthy disks. CONCLUSIONS: Mildly and moderately degenerated lumbar disks were subject to higher stress during LRM in the sitting position than during LRM in the side-lying position. Intradiskal pressure and the maximum von Mises stress in the annulus of moderately degenerated disks increased, suggesting the need for caution when treating patients with moderately compromised disks. Although our results are in accordance with previously published data, they are simulated and preliminary and do not necessarily replicate the clinical condition.

Physiological effects of physical therapy interventions on lumbar intervertebral discs: A systematic review.

BACKGROUND CONTEXT: The use of physical therapy has been recommended in the treatment of low back pain based on primarily mechanical and neurophysiological effects. Recent studies have measured the physiological effects of physical therapy interventions, including manual therapy and traction, on the intervertebral discs (IVD), and these findings may have implications for the long-term management or even prevention of low back pain. PURPOSE: The objective of this systematic review is to investigate the literature regarding possible physiological effects of physical therapy interventions on the intervertebral disc (IVD). STUDY DESIGN: Systematic Review. METHODS: A literature search of published articles through December 2014 resulted in the retrieval of 8 clinical studies assessing the influence of physical therapy interventions on the physiology of the IVD. RESULTS: Three studies, including two using animal models, investigated the effects of 30-minute intermittent traction on disc height. One in vivo animal study and two studies using human subjects assessed changes of disc height associated with static traction. Three studies investigated the effects of lumbar spine manipulation and mobilization on changes in water diffusion within the IVD. All studies confirmed, either directly or indirectly, that their respective intervention influenced disc physiology primarily through water flow. CONCLUSION: Physical therapy interventions may have an effect on the physiology of the IVD, primarily through water diffusion and molecular transport, which are important for the health of the IVD.

A finite element study of traditional Chinese cervical manipulation.

PURPOSE: Traditional Chinese cervical manipulation (TCCM) has been claimed as an effective treatment for diseases of the cervical spine, but its biomechanical effects on the vertebral body and intervertebral discs remain unclear. The aim of this study was to develop and validate a detailed finite element model of cervical spine, which was then used to investigate the biomechanical response of the cervical spine to TCCM. METHODS: The model of a C2-T1 cervical spine was constructed based on CT images of a healthy male volunteer and validated against published in vitro studies under different loading conditions. The detailed force-time data of TCCM were measured on the same volunteer through dynamometric diaphragms. The data were applied on the validated finite element model to simulate TCCM. RESULTS: The current model could offer potentials to effectively reflect the behavior of human cervical spine suitable for biomechanics studies of TCCM. Under simulated TCCM condition, the stress distributions in cervical spine and intervertebral discs could not be completely explained through the traditional theory. CONCLUSION: Spinal manipulation, or TCCM, might play no role in reducing intradiscal pressure for treating cervical spondylosis. It could cause less stress concentration in intervertebral discs while operating spinal manipulation or TCCM when the adjustment points was chosen near the root of spinous process than the top of spinous process.

Assessment of Lumbar Spine Height Following Sustained Lumbar Extension Posture: Comparison Between Musculoskeletal Ultrasonography and Stadiometry.

OBJECTIVES: The purpose of this study was to correlate sitting height measured by stadiometry with lumbar spine height (LSH) modifications measured by musculoskeletal ultrasonography (MSU). METHODS: Eighteen healthy young adults were recruited for this study (mean age: 21.5 ± 1.5 years). All subjects were tested in the following sequence: (1) lying supine for 10 minutes, (2) sitting under loaded (9.5 kg) and unloaded conditions for 5 minutes each, (3) lying supine for 15 minutes with passive lumbar extension, and (4) sitting unloaded for 5 minutes. Both stadiometry and MSU measurements were taken after each step of the testing sequence. RESULTS: Following the loaded sitting step, sitting height (measured by stadiometry) decreased by 3.4 ± 1.6 mm, whereas following sustained lumbar extension, sitting height increased by 5.4 ± 3.5 mm (P < .05). Following loaded sitting and sustained lumbar extension, LSH decreased by 3.8 ± 1.7 mm and increased by 6.2 ± 4.1 mm, respectively (P < .05). On the basis of the mean differences (between the different steps of the testing sequence), the mean correlation coefficient and the mean coefficient of determination between stadiometry and MSU measurements were calculated at 0.93 ± 0.07 and 0.88 ± 0.13, respectively, and no statistical differences were observed (P > .05). CONCLUSIONS: In vivo measurements of sitting height changes, measured using stadiometry, were strongly correlated with LSH changes, measured using ultrasonography.

