Lumbar  spinal manipulation

Specific Ligaments - Specific Motions

Routine daily activity involves the use of combined motions of flexion, lateral bending, and twisting of the lumbar spine, which can result in high stresses to the spinal tissues. This study analyzed the ligamentous stretches and strains in the lumbar motion segments under the permutations of applied combined motions.

A computer model incorporating the L4-L5 geometry was used.

Permutations of combined flexion, lateral bending, and axial twist were systematically varied to test for any sequence effects. Motion-segment geometry ranging from 80-120% of mean published values also were tested. The analytical model predicted that specific ligaments are primarily responsible for controlling specific motions. Pure flexion stretches all posterior ligaments, while lateral bending primarily stretches intertransverse and capsular ligaments. Twisting motions are opposed mainly by stretch in the capsular ligaments. Combined motion increases the ligament stretches of intertransverse ligament and capsular ligaments significantly.

A View Inside the Lumbar Erector Spinae: the Visible Human Project

The portion of the lumbar erector spinae that delivers force over the lumbar spine consists of the iliocostalis lumborum and logissimus thoracis. Recent studies have shown discrepancies in the precise anatomical characteristics of the lumbar portion of the erector spinae, leading researchers to speculate on whether lumbar fascicles of iliocostalis lumborum exist, and whether such fascicles have direct attachments to the ilium.

This study relied on cadaveric image data from the Visible Human Project. Shortly after death, a male and female were frozen and fixated in gelatin. The cadavers were then dissected at intervals of one millimeter or less, using a process called cryosectioning. Images of each section were taken in 24-bit true color. The authors of this study used the lower trunk of both subjects to clarify the anatomy of the lumbar portion of the human lumbar erector spinae muscles. Software was produced to visualize cadaver sections oriented in any direction and with maximum resolution. Three-dimensional coordinates of anatomic structures in the image space could be marked, deriving geometry and physiologic cross-sectional areas of the erector spinae fascicles of lumbar origin.

Results: In both male and female specimens, a large portion of the erector spinae fibers of lumbar origin attached to the erector spinae aponeurosis, supporting classification of the lateral fascicles of the lumbar portion of the lumbar erector spinae as part of the iliocostalis lumborum. 

The authors note that accurate anatomic description of the lumbar erector spinae is vital to understanding injury mechanisms of the lumbar spine. They add that their findings are important for biomechanical analysis of force transmission in the lumbar spine.

Measuring Intradiskal Pressure and Movements

Although spinal manipulation is well regarded for the treatment of low back pain, the mechanisms by which the beneficial results are achieved require further investigation. Four basic effects have been identified:

* release of entrapped synovial folds;
* relaxation of hypertonic muscle by sudden stretching;
* disruption of articular or periarticular adhesions; and
* unbuckling of motion segments that have undergone disproportionate displacement.

The authors contend that these effects suggest that movement may affect the pressure inside of the intervertebral disk.

The present study was performed to investigate relative movement of the vertebrae and variations in intradiskal pressure during flexion or extension lumbar spinal manipulations.

A pressure sensor was inserted into the L3-4 disk in a cadaver, and into the L1-2 to L4-5 disks in another cadaver. Two adjacent vertebrae (L3 and L4 in cadaver one, and L4 and L5 in cadaver two) were each equipped with two accelerometers to record acceleration in the horizontal anatomic plane. Two osteopathic lumbar thrust maneuvers were applied. The first manipulation studied was the "basic lateral decubitus technique in flexion," also known as a spinous push-pull. The second was a manipulation in extension, which was used to produce rotation of the lumbosacral spine and to force extension into the spine.

Results showed that during the thrusts, relative intervertebral movements were apparent; movements differed with the type of manipulation (in flexion and extension). Intradiskal pressure initially increased, then decreased during the manipulation.

