Table driven or ‘pushing’ devices and are still being marketed today for the spinal decompression table
Non-surgical decompression was originally developed and pioneered by Allan Dyer, PhD, MD, in 1985, and the first non-surgical spinal decompression table, the Vax-D, was introduced by him in 1991. As I graduated from the National College of Chiropractic (now National University of Health Sciences) in 1988, we called a very similar modality traction. Over the past 30 years many other doctors, scientists and corporations have developed other “non-surgical spinal decompression tables,” each with features believed to mimic or enhance the effectiveness of the original concept.
Spinal decompression table: debatable methods of force
One thing decompression tables share worldwide is the use of a pelvic harness or belt that is placed above the pelvic brim so that a traction motor can caudally pull on the pelvis to place a traction or decompressive force on the spine.
The thing that brings debate among chiropractors is that there are tables that provide a distractive force by two other methods:
- The “pushing” type of table where an actuator or worm-gear elongates the lower half of the table and inversion-tables
- And most of these “inversion” tables do not utilize belting, have no motor, rely solely on gravity, and as such, do not push or pull the patient
The first generation of spinal decompression therapy tables were “pushing” tables or “table driven” and are still being marketed today by several manufactures. There is little clear evidence or research as to why a manufacturer would choose a “pushing” over a “pulling” type of traction system for their table but it is interesting that nearly 100% of physical therapists use traction or decompression units utilizing a pulling motor.1
Since FDA approval is more stringent for traction motors and they are more expensive to produce, it would seem the selection is based more on cost and manufacturing convenience. There are currently only five traction motors available in the United States for use in decompression or traction tables.2
Variable patient positioning
After 30 years of observation, personal use and teaching in the spinal decompression therapy market, it is my opinion manufacturing a pushing table would have lower production costs and would allow a company to over-simplify the patient setup and treatment for the doctor. The pusher-type systems seem to be inexplicably limited to just one patient position even though 30-plus years of research point to the necessity of variable patient positioning.3
It remains uncertain why the “table-driven or pushers” typically market at prices that are two to three times more than motor-mounted units when there is no research to imply superior clinical efficacy.
All decompression/traction units require some method of capturing or securing the pelvic-crest while restraining the thorax by way of a wing vest, axilla posts, Slip Stops or a hand-type grab. Belting can’t be eliminated based on the spinal decompression table type. Pelvic belting in pusher-type units is generally a Velcro wrap-over or a cinching strap incorporated into the tabletop, similar to a seatbelt.
Potential slip-through issues become evident at higher pulling forces and require a much greater reliance on some form of thoracic restraint. Tight thoracic belting or strapping can trigger breathing difficulties and trigger muscle spasm or guarding for some patients.4
The most frequent mechanical issue with pelvic strapping is usually effectively “pre-seating” the pelvic belt over the pelvic brim prior to the tabletop reaching its full traction pull weight. The belt should slip or pre-seat into its proper position simultaneously with the table’s caudal motion.
A pre-seatbelt failure allows the table to be excessively open under the patient’s lower back and sacrum, reducing treatment efficacy and creating discomfort in some.5 Separating the actual “table separation” from the patient’s perception of the “application of tension” just makes more sense mechanically and clinically.6 Some manufacturers of “pull” traction tables utilize a table lock and a variable spring resistance feature so patients will “feel” more traction without excessively increasing their actual pull weight.
Manufacturer harness options
Because patients are not as relaxed and comfortable wearing a thorax harness, some manufacturers have abandoned using them and simply have the patient hold onto a bar or handles. The patient is advised to “release your grip if you feel pain.” This simplistic approach has been recognized by the FDA as a significantly effective and safe means of restraint.7
This hold-on advice is only a feasible option with a prone patient. I recommend my patients hold on to restrain their upper body in prone applications by placing their elbows down in the patient position of an adjusting table to assure their maximum comfort and compliance during decompression.
Flexion-distraction table manufacturers mostly abandoned direct pelvic capture and moved to the combination of the doctor hand contact on the spine along with ankle strapping. As flexion-distraction begins, the tension on the lower back is immediately felt. Supposedly this type of “traction” can produce adverse effects in some discs and many strain/sprain conditions as the unavoidable flexion stress is not uniformly applied. This form of traction is also very hard on the practitioner, as standing in slight flexion over patients day after day causes significant stress on their own lumbar spine, wrists and shoulders.
Excess flexion and position guiding
Disc damage is not easily demonstrated or diagnosed.8 Some discs are receptive to flexion but in my opinion, and disc research, excess flexion or extension stress, whether upright or recumbent, can have dire consequences for many.
Practically all compression-disc issues will either tolerate and/or benefit from axial traction/decompression, but the patient posture on the table should be based on their comfort, or positional preference, pre-traction and shouldn’t be forced via the table’s resultant traction “pull.” This means that if flexion, extension or lateralization is required it should be a pre-traction event and never be further imposed during the table’s “pull.” The traction pull force should preferably remain axial so it doesn’t further aggravate sensitized tissue. Using pre-traction pain relief as your positioning guide assures the least irritating and most effective decompressive treatment.
Adding flexion or extension will provide no additional long-term benefit to the decompression effect from table distraction, but it can help provide centralization in many cases. Actually, distraction predictably reduces intradiscal pressure with the effect being dependent on the stage of degeneration of the affected disc. Research shows nearly 50% of moderately-degenerative discs achieved negative intradiscal pressure gradients with traction/decompression; however, only one in seven severely degenerative discs achieved the same reduction.9
Never underestimate the difference between pre-traction positioning and “flexed”-traction. I suggest pre-positioning patients into various enhanced flexion/extension or lateral postures while always remembering this important rule — keep the pull force axial. When the pull is coming from a pulling motor distant to the patient, the spinal decompression table articulations are utilized as a means to reduce neural and/or mechanical compression or irritation that remains — with a recumbent patient the pull vector must remain parallel to the spine.