Evidence on the Ability of a Pneumatic Decompression Belt to Restore Spinal Height Following an Acute Bout of Exercise.

OBJECTIVE: The purpose of this study was to evaluate the ability of a pneumatic decompression belt to restore spinal height lost following an acute bout of exercise that induced compression. METHODS: This study implemented a test-retest repeated measures design in which twelve participants (male = 10, female = 2) age, 21.5 ± 1.0 years; height, 179.0 ± 7.70 cm; weight, 84.0 ±11.5 kg; were recruited from a university population and acted as their own control. All participants were healthy with no previous history of disabling back pain, and were frequent weight trainers. A stadiometer was used to measure spinal height at baseline, then following an acute bout of exercise and then again following the intervention (use of a pneumatic decompression belt for 20 minutes) or control (lying supine for 20 minutes). A 2-way repeated measures ANOVA was performed on the change in spinal height in order to evaluate differences between measurement phases and intervention conditions. RESULTS: The use of the decompression belt increased spinal height gain (4.3 ± 3.0 mm) significantly more than the control condition (1.8 ± 1.2 mm) following an acute bout of weightlifting exercises known to elicit high compressive loads on the lumbar spine. CONCLUSION: The pneumatic decompression belt restored spinal height faster than a non-belt wearing condition in young healthy asymptomatic participants.

Effects of Axial Torsion on Disc Height Distribution: An In Vivo Study.

OBJECTIVES: Axial rotation of the torso is commonly used during manipulation treatment of low back pain. Little is known about the effect of these positions on disc morphology. Rotation is a three-dimensional event that is inadequately represented with planar images in the clinic. True quantification of the intervertebral gap can be achieved with a disc height distribution. The objective of this study was to analyze disc height distribution patterns during torsion relevant to manipulation in vivo. METHODS: Eighty-one volunteers were computed tomography-scanned both in supine and in right 50° rotation positions. Virtual models of each intervertebral gap representing the disc were created with the inferior endplate of each "disc" set as the reference surface and separated into 5 anatomical zones: 4 peripheral and 1 central, corresponding to the footprint of the annulus fibrosus and nucleus pulposus, respectively. Whole-disc and individual anatomical zone disc height distributions were calculated in both positions and were compared against each other with analysis of variance, with significance set at P < .05. RESULTS: Mean neutral disc height was 7.32 mm (1.59 mm). With 50° rotation, a small but significant increase to 7.44 mm (1.52 mm) (P < .0002) was observed. The right side showed larger separation in most levels, except at L5/S1. The posterior and right zones increased in height upon axial rotation of the spine (P < .0001), whereas the left, anterior, and central decreased. CONCLUSIONS: This study quantified important tensile/compressive changes disc height during torsion. The implications of these mutually opposing changes on spinal manipulation are still unknown.

Real-time monitoring of stresses and displacements in cervical nuclei pulposi during cervical spine manipulation: a finite element model analysis.

OBJECTIVE: The objective of this study was to research the distribution of stresses and displacements in cervical nuclei pulposi during simulated cervical spine manipulation (CSM). METHODS: A 3-dimensional finite element model of C3/4~C6/7 was established. The detailed mechanical parameters of CSM were analyzed and simulated. During the process, the changes in stresses and displacements of cervical nuclei pulposi within the model were displayed simultaneously and dynamically. RESULTS: Cervical spine manipulation with right rotation was targeted at the C4 spinous process of the model. During traction, levels of stresses and displacements of the nuclei pulposi exhibited an initial decrease followed by an increase. The major stresses and displacements affected the C3/4 nucleus pulposus during rotation in CSM, when its morphology gradually changed from circular to elliptical. The highest stress (48.53 kPa) occurred at its right superior edge, on rotating 40° to the right. It protruded toward the right superior, creating a gap in its left inferior aspect. The highest displacement, also at 40° right, occurred at its left superior edge and measured 0.7966 mm. Dimensions of stresses and displacements reduced quickly on rapid return to neutral position. CONCLUSION: The morphology of the C3/4 nucleus pulposus changed during CSM with right rotation, and it created a gap in its left inferior aspect. Biomechanically, it is more safe and rational to rotate toward the healthy side than the prolapsed side of the intervertebral disk during CSM. Upon ensuring due safety, the closer the application force is to the diseased intervertebral disk, the better is the effect of CSM.

Shape-memory porous alginate scaffolds for regeneration of the annulus fibrosus: effect of TGF-ß3 supplementation and oxygen culture conditions.

