Roger Wilhelm, D.C.

Evolving Models

 A large recent review of the chiropractic profession confirms that chiropractors specialize in the management of back and neck pain (1). The study, from the National Health Interview Survey, which is the principal and reliable source of comprehensive health care information in the United States, found that 63% of chiropractic patients presented with low back pain and 30% presented with neck pain. Overall, 93% of chiropractic patients presented with spinal pain complaints (1).

When assessing spinal pain complaints, it is commonplace for chiropractors to take x-rays. Spinal x-rays serve many purposes. The primary purposes for taking spinal x-rays were summarized in 2020 in the journal Quantitative Imaging in Medicine and Surgery. The study was titled (2):

The Role of Radiography in the Study of Spinal Disorders

The authors state:

“Radiography plays an important role in many conditions affecting the spine.”

The authors advocate spinal x-rays for the assessment of these potential problems:

• Traumatic Fracture
• Congenital Abnormalities
• Osteoporotic Vertebral Fracture
• Degenerative Spinal Pathology
• Spinal Instability
• Spondylolisthesis
• Alterations in Spinal Curvature
• Inflammatory Pathology
• Infectious Pathology
• Neoplastic Pathology

The authors note that the most frequent origin of spinal pain is classified as “non-specific” (approximately 70%) because the specific nociceptive source cannot be proven. The second most prevalent cause of spinal pain is mechanical. Mechanical spinal pain includes degenerative disorders of the spine, alignment abnormalities, and vertebral fractures. X-rays are very valuable in diagnosing all of these mechanical causes of back pain.

Spinal degenerative pathology is also known as:

• Arthritis
• Osteoarthritis
• Degenerative Arthritis
• Degenerative Joint Disease (DJD)
• Spondylosis, primarily applied to the spinal facet joints
• Spondyloarthritis, again primarily applied to the spinal facet joints
• Degenerative Disc Disease (DDD)

Degenerative spinal pathology can affect any and all of the spinal joints. Degenerative spinal pathology is extremely common in adults, and its incidence increases with age (3).

Spinal x-rays are one of the most frequently employed modalities used in the study of spinal pain. Publications advocate taking x-rays on patients for these reasons (2):

• When the patient presents with a history of trauma that may result in fracture or instability.
• When there is suspicion of vertebral compression fracture secondary to osteoporosis or from a history of steroid use.
• When there is a history of congenital pathologies, including hyperkyphosis, hyperlordosis, scoliosis, kyphoscoliosis, hemi- vertebrae, block vertebrae, Klippel-Feil syndrome, sacralization, lumbarization, facetal tropism, etc.
• When there is a history or suspicion of spondylolisthesis, Scheuermann’s disease, and/or Schmorl nodes.

History records that the chiropractic profession pioneered the use of x-rays on the spine in 1910 (4, 5). At the time, spinal x-rays were referred to as “spinographs.”

Today, spinal x-rays are at the center of much of chiropractic education and clinical practice. Chiropractic educational curriculum has between 6-10 courses that are entirely dedicated to the taking and interpreting of x-rays. Additionally, x-rays are woven into the majority of clinical science and adjustive technique courses.

Leading scientific/medical journals have confirmed the competency of chiropractors in reading/interpreting spinal x-rays (6, 7, 8).

A study published in 1997 in the Journal of Manipulative and Physiological Therapeutics detailed the use of x-rays by chiropractors (9):

• 74% of chiropractors have x-ray facilities in their offices.
• 71% use x-rays to screen for contraindications to chiropractic care.
• 63% use x-rays to assess existence of pathological conditions.
• 51% use x-rays to observe/measure altered biomechanics and posture.
• 84% of the chiropractors refer to medical radiologists and/or to chiropractic radiologists for a formal interpretation of their radiographs.

A valid concern pertaining to x-ray exposure is the ionization issue and the cost to patients and to the health-care system. These concerns were addressed in 2017 in the journal Mayo Clinic Proceedings: Innovations, Quality & Outcomes (10). The authors note that chiropractors frequently use spinal x-rays. They also speculate that the increased use of x-ray imaging may be responsible for the reduction of the use of advanced imaging, such as MRI and CT, resulting in a net benefit for both the patient and the reimbursing parties, saving the system money, time, and personnel resources.

In chiropractic clinical practice, ablative pathology (infection, malignancy, tumor, etc.) is quite rare. In contrast, degenerative arthritic changes are very common. An important article pertaining to degenerative arthritis was published in 2006 by Susan Garstag, MD, and Todd Stitik, MD (11).

These authors note that osteoarthritis is the most prevalent form of arthritis and a major cause of disability in people aged 65 and older. Osteoarthritis affects the majority of adults over age 55, and that 58% of those older than 70 years have symptomatic osteoarthritis.

