The Science and Theory Behind CLEAR’s Approach to Scoliosis

The following is an excerpt from the full-text of the article, Chiropractic treatment of idiopathic scoliosis using the CLEAR Institute method: a description of the protocol and the tenets behind its application, which was presented at the SOSORT Congress in Chicago, IL, in 2013, and the abstract published in Scoliosis journal.  Please click here if you would like to download the full article.

By definition, idiopathic scoliosis involves an incomplete understanding of its etiology. A more comprehensive approach to patient evaluation and assessment may be considered justified in the management of idiopathic diseases to ensure individual patient expectations of care are met.  A thorough patient evaluation consisting of multiple pre- and post-treatment outcome assessments may be considered especially useful when a novel method of treatment is being introduced for an idiopathic condition.

Before the CLEAR Institute method can be adequately understood, it is vital to identify the tenets behind its application.

  1. Motion is essential for healthy spinal discs.
  2. Hypertonic paraspinal muscles impede the spinal flexibility, and hypotonic muscles reduce spinal stability.
  3. Ligamentous abnormalities contribute to proprioception feedback mechanisms and sensory dysfunction. [46-48]
  4. Posture, proprioception, balance, and equilibrium are involuntary mechanisms, regulated by the cerebellum, brainstem, and the automatic postural control centers. [49-51]
  5. Spinal misalignments are universally present in scoliosis; the purpose of CMT is to treat spinal misalignments and their associated effects upon the body.

It is unlikely that one therapy could address all of the components involved in IS.  A multifactorial, “Whole Systems” approach [19] to treatment involving a series of therapies designed to work in conjunction with each other may be of benefit in the management of complex, multifactorial diseases such as IS.

Summary

The CLEAR Scoliosis Treatment Protocols are centered around five tenets which are based on clinical experience and anatomical and physiological research.

Research on spinal intervertebral disc biomechanics suggests that motion is designed to occur in the spine and that cyclic repetitive loading and unloading, through the process of osmosis and imbibition, may positively influence disc function.

Paraspinal muscle imbalances are well-documented to occur in scoliosis, and evidence indicates they are linked to the risk of progression.  Some exercises designed for scoliosis patients have the ability to activate specific muscle groups in an asymmetrical fashion.  Therapeutic stretches are also commonly used to rehabilitate hypertonic muscles; these stretches can similarly be done in an asymmetrical manner.

Ligaments are not purely a mechanical structure, but also play a role in posture, proprioception and sensory integration.  Ligamentous abnormalities are well-documented to occur in scoliosis patients, and may be linked to problems with sensory integration.  Rehabilitation of documented impairments is the desired goal, but initially the poorly-functioning ligaments must be identified and injury/aggravation of any existing issues avoided.

If a sensorimotor integration disorder is involved in the etiopathogenesis and/or progression of idiopathic scoliosis, approaches such as vestibular rehabilitation, balance training exercises, and whole-body vibration (WBV) therapy are currently being investigated for their effect in improving function in populations with vestibular impairment; it may be worth the effort of further research to determine if these approaches may be of benefit in the management of IS.

The likelihood of a successful treatment outcome for the person living with scoliosis increases when scoliosis-specific approaches are applied.  Evidence does not support diversified full-spine CMT for mild cases of scoliosis.  In the same manner that scoliosis-specific exercises are more likely to be of benefit in the management of IS, more specific applications of CMT may be worthy of further investigation to determine if the same principle applies.

The CLEAR Institute scoliosis treatment method aims to treat disc problems through motion, muscle imbalances through exercises and stretching, spinal biomechanics through specialized CMT procedures, and neuromuscular function through balance exercises and WBV therapy.  It focuses upon the inclusion of functional, cosmetic, and quality-of-life indices alongside radiographic measurements.  It is intended to provide an evidence-based option to scoliosis patients who wish to self-select chiropractic treatment for their condition.