Disc herniation as a result of degenerative or traumatic injury is believed to be the primary instigator of low back pain. At present there is a lack of viable treatment options to repair damaged annulus fibrosus (AF) tissue. Developing alternative strategies to fill and repair ruptured AF tissue is a key challenge. In this work we developed a porous alginate scaffold with shape-memory properties which can be delivered using minimally invasive approaches and recover its original geometry once hydrated. Covalently cross-linked alginate hydrogels were created using carbodiimide chemistry, followed by a freeze-drying step to impart porosity and create porous scaffolds. Results showed that porous alginate scaffolds exhibited shape-memory recovery and mechanical behaviour that could be modulated depending on the cross-linker concentrations. The scaffold can be repeatedly compressed and expanded, which provides the potential to deliver the biomaterial directly to the damaged area of the AF tissue. In vitro experiments demonstrated that scaffolds were cytocompatible and supported cell seeding, penetration and proliferation under intervertebral-disc-like microenvironmental conditions (low glucose media and low oxygen concentration). Extracellular matrix (ECM) was secreted by AF cells with TGF-ß3 stimulation and after 21days had filled the porous scaffold network. This biological matrix was rich in sulfated glycosaminoglycan and collagen type I, which are the main compounds of native AF tissue. Successful ECM deposition was also confirmed by the increase in the peak stress of the scaffold. However, the immaturity of the matrix network after only 21days of in vitro culture was not sufficient to attain native AF tissue mechanical properties. The ability to deliver porous scaffolds using minimal invasive approaches that can potentially promote the regeneration of AF defects provides an exciting new avenue for disc repair.

An injectable hydrogel incorporating mesenchymal precursor cells and pentosan polysulphate for intervertebral disc regeneration.

Intervertebral disc (IVD) degeneration is one of the leading causes of lower back pain and a major health problem worldwide. Current surgical treatments include excision or immobilisation, with neither approach resulting in the repair of the degenerative disc. As such, a tissue engineering-based approach in which stem cells, coupled with an advanced delivery system, could overcome this deficiency and lead to a therapy that encourages functional fibrocartilage generation in the IVD. In this study, we have developed an injectable hydrogel system based on enzymatically-crosslinked polyethylene glycol and hyaluronic acid. We examined the effects of adding pentosan polysulphate (PPS), a synthetic glycosaminoglycan-like factor that has previously been shown (in vitro and in vivo) to this gel system in order to induce chondrogenesis in mesenchymal precursor cells (MPCs) when added as a soluble factor, even in the absence of additional growth factors such as TGF-ß. We show that both the gelation rate and mechanical strength of the resulting hydrogels can be tuned in order to optimise the conditions required to produce gels with the desired combination of properties for an IVD scaffold. Human immunoselected STRO-1+ MPCs were then incorporated into the hydrogels. They were shown to retain good viability after both the initial formation of the gel and for longer-term culture periods in vitro. Furthermore, MPC/hydrogel composites formed cartilage-like tissue which was significantly enhanced by the incorporation of PPS into the hydrogels, particularly with respect to the deposition of type-II-collagen. Finally, using a wild-type rat subcutaneous implantation model, we examined the extent of any immune reaction and confirmed that this matrix is well tolerated by the host. Together these data provide evidence that such a system has significant potential as both a delivery vehicle for MPCs and as a matrix for fibrocartilage tissue engineering applications.

Fiabilidad interobservador del test de movilidad pasiva accesoria intervertebral lumbar y su correlación con la galvanopalpación en sujetos sanos / Inter-observer reliability of the passive accessory intervertebral motion test and its correlation with the galvanic palpation in healthy subjects