These findings suggest it is possible to identify variations in intradiskal pressure and relative movement of the adjacent vertebrae during manipulative thrusts. Lumbar spinal manipulations have a biomechanical effect on the intervertebral disks, producing a brief but marked change in intradiskal pressure. This effect, which differs slightly with the different types of manipulation studied, is the consequence of movements of the adjacent vertebrae. 

Cauda Equina and Nerve Conduction Velocity

The cauda equina marks the lower termination point of the spinal cord and consists of the aggregated sacral and coccygeal nerves.

Although double-level cauda equina compression produces more symptoms in patients and more changes in acute experimental models than does single-level compression, few studies have investigated chronic multiple-level compression of this area of the spine.

A study of 20 dogs subjected to double-level compression analyzed the effects of such compression in terms of nerve conduction velocity (NCV).Balloons were placed under the lamina of the seventh lumbar vertebra and the first sacral vertebra. One week and again one month after inflation, NCV was assessed by local electrical stimulation and recording of muscle action potentials.

After one week there was a significant reduction in nerve conduction velocity induced by 10mm Hg compared with that induced by 0mm Hg; the reduction was similar to that seen in studies on single-level compression. After one month, this initial reduction in NCV had been partially restored.

Results suggest that chronic double-level compression does not induce more changes in nerve conduction velocity than single-level compression after one week, and that the NCV recovery after one month is less complete after double-level compression. This distinction may provide evidence of adaptation of the nerve tissue and the vascularization of the cauda equina nerve roots in response to applied pressure.

Detecting Disc Herniations via Sensibility Tests

Most patients with lumbosacral radicular syndrome (LRS) report pain and sensory impairments rather than decreased muscle strength. Sensibility tests, procedures which assess the sensory system, are frequently used when LRS is suspected.

Fifty-one patients presenting with radicular pain in the lumbosacral nerve roots for at least four weeks were examined to determine differences in sensibility between affected/unaffected lower limbs, and to determine the diagnostic value of the test using very thin monofilaments.

Results indicated that significant differences existed between the affected and unaffected limbs in the L4 dermatome in patients with an L4-L5 disc herniation, and in the L5-S1 dermatome in patients with a L4-L5, L5-S1 herniation.

The sensibility test using monofila-ments may be useful in the clinical evaluation of patients with a lumbosacral radicular syndrome. The monofilament test is capable of excluding the presence of a disc herniation with respect to dermatomes L4, L5 and S1 and at the L4-L5 and L5-S1 levels.

A View Inside the Lumbar Erector Spinae: the Visible Human Project

The portion of the lumbar erector spinae that delivers force over the lumbar spine consists of the iliocostalis lumborum and logissimus thoracis. Recent studies have shown discrepancies in the precise anatomical characteristics of the lumbar portion of the erector spinae, leading researchers to speculate on whether lumbar fascicles of iliocostalis lumborum exist, and whether such fascicles have direct attachments to the ilium.

This study relied on cadaveric image data from the Visible Human Project. Shortly after death, a male and female were frozen and fixated in gelatin. The cadavers were then dissected at intervals of one millimeter or less, using a process called cryosectioning. Images of each section were taken in 24-bit true color. The authors of this study used the lower trunk of both subjects to clarify the anatomy of the lumbar portion of the human lumbar erector spinae muscles. Software was produced to visualize cadaver sections oriented in any direction and with maximum resolution. Three-dimensional coordinates of anatomic structures in the image space could be marked, deriving geometry and physiologic cross-sectional areas of the erector spinae fascicles of lumbar origin.

Results: In both male and female specimens, a large portion of the erector spinae fibers of lumbar origin attached to the erector spinae aponeurosis, supporting classification of the lateral fascicles of the lumbar portion of the lumbar erector spinae as part of the iliocostalis lumborum.

The authors note that accurate anatomic description of the lumbar erector spinae is vital to understanding injury mechanisms of the lumbar spine. They add that their findings are important for biomechanical analysis of force transmission in the lumbar spine.

Cervical Manipulation 

Cervical ROM Assessment: Is One Method Better than Another?

