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TRABAJOS CIENTIFICOS

TRABAJO CIENTIFICO Nº 1

JOURNAL OF NEUROLOGICAL RESEARCH VOL 20, NO 3, APRIL 1998

Vertebral Axial Decompression Therapy for pain associated with herniated or degenerated
discs or facet syndrome: An outcome study

Earl E. Gose, William K. Naguszewski* and Robert K. Naguszewski*
Department of Bioengineering, University of Illinois at Chicago, Chicago, IL. USA
*Coosa Medical Group, Rome, Georgia, USA

The outcomes of vertebral axial decompression (VAX-D) therapy for patients with low back pain from various causes are reported. Data was collected from twenty-two medical centers for patients who received VAX-D therapy for low back pain, which was sometimes accompanied by referred leg pain. Only patients who received at least ten sessions and had a diagnosis of herniated disc, degenerative disc or facet syndrome which were confirmed by diagnostic imaging, were included in this study; a total of 778 cases. The average time between the initial onset of symptoms and the beginning of this therapy was 40 months, and it was four months or more in 83% of the cases.

The data contained the patients' quantitative assessments of their own pain, mobility, and ability to carry out the usual 'activities of daily living'. The treatment was successful in 71% of the 778 cases, when success was defined as a reduction in pain to 0 or 1, on a 0 to 5 scale. Improvements in mobility and activities of daily living correlated strongly with pain reduction. The causes of back pain and their relationship to this therapy are also discussed.

 

INTRODUCTION

For most patients, the cause or causes of persistent low back pain remains poorly understood. Although imaging procedures, including CT and MRI, are able to accurately define structural pathology, the correlation of these anatomic findings with physiology, back pain, and other clinical complaints is imprecise(1). Although surgical decompression, epidural blocks, and spinal instrumentation can sometimes help patients suffering from back pain, these treatments do not completely take the biomechanical function of the disc into account, and may leave patients unrelieved of their suffering. In addressing the dysfunction of the disc with discectomy or surgical instrumentation, the biomechanical and physiological function of the disc is permanently disrupted.

Mechanical low back pain is usually aggravated by activities that increase axial loading on the spine, such as sitting, standing, and lifting. Patients may describe some relief with walking, but more particularly, by lying down, which unloads the spine and reduces intradiscal pressure (2,3). The causes of mechanical low back pain may include degenerative disc disease, degenerative spondylosis with limitation of range of motion, facet arthropathy, relative lateral recess stenosis from a combination of the above, microenvironment pressure changes affecting the thecal and epidural space from disc bulging, subligamentous and/or extruded herniation, and segmental instability.

Pain generation from degenerative disc disease is probably multifactorial. A number of potential mechanisms are specifically addressed by the lumbar vertebral body separation achieved during therapy. With aging, disc desicction occurs, disc height is lost, and this process is accelerated with activities which produce high physical loading of the lumbar spine (4). Osteophytes develop along the anterolateral and posterior border of the vertebral bodies, and facet arthropathy increases as degenerative disc change advances (5). Normal vertebral body separation is lost as the disc degenerates. Redundancy of the posterior longitudinal ligament and ligamentum flavum combine with osteophyte encroachment upon the neuroforamen or central canal, resulting in stenosis at these sites, which is increased by axial loading of the spine.

The blood supply to the nerve roots of the cauda equina is sensitive to compression. Even at pressures of only 5-10mmHg, the flow in over 20% of the venules was completely stopped (6). Flow in all the capillaries stopped at pressures between 20 and 50mmHg. A pressure of 50mmHg is slightly less than one pound per square inch, so solute transport is easily reduced. Even vertebral distractions (increased separation) of 1 or 2mm per disc would reduce ligamental redundancy and help to restore canal/foraminal patency, reduce venous congestion and increase axoplasmic flow. Furthermore, the effects of lumbar spine lengthening may be sustained for a period of time after lumbar distraction has been stopped.

Twomey (7) placed lumbar vertebral columns removed from 23 male cadavers under 9Kg of sustained traction for 30min and measured an average increase in length of 9mm. Thirty minutes after traction was removed, 13 of the 23 specimens had returned to baseline length, but the remaining 10 spines showed residual elongations ranging from 0.3mm to 4mm. Additionally, the data suggested that sustained traction had had a longer lasting effect on elderly spines. The mechanism of this residual deformation was not elaborated upon by the author, but disc rehydration may have been a factor since each column was soaked in normal saline and remained saturated by periodic additions of saline to a close fitting bag surrounding each column during the study.

That lumbar traction, if adequately applied, can effect physical change in patients suffering from back pain is well described by Gupta and Ramarao (8). They used water soluble contrast medium and epidurography to study 14 patients with prolapsed intervertebral disc syndrome before and after 10 to 15 days of continuous traction. Ten patients showed definite clinical improvement, with reduction in back pain and sciatica. Nine of these patients showed complete resolution of the defect on epidurogram and one of them showed partial reduction.

The authors concluded that disc protrusion may be safely treated by traction. Mathews also demonstrated the effectiveness of lumbar traction in two patients by epidurography. Disc protrusions were decreased and an average vertebral distraction of 2mm per disc space was shown in radiography (9). Judovich found that a traction force of approximately 26% of the body weight was needed just to overcome the resistance between the lower half of the patient and a (nonsplit) table (10).

Intuitively, lumbar traction should be successful in alleviating many of the conditions which cause low back pain and associated radiculopathy. Unfortunately, studies of clinical efficacy have yielded equivocal results. Previously, the successful application of lumbar traction has been limited by patient tolerance and the design of mechanical devices. Patients had difficulty tolerating the forces needed to relieve pain if delivered continuously. Furthermore, the thoracic corsets worn by patients to prevent movement on the table were uncomfortable, restricted respiration, and can compromise venous return to the heart. Technological advances have now led to the development of equipment that has been found to achieve decompression of lumbar discs without stimulating the reactive reflexes of the lumbar musculature that can otherwise overcome efforts to effectively distract vertebral bodies.

The VAX-D therapy table is shown in Figure 1. The split table design eliminates frictional resistance between the patient and the table and allows controllable effective axial distraction tensions to be applied to the lumbar vertebral column. The equipment applies distractive forces in a gradual, progressive fashion, designed to achieve distraction of the vertebral bodies without eliciting reactive reflex muscular resistance. A portion of a typical chart recording of the tensile force applied to a patient's spine as a function of time is shown in Figure 2


Figure 1: VAX-D Therapy Table

Each decompression phase, during which the tension is increased, normally lasts for one minute. The force is increased more slowly in the latter part of the decompression phase. The tension is then gradually decreased, over a period of 30sec, to about 20 pounds, which is maintained during the rest phase. Another cycle then starts. The avoidance of paravertebral muscle contraction, stimulated by

 


Figure 2:

homeostatic proprioceptor and axon reflex mechanisms allows the distraction of the vertebral bodies necessary to achieve decompression of the intervertebral disc. The therapy is administered via an automated logic control mechanism which systematically applies distractive tensions and rest periods in a cyclic fashion. The typical therapy session consists of 15 cycles of tension and relaxation. This periodic process allows patients to withstand stronger forces than can be tolerated when static techniques are used and it promotes accommodation and relaxation during the therapy session. The upper body is fixed by means of the patient grasping adjustable hand grips, designed to eliminate the use of a thoracic corset. Consequently, there is no risk of circulatory or respiratory compromise. The pelvis is secured with a specially designed harness that adjusts snugly and applies forces primarily to the lateral pelvic alae, thus minimizing anterior-posterior pressures and reactive muscle spasm during the distractive period of cycle.
VAX-D treatment has been shown (11) to decompress the nucleus pulposus to pressures below -100mmHg. This creates a tremendous potential diffusion gradient across the disc space, which is otherwise an avascular structure. Glucose and oxygen enter the disc at the end plate region while sulphate ions needed for the production of new glycosaminoglycans enter from the annulus fibrosis (12). Thus therapy may augment nutrient flow into the disc, facilitating structural restoration of the disc and promoting disc rehydration, since proteoglycans bind water (13). These effects may be cumulative with repetitive therapy sessions.

