Studies on VAX-D
GUSTAVO RAMOS, M.D., AND WILLIAM MARTIN, M.D.
 Departments of Neurosurgery and Radiology, Rio Grande Hospital, McAllen, and
Division of Neurosurgery, Health Sciences Center University of Texas, San Antonio, Texas
The object of this study was to examine the effect of vertebral axial decompression on pressure in the nucleus pulposus of lumbar discs. Intradiscal pressure measurement was performed by connecting a cannula inserted into the patient's L4-5 disc space to a pressure transducer. The patient was placed in a prone position on a VAX-D therapeutic table and the tensionometer on the table was attached via a pelvic harness. Changes in intradiscal pressure were recorded at resting state and while the equipment applied controlled tension to the pelvic harness. Intradiscal pressure demonstrated an inverse relationship to the tension applied. Tension in the upper range was observed to decompress the nucleus pulposus significantly, to below - 100 mm Hg.

    SURGICAL procedures utilizing conventional and percutaneous approaches have established the merits of decompression of intervertebral disc spaces in the management of low-back pain syndrome associated with lumbar disc herniation. Surgery will continue to play an important role in the treatment of patients with low-back pain and sciatica associated with herniated discs and degenerative disc problems. However, for patients who are not candidates for surgery, there is a need to establish a conservative approach that offers an effective means of returning the patient to a functional level of activity.

 

Considerable controversy exists In regard to the various techniques currently employed. Aside from basic bed rest, there are few non-interventional modalities that have been adopted as standards of therapy. Manipulative techniques for mechanical low-back pain associated with posterior facet syndrome or muscle strain have not been found as useful in the management of herniated or degenerated lumbar discs. Similarly, other modalities including ultrasound treatments, various electrical stimulation techniques, shortwave therapy, acupuncture, steroid injections, and the administration of anti-inflammatory agents and muscle relaxants all have a following among some practitioners but fall short of addressing the underlying problems associated with intervertebral disc lesions. All of these treatment methods fail by comparison to surgery, in our opinion, because they have the common problem of not relieving the pain from neurocompression or from the stimuli associated with a prolapsed nucleus pulposus. The only noninterventional method that has been shown to hold any promise of relieving pressure on vital structures of the lumbar region is that of distraction of the lumbar vertebrae by mechanical forces applied along the axis of the spinal column.

 

There has been some investigation into the effects of distracting segments of the spinal column excised from cadavers, as well as radiological studies that provided evidence that the application of certain forms of tension can distract vertebral bodies. One the other hand, there are equally pertinent studies that failed to demonstrate any positive effects from other methods of applying spinal traction. Nachemson and Elfstrom have studied the effects of movement and posture on intradiscal pressure. Their measurements show pressure changes caused by positioning and posture range between 25 and 275 mm Hg, suggesting that some positions and postures may be inadvisable for patients suffering from lumbar disc lesions. Anderson, et al., and others have shown that certain traction techniques can actually cause an increase in intradiscal pressure, which would be undesirable in the treatment of low-back pain associated with herniated discs and a neurocompression etiology.

A new form of therapy, termed "vertebral axial decompression," has recently been introduced in the physical therapy department of the Rio Grande Regional Hospital. This treatment modality has shown considerable promise in relieving low-back pain associated with herniated discs or degenerative disc disease of the lumbar vertebrae in patients who are not considered candidates for surgery. The purpose of this research project was to investigate the influence of this new treatment modality on intradiscal pressure of the lumbar spine of patients receiving this form of therapy.


Fig.1. Photograph illustrating the equipment and the position of the patient as the system is activated. ' The caudal end of the table extends, applying tension to the pelvic belt. Upper body movement is restrained by having the patient grasp the handgrips. A chart recorder on the control console plots a graph of the tension applied and the intradiscal pressure readings are entered on the same graph at the apex of each distraction curve.