Research on range-of-motion (ROM) often utilizes so many measuring instruments and statistical analyses that it can be difficult to select suitable instruments, procedures and normative values to apply in the clinical setting.

Although ROM reviews have detailed various measurement methods for the cervical spine and have included brief reviews of the literature, the authors contend that no previous study has served as a "comprehensive synthesis of the normative cervical ROM literature."

Studies were included in this review if they reported ROM values, variability or reliability using asymptomatic subjects, or if they represented a specific type of study known as a concurrent validity study. ROM and data regarding the reliability of ROM procedures were grouped by technology and types of motion; clinical validity was assessed; and changes in ROM as a function of age were determined by comparing decade ratios.

Nine different technologies for assessing ROM were identified in the review. Variations within each technology were as large as (or larger than) those between technologies, which the authors suggest may indicate that clinical procedures are as important as the accuracy and precision of the technology itself. Additionally, passive motion was determined to be greater than active motion, and range of motion decreased as age increased (with women exhibiting greater ROM than men). The authors noted that reliability was not adequately tested for the majority of technologies reviewed.

The authors suggest that "...practitioners limit their selection of instruments and the types of motion to those that have demonstrated good reliability." They offer examples such as single inclinometry for assessing active motions and potentiometry for measuring static and dynamic ROM of active and passive motions.

Cervical or Sacroiliac Manipulation Increases Hip ROM

For some, it is controversial to propose that spinal manipulation can be directed for treatment of peripheral joints. Yet practitioners within several manual therapy professions strongly support these approaches.

The objective of this study was to compare the effectiveness of upper cervical spine (C/S) manipulation with manipulation of the sacroiliac joint (SIJ) for increasing hip range of motion (ROM).

At the Macquarie University Centre for Chiropractic Outpatient Clinic, 52 randomly chosen students (aged 18-34) were divided into three groups: those receiving C/S manipulation, those undergoing SIJ manipulation, and those placed in a sham/placebo group.

Manipulation of the C/S and SIJ increased flexion of the hip. But only the upper cervical treatment produced a statistically significant increase. Moreover, post-treatment increases in the cervical group were significantly greater than post-treatment changes seen in the sacroiliac group.

Part of the authors' report stated that "a single manipulation of the first vertebra of normal university students statistically improved hip flexion ROM. By contrast, a single manipulation of the sacroiliac joint did not statistically improved hip flexion ROM in the same population of subjects."

These findings suggest that there is a link between the cervical spine and the lower extremity and that manipulation of the upper cervical area may significantly affect hip ROM and thus play a role in conditions that cause loss of hip ROM. This is the second paper reviewed in this issue of the CRR that discusses the peripheral effects of spinal manipulation. See the first summary for the other paper.

Cervical Manipulation in Extreme Rotation and Extension: Just Say No!

Middle-aged and elderly patients frequently present with cervical spondylotic syndrome. The objective of this study was to obtain experimental and clinical data on the effects of neck extension and extension-rotation of the head on the blood flow of the vertebral artery.

The study was conducted at the Institute of Clinical Anatomy and Biomechanics and the Department of Ultrasound, NanFang Hospital of the First Military University, Guangzhou, China

The investigators examined 3 groups of subjects; 10 fresh spines (T1-2 to the occiput) taken from individuals who had suffered acute brain death, 27 elderly asymptomatic patients, and 23 university students. The investigators observed the dissected spines to see if there was a drop in pressure in the vertebral artery during extreme extension and rotation of the spine. The patients were observed for changes in blood flow velocities during the same movement.

The results indicate that blood flow in the veterbral arteries can be dangerously reduced during cervical manipulation. Since rotary manipulation is one of the oldest and most widely used forms of manual medicine, chiropractors should take special pains to ensure that what they consider appropriate conservative management does not lead to the sorts of damaging complications the results of this study describe.