Intervertebral discs in the scoliotic spine

Axial loading of growth plates influences growth in accordance with the Heuter-Volkmann law. [52,53]

Asymmetric loading of the spine causes asymmetrical wedging of the discs resulting in scoliosis, which eventually leads to vertebral wedging. [52, 54] Intra-discal pressures and stresses upon the discs in scoliosis are high, and remain high even in the absence of significant muscle loading and gravitational forces. [55] One suggested explanation for this could be dehydration of the annulus (especially on the concave side of the disc), contributing to soft tissue changes in the discs and ligaments, and alterations in the fascial mechanics.  Nutrient supply to the disc may play a role in this process. [56] Widespread changes in the endplate and nucleus pulposus of the scoliotic disc have been found even when minimal wedging is present, suggesting nutritional factors as the primary mechanism of degeneration induced by mechanical stress. [57] The water content of the scoliotic disc has been found to be lower than normal [58], turnover of the proteoglycan matrix is impaired, and there is decreased permeability of the end-plates. [59,60]  The permeability of the end-plates is essential for normal fluid and nutrient transport [61,62], and calcification of the end-plate could initiate and promote degeneration of the intervertebral disc. [63]  It has been suggested that the process of disc degeneration can be accelerated if motion is restricted, and can be avoided if motion is preserved, [64-67]  the implication being motion may be essential to maintaining ideal hydration and nutrient supply to the intervertebral disc.

While intervertebral discs cultured under high amounts of dynamic, cyclic compressive stress exhibit decreased collagen and glycosaminoglycan content, discs cultured under smaller amounts of cyclic compressive stress actually exhibit increased collagen and GAG content. [68]  Dynamic compression facilitates the diffusion of nutrients and thus increases the nutrition level around the cells of the intervertebral disc. [69] Cyclic loading and unloading of the intervertebral disc restores normal disc mechanics through fluid transport; fluid exudation and recovery may be integral to maintaining adequate disc nutrition and preventing degeneration. [70]

Conservative treatment of idiopathic scoliosis is designed to counter-act the asymmetrical forces acting upon the growth plates, in an attempt to alter growth mechanics through the Heuter-Volkmann law.

The majority of studies have focused upon the paraspinal musculature (and to a lesser extent gravity) as the origin of the asymmetrical loading; however, the presence of significant, high-magnitude stresses upon the disc even in the absence of gravity and muscle loading is interesting.  These stresses may exist due to degradation of the scoliotic disc structures caused by insufficient fluid and nutrient transport.

Based upon this, it may be possible to reduce stresses upon the disc by stimulating hydration and nutrition through exercise and gentle, repetitive cyclic loading and unloading.

Paraspinal muscles surrounding the scoliotic spine

Cheung et al observed asymmetrical electromyographic (EMG) activity in AIS patients, and found that higher imbalances were strongly predictive of curve progression [71-73].  In these studies and in others [74,75], the muscles on the convex side of the curvature demonstrated increased EMG activity.  Cheung et al agreed with the point of view expressed by Riddle and Roaf [76], namely that this increased EMG amplitude indicated that the muscles on the convexity of the curve were stronger or more hypertonic than the muscles on the concave side.  This is further supported by histological evaluation of muscle tissue in the concavity of the curve, which finds a decreased proportion of oxidative slow-twitch (type 1) fibers [77], suggestive of decreased tonic activity.

Schmid et al evaluated EMG amplitudes of paraspinal muscles during exercise, and found that certain exercises increased the EMG amplitudes of the paraspinal muscles in the concavity[78]; the authors hypothesized that, by strengthening the weaker side, improved muscle-performance capacity could be responsible for the 20% improvement of the scoliotic curvature observed by Mooney et al [79] and the short-term reduction in progression observed by McIntire [80].  Weiss has shown that an intensive inpatient rehabilitation program based on asymmetrical exercises can improve the muscle-performance capacity of the paraspinal muscles, and suggested that this could lead to a functional correction of the scoliotic curve [81].  Schmid et al suggested that weights and exercises could be individually adapted to each patient for maximum benefit, which concurs with the Cochrane Review by Romano et al [82] that found evidence of increased effectiveness of scoliosis-specific exercises (SSE’s) as compared to general physiotherapy.  While additional research on SSE’s is needed, it can be said that decreased EMG activity in the concave paraspinal muscles in scoliotic patients exists; that this imbalance may be linked to progression; and, that certain exercises may increase EMG activity asymmetrically in the paraspinal muscles.  The hypothesis is that increasing EMG activity in the concavity through SSE’s may have a beneficial effect upon the functional aspect of the curve and possibly reduce the risk of progression.