MATERIALS AND METHODS

Data was collected from twenty two medical centers in the USA for patients who received VAX-D therapy for low back pain. Only patients who received at least 10 treatments and had a diagnosis of herniated disc, degenerated disc, or facet syndrome, which was confirmed by imaging studies, were included in the study. The average number of treatments was 17 for facet syndrome, 19 for degenerative disc disease, and 20 for other diagnoses. The data contained the patients' assessment of their own pain, mobility, and ability to walk and sit. The pain scale ran from no pain (0) to severe pain (5). The mobility limitation scale was: No limitation (0), slightly limited (1), very limited (2), and completely immobile (3). The activity limitation scale was: walks frequently (0), walks occasionally (1), chairfast (2), and bedfast (3). The treatment schedule, including the use of other modalities, the duration and frequency of VAX-D therapy, and medication was also recorded, as well as the patient's history. The symptoms were recorded at the beginning, mid-point, and end of the treatment schedule. The patients' satisfaction with the treatment was quantified as: not satisfied (0), slightly satisfied (1), very satisfied (2), and completely satisfied (3).

The data were divided into five groups:
The first group which contained 34 cases, included all patients with extruded herniated discs, whether or not additional lesser problems were present.
The second group contained 195 cases of multiple herniated discs, without extrusion, with or without degenerative disc disease.
The third group consisted of 382 patients with a single herniated disc, regardless of degenerative disease.
The fourth group contained 147 cases of degenerative disc disease, without herniation.
The fifth group contained 19 cases with facet syndrome had a pain reduction to 0 or 1 before 10 treatments, and one that had a reduction to 2, received less than 10 total treatments, so they were not included in the data base.

 

RESULTS

If treatment success is defined as a reduction in pain to 0 or I on a 0 to 5 scale, the treatment was successful in 71% of the 778 cases. The success rate varied from 53% for the patients with extruded herniated discs, to 73% for patients with a single herniated disc. It was 72% for people with multiple herniated discs and 68% for facet syndrome. On a pain scale of 0 to 5, the people with extruded herniated discs had an average pain of 4.16 at the beginning of treatment and an average of 1.82 after treatment, a reduction of 56%. The cases of multiple herniated discs went from 4.13 to 1.18, a reduction of 71%. The patients with a single herniation had a reduction from 4.16 to 1.09, or 71%. The degenerative disc cases reduced from 3.93 to 1.17, a 70% reduction. The patients with facet syndrome had a reduction of 4.00 to 1.13, a 72% reduction in pain. Overall, 71 % of the patients experienced a reduction in pain to 0 or 1. The reduction in the average pain score was also 71%. One percent of the patients reported increased pain, 7% had no change, 92% improved by 1 unit or more, 87% improved by 2 units or more, and 70% improved by 3 units or more. A summary of these findings is shown in Table 1.

Diagnosis

No of Cases

Pain before treatment

Pain after treatment

5 of reduction

5 of success

Extruded herniation

34

4.16

1.82
56
53
Multiple herniation
195
4.13
1.18
71
72
Single herniation
382
4.16
1.09
70
72
Degenerative disc disease
147
3.93
1.17
70
72
Facet syndrome
19
4.00
1.13
72
68
Average over 778 cases
4.10
1.21
71
71

Table 1: Pain outcomes for various disgnoses

Table 2 shows how the average pain, mobility, and activity scores for the entire group of 778 patients improved during treatment. Although 51% of the pain reduction occurred during the first half of the course of treatment, 56% of the mobility improvement and 55% of the activity improvement occurred during the last half.

Pain (0 -5 scale)

Mobility limitations (0 - 3 scale)

Activity limitations (0 - 3 scale)

Before therapy

4.10

1.81

1.24
After therapy
2.62
1.30
0.80
At midpoint
1.21
0.64
0.27
Overall improvement
71%
65%
78%
Improved by 1 unit or more
92%
77%
63%
 
Table 2: Variation of average pain, mobility, and activity scores during treatment, and final outcome measures for the entire group

On a rating scale of 0 to 3, increases in spine mobility of one grade or more was seen in 77% of the patients with mobility limitations. Functional increases of I or more grades in the activity score was recorded in 78% of the patients who, before treatment were either unable to walk or capable of only limited walking. The coefficient of linear correlation (14) between mobility and pain scores was 0.72. Between pain and activity the correlation was 0.60, and between activity and mobility it was 0.59. On a scale of 0 to 3, the average satisfaction with treatment was 2.4, which lies between 'very satisfied' and 'completely satisfied'.

In this study, 31 patients had previous lumbar disc surgery. MRI scans showed scar tissue that could potentially entrap nerve roots. Despite this, 84% of this group’s pain scores and 71% of their mobility scores and 61 % of their activity scores improved by one unit or more with therapy, and 65% of their pain scores were reduced to 0 or 1. Vertebral axial decompression was well tolerated.

 

DISCUSSION

We consider VAX-D therapy to be a primary treatment modality for low back pain associated with lumbar disc herniation at single or multiple levels, degenerative disc disease, facet arthropathy, and decreased spine mobility. Physiology (pain and mobility) and pathology correlate imprecisely. We believe that post-surgical patients with persistent pain or "Failed Back Syndrome' should not be considered candidates for further surgery until a reasonable trial of vertebral axial decompression has been tried.

Low back mobility increased subsequent to therapy and correlated well with pain reduction. Both of these factors are important in areas such as Workers Compensation and personal injury. Estimates of permanent partial impairment rely heavily on mobility aspects, as seen in the AMA Guides to the Evaluation of Permanent Impairment, 4th edition. Although allowance for pain is made in the percentage of impairment, the determination of impairment is made by determination of spine mobility using the range of motion model.

By definition, no patient can be assigned any impairment rating until maximum medical improvement (MMI) is reached. We submit that patients can usually be brought to a higher level of MMI by this therapy because of the anticipated improvements in mobility.

In summary, the pain, activity, and mobility scores were all greatly improved after therapy. VAX-D, by its unique design, may more precisely address the physiology of persistent low back pain than other conventional therapies. We consider it to be a front line treatment for degenerative spondylosis, facet syndrome, disc disease and nonsurgical lumbar radiculopathy.

REFERENCES

Heldeman S. North America Spine Society: Failure of the pathology model to predict low back pain. Spine 1990; 15:718-724. Wheeler A.D. Diagnosis and management of low back pain and sciatica. Am Family Physician 1995; 52:1333-1341.

Wheeler A.D. Diagnosis and management of low back pain and sciatica. Am Family Physician 1995; 52:1333-1341.

Scientific approach to the assessment and management of activity-related spinal disorders. A monograph for clinicians. Report of the Quebec Task Force on spinal disorders. Spine 1987; 12(Suppl 7):1-59.

Videman T, Saina S, Crites Battle M, Koskinen S, Gill K, Paanaman H. The long term effects of physical loading and exercise lifestyles on back- related symptoms, disability, and spinal pathology among men. Spine 1995; 20-699-709.