Conclusions, with a warning: "Extreme extension and extension-rotation of the head should be avoided during cervical manipulation in most patients.� This is because extreme extension-rotation of the head can produce a greater effect on the velocities in the vertebrobasilar arteries than simple extension of the head. �Doctors should be especially careful when rotating the patient�s head to the right side." 

Vertebral Artery Volume Flow: No Change with Rotation or Spinal Manipulation

The vertebral artery is a source of great interest to chiropractors because of its intimate relationship with the cervical vertebrae and because of concern of cerebrovascular complications following spinal manipulation.

Previous studies have quantified blood flow velocity, but few, if any, have investigated vertebral artery volume flow during cervical rotation.

To remedy this deficiency, a study involving 20 students utilized advanced color-coded duplex sonography to assess volume flow through the right vertebral artery. Measurements were taken in the neutral position, during 45° of rotation and at maximal rotation. Subjects were then randomized to a control group or a group that received spinal manipulation of a biomechanical dysfunction of the cervical spine, and volume blood flow was again measured, 3, 10 and 15 minutes after the intervention.

Results: Sonogram analysis revealed no significant difference in volume blood flow with cervical rotation or spinal manipulation, despite changes in flow velocity. 

Chiropractic Technique and the Occipitoatlantal Joint

The occipitoatlantal (OA) joint is the most superior weight-bearing synovial joint in the body. Because the OA articulation is one of the final locations at which the body can adapt to asymmetry or dysfunction below, the author contends that this joint requires evaluation in the context of the entire body.

This article presents a concise physical evaluation process for the OA joint complex and discusses some of the more prominent clinical findings indicative of dynsfunction, particularly as they relate to the "integrated manual care" approach presented by the author. Manual treatment processes are also presented to help clinicians manage dysfunctional findings. Evaluation procedures discussed include:

* postural assessment;

* muscle and joint manual palpation techniques;

* range-of-motion testing; and

* anterior-posterior and lateral gliding tests.

Treatment methods upon finding OA dysfunction are organized around clinical findings of the examination. The author suggests:

* positional release;

* direct methods (low velocity, muscle energy, high velocity);

* myofascial release; and

* general techniques (ischemic compression, isometric contractions, deep stroking massage, friction, etc.).

This paper presents the author's approach to managing OA problems. As he notes, these concepts present practitioners with a variety of methods to manage this part of the spine. Elementary evidence, such as case reports or case series, have not yet been presented to describe relevant clinical scenarios or patient reactions to care. 

Discovery of Dural Attachments in the Cervical Spine

The cervical spine is stabilized posteriorly by the ligamentum nuchae and other ligaments. While previous research has described the ligamentum nuchae in general terms, this study attempted to describe more detailed attachments to the cervical posterior spinal dura and to posterolateral parts of the occipital bone.

Ten heads from embalmed cadavers were sectioned to reveal the ligamentum nuchae and its connection to the cervical posterior spinal dura, allowing for particular attention and reference to the deep aspects of the suboccipital triangle and upper cervical region.

In the midline between the first and second cervical vertebrae, researchers found a fibroelastic ligamentous attachment to the cervical posterior spinal dura derived from the ligamentum nuchae. As the ligamentum passed cranially, part of it passed bilaterally to the posterior aspect of the base of the occipital bone, as far superiorly as the inferior nuchal line and as far laterally as the sutures with the temporal bones.

This study reveals a more complex morphology of the ligamentum nuchae than has previously been described. The bilateral attachments of the nuchae to the occipital bone reaffirm its role in stabilizing the head during rotation of the cervical spine. These findings may have implications in the understanding of facial and cervical pain and associated disorders. 

Mysteries of Cervical Uncovertebral Joint Function Revealed

The cervical uncovertebral joint consists of the uncinate process and its corresponding recess located on the surface of the upper vertebral body. Because osseous spurs in this region can cause cervical radiculopathy, understanding the biomechanical role of these joints may assist clinicians in better treating their patients.