The role of ligaments in the neurology and physiology of the scoliotic patient

Ligament laxity is a common finding in IS patients [83], as are proprioceptive deficits [15-17]; a correlation between the two may exist.  In one study, 48% of children diagnosed with joint hypermobility (JH or ‘ligament laxity’) were considered ‘clumsy,’ and 36% demonstrated problems with co-ordination [84].  Ligaments are well-innervated, and play an important role in the neurological feedback mechanisms responsible for the protection and stability of the spine; although traditionally considered only as a mechanical structure, there is increasing evidence to suggest that ligaments participate in neuromuscular reflexes [48].  Patients with idiopathic scoliosis show a degeneration of the neural ligaments, and a significantly lower density of Ruffini corpuscles, single nerve fibers, and total neural elements when compared to controls [46].  Ruffini corpuscles are involved in providing awareness of joint position and movement (proprioception), and are particularly common in articulations where static position sense is necessary for the control of posture [48, 85].  In the supra-spinous and infra-spinous ligaments, innervation of the Ruffini corpuscles plays a key role in ensuring symmetry of the spine in the coronal plane, and may participate in active balancing of the spine laterally [48]; dysfunction in the innervation of these ligaments may contribute to imbalances in neuromuscular function.

When CMT is delivered to the cervical spine manually by rotating and/or laterally flexing the patient’s head, it is possible that this maneuver could place stress upon certain ligaments or aggravate pre-existing hypermobility.  As stated by the World Health Organizations’ Guidelines on Basic Training and Safety in Chiropractic, successful spinal mobilization and/or manipulation [CMT] involves the application of a force to the areas of the spine that are stiff or hypomobile, while avoiding areas of hypermobility or instability [86].  The protocols described in this study are designed to evaluate and address upper cervical instability/hypermobility.  If cervical hypermobility is present, specific exercises aimed at activating the muscles of the sub-occipital triangle are prescribed in an attempt to increase stability and protect the ligaments from additional injury.

Sensorimotor re-integration

The hypothesis that a sensorimotor integration disorder underlies the pathogenesis of IS has been gathering increasing evidence. [87]  As mentioned earlier, IS patients demonstrate a wide variety of neurophysiological deficits related to balance and postural control [15-17]; these deficits tend to be more pronounced in dynamic conditions [88, 89].

It has been classically assumed that one or a few balance centers in the central nervous system (CNS) were responsible for the control of balance; however, this viewpoint fails to capture the integrative nature of all of the neural systems responsible for balance, proprioception, co-ordination, equilibrium, and posture.  Although referring to balance control in an elderly population, Horak states, “[P]eople with balance disorders suffer from multiple impairments… it is often assumed that these impairments lead directly to functional loss…. Too often we forget that impairments alone do not lead to functional deficits because some people with a particular impairment have much better function than others, depending upon the type of impairment and the strategies each uses to compensate for the impairment.” [90]  Clinically and scientifically, how we quantify and measure the functional aspects of any underlying sensorimotor integration disorder(s) in IS is extremely important.  In the paper by Horak, the first sentence states “our assumptions concerning how balance is controlled shape how we assess and treat balance disorders.”  Therefore, the broad term “balance control” is broken down into six primary resources required for postural stability and orientation as described in this paper, and each individual component examined as it pertains to the specific deficits observed in IS.  Those six aspects of balance are: cognitive processing (attention, learning); biomechanical constraints (degrees of freedom, strength, and limits of stability); movement strategies (reactive, anticipatory, voluntary); sensory strategies (sensory integration, sensory reweighting); orientation in space (perception, gravity/surfaces