These authors categorize joint degenerative changes to local factors and systemic factors:

Local Factors include:

• • Altered joint biomechanics
  • Malalignment
  • Muscle weakness
  • Impaired proprioception neurology

Systemic Factors include:

• • Age
  • Genetic Factors
  • Nutritional Factors, especially inflammatory profile and free radical burden (generators of oxidative stress)

Drs. Garstag’s and Stitik’s comments linking osteoarthritis to malalignment, muscle weakness, impaired proprioception, and altered joint biomechanics are particularly interesting to chiropractors, as these are all components of what chiropractors call the subluxation.

Traditional chiropractic teaches that untreated joint subluxations lead to osteoarthritic changes.

There is no doubt that spinal degenerative changes can cause spinal pain syndromes. Yet, there is also no doubt that spinal degenerative changes can exist in subjects that have no pain whatsoever (3, 11, 12, 13, 14, 15, 16).

Less controversial is the contention that asymptomatic spinal degenerative changes are a weakness that increases the vulnerability of the afflicted articulations to injury and pain when subjected to increased stress, prolonged stress, or injury:

• In 1964, whiplash injury expert and pioneer, Ruth Jackson, MD, published an article titled “The Positive Findings in Neck Injuries” in the American Journal of Orthopedics. Dr. Jackson’s conclusions in this article were based on her evaluation of 5,000 injured patients. She notes (17): 

“[Pre-existing pathological conditions of the cervical spine, when injured], “result in more damage than would be anticipated in a so-called ‘normal’ cervical spine.”

• In 1977, Samuel Turek, MD, clinical professor from the Department of Orthopedics and Rehabilitation at the University of Miami School of Medicine, and author of the reference text, Orthopaedic Principles and their Applications, states (18):

“The injury may be compounded by the presence of degenerative disease of the spine.”

 “With advancing age, especially in the presence of degenerative disease, the tissues become inelastic and are easily torn.”

• In 1981, Rene Cailliet, MD, professor and rehabilitation specialist from the University of Southern California, and author of the book Neck and Arm Pain, states (19):

“The pre-existence of degeneration may have been quiescent in that no symptoms were noted, but now minor trauma may ‘decompensate’ the safety margin and symptoms occur.”

• In 1983, Norris and Watt followed 61 whiplash-injured patients for a minimum of six months in order to establish factors that were prognostic for recovery. They published their findings in the British Journal of Bone and Joint Surgery, titled “The Prognosis of Neck Injuries Resulting from Rear-End Vehicle Collisions.” Their conclusions include (20):

“Factors which adversely affect prognosis include the presence of objective neurological signs, stiffness of the neck, [loss of cervical lordosis], and pre-existing degenerative spondylosis.”

“Pre-existing degenerative changes in the cervical spine, no matter how slight, do appear to affect the prognosis adversely.”

• In 1985, Webb, in his article titled “Mechanisms and Patterns of Tissue Injury,” notes (21):

“Degenerative joint disease is recognized as a major influence on subsequent tissue damage both in severity and pattern.”

“In any individual where changes consistent with degenerative joint disease are present, one can expect the injury to be more severe or a very minor injury to produce severe symptoms requiring prolonged treatment.”

• In 1986, Arthur Ameis, MD, from the Faculty of Medicine at the University of Toronto, notes (22):

“For the elderly, neck injury can be very serious.  The degenerative spine is biomechanically ‘stiffer’, behaving more like a single long bone than like a set of articulating structures.  Deforming forces are less evenly dissipated, and more damage is done.”

• In 1987, physicians Edward Dunn and Steven Blazar authored “Soft-Tissue Injuries of the Lower Cervical Spine” for the American Academy of Orthopedic Surgeons. In this publication they note (23):

“If present, degenerative changes should be duly noted as they may affect the prognosis.” 

“…pre-existing degenerative changes adversely affected the outcome.”

• In 1988, Mairmaris and colleagues published a study titled “Whiplash Injuries of the Neck.” They reviewed 102 whiplash-injured patients 2 years after injury. They concluded (24):

“The analysis of the radiological results showed that pre-existing degenerative changes in the cervical spine are strongly indicative of a poor prognosis.”

• In 1988, physician Hirsch and colleagues published a paper titled “Whiplash Syndrome, Fact or Fiction?” in Orthopedic Clinics of North America. These authors note (25):

“[Pre-existing structural changes and degenerative changes are] frequently associated with a more difficult, more prolonged, and less complete recovery.”

“These changes may include the presence of osteophytes, foraminal encroachment on the oblique projections, and the presence of intervertebral disc space narrowing.” 

