A Historical Perspective on Treating the Spine
The application of a traction force, or set of forces, on those elements integral to the human spine for the treatment of chronic low back pain has been a part of medicine for nearly 4,000 years. In 3000 to 400 BC, the “falling ladder” was used as a therapeutic maneuver, in which the patient was fastened to a ladder that could be raised and then would suddenly be dropped from a height producing a non-specific thrust action to the spine. Hippocrates was known to have used traction as a therapeutic force for both spinal and peripheral joint ailments in 460 to 377 BC.¹
When people of the middle ages became dissatisfied with the way manual medicine was being practiced by physicians of the time, the formation of “bone setters” emerged in 200 to 1500 AD, which paved the way for the manipulative disciplines of chiropractic, osteopathy, and physical therapy in the 1800’s.¹⁻²
Hippocrates, the Greek physician known as the father of modern medicine, understood the value of the spine in human health and disease at an early age and that physicians should strive to master spinal anatomy/physiology. He stated that “One should first get a knowledge of the structure of the spine; for this is also requisite for many diseases."
Many years later, Galen expounded on these ideas and wrote:
“Nature, tends to keep everything in motion and at the same time aims at the security of its components. The vertebral column exemplifies how these two more or less opposite trends can keep in balance. If the spine was a single, rigid bone, then it would be invulnerable but also inflexible like a statue. In that case man would have been deprived of motion, which is the vital feature of life. On the other hand, a spine consisting of many small parts would be more flexible, but the unavoidable consequence of this flexibility would have been its vulnerability. The number of the existing vertebrae is the ideal as it allows the spine to bend in a circular rather than in an angular manner thus avoiding the injury of the spinal cord." ³
The importance of the spine and the more vital spinal elements continues to be studied by modern practitioners and researchers. Although we now better understand the complexities of the spine, in some ways our approaches are still nascent in curing spinal ailments and deformities.
Spinal distraction with the aim of relieving pressure from vertebral segments has remained remarkably similar for thousands of years and still consists of applying two opposite forces:
one acting in a cephalad direction by harnessing the torso and pulling up
one antagonistic force applied caudally to the lower body (pelvis) typically via harnesses and straps that pull down
The separation force created must then be focused to the desired target spinal segments, which is done through patient positioning, harnessing, and changing the lines (angles) of pull and is typically performed by a mechanical device.
Current Treatments for Disc Compression or Instability
Surgical Decompression or Fusion
Conditions that often precipitate surgical recommendations fall primarily into two categories of disorders:
compressive (disc/cord/nerve root)
instability (disc, vertebral body/deformities)
These are most often surgically treated with decompression and/or fusion procedures. These invasive procedures have well-documented risks and associated costs stemming from those complications. For instance, Yeramaneni et al conducted a systematic review of the literature and found 355,354 patients within 17 studies of which 11,148 reported complications.⁴ Infection was the most common complication and ranging between $16,000 and $39,000 to treat. Others have reported complication rates significantly higher including Nasser et al, who found an approximate 16% incidence rate in spinal surgery related adverse events in their review of 105 articles.⁵ As a result of both cost and risk factors, many people are turning to both conservative (non-invasive) and complementary and alternative (CAM) options for pain relief with subsequent restoration of function.⁶
Non-Invasive Spinal Decompression
The concept underlying non-surgical spinal decompression refers to the application of distraction forces directed to a spinal segment or segments that have been adversely affected by injury, age, or disease including spinal deformity, in which compressive forces have led or contributed to painful symptoms.
Figure 1 illustrates a lumbar disc compressing on a spinal nerve with subsequent mechanical irritation leading to inflammation and pain. Inherent disc deterioration can and does occur without any external changes to the disc structure, making radiographic diagnosis a challenge. Provocative lumbar discography and spinal disc injections have been proposed as confirmatory diagnostic procedures, but their invasive nature and risk for adverse effects have limited their use.⁶
Figure 1: Nerve Root Impingement
Intersegmental Spinal Decompression
Many patients have chosen to explore more conservative methods of reducing low back pain, and although there are myriad physical interventions available to the population, one of the more intriguing, but not least controversial interventions, is that of conservative intersegmental spinal decompression.
The differences between spinal traction and non-surgical spinal decompression (NSSD) devices have been debated for years, but both apply a distraction force to the spine. They are, in a sense, two parts of the same phenomenon in that a traction or distraction force is required to decompress (relieve pressure) a spinal structure such as a disc, nerve, facet joint, or vertebral body. It is the manner in which the force is applied that differentiates the two treatment modalities.
Conventional Spinal Traction
Conventional spinal traction devices have been known to use excessively high and generalized distraction forces applied to a painful lower spine, which can cause more muscle spasm and/or tightness post-treatment.
Decompression systems focus more on specificity or the ability to isolate a specific spinal segment and subsequently modulate the pull force, which has the effect of attenuating (lowering) the amount of pull force required for the treatment and can translate to fewer adverse treatment effects.⁷
There is a greater cost associated with this higher level of modulatory control, and it can be prohibitive for many smaller centers to afford the more sophisticated technology in NSSD systems, especially given that private insurance reimbursement has historically not distinguished between conservative spinal traction versus spinal decompression therapy.
