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.