Anderson GBJ, McNeill TW. Lumbar-Spine Syndromes Evaluation and Treatment. New York: Springer-Veriag Wien, 1989: pp. 1-215.

0lmarker K, Rydeuik B, Holm S, et a[. Effects of experimental graded compression on blood-flow in spinal nerve roots. J Orthop Res 1989; 7:817-823.

Twomey LT. Sustained lumbar traction: An experimental study of long spine segments. Spine 1985; 10:146-149.

Gupta RC, Romarao SV. Epidurography in reduction of lumbar disc prolapse by traction. Arch Phys Med Rehabilitation 1978; 59:322-327.

Mathews JA. Dynamic discography: A study of lumbar traction. Ann Phys Med 1968; IV:275-279.

Judovich BC. Lumbar traction therapy-elimination of physical factors that prevent lumbar stretch. JAMIA 1955; 159:549-550.

Ramos G, Martin W. Effects of vertebral axial decompression on intradiscal pressure. J Neurosurg 1994; 81:350-353.

Nachemson AL. The lumbar spine: An orthopaedic challenge. Spine 1975; 1:59-71.

Ballard WT, Weinstein JN. Biochemistry of the intervertebral disc. In: Kirkaldy-Willis WH, Burton CV, eds. Managing Low Back Pain, New York: Churchill Livingston, 1992: pp.39-48.

Gose EE, Johnsonbaugh R, Jost S. Pattern Recognition and Image Analysis, Upper Saddle River, NJ: Prentice-Hall PTR, 1996: pp.1-484.


TRABAJO CIENTIFICO Nº 2
arriba

JOURNAL OF NEUROSURGERY 81: 350-353, 1994

Effects of Vertebral Axial Decompression On Intradiscal Pressure
Ramos G., MD, Martin W., MD.

 

ABSTRACT

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 controlled tension was applied by the equipment 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 -100mmHg.

INTRODUCTION

Surgical procedures utilizing conventional and percutaneous approaches have established the merits of decompression of intravertebral disc spaces in the management of low-back pain syndrome associated with lumbar disc herniation.(4,12,13,15) 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 noninterventional 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, short-wave 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 neuro-compression 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.(2,3,5,14)

There has been some investigation into the effects of distracting segments of the spinal column excised from cadavers,(11,14) as well as radiological studies that provided evidence that the application of certain forms of tension can distract vertebral bodies.(3,5) On the other hand, there are equally pertinent studies that failed to demonstrate any positive effects from other methods of applying spinal tractions.(1,10) Nachemson and Elfstrom (6,9) 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 mmHg, suggesting that some positions and postures may be inadvisable for patients suffering from lumbar disc lesions. Anderson, et al.,(1) 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 in the lumbar spine of patients receiving this form of therapy.

MATERIALS AND METHODS

Five cases were selected from among individuals who were referred for a neurosurgical consultation and had previously sustained a work-related injury that resulted in herniation of a lumbar disc at one or more levels. The diagnosis in each case was confirmed by magnetic resonance imaging. The patients chosen were scheduled for percutaneous discectomy. Introduction of the cannula for the purpose of performing percutaneous discectomy offered an opportunity to measure pressure changes in the disc prior to the operative procedure.

The patient was prepared and a cannula was inserted under local anesthesia into the nucleus pulposus of the L4-5 intervertebral disc using anteroposterior and lateral fluoroscopy to position the end. With the cannula in place, the patient was moved to a VAX-D table. The VAX-D equipment is routinely utilized in our nonsurgical treatment program for patients suffering from low-back pain. The equipment consists of a split table design with a tensionometer mounted on the caudal, moveable section. The patient lies in a prone position and grasps hand grips to restrain movement of the upper body, which is supported on the fixed section of the table (Figure 1)


Figure 1: Dr. Ramos monitorring procedure
The cannula was then connected to a pressure monitor using a disposable pressure transducer. The lines were filled with normal saline. The pelvic harness designed for this therapy was fastened around the pelvic girdle and connected to the tensionometer via straps attached to the harness. When the system was activated the caudal section supporting the lower body extended slowly, applying a distraction force via the pelvic harness connected to the tensionometer. The level of tension was preset by the operator on the control console and observed and plotted on a chart recorder. The movement of the table was stopped

and held when the desired tension was reached. An average course of therapy consisted of 30-minute sessions on the table once a day for 10 to 15 days. During each session the patient undergoes alternating cycles of distraction and relaxation, the timing and periodicity having been programmed by the therapist. In this study various distraction tensions, ranging from 50 to 100 lbs, were used for vertebral axial decompression therapy. The distraction tensions applied were monitored on a digital readout and recorded on a continuous graph tracing by a chart printer incorporated in the control console. The resulting changes in intradiscal pressure in the L4-5 nucleus pulposus were observed on a digital readout on the pressure monitor, and the readings were entered onto the chart recording at the point when the apex of distraction tension was achieved. The pressure readings were then applied to the negative-range calibrated curves prepared for each transducer to derive accurate intradiscal pressure readings.

The biological transducers employed in this study are primarily designed to measure pressure changes in the positive range. Following each procedure the presssure monitor and the disposable pressure transducer used for each patient were individually calibrated and a correction curve was plotted showing the transducer readings versus actual pressures, to correct for the nonlinearity of the instrumentation in the range of negative pressures achieved. A pneumatic calibration analyzer with an accuracy of +/- 2% was used for this purpose.

RESULTS

Intradiscal pressure measurements showed that distraction tension routinely applied by the VAX-D equipment reduced the intradiscal pressure significantly to negative levels in the range of -100mmHg to -160mmHg. The relationship between distraction tensions and intradiscal pressure changes for three patients is presented in Table 1. The extent of decompression (measured in mm Hg) shows an inverse relationship to the tension applied and may be expressed by a polynomial equation (Figure 2).

Case Number

Sex
Age

Index Monitor

Session Number

1

2

3

4

5

6

7

8

3

M
23

Traction tension (lbs)
Intradiscal Pressure (mmHg)

0
75
47
-25
55
-39
58
-43
69
-66
4
F
41
Traction tension (lbs)
Intradiscal Pressure (mmHg)
0
60
20
30
40
-76
55
-110
60
-126
63
-117
65
-160
70
-106
5
M
34
Traction tension (lbs)
Intradiscal Pressure (mmHg)
0
62
50
-106
90
-138
94
-134
98
-157
Table 1. Effect of lumbar traction on intradiscal pressure. Measurements in the first two patients could not be
translated accurately and are omitted (see text).

Figure 2: Graphs showing the intradiscal pressures recorded in the L4-5 nucleus pulposus of three patients (Case 3, upper left; Case 4, upper right; and Case 5, lower left) with a herniated disc at this level. Pressure is plotted against distraction tension consistent with the range of tension recommended as the therapeutic protocol for the equipment used in this study.

DISCUSSION

Intradiscal pressure changes were monitored in five patients. When the first two patients were tested, it was not recognized that biological transducers produce nonlinear measurements in the negative ranges at the levels achieved in this study. Since the disposable units had been discarded it was not possible to translate the findings accurately; however, the intradiscal pressures were observed to be significantly lowered. Also, the findings were consistent with the later three patients, for whom the transducers were retained and individually calibrated, permitting accurate interpretation of the results.