The idea that disc health can be improved, while at the same time relieving compression induced disc/nerve pain symptoms is an appealing alternative and one that is becoming even more popular. There is evidence to suggest that externally applied distraction can have a profound effect on low back pain with or without pain radiation in a well-selected cohort.⁸˒⁹
How Distraction Forces Work
The application of a distraction force on a specific motion segment (and surrounding tissue) of the spine also appears to have the effect of increasing disc height.⁷˒¹⁰ The mechanism involved continues to be speculative, however there is evidence to suggest that distraction forces causing true disc decompression can activate the disc’s natural biological mechanism to imbibe water and over the course of minutes to hours can affect a change in water content in the nuclear material.¹¹ This phenomenon is consistent with prior research that demonstrated an osmotic gradient within the disc that needs to be maintained and influenced by mechanically transduced external forces leading to internal disc decompression.¹²
In cases of disc herniation or prolapse there is evidence from cervical spine studies that traction forces can in time reduce the herniation completely.¹³
Treating Chronic Low Back Pain Going Forward
Non-Invasive Interventions
In the author’s view, non-invasive alternative interventions to the treatment of low back pain and impairment should be encouraged prior to the more invasive procedures, given the epidemic scale of this condition and the associated risk and cost of surgical options.
The use of the various types of distraction techniques available in the marketplace today allows back pain sufferers to mitigate the often devastating effects of discogenic pain symptomatology, including the more serious secondary impingements on peripheral spinal nerves such as thecal sac effacement. The pressure over mechanically sensitive tissues (spine, nerves, spinal membranes, and ligaments) as a result of degenerative disc disease and the resulting structural alterations with subsequent biomechanical changes can be significant.⁸˒¹⁴
Distraction Therapy
Although the use of distraction therapy in all its iterations is not necessarily a cure for all discogenic lower spine pain from all etiologies, the application of a distractive force to alleviate what is essentially a primary compression problem should be intuitive to MSK practitioners at all levels, including spine surgeons. Laminectomies are, after all, classified as “decompression” procedures, acknowledging the sinister role that pathologic compression can have on the spine over time.
Benefits of Distraction Therapy
In a truly patient-centric healthcare culture that values patient preference and rewards providers whose behaviors contribute to positive outcomes and patient well-being, while at the same time is mindful of finite resources and escalating costs of care, the use of non-invasive, accessible, and evidence-informed treatments should be encouraged. Spine distraction techniques in their various forms have been around and used by civilizations for 4,000 years for good reason. Spinal distraction forces are known to change or alter the morphology of the spine, including increasing disc height as measured using MRI and also act to modulate muscle activity.⁹˒¹⁵⁻¹⁸
As well, the use of spinal traction has been demonstrated by MRI to reduce or lessen disc herniation, which can lead to restoration of normal spine mechanics and decrease nerve compression-related symptoms.⁷ When compared to more traditional traction, the more contemporary decompression devices have demonstrated an advantage in their ability to provide better pain relief and subsequent functional improvements in some studies, although it is difficult to provide a definitive conclusion until more robust comparative effectiveness outcomes research is completed.¹⁹˒²⁰
Distraction Techniques
What is known is that traction research is extremely varied, and comparing the various published clinical trials is challenging given the various types of traction methods studied (auto, mechanical, aqua, manual, and gravitational traction) along with varying treatment times, forces applied, rhythm, session duration, and treatment frequency.²⁰
The three more common patient configurations for applying clinical spinal traction/decompression include seated and table style setups. There are various other configurations beyond those described below for the home marketplace and beyond the scope of this review. Prospective patients interested in trying home traction devices should consult with their primary care physician, physical therapist, or chiropractic provider first and even try a device prior to purchase, as home inversion tables can cause adverse reactions to those who with breathing, vertigo, or circulatory problems.
Commonly used traction device configurations used by MSK practitioners familiar with using distraction forces to the spine as a way to decompress painful spinal structures including discs, end plates, membranes, facet joints, and nerve tissue.
The Protec Spine FMT takes a novel approach to the application of a distraction force to the lower spine by having the patient sit upright and force is applied by adjusting the degree of patient unloading. A sturdy upper body bolstering system ensures that the patient does not drop through while gravity is taking over and pulling down on the lower half of the body as the hydraulic seat is lowered. The sitting position is advantageous to those who cannot lie in prone or supine.
Figure 2: Conventional spinal traction device where the patient is supine or prone and the pull is controlled using pre-set programs with pre-selected pull parameters (force, time, continuous, interrupted). The pelvic harness is attached to a pulley cable that is connected to the traction motor unit where the pulling force is controlled.
The evolution of simple spinal traction has led to the development of more sophisticated spinal decompression tables where there is greater control of pull angles/forces including greater precision in targeting specific spinal segments. However, this greater specificity comes with a much greater cost.
Conclusion
Conservative spinal distraction leading to peri-articular elongation and disc decompression has been used for hundreds of years and continues to evolve today with more modern equipment and a better understanding of both spinal biomechanics as well as pathological processes. The addition of machine learning for predictive modelling and artificial intelligence applications that can evaluate functional status in a more granular manner promises to offer new insights for personalized medicine when it comes to spinal rehabilitation.
The anatomy of the human spine including the 23 discs interposed between vertebral bodies is a bioengineering marvel but aging and gravity can act to erode these structures which combined with injury, disease and other environmental exposures eventually lead to spinal decay, degeneration and even deformity, in particular, aimed at discal structures. The use of decompression forces to reverse the damaging effects of a lifetime of disc compression continues to be a central tenet in conservative spine rehabilitation.
The possibility that the disc can more efficiently imbibe water when decompressive unloading is applied to it which ultimately can lead to improved disc hydration and, in some cases, disc bulge resorption is an enticing rationale. Spine surgery is costly, is fraught with possible risks and offers no guarantee of improved outcomes over conservative, non- surgical and non-invasive methods. There are certainly cases when surgery is the best option for degenerated disc pathology, however, there are also conservative options that could also be considered and explored prior to spine surgery including decompression type interventions where the early evidence suggests good reason to be optimistic regarding pain reduction and improved function.
Also in this series:
Part I: Low Back Pain
Part II: Disc Degeneration