“When hyperextension injury occurs in the presence of pre-existing osteophyte formation, there is further narrowing of the spinal canal, which increases the potential for injury to the nerve roots or cord.”

• In their 1988 reference text on whiplash injuries titled Whiplash Injuries, The Acceleration/Deceleration Syndrome, Steve Foreman and Arthur Croft note (26):

“…the presence of preexisting degenerative changes, no matter how slight, appears to alter the prognosis adversely.”

• In 1989, physician Porter published an article in the British Medical Journal titled “Neck Sprains After Car Accidents.” He noted (27):

“Pre-existing degenerative changes may worsen the prognosis.”

• In 1991, Watkinson, along with Gargan and Bannister, radiographically reviewed 35 whiplash-injured patients 10.8 years after injury. In this study, 87% of patients with spondylosis on initial radiographs reported continued symptoms, compared with only 20% of patients with normal initial radiographs. They concluded (28):

“Patients with degenerative changes initially have more symptoms after 2 years than those with normal radiographs at the time of injury.”

“Degenerative changes occurred significantly more frequently in patients who had sustained soft tissue injuries than in a control population.”

• In 1995, physicians Jerome Schofferman and S. Wasserman published an article in Spine titled “Successful treatment of low back pain and neck pain after a motor vehicle accident despite litigation.” The authors evaluated 39 consecutive patients with low back pain or neck pain that resulted from a motor vehicle accident. These authors noted (29):

“Pre-existing degenerative changes on initial x-rays, no matter how slight, had a worse prognosis.”

• In 1996, Squires, Gargan and Gordon Bannister, published a 15.5-year follow-up evaluation of 40 patients who had been injured in a motor vehicle collision in the British Journal of Bone and Joint Surgery, titled “Soft-tissue Injuries of the Cervical Spine. 15-year Follow-up.” In this article, these authors note (30): 

“80% of the patients who had deteriorated in the last five years had degenerative changes.” 

“100% of patients with severe ongoing problems had cervical degeneration at 11 years after injury.”

• In 1999, the reference text Whiplash and Related Headaches, by neurologist Bernard Swerdlow, MD, makes the following point (31):

“[Risk factors that may lead to chronicity include] pre-existing degenerative osteoarthritic changes.”

“Other conditions that may pre-exist the accident that may contribute to a chronic state following the accident are osteoarthritis, degeneration of vertebral body joints, disc degeneration and inflammatory processes.” 

“Studies indicate that pre-existing osteoarthritic changes contributed to alter the prognosis adversely.” 

“As we get older there is a degeneration of the intervertebral disc. This degeneration affects the height of the disc. When there is loss of disc height, then this may cause a decrease in motion of the posterior facets and lead to restriction of motion at that level. Therefore, the biomechanical function of these vertebrae are affected.”

• In 2002, in their reference text titled Whiplash, Gerard Malanga, MD and Scott Nadler, DO, state (32):

“Several researchers have associated poor clinical outcomes with spondylosis, reporting a higher prevalence of spondylosis in patients with continued symptoms.”

“It is certainly theoretically possible that symptoms from a previously asymptomatic cervical spondylosis are precipitated by trauma and are responsible for the continuing pain.”

“It is generally accepted, for example, that a previously asymptomatic hip or knee with long-standing radiographic degenerative changes can become painful after an apparently minor injury.”

“It seems reasonable to presume that a similar outcome can occur with so-called soft tissue strains to the cervical spine.”

• In 2005, physician Schenardi published a study titled “Whiplash injury, TOS and double crush syndrome, Forensic medical aspects.” The author addresses the issue of pre-injury cervical spine degeneration, stating (33):

“[A substantial percentage of people will have whiplash symptoms for more than a few months], especially the elderly or those with pre-existing neck problems who may develop chronic long-term problems which may never resolve.”

••••

The benefits of spinal adjusting for patients suffering from spinal degenerative arthritis is attributed primarily to two mechanisms:

A) Mechanical dispersion of inflammatory chemicals (34):

Spinal joints with degenerative arthritis tend to also have stiffness, a reduction in the range of motion. Spinal adjusting improves spinal motion, and improved spinal motion disperses the accumulation of inflammatory chemicals that initiate pain.

B) Closure of the pain gate (35):

The pain electrical signal in the brain can be “blocked” by the closing of the “pain gate.” Spinal stiffness allows the pain gate to be open to pain electrical signals. Spinal adjusting improves mechanical motion and closes the pain gate to these electrical signals. This explanation was championed by Canadian orthopedic surgeon William H. Kirkaldy-Willis in 1985. Dr. Kirkaldy-Willis stated (35):

“[Melzack and Wall proposed the Gate Theory of Pain in 1965, and this theory has] withstood rigorous scientific scrutiny.”