Introducción El diagnóstico de fisioterapia de las disfunciones vertebrales es fundamental para clasificar las alteraciones musculoesqueléticas. La evaluación pasiva de la cantidad y la calidad del movimiento en los diferentes segmentos vertebrales guía la toma de decisiones en relación con el tratamiento de fisioterapia. Los objetivos del presente estudio son determinar la fiabilidad interobservador del test de movilidad pasiva accesoria posteroanterior intervertebral unilateral lumbar como test indicado para identificar sujetos con disfunción articular y analizar la corriente galvánica como herramienta diagnóstica en la identificación de disfunción articular en la columna lumbar con dicho test ortopédico. Material y método Dos fisioterapeutas expertos en fisioterapia manual realizaron el test en una muestra de 30 sujetos asintomáticos en los niveles L1-L5 (lado derecho e izquierdo), realizándose un total de 300 pruebas. Se determinó que un nivel lumbar estaba en disfunción basándose en una sensación final anormal, la calidad de la resistencia anormal y la posible aparición de dolor asociado al movimiento. Para determinar la utilidad diagnóstica de la corriente galvánica, otros dos fisioterapeutas realizaron galvanopalpación consecutivamente al test de movilidad en las articulaciones interapofisarias lumbares de los mismos sujetos asintomáticos. Resultados En el test de movilidad, el porcentaje de acuerdo fue del 86,3%. El índice kappa (k) mostró un acuerdo moderado (k=0,5). El test fue más fiable en los niveles lumbares L3-L4 y L4-L5. En la galvanopalpación el porcentaje de acuerdo fue del 83%. El k mostró un acuerdo moderado en la identificación de disfunción articular (k=0,41). La sensibilidad fue alta en el nivel lumbar L3-L4 y L4-L5 y baja en L1-L2; la especificidad fue elevada (82,7–96,3%) en toda la columna lumbar. Conclusiones La fiabilidad interobservador del test de movilidad es moderada (k=0,5). La galvanopalpación identifica disfunciones articulares, pero en la columna lumbar alta la sensibilidad es baja (AU)

Introduction The physical therapy diagnosis of a vertebral dysfunction is essential in order to classify musculoskeletal diseases. Passive assessment of quantity and quality of movement on the different vertebral segments guides the decision-making process relative to manual therapy treatment. The aims of this present study have been to determine the interobserver reliability of passive accessory intervertebral postero-anterior unilateral lumbar motion test as a test to identify subjects with joint dysfunction, and to analyze galvanic current as a diagnostic tool to identify joint dysfunction in the lumbar spine with the motion test. Material and methods Two physiotherapists, experts in manual therapy, carried out the test in 30 asymptomatic subjects at L1 to L5 levels (right and left sides), performing a total of 300 tests. To determine the diagnostic value of galvanic current, two other physiotherapists performed galvanic palpation consecutively to the motion test in lumbar zygapophysial joints in the same asymptomatic subjects. Results Percentage agreement was 86.3% for the motion test. The Kappa index showed substantial agreement (according to Landis and Koch, 1977) (k=0.5). PA accessory motion test was more reliable to identify symptomatic spinal L4-L5 and L5-S1 level. Regarding galvanic palpation, the agreement percentage was 83%. Kappa coefficient (k) showed moderate agreement for identification of joint dysfunction (k=0.41). Sensitivity was high in the lumbar level L3-L4 and L4-L5 and was low in L1-L2 level; specificity was high (82.7–96.3%) throughout the lumbar spine. Conclusions Interobserver reliability of the passive motion test is moderate (k=0.5). Galvanic palpation identifies joint dysfunction, however sensitivity is low in the upper lumbar spine (AU)

Changes in spinal height following sustained lumbar flexion and extension postures: a clinical measure of intervertebral disc hydration using stadiometry.

BACKGROUND: Decreased intervertebral disc height can result in diminished load carrying capacity of the spinal segment. Clinical means of assessing postures able to rehydrate the discs were investigated. OBJECTIVE: The purposes of this study were 3-fold: (1) to determine if our test protocol using a commercially available stadiometer demonstrated findings consistent with prior laboratory-based protocols; (2) to determine if hyperextension in the prone position and trunk flexion in the supine position caused increased spine height after sustained loading; and (3) to compare the effects of hyperextension in the prone position and trunk flexion in the supine position on spine height changes after a period of sustained loading. METHODS: This study used a pretest, posttest crossover design. Ten women and 11 men (mean age, 24 +/- 2.6 years) participated. Subjects held either 10 minutes of hyperextension in the prone position or 10 minutes of trunk flexion in the supine position in the recovery phase. Spine height was measured using a commercially available stadiometer. Spinal height change was determined from measurements taken after loaded sitting and measurements taken after hyperextension in the prone position and trunk flexion in the supine position. RESULTS: A 1-sample t test indicated no significant difference existed between our mean height change after 5 minutes of sitting and previously published validated findings. A paired t test indicated significant increase in height after both supine flexion and prone extension lying (P< .0001). The mean height gain was 3.11 mm using prone extension and 3.19 mm using the supine flexion protocol. A paired t test indicated no significant difference between these 2 recovery positions (P = .927). CONCLUSION: The stadiometer measurement protocol demonstrated that hyperextension in the prone position and trunk flexion in the supine position were easily effective positions for the temporary recovery of spine height after sustained loading. These findings lay the foundation for future research into the viscoelastic creep properties of the intervertebral disk under loading and therapeutic conditions.