In this study, 14 human cadaver specimens underwent sequential uncovertebral joint resection.

At each stage of resection the joints were analyzed for function, including torsion, flexion, extension and lateral bending, and several conclusions drawn:

* Different subdivisions of the uncovertebral joints may have different biomechanical contributions.

* Statistically significant differences can be observed in different locations of the spine.

* The major biomechanical function of the uncovertebral joints includes the regulation of extension and lateral bending motion, followed by torsion.

Although this study sought to clarify the biomechanical role of uncovertebral joints in cervical segmental stability relating to the surgical setting, the information presented can help all health care professionals to better understand the function of these joints as it relates to patient care.

Blood Pressure Influenced by Upper Cervical Adjustments

Several theories have been suggested for the effects of manipulative treatment and arterial blood pressure (BP). Subluxation and musculoskeletal dysfunction in spinal segments may result in stimulation of sympathetic tone, which may cause vasoconstriction and result in a rise of systemic BP.

Other theories include the effects of manipulation and changes in hormone levels, vestibulosympathetic and cervicosympathetic reflexes which alter BP, and the pressor reflex.

This two-part study attempted to determine whether a vectored adjustment of the atlas would cause a lowering of blood pressure. Eighty patients were evaluated by palpation, for BP (using a digital oscillometric sphygmomanometer) and for signs of pelvic rotation and a supine leg length check. Forty patients demonstrating signs of upper cervical subluxation were designated to the treatment group and 40 patients without such signs were assigned to the control group. Sideposture and upper cervical adjustments were performed on the participants in the treatment group. The control group patients were positioned in side posture but not adjusted. After two minutes BP was checked again. In the second part of this study, only patients with postural distortion were recruited. Pre-adjustment measurements with the patient in the supine and sitting positions were used as 'control' data, which was compared to the BP measurements taken after the upper cervical adjustment.

The results for both portions of this trial show significant differences between pretreatment and post treatment measurements in BP. The results also indicate that palpation and upper cervical adjustments may decrease systolic blood pressure, although it is uncertain how long this effect lasts. The authors recognize the weaknesses of this study, including the lack of blinding, repeated BP checks without adequate time for stabilization and no randomization. This article provides an interesting discussion on some of the possible theories that may explain the phenomenon of BP changes with upper cervical adjustments. 

Vertebral/Manipulation

Manipulation Facilitates Motoneuron Excitability

Despite an increase in the use of spinal manipulation for low back pain (LBP), the mechanism for its efficacy at reducing pain and muscle spasms is not fully understood. Manipulation may involve a decrease of resting motoneuron activity, leading to a decrease in hypertonicity.

To evaluate the effects of lumbar spinal manipulation on motoneuron excitability, the authors utilized a process called transcranial magnetic stimulation (TMS) to measure the amplitude of motor-evoked potentials (MEPs) in the right gastrocnemius muscle of 24 subjects who were in either a control or intervention group.

The intervention consisted of a single side-posture L5-S1 high-velocity, low-amplitude spinal manipulation, given to 12 patients. The 12 patients in the control group were placed in the side-posture position, without any lower-limb flexion or trunk torque; no contact was made on the spine and no manual force was introduced.

Results: MEP amplitudes were "significantly facilitated" for 20 to 60 seconds following spinal manipulation and continued to remain facilitated for up to five minutes, although at a lower amplitude. The control group showed no significant change in MEP amplitude after side positioning.

Conclusion: A significant facilitation, although temporary, appears following spinal manipulation when motoneuron pool excitability is measured by central corticospinal activation using TMS. Therefore, central motor facilitation was demonstrated as a neurophysical reaction to manipulation. This is the first study to report on these central motor changes after spinal manipulation, according to the authors; the next step will be to compare this response in healthy individuals vs. those with LBP. 