“The central transmission of pain can be blocked by increased proprioceptive input.” “[Pain is facilitated by] lack of proprioceptive input.” “[This is why it is important for] early mobilization to control pain after musculoskeletal injury.”

The facet capsules are densely populated with mechanoreceptors: “Increased proprioceptive input in the form of spinal mobility tends to decrease the central transmission of pain from adjacent spinal structures by closing the gate. Any therapy which induces motion into articular structures will help inhibit pain transmission by this means.”

This closure of the pain gate model of the mechanism of pain suppression by spinal adjusting has continued to gain support (36, 37). The model indicates that the adjustment activates regions in the brain and brainstem that inhibit pain. This model is continuing to gain support and advancement. The most recent published advancement appeared in the journal Current Rheumatology Reports June 2022, titled (38):

Autonomic Nervous System Dysregulation and Osteoarthritis Pain:
Mechanisms, Measurement, and Future Outlook

“This review discusses potential overlap among autonomic dysregulation,
osteoarthritis (OA) progression, and chronic pain.”

The authors are from the University of Florida, and their study was funded by the National Institutes of Health. As with the pain gate, the autonomic nervous system resides in the brain and the brainstem. Consequently, it is plausible that when spinal adjusting closes the pain gate that it also influences the autonomic nervous system.

The authors note that the autonomic nervous system changes in chronic pain states and that it plays a role in osteoarthritis progression. There are functional overlaps between the autonomic nervous system and pain processing centers in the brain.

The authors note that medications fail to fully resolve pain and have serious long-term side effects. Consequently, there is a need for a paradigm shift to create new solutions for osteoarthritis treatment, especially for nonpharmacological therapeutics.

Specifically, the authors note that the pathophysiologic progression of osteoarthritis is enhanced by increased activity of the sympathetic nervous system and inhibited by increased activity of the parasympathetic nervous system. The sympathetic nervous system primarily uses the neurochemical norepinephrine. The parasympathetic nervous system primarily uses the neurochemical acetylcholine. The authors make these points:

• Increased sympathetic tone and release of norepinephrine activates pain-sensing nerve fibers.
• Increased parasympathetic tone and release of acetylcholine attenuates pain-sensing nerve fibers.
• Increased parasympathetic tone increases signals to the gut, which “regulates the production and absorption of nutrients and the diversity of gut microbiota.” This explains the physiologic link between osteoarthritis and gut dysbiosis.

The authors note that non-pharmacological interventions that target the autonomic nervous system are becoming increasingly supported.  They also note the link between the autonomic nervous system and osteoarthritis.

Although chiropractors use spinal adjusting (specific line-of-drive manipulation) for the management of spine pain syndromes, the mechanisms for the proven benefits continue to be updated. A few of these supportive studies are briefly presented here:

The Neurochemically Diverse Intermedius Nucleus of the Medulla as a Source of Excitatory and Inhibitory Synaptic Input to the Nucleus Tractus Solitarii (39)

The Intermedius Nucleus of the Medulla: A Potential Site for the Integration of Cervical Information and the Generation of Autonomic Responses (40)

Cerebral Metabolic Changes in Men After Chiropractic Spinal Manipulation for Neck Pain (41)

Neck Muscle Afferents Influence Oromotor and Cardiorespiratory Brainstem Neural Circuits (42)

Measurable Changes in the Neuro-endocrinal Mechanism Following Spinal Manipulation (43) 

Glucose Metabolic Changes in the Brain and Muscles of Patients with Nonspecific Neck Pain Treated by Spinal Manipulation Therapy (44)

SUMMARY and CONCLUSIONS

As the evolving models for the influence of chiropractic spinal manipulation in the management of spinal osteoarthritic changes and related spine pain syndrome, the presented studies support these concepts:

• Spinal osteoarthritic changes are very common and nearly universal in humans older than age 50.
• Spinal osteoarthritic changes may be asymptomatic. Yet, asymptomatic spinal osteoarthritic changes are a biomechanical weakness, reducing the ability of the arthritic joint to optimally disperse the forces imparted to the joint during stress, load, and injury. Hence, asymptomatic spinal osteoarthritic joints are likely to become symptomatic when exposed to trivial or prolonged biomechanical stress.
• Despite the model or models of explanation for the pain associated with osteoarthritic changes, chiropractic manipulative management is both very safe and effective.

REFERENCES

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“Authored by Dan Murphy, D.C.. Published by ChiroTrust^® – This publication is not meant to offer treatment advice or protocols. Cited material is not necessarily the opinion of the author or publisher.”