An interesting observation was that changes in intradiscal pressure appeared to be minimal until a threshold distraction tension was reached. When the threshold was exceeded the intradiscal pressure was observed to decrease dramatically to levels in excess of 200 mm Hg below the positive pressure observed prior to the application of pelvic tension. As indicated in the curves plotted for intradiscal pressures versus distraction tension, ( Figure 2.) it appeared that the decrease in pressure tends to level off as the applied distraction tensions approached 100 lbs. The concept of a threshold distraction tension and the levels observed in these trials are consistent with radiographic studies of vertebral body separation reported in other publications.(2) The results indicate that it is possible to lower pressure in the nucleus pulposus of herniated lumbar discs to levels significantly below 0mmHg when distraction tension is applied according to the protocol described for vertebral axial decompression therapy. These findings may offer a plausible explanation for the mechanism of action for this therapeutic modality. Future research is warranted to study the decompression phenomenon achieved with this technology and its relationship to clinical outcome in patients with anatomical dysfunction of the lumbar spine. We are preparing a follow-up study on the clinical efficacy of this treatment modality.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the director and staff of the Department of Physical Therapy for their assistance in administering the vertebral axial decompression therapy.

DISCLOSURE

The authors have no financial interest in either the equipment or the methodology advanced in this study.

REFERENCES

Anderson GBI, Schultz AB, Nachemson AL: Intravertebral disc pressures during traction. Scand J Rehabil Suppl 9:88-91, 1983

Colachis SC Jr, Strohm BR: Effects of intermittent traction on separation of lumbar vertebrae. Arch Phys Med Rehabil 50:251-258, 1969

Gupta RC. Ramarao SV: Epidurography in reduction of lumbar disc prolapse by traction. Arch Phys Med Rehabil 59:322-327, 1978

Hirsch C. Nachemson A: Lyle reliability of lumbar disk surgery. Clin Orthop 29:189-195, 1963

Mathews JA: Dynamic discography: a study of lumbar traction. Ann Phys Med 9:275-279, 1968

Nachemson A: The load on lumbar disks in different positions of the body. Clin Orthop 45:107-122. 1966

Nachemson A:


TRABAJO CIENTIFICO Nº 3
arriba

THE AMERICAN ASSOCIATION OF ORTHOPAEDIC MEDICINE,
FEBRUARY 1999

THE SCIENCE OF DECOMPRESSION
The Spine in Health and Disease
Dyer A.E., B.Sc., Phm.B., MD., Ph.D.

Vertebral disc biomechanics and pathophysiology have been studied by researchers both in vitro and in vivo. Dr. Frank Tilaro published an overview in the Canadian Journal of Clinical Medicine that presents a succinct summary and references to current concepts regarding the management of discogenic dysfunction, and is recommended reading for everyone involved in VAX-D treatments.

Do not be misled that the decompression of intervertebral discs can be determined with fluoroscopy. The flattening of bulges observed under fluoroscopy can easily be achieved by tightening of the posterior longitudinal ligament through flexion and/or distraction. In order to measure intradiscal pressures, an expert skilled at avoiding damage to the nerve root and vascular structures, must perform the insertion of a cannula into the nucleus pulposus. Because there are no biological pressure monitors calibrated in the negative range, special instrumentation and calibration technology must be employed to measure accurately any changes in the internal pressure of the disc other than those in the normal physiological range.

Figure 1 shows the complex mathematical relationship between the logarithmic function of time on the right of the equation and tension on the left. This distraction relationship is a critical element in controlling the process of Vertebral Axial Decompression. Starting at the pretension base line the ordinate (tension) is shown as a percentage of the maximum reached in 60 seconds. It should take approximately 17 to 20 seconds to reach 50%. 25 to 28 seconds to reach 70% and 42 to 45 seconds to attain 90% of the maximum. Retraction follows a linear time / tension relationship and should return to the base line in a controlled fashion in approximately 25 to 30 seconds.

Distraction devices that apply either static or linear distraction forces have been found to increase the pressures of lumbar discs as noted by Dr. Tilaro in his review article. This is one of the reasons why such modalities have fallen into disrepute over the years. The concept of decompression was further expanded by an analysis carried out by Dr. Tilaro in collaboration with Dr. Miscovich of test results using the Current Perception Threshold (CPT) Neurometer. This is an objective means of assessing the dysfunction of peripheral sensory nerves.

Their analysis demonstrated that sensory dysfunction showed a significant level of recovery after a course of VAX-D treatments. In fact 64 % of the cases achieved complete remission. Their study demonstrated a recovery of neurological defect in a significant number of patients. This study was published in the Canadian Journal of Clinical Medicine. This study extends the clinical evidence on VAX-D to include the conventional definition of decompression, that is the relief of the signs of neurocompression associated with discogenic dysfunction.

The following MRI films taken before and after VAX-D treatments demonstrate reduction of a large extruded herniated disc that was impinging and displacing the S1 nerve root. (Figure 3 and Figure 4). We do not know what is the incidence of such findings and are trying to organize a study to examine this phenomenon.

Figure 3: MRI’s demonstrating the retraction of an extruded herniated nucleus pulposus after VAX-D treatment.

Figure 3: MRI’s demonstrating the retraction of an extruded herniated nucleus pulposus after VAX-D treatment.

Pre VAX-D treatment MRI:
There are two axial MRI views of a large extruded herniated nucleus pulposus taken at two separate cuts through the same L4-L5 disc illustrating the size of the herniation and impingement on the cauda equina and retro-displacement of the nerve roots.

Post VAX-D treatment MRI:
Post VAX-D MRI views (comparable cuts) at the same L4-L5 level were repeated showing retraction of most of the extrusion. A small segment remains sequestered but no longer impinges on the cauda equina and/or displaces the nerve roots. The Radiologist that read and compared the before and after films commented that he was not aware of what "type of surgery" had been performed but that it was the most remarkable reduction of an extruded herniated disc that he had seen

Retraction of protruding segments has been observed in other cases and is an interesting phenomenon that intrigues the skeptics, however it has not been a consistent finding in all cases that have achieved complete remission. Therefore the significance and correlation is yet to be established.

I want to first discuss the concepts relating to the class of herniated discs. The metabolism of the intervertebral discs, as in most tissues, deteriorates with age. This is exaggerated by the fact that the spinal column discs collectively represent the largest avascular structure in the body.

Studies show that during the waking hours, or two thirds of the day, the intradiscal pressures exceed the diastolic pressure in the capillary network of the vertebral endplates. During this period the metabolism of the disc is essentially anaerobic resulting in accumulation of metabolites of the glucose metabolic cycle such as CO2 and lactic acid. It is proposed that an anaerobic state also favors a shift of normal nuclear matrix to the more acidic compounds of chondroitin sulfates.

Aging augmented by gravity leads to loss of elasticity of the annulus. This is a precursor to the development of annular fissures exposing the annulus and thereby the disc integrity to stress trauma especially from asymmetric loading which leads to coalescence of annular fissures to form a radial extension leading to progressive intrusion of the nucleus pulposus and herniation.

The first genesis of low back discomfort is thought to occur when anaerobic nuclear contents, such as accumulated lactic acid and the more acidic forms of chondroitin sulfate reach the sinuvertebral nerve that innervates the outer one third of the annulus. Not infrequently patients will give a history of low back pain for a week or so prior to the onset of an acute episode.

Annular fissures develop in an environment that does not support tissue repair. Fibroblast and chondroblast cellular activity is suppressed in an anaerobic environment and is further dampened by the products of degradation. Fortunately when the body assumes a horizontal position at bed rest the intradiscal pressure normally lowers below that of the diastolic blood pressure permitting oxygen diffusion and reversal to an aerobic state. Cellular activity is enhanced and normal tissue repair can occur.

This is probably one of the beneficial effects of bed rest in the management of discogenic dysfunction. Unfortunately the effects of the positive diffusion gradient that occurs in the horizontal position is limited by the fact that imbibation of fluid into the disc gradually raises the intradiscal pressure reducing the diffusion gradient. This is estimated to reach equilibrium within a few hours.

Due to the normal anatomical configuration of the capillary network in the end plate, when a diffusion gradient favors inflow to the disc, oxygen transport has a steep concentration gradient across the disc with the peripheral diffusion some 20-30 times that of the center of the disc. Negative pressures in the decompression phase facilitate migration and equilibration of oxygen throughout the disc. Because this structure is avascular, there is no concentration gradient effect in reverse. Therefore oxygen tends to be retained and utilization by cellular elements continues beyond the end of the decompression phase. Thus aerobic metabolism is thought to persist during the relaxation phase of a VAX-D cycle and even for a period of time after a treatment session.

In addition to the Therapeutic Curve – cyclic periodicity is an essential component of VAX-D. Retraction and relaxation phases must be controlled to achieve an optimum effectiveness. Furthermore the length of the cycles is fairly critical. Decompression and relaxation phases of two minutes duration are not as effective as the current protocol. Although the controls permit setting varied time duration for the decompression phase and the relaxation phase the optimum is still sixty seconds and sixty seconds. Shortening either phase appears only to increase throughput slightly at the possible sacrifice of efficacy.

It is interesting that certain repetitive exercises perfected by the McKenzie technique may reduce the extent of protrusion of a bulging disc. If performed properly, these programs can prove complimentary to the aerobic metabolism and nutrient transport created through VAX-D therapy. When static distraction forces are applied, the hydraulic equilibrium that normally develops in a few hours at bed rest, tends to be reached in a much shorter period of time. This phenomenon is also thought to be a contributing factor to the increase in intradiscal pressure that has been observed when devices apply distraction forces in a linear fashion. This would be counterproductive in the management of discogenic dysfunction.

Internal Disc Disruption (IDD) is a condition marked by alterations in the internal structure and metabolic functions of one or more discs. It is a common cause of low back pain in a substantial number of young, otherwise healthy adults. Crock described this painful entity and reported annular fissures that distort the internal architecture of the disc. A pathological marker has been described as the High Intensity Zone (HIZ) viewed on MRI scans using spin echo gradient T2 imaging (Figure 5). Discography studies have demonstrated a significant correlation with the presence of HIZ in patients with symptomatic grade three annular fissures.


Figure 5: MRI of HIZ

he high intensity of the zone differentiates the material entrapped from that of herniated nuclear matrix, and is believed to indicate that the HIZ reflects the presence of inflammatory fluid. These observations indicate that inflammation could play a significant role in the development of localized irritation associated with some discogenic disorders.

Dr. Tilaro points out in the Journal of Clinical Medicine, that experience using anti-inflammatory drugs in the management of patients with discogenic dysfunction has in the past been disappointing. However in combination with VAX-D, certain non-steroidal anti-inflammatory compounds have been found to exert definite benefits for some patients. While there have not been research studies to identify the contributing properties, the more active products appear to share anti-prostaglandin and COX-II inhibition properties, and only non-albumin bound molecules in the serum would be free to diffuse into the disc space under a magnified diffusion gradient.


NSAID's that freely dissociate from the protein bound state are reflected generally by certain pharmacological parameters. Such as whether a particular compound passes the blood-brain barrier and the percentage excreted intact in the urine. Drugs that are highly conjugated with albumin tend not to transfer into the cerebral spinal fluid and also do not pass through the glomeruli into the urine. These may be common characteristics of compounds that fail to diffuse into the HNP under positive diffusion gradients.

Dr. Ramos, the neurosurgeon whose research demonstrated in-vivo negative intradiscal pressures, carried out a prospective clinical evaluation of the effect of administering half the number of sessions recommended in the VAX-D protocol. This clinical trial is typical of two-dose relationship commonly used in pharmaceutical research where placebos are not applicable. Because the level of success was governed by a dose response relationship, among other interesting aspects, this study indicates that a biological mechanism of action is involved in addition to the biomechanical retraction of a prolapsed disc.

While retraction of a prolapse is believed to contribute to the reduction in low back pain and radiculopathy, remission of symptoms and disability does occur without visible change in the MRI picture. The MRI may not disclose closure of the radial fissure that interrupts the integrity of the annulus and restores the function of the intervertebral disc.

A large-scale clinical study showed a success rate for degenerative disc disease comparable to that achieved in cases with subligamentous herniation. It is interesting that apparently none of the 147 cases of degenerative disc disease were diagnosed as suffering from IDD. It is possible that since the average chronicity was reported to be 42 months it could be that there were no cases of IDD because such cases either ended up on the surgical table or converted over time to classic degenerative disc disease with loss of disc height and configuration.

One of the problems in this regard is that radiology reports of MRI films generally do not distinguish IDD from degenerated disc disease. Although T2 weighted imaging displays a loss of signal intensity similar to degenerative disc disease. A loss in disc height on an MRI scan is not prevalent in IDD as with degenerative disc disease.

Maintenance of the disc height in IDD presents a problem in relying on normal radiological views in the confirmation of the clinical symptoms. IDD is described, as a condition marked by alterations in the internal structure and metabolic functions of the disc usually following significant trauma. What happens if after major trauma, edema or inflammation results in a sustained elevation of intradiscal pressure and the benefit of the normal diurnal physiological variation in oxygen uptake is insufficient to reverse degradation? A persistent anaerobic state might predispose the nuclear matrix to a type of necrotizing discopathy. The release of protein and cellular degradation that permeate into the peripheral venous plexus is believed to give rise to the systemic complications.

Unlike herniation of the nucleus pulposus IDD is not in itself associated with annular fissures and the escape of nuclear contents from the confines of the disc space. The etiology of both localized and radicular pain is thought to be principally from chemical irritation. This shifts the emphasis of treatment from mechanical origins of nerve root compression to more complex aspects of a biochemical nature.

IDD presents localized and peripheral symptomatology similar to that of herniated discs, however, the pain is more diffuse in nature and it is more likely to involve generalized systemic symptoms such as fatigue, malaise and loss of weight. Neurological deficits are not commonly associated with IDD. Typically a patient with IDD does not find relief from bed rest as is the case with disc prolapse, and physical exercises tend to exacerbate localized and radicular symptoms (if present). Local steroid injections, as well as the routine use of non-steroidal anti-inflammatory drugs have been disappointing as a pharmacological adjunct in the treatment of IDD.

However in combination with VAX-D, anti-inflammatory products should be routinely employed in the treatment of IDD to reduce the chemical irritation from catabolites. Experience indicates, in some patients the combination appears to be synergistic. Neurological sensitivity is heightened to chemical irritation by even minor changes in blood flow or hypoxia therefore the application of tight pelvic belts can cause discomfort. Patients on VAX-D that experience an increase or shift in their pain syndrome in the initial stages of VAX-D treatments, may be due to the tight harness affecting venous congestion which could increase the sensitivity to chemically irritant catabolites. This could be one of the reasons for non-compliance especially when the therapist or patient become discouraged and discontinue treatment prematurely. If the treatment succeeds in improving the catabolic state this complication should subside as treatment progresses.

Experience and further clinical trials aimed at addressing this particular problem will hopefully provide further guidelines in managing these difficult cases. Patients with IDD that have lost intrinsic cellular viability could be expected to be refractory to VAX-D treatments and likely will not be able to be helped until we succeed in developing the science of bio-transplant.

In the future, destructive surgery causing iatrogenic stenosis should be replaced by reconstructive surgery that combines nucleus pulposus transplant procedures facilitated by specially designed VAX-D tables that will be adapted to the surgical operatory. The viability of such transplants will require follow up VAX-D to provide the aerobic environment necessary for transplant tissue survival and healing.


TRABAJO CIENTIFICO Nº 4
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A Prospective Randomised Controlled Study of VAX-D and TENS
for the Treatment of Chronic Low Back Pain


Eugene Sherry* MD, FRACS Department of Orthopaedics, Sydney University
Peter Kitchener** M.B. B.S. FRANZCR; Russell Smart*** M.B.Ch.B. (Otago)
Journal of Neurological Research Vol 23, No 7, October 2001
*Senior Lecturer in Orthopedics, Sydney University, ** Consultant Radiologist, ***Medical Director, VAX-D Australasia PTY Ltd. NSW, Australia

ABSTRACT

Low back pain is one of the most significant medical and socioeconomic problems in modern society. International guidelines call for evidence-based management for the pain and disability associated with musculoskeletal disorders. The purpose of this randomised controlled trial is to address the question of efficacy and appropriateness of VAX-D (Vertebral Axial Decompression) Therapy, a new technology that has been shown in clinical research to create negative intradiscal pressures, and has been shown to be effective in treating patients presenting with chronic low back pain (>3 months duration) with associated leg pain. Successful outcome was defined as a 50% reduction in pain utilising a 10cm Visual Analogue Pain Scale and an improvement in the level of functioning as measured by patient-nominated disability ratings. Patients were randomly assigned to VAX-D or to TENS which was used as a control treatment or placebo. The TENS treatment demonstrated a success rate of 0% while VAX-D demonstrated a success rate of 68.4% (P<0.001). A statistically significant reduction in pain and improvement in functional outcome was obtained in patients with chronic low back pain treated with VAX-D. (Neurol Res 2001; 23:780-784)

INTRODUCTION

Low back pain is a major cause of disability in today’s society. According to the National Health and Medical Research Council (NHMRC), each year approximately 600,000 Australians present with low back pain as a recent illness. Although a high percentage of patients with acute low back pain recover within 4-6 weeks, a significant number of patients suffer from recurrences. Von Korff has studied the natural history and found that approximately 60% will have recurrences. (1) In a study of back pain in primary care, Von Korff and Saunders found that 60% to 75% improve in the first month, 33% report intermittent or persistent pain at year one, and 20% of patients describe substantial limitations at this time. (2) Klenerman et al demonstrated that 7.3% of individuals with acute low back pain who had not recovered by two months still reported high levels of pain and disability at twelve months after onset. (3) Chronic low back pain is increasing faster than any other disability, and 5-7% of the population will report their back problems as being a chronic illness. Fifty percent of work loss caused by back pain is accounted for by duration of disability for longer than 4 weeks. In Australia chronic low back pain affects more than 1,900,000 individuals and costs Australia more than 10 billion dollars each year.

International guidelines call for evidence-based management for the pain and disability associated with musculoskeletal disorders. Today's primary care practitioners have a comprehensive responsibility in the management of their patient’s low back conditions, and they must be aware that recurrences after the presenting episode are likely. The literature suggests that for those who have not recovered by two months, management efforts should begin. (4)

Acute disc injury and discogenic pain is one of the primary processes leading to low back pain and lumbar radiculopathy, although the pathophysiologic mechanisms are still not well understood. It is believed that increases in disc pressures resulting from heavy lifting, vibrational and postural forces etc. are important factors in the pathogenesis of low back pain. The effects of disc hydraulics in herniations or protrusions may cause a mechanical deformation of the nerve roots and a compression-induced impairment of the vasculature. In addition, it has been found that the biochemical properties of the nucleus pulposus may induce a toxic or inflammatory reaction in the nerve root.

There have been many studies indicating that the disc and its associated pathology are identified as a primary cause of low back pain and lumbar radiculopathy. Hirsch stimulated various lumbar tissues in awake patients with the use of carefully placed needles. (5) Stimulation of the posterior portion of the annulus produced low back pain in many individuals. Furthermore, he was able to eliminate the pain by the injection of a minute volume of local anaesthetic into the annulus. Smythe and Wright placed nylon threads into various lumbar tissues while performing lumbar spinal operations. (6) During the postoperative period, they pulled on the threads and asked the patients to describe the location of any pain produced. The annulus fibrosus was the most common site of low back pain, and the compressed nerve root was responsible for sciatic pain. Tension placed on a normal nerve root resulted in no pain.

Falconer and associates published their observations made during exploration of the lumbar spine under local anaesthesia. (7) Murphy reported similar results in his small series of surgical cases. (8) Both authors concluded that the annulus and nerve root were the pain generating tissues. Wiberg in 1950, operating on 200 patients using local anaesthesia of the skin and muscles only, reported that pain emanated from the disc. (9) Kublisch operated on 193 patients using local anaesthesia and drew certain conclusions about the likely origin of back and leg pain. (10) Sciatica could only be produced by stimulation of a swollen, stretched, or compressed nerve root. Back pain was produced in the majority of cases by stimulating the outer layer of annulus fibrosus and the posterior longitudinal ligament.

If the disc is a major source of low back pain then applying specific target therapy for the treatment of disc pathology should improve patient outcomes. VAX-D is a primary, non-surgical treatment for the management of patients with disabling low-back pain and neurological symptoms associated with herniated and degenerative disc disease. Research has shown that the VAX-D table is a decompression device that is capable of reducing intradiscal pressures to negative levels. (11)

Successful reduction of intradiscal pressures with VAX-D represents a technological advance that should provide a means of addressing compressive disc pathology. Creating negative intradiscal pressure is likely to affect both the biomechanical and biochemical causes of discogenic pain. Patients suffering from discogenic pain and/or associated sciatic pain are seeking conservative treatment without the risks associated with injections and surgical procedures.

VAX-D incorporates advanced technology that permits the application of distractive tensions without eliciting reflex muscle guarding. Conventional traction devices have not demonstrated this ability or the ability to reduce intradiscal pressures to negative levels. Studies published in the medical literature report that intradiscal pressure either remains unchanged or increases during traction. (12) It has also been demonstrated that paraspinal muscles are not able to fully relax during conventional traction.

The beneficial effects of VAX-D decompression in the relief of peripheral nerve dysfunction has been previously reported in the literature, (13) and a multi-center outcome study reported that VAX-D treatment was successful in 71% of the 778 cases studied. (14)

This study was designed to evaluate the effect of VAX-D on chronic low back pain.

MATERIAL AND METHODS

In association with Quintiles, the world's largest health care consultancy organisation for data analysis in clinical trials, a protocol was developed and then approved by the Human Research Ethics Committee at the University of Wollongong, New South Wales, Australia.

It was predetermined that the treatment would be considered a success if the patient attained a fifty percent (50%) decrease in pain, numerically on the Visual Analogue Scale (VAS). Absolute changes in pain score determined by VAS over time were analysed with repeated measures analysis of variance and t-test. In addition, improvements in disability were recorded on a patient nominated disability rating. Any level of improvement in disability was acceptable. The instruments for determination of these outcomes were supplied by the National Musculoskeletal Initiative of Australia. The study itself was to be conducted in the medical clinics of the VAX-D Spinal Institute and so to prevent bias in the data collection Quintiles were engaged to collect and analyse the data. TENS was selected as an appropriate placebo treatment as a means of establishing a plausible but (probably) ineffective control for an unblinded treatment.

Through advertisement in local papers forty-four patients with chronic low back pain greater than 3 months in duration, with associated leg pain, and a confirmed disc protrusion or herniation on CT Scan or MRI were selected and randomised into the two treatment methods, either VAX-D or TENS. The patients were randomised in sequential order and treatments were determined by a predefined central randomisation list.

The average duration of pain in the patient population was 7.3 years. The conditions for receiving either treatment including travelling to and from the clinic and duration of therapy were designed to be the same for both populations. Inclusion criteria for the study were: age 18-65 years; a minimum VAS score of 2; candidates must live within 45 minutes of the clinic location; capable of thoroughly understanding the information given and following protocol. All candidates signed an informed consent form.

Exclusion criteria were: osseous stenosis; unstable spine (bilateral pars defect or Spondylolisthesis of Grade II or greater); spinal surgical implants; shoulder problems which prevent compliance with VAX-D therapy; spinal pain due to tumor, infection, or inflammatory disease; pregnancy; and previous VAX-D therapy.

Patients randomised to VAX-D were treated according to the manufacturer's protocol. Patients lie on the split table device in a prone position. VAX-D utilises handgrips that the patient grasps with arms extended above the head to stabilise (restrain) the shoulder girdle and upper body. This is thought to be the most effective means of assuring that tensions applied to the pelvis are transmitted accurately along the linear axis of the spinal column during the procedure. The fact that the patient may release at any time during the treatment provides an important safety factor. A special harness designed to apply forces primarily to the lateral pelvic alae is fitted and tightened around the patient. The pelvic harness is connected to a tensionometer at the caudal end of the table. The function of the tensionometer is to provide constant feedback to the programmed logic control and operating system. During the VAX-D session a continuous chart recording is generated plotting the controlled time/energy progress of the entire procedure.

Tensions are applied to the lumbar spine in a cyclic fashion from the baseline tension up to the therapeutic range of fifty to ninety-five pounds. Each treatment session is thirty minutes in length and is comprised of fifteen cycles of decompression alternating with relaxation. Each decompression and relaxation phase may be individually varied as suitable for the particular treatment parameters.

A chart recorder prints the time energy curve for each decompression-relaxation cycle. This affords the technician a means of monitoring and adjusting the decompression process. Patients received VAX-D therapy five times per week for four weeks and then once per week for four weeks in accordance with protocol. All VAX-D treatments were administered by certified VAX-D technicians at four clinics in the Sydney area.

Patients randomised to TENS therapy received treatment at one of the four clinics. Electrodes were placed according to the manufacturer's protocol. Patients lay prone on a treatment table and received TENS for thirty minutes daily for twenty days then once a week for four weeks. All patients receiving TENS were monitored by a technician.

Neither group received any physical therapy modalities, epidural steroid injections or other treatments during the trial. Both patient groups were allowed to take non-narcotic pain relievers and anti-inflammatory medication if necessary.

A 10-cm Visual Analogue Scale (VAS) for pain and a four-point disability rating scale were used to assess patient response. The level of pain on the VAS was recorded on a 10cm line marked at one end ‘No Pain’ and marked at the other end ‘The Worst Pain Imaginable’. The written instruction to the patient was to ‘please place a mark on the line below to indicate your current level of pain’. The self-nominated disability rating scale required patients to list the four activities that were most affected by their low back pain. These were scored according to the following criteria: 1 = cannot do at all; 2 = can do but severely limited; 3 = can do but slightly limited, 4 = can do without limitation.

Data was collected at the initiation of the study prior to randomization and at the end of the eight week treatment period in a separate interview. Success was defined as (equal to or greater than) a 50% improvement in the patient's pain and any improvement in their disability rating.

Patients were free to withdraw from the study on their own volition at anytime. The study treatment could be terminated prematurely if any of the following events occurred: patient wished to terminate his/her participation for whatever cause (two cases); the investigator judged it was in the best interest of the patient to withdraw (zero cases); the patient was unable to comply with protocol (zero cases).

The efficacy-evaluable population used for statistical analysis of efficacy is comprised of all patients who were randomised to study treatment, received at least 10 study treatments, had efficacy data recorded after Baseline, and satisfied the inclusion/exclusion criteria.

The primary efficacy measure in this study was the proportion of successfully treated patients in each of the treatment groups. The difference in proportions of successfully treated patients in each treatment group was tabulated and compared using Fisher's Exact Test and 95% confidence limits.

Successfully treated patients were to be followed up at six months to determine whether the successful outcome was sustained.

RESULTS

Forty-four patients were enrolled into the study. Twenty-two were randomised to each of the treatment groups. A summary of demographic characteristics for the 44 enrolled patients is presented in Table 1.

Characteristic

Statistic

All

VAX-D

TENS

No of Patients

n

44

22
22
Age (years)
Mean
42
41
43
Range
22 - 57
27 - 57
27 - 55
Sex Female
n
21
11
10
Male
n
23
11
12
Race White
n
40
20
20
Asian
n
4
2
2
Chronicity
Yrs of Pain
Mean
7.3
8.4
6.2
Range
0.25 - 30
0.25 - 30
0.25 - 28
 
  Table 1: Demographic data

Two patients (4.5% of 44), Patient 029 and Patient 003, were regarded as having withdrawn/not completed the study according to the protocol. Patient 029, randomised to TENS, withdrew due to not wishing to continue and Patient 003, randomised to VAX-D, withdrew due to treatment no longer being required. No patients were withdrawn by the investigator. Patients 018 and 034 both randomised to VAX-D, did not comply with the study criteria and are therefore excluded from the efficacy-evaluable population. They both had a baseline VAS score less than 2 but this error of inclusion was not picked up until the completion of the trial. The efficacy-evaluable population therefore comprised of 40 patients: 19 patients randomised to VAX-D, 21 randomised to TENS.

A summary of the data collected at baseline and post-treatment in the efficacy-evaluable population is presented in Table 2.

Characteristic

Statistic

VAX-D

TENS

No of Patients

n

19

21

Number of treatments
Mean
24.1
18.0
Range
18 - 36
10 - 24
Baseline pain (VAS)
Mean
5.99
5.44
Range
2.1 - 8.7
2.7 - 8.5
Post treatment pain (VAS)
Mean
1.85
5.97
Range
0 - 5.6
1.8 - 8.5
Decrease in pain (%)
Mean
69.1
-17.1
Range
11.1 - 100
-123 - 33.3
Disability Rating Pre-treatment
Mean
2.2
2.2
Range
1.5 - 3
1.75 - 3.0
Post treatment
Mean
2.9
2.2
Range
2.0 - 4.0
1.5 - 3.0
Improvement in disability rating (%)
Mean
33.8
-2.23
Range
0 - 100
-36.4 - 50.0
Successful cases
n
13
0
Percent
68.4%
0%
 
Table 2: Efficacy-evaluable population

In the efficacy-evaluable population the proportion of successfully treated patients was 13 out of 19 patients (68.4%) for the VAX-D treatment group compared to zero out of 21 (0%) for the TENS treatment group. There was a high statistically significant treatment group comparison p-value of <0.001. The 95% confidence interval for the difference in proportions of successfully treated patients, comparing VAX-D with TENS was 47.5% to 89.3%.

In the VAX-D group all patients recorded some improvement in their pain levels whereas in the TENS group 13/ 21 recorded an increase in pain.

At six-month follow-up, of the 13 successful cases, 2 have been lost to follow-up, 1 case suffered a significant other injury and of the remaining 10, seven have shown sustained success (ie. they still meet the criteria for successful outcome).

The results reported for the TENS group were less that that expected for a placebo control. The negative outcomes may have been due to the fact that the TENS patients (and the VAX-D patients) had to travel to and attend a medical clinic five days per week for four weeks, and one day per week for four weeks. This fact that both treatment groups had to travel to, and attend the clinic, was necessary to ensure that the only variable between the two groups was in the type of treatment that they received. The benefits of treatment in the VAX-D group clearly outweighed the negative effects of travelling, which became evident in the placebo group.

DISCUSSION

Disc stresses coupled with ongoing increased intradiscal pressures from mechanical loading may lead to failures in the normal biomechanics of the disc and progress to degeneration, posterior displacement of the nuclear material, annular disruptions and herniations. Other causative factors in the course of disc degeneration are negative diffusion gradients, reduction of the fluid content of the nucleus pulposus, and abnormal disc metabolism. With positive disc pressures throughout the day that are above diastolic pressure, the metabolism of the disc becomes anaerobic thus impeding the normal reparative healing abilities.

Proteolytic enzymes (matrix metalloproteinases) reside in the disc and have been implicated in disc degeneration. (15) The matrix metalloproteinases are regulated by specific inhibitors (TIMPS), cytokines (Interleukin-1) and growth factors. (16) Spinal loading may interfere with diffusion into the disc by reducing the gradient across the vertebral endplate. As disc metabolism becomes anaerobic, there is an accumulation of lactic acid, fall in pH, loss of chondrocyte and fibroblast function, and activation of the metalloproteinases.

Although the mechanism of action may not be fully understood the thixotrophic (17) properties of the nucleus material may facilitate nuclear migration toward the centre of the disc under negative pressures created by VAX-D.

It has been shown experimentally that elevated lactate levels and low pH in the disc prohibit disc proteoglycan synthesis and accelerates matrix degeneration (18).

Destruction of the proteoglycan matrix and fluid retention properties can lead to a degenerative cascade with loss of cellular reparative functions and vitality. The reduction of intradiscal pressures may enhance the diffusion gradient across the endplate into the avascular disc. It has been postulated that mechanisms that facilitate oxygen and nutrient uptake in the disc may exert a beneficial effect on the metabolism and restorative functions.

Successful reduction of intradiscal pressures with VAX-D therapy represents a technological advance in lumbar spinal treatment and is likely to affect both the biomechanical and biochemical causes of discogenic pain. The results from this study demonstrate that VAX-D is an effective treatment for the management of patients with chronic low back pain and is significantly superior when compared to TENS therapy. Analysis of the data demonstrated an attributable success rate of 68.4% for VAX-D. These findings are consistent with earlier studies by Gose E, Naguszewski W, Naguszewski R. (14)

The results of this prospective study demonstrated that VAX-D can achieve a statistically significant improvement in pain and functional outcome in managing patients suffering from disc related chronic low back pain.

ACKNOWLEDGMENTS

Australian National Musculoskeletal Initiative: For advice and instruction on the use of instruments for the outcome measures used in the present study.

Jane Ambrose, Biostatistician Quintiles: For statistical analysis of the data.

DISCLOSURE

Dr Russell Smart is contracted to and a shareholder in VAX-D Australasia Pty Ltd, a private company that delivers VAX-D service in Australia.

REFERENCES

1. Von Korff M. Studying the natural history of back pain. Spine 1994; 19(18 Suppl): 2041S-2046S.
2. Von Korff M., Saunders J. The course of back pain in primary care. Spine 1996; 21: 2833-2837.
3. Klenerman L, Slade, PD Stanley IM. et al. The prediction of chronicity in patients with an acute attack of low back pain in general practice setting. Spine 1995; 20:478-484.
4. Bogduk N, Evidence Based Clinical Guidelines for the Management of Acute Low Back Pain; The National Musculoskeletal Medicine Initiative NHMRC;Nov 1999
5. Hirsch C. An attempt to diagnose the level of disc lesion clinically by disc puncture. Acta Orthop Scand 1948;18:132-140
6. Smythe MJ. and Wright V. Sciatica and the intervertebral disc. An experimental study. J Bone Joint Surg (Am) 1958;40:1401-1418
7. Falconer MA; McGeorge M, Begg AC; Observations on the cause and mechanism of symptom production in sciatica and low back pain. J Neuro Neurosurg Psychiatry 1948;11:13-26
8. Murphy F. Experience with lumbar disc. Clin Nerurosurg 1973;20:1-8
9. Wiberg G. Back pain in relation to the nerve supply of the intervertebral disc. Acta Orthop Scand 1950;19:211-221
10. Kublisch S, Ulstrom C, Michael C. The Tissue of Low Back Pain and Sciatica: A Report of Pain Response to Tissue Stimulation During Operations on the Lumbar Spine Using Local Anesthesia. Orth Clinics of North Am 1991; 22:181-187
11. Ramos G, and Martin W. Effects of vertebral axial decompression on intradiscal pressure. J. Neurosurg 1994; 81: 350-353.
12. Anderson G, Schultz A, Nachemson A. L. Intervertebral Disc Pressures During Traction. Scand J Rehabil Supp 1983; 9:88-91
13. Tilaro F, Miskovich D. The Effects of Vertebral Axial Decompression On Nerve Sensory Dysfunction; Can J of Clinical Medicine 1999 Vol 6 No 1: 2-7
14. Gose E, Naguszewski W, Naguszewski R. Vertebral axial decompression therapy for pain associated with herniated or degenerated discs or facet syndrome: An Outcome Study. J Neurological Research 1998 Vol 20:186-190.
15. Bogduk N. Clinical Anatomy of the Lumbar Spine and Sacrum. Third Edition. Churchill Livingstone 1997.
16. Fujita K, Nakagawa T, Hirabayashi K, Nagai Y. Neutral Proteinases in Human Intervertebral Disc. Role in Degeneration and Probable Origin. Spine 1993; 18:1766-1773
17. Nachemson A. Elfstrom G. Intravital Dynamic Pressure Measurements in Lumbar Discs. Scand J. Rehabil Med (Supp) 1970; 1:4-40
18. Matsui Y, Macda M, Nakagami W, Iwata H. The Involvement of Matrrix Metalloproteinases and Inflammation in Lumbar Disc Herniation. Spine 1998; 23:863-69

TRABAJO CIENTIFICO Nº 5

Proceedings of the Royal Society Of Medicine, 48, 805-814
.

Discussion on the treatment of backache by traction
Cyriax, J. H. (1955).

Cyriax mentions that some people do better prone and some supine. Patients were treated once or twice a day for half to one hour each time. Traction weight may be only 100 pounds with a "small woman," but up to 200 pounds in a "large man." He emphasized, "As soon as the traction becomes effective, certain alterations in the pain are felt by the patient." The changes are that the pain usually ceases, but a unilateral lumbar pain may become central, a root pain may become alumbar pain, a root pain may shorten (that is, move from the calf to the thigh above it), a root pain may remain in the same place but become less intense, or the pain may remain unaltered.

He emphasized that the patient must be treated daily; otherwise, it is not worth doing. He abandons treatment if pain is not improved after 12 sessions, and treatment is continued up to at least 4 weeks if necessary. In some patients with constant backache, adequate therapy may require 2-3 months.

The indications, in his opinion, are a protrusion of a disc, failure of manipulation, impaired nerve conduction (a weak muscle, absent ankle jerk, or cutaneous analgesia), failure of epidural local anesthetics, reference of pain to the coccyx or genital area, first and second lumbar disc lesions, and recurrence of pain after laminectomy. He considers contraindications to traction as "purely annular displacements," painful arc during trunk flexion, pain caused by side flexion awayfrom the painful side, pain which ceases as soon as the traction is applied but increases significantly when traction is released, and patients with impaired cardiac or respiratory function.

(NOTA : PUBLICACION PARCIAL)

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