Neurophysiological Responses to Lumbar Spinal Manipulation

Research has uncovered a variety of pain generators present in spinal tissues. The presence of mechanosensitive and nociceptive afferent fibers in spinal tissues, and subsequent research documenting the role of afferent stimulation in pain production and neuromuscular stabilization of the spine, provide a possible framework for investigating the mechanisms of spinal manipulative therapy (SMT).

Only recently, however, have the mechanical and physiological influence of spinal manipulative therapy begun to be quantified experimentally.

The purpose of this study was to simultaneously quantify vertebral motions and neuromuscular and spinal nerve root responses to mechanical force, manually assisted, short-lever spinal manipulative thrusts (SMTs). In the study, four patients underwent lumbar laminarthrectomy to decompress the central spinal canal and neuroforamina. Prior to decompression, intraosseous pins were affixed to the lumbar spinous process, with accelerometers mounted to the pins. Following decompression, electrodes were inserted into the musculature adjacent to the pins and around the left and right S1 spinal nerve roots. With the spine exposed, SMTs were delivered internally to the lumbosacral spinous process and facet joints, and externally by contacting the skin overlying the respective spinal landmarks using two force settings and two force vectors.

SMTs resulted in positive electromyographic (EMG) and compound action potential (CAP) responses, usually lasting several milliseconds in duration. Multiple responses were observed in numerous cases. The time between the initiation of the mechanical thrust and the neurophysiologic response to internal and external SMT thrusts ranged from 2.4 to 18.1 milliseconds for EMG responses, and 2.4 to 28.6 milliseconds for CAP responses.

The researchers conclude: "Spinal manipulation results in measurable biomechanical and neurophysiologic responses, which appear to be individualized among patients. The vertebral motions that occur (rotations and translations) and resulting spinal nerve root and muscular reflex responses appear to be temporally related to the applied force during SMT. These findings suggest that intersegmental motions produced by spinal manipulation may play a prominent role in eliciting physiologic responses." 

Neuromechanical Vertebral Motion During Manipulation of the Lumbar Spine

While the clinical outcomes of spinal manipulation (SM) and chiropractic adjustments are the subject of much investigation, basic research into the mechanisms of these procedures remains poorly understood.

Because spinal manipulation is a mechanical intervention, it is reasonable to assume that its benefits may be derived from the mechanical properties of the force applied to the body, the body's response to such force, or a combination of these (and other) factors. Biomechanical investigations of spinal manipulation may help researchers, educators and clinicians better understand the mechanisms of SM, develop SM techniques, train clinicians more effectively, and minimize risks while achieving better patient results.

The objective of this study was to quantify vertebral and intervertebral lumbar spinal motions that occur during spinal manipulation in a live human subject. Four patients (two male, two female) undergoing decompressive spinal surgery volunteered to participate. While under anesthesia, the patients were subjected to a series of 14 mechanical force, manually assisted (Activator instrument) SM thrusts delivered at different facet joints and contact points. Effects were measured using accelerometers affixed to surgical pins fixed to the lumbar spinous process.

Results: Peak-to-peak medial-lateral (ML), posterior-anterior (PA) and axial (AX) vertebral displacements increased significantly with increased applied force. Pronounced coupling was observed between all axes for thrusts delivered over the facet joints; for thrusts delivered to the spinous processes, only the AX and PA axes showed a significant degree of coupling. Posterior-anterior vertebral displacements decreased significantly when the facet joint contact point was caudal to the surgical pin, compared to contact cranial to the pin. Spinal manipulative thrusts over the spinous processes produced significantly greater PA and AX displacements compared to ML displacements. The combined medial-lateral, posterior-anterior and axial peak-to-peak displacements for the force settings and contact points ranged from 0.15 to 0.66 mm, 0.15 to 0.81 mm, and 0.07 to 0.45 mm, respectively.

The authors conclude that their measurements of the spine during the application of spinal manipulative thrusts "corroborate previous spinous process measurements in human subjects." They add, "Our findings demonstrate that PA, ML, and AX spinal motions are coupled and dependent on applied force and contact point."