A “pulling” motor is perfectly suited for this use and will most ideally replicate what a clinician would do if manually stretching a spine.10 For example, my puller tables allow for multi-vector pull options which provide a very precise, controllable pull that drives the decompression force direct to the spine with little to no patient slippage or movement. A certain puller spinal decompression table has a variable compression spring which allows the clinician to control the table movement or the patient’s “perception of the pull” safely without increasing pull force, which all others do.
As reported by Maitland, Saunders, Cyriax and others, mechanical traction is used because manual means are unsustainable and reproducibility is necessary. Mechanical devices were born out of the limitations of manual traction. It is rare for a clinician to lay a patient on a sliding table and “push” the table section — they grab and hold the body-region and pull it toward them using skillful and progressive distractions.
Laterality and rotation are two additional considerations of patient positioning. Laterality or lateral bending is clinically needed in about 15-20% of clinical presentations but rotation, in my opinion, is never suggested due to the construction of the spinal disc, the prevalence of rotation-induced disc injuries, and the real risk of re-injury when rotation is combined with distraction.
I have not treated conditions which require more than 25 degrees of lateral bending that can easily be achieved by pulling the patient’s hips 3-6 inches toward the edge of the spinal decompression therapy table prior to applying traction. All modern traction units will allow the pull motor to be offset at least 6 inches. This will allow ample treatment of any lateral disc condition. If a larger laterality exists as in a medial disc/nerve compression, a side-lying traction may be a viable option if the table allows this setup.10
This is why table section articulation to accommodate various relief or positional preference postures is a clinical necessity and must be considered when selecting a decompression table. Positional preference is most important in the extension range of motion, since at least 80% of herniations demonstrate some relief with patient extension.11
Consequently, it’s very important the table’s superior or cephalad section bends at the L5-S1 level and not at the mid-sternal region. Having the ability for full-torso extension is perhaps the most important of all pre-traction positional preference positioning options. If your decompression table is a “supine-only” model, I’d highly recommend safely trying to modify it to accommodate prone treatment or considering trading it for one that will. Flexion distraction has been used for more than 100 years to treat herniated nucleus pulposus with the patient prone. Mackenzie research has more than 300 published trials; McGill, Saunders, Fritz and many others all focus on treating herniated disc patients with prone treatment.
“Gravitational bias” now refers to the tendency of the nuclear material to migrate back to the anterior/central region of the disc and is a phenomenon difficult to visualize in a supine patient, especially with a patient supine for 15-30 minutes as the disc is isotropic.12
Disregarding patient testimonials, science, biomechanics and published research all point to the effectiveness and short treatment plans of prone disc treatment. To argue against it seems a bit irresponsible.
Expedite patient encounters
In today’s chiropractic clinics the use of a decompression/traction belt is either hated or revered. If your assistants break their fingernails, spend five minutes re-tightening belts or your patients routinely have their pants pulled down and their breasts pushed up, you probably need a quick tutorial. Belting should be quick, easy and reproduceable time after time, ideally requiring one minute or less of setup time. I would also suggest saving staff and patient time by utilizing a pelvic belt that works for all treatment positions on a spinal decompression table.
With some manufacturers offering drop table option and “open” harnesses, clinicians now have the ability to apply modalities and simultaneously adjust the spine with the patient on the decompression table providing specific and directed segmental contact when warranted during the axial distraction very similar to F/D but without the flexion component or wear-and-tear on the doctor.
Don’t let your patient results, clinic flow or capacity suffer because of inefficient belts or belting issues. Learn to expedite patient encounters by doing two or more things at once. Use a belting system that allows the application of laser, ultrasound, EMS, heat/ice or diathermy during decompression. A synergy of several safe, effective and efficient treatments with spinal decompression therapy enhances patient flow as well as your patient results.
DAVID BOHN, DC, graduated from National University of Health Sciences (formerly National College of Chiropractic) in 1988 and has since been in continuous practice. Since 2004 he has pursued development of both documentation and X-ray analysis software. He has extensive experience with developing, marketing and maintaining a successful practice, and is an instructor for KDT Decompression Therapy Seminars. For more information, go to kdttechnique.com/upcoming-seminars.
1. Harte et al. Efficacy of traction for back pain: a systematic review. Arch phys med rehab Oct (84) 2003.
2. FDA website 2014/pre-market traction clearance.
3. Motorized traction. United Health Care. July 1, 2013. Pellecchia G. Lumbar traction: a review of the literature. JOSPT Vol 20(5) Nov 1994.
4. Letchuman R, Deusinger RH. Comparison of sacrospinalis myoelectric activity during two types of traction. Spine; 18(10) 1993.
5. Grieves G. Modern manual therapy. Churchill Livingstone. 1996.
6. Ibid; 791-794
7. Gose E. et al. Vertebral axial decompression for pain assoc. with herniated discs. Dept of bioengineering, Univ of Chicago. 1997.
8. Jensen MC et al. MRI of the lumbar spine in people without back pain. N Engl J Med Jul14;331(2) 1994.
9. Gay et al. Stress in lumbar intervertebral discs during distraction. Spine Nov;8(6) 2007.
10. Michelle Cameron MD. Physical agents in rehabilitation. Saunders. 2009
11. Hefford, C. McKenzie classification of mechanical spinal pain. Man ther 2008. Gagne AR, Hasson SM. Lumbar extension exercises in conjunction with mechanical traction in the management of a patient with a herniated disc. PT Prac May;26(4) 2010.
12. Adams, Bogduk, Burton, Dolan. Biomechanics of back pain (135-140). Churchill Livingstone. 2006.