Viscoelastic stresses on anisotropic annulus fibrosus of lumbar disk under compression, rotation and flexion in manual treatment.

BACKGROUND: Twisting (spinal rotation) and bending (flexion) are commonly reported as triggers for low back pain. This paper addresses whether the twisting stress on the annulus fibrosus of the lumbar disk is greater or less than the bending stress for the same angle of twist or bending. METHODS: Stress-strain relation for transversely isotropic material is applied to the transversely isotropic annulus fibrosus of the lumbar disk to analyze the viscoelastic stresses produced due to 6% compression, 10 degrees twist and 10 degrees bending. FINDINGS: The bending stress is 450 times greater than the twisting stress for the same angle of twist or bending of the annulus fibrosus. The twisting and bending moments increase two-fold in quick maneuvers lasting 0.1s (as in high velocity manipulations), compared to slow maneuvers lasting 60s. INTERPRETATION: From biomechanical perspective, in situations where both flexion and spinal rotation occur, the stress on the intervertebral disk is markedly higher with flexion compared to rotation. In patients with low back pain that has a disk mediated (discogenic) component, manipulation and mobilization therapies should avoid flexion to minimize stress on the disks. This is particularly relevant for high velocity manipulations where the stress on the disk is doubled for both flexion and rotation. The results in this paper can help guide manual therapists to adjust their treatments to minimize stress on the intervertebral disk.

Torsion-induced pressure distribution changes in human intervertebral discs: an in vitro study.

STUDY DESIGN: Biomechanical testing of human cadaveric lumbar specimens was performed to evaluate the effects of torsional torque on intradiscal pressure and disc height. OBJECTIVE: Evaluate the effects of small torsion torques on intradiscal pressure and disc height in human lumbar specimens. SUMMARY OF BACKGROUND DATA: Nuclear depressurization in addition to an instantaneous disc height increase were found in previous porcine research when small (<2 degrees) axial vertebral rotations were applied. If applicable to human spines, this phenomenon may support spinal manipulation for the relief of low back pain. METHODS: Six human lumbar cadaveric functional spine units (FSU) were loaded in the neutral position with 600 N axial compression. Intranuclear pressure measurements were then obtained at 0, 0.5, 1.0, and 2.0 Nm of torsion. Posterior elements were removed and measurements were repeated for the disc body unit (DBU). RESULTS: There was no statistically significant difference in nuclear pressure or intervertebral disc height with different torsion torques among or between the FSUs and DBUs. However, a disc height increase ranging from 0.13 mm to 0.16 mm occurred with the insertion of a 1.85-mm diameter pressure probe cannula. CONCLUSIONS: Small torsion torques showed no significant difference in intradiscal pressures or disc heights. This is an unlikely mechanism for the perceived benefits of spinal manipulation.

Historical perspective milestones in the evolution of lumbar spinal postural health in seating.

The best knowledge on seated posture before the Enlightenment was not scientific, but influenced by sociocultural, economic, and manufacturing factors. Although the pursuit of knowledge related to spinal postural health was advanced with the advent of empirico-analytic research, academic opinion continued to be influenced by unsubstantiated information, often resulting in incorrect advice to the public. Only in the past decade has advice on "correct" seated posture, spanning the time from the Hippocratic texts to the present, been brought into question by evidence-based research. By exploring seating from 3100 B.C to the present, this article discusses key influences that have an impact on seating functional to spinal postural health. Emphasis is placed on the role of medical opinion.

The response of posteroanterior lumbar stiffness to repeated loading.

Lumbar posteroanterior (PA) responses are determined by manual examination and are used to guide treatment decisions and interpret changes in symptoms within and between treatments. Mechanical devices that simulate manual assessment have been developed to measure lumbar PA responses. The two variables used to describe lumbar PA responses to mechanical loading are stiffness coefficient K and displacement D30. The purpose of this study was to investigate the behaviour of lumbar PA responses with repeated loading over time. Lumbar PA responses at L4 were measured in 18 pain-free subjects using a mechanical device. Measurements were made for five consecutive loading cycles on three test occasions. The responses were compared between the five cycles within a single test occasion and between three test occasions. An identical procedure was also used to test a set of elastic springs for comparison. There was a significant increase in both stiffness coefficient K and displacement D30 between the first cycle and subsequent cycles of a single test occasion on human subjects. This response which demonstrates an increase in stiffness and displacement between the first and subsequent cycles can be considered a normal response to PA loading. PA stiffness remains constant over several tests both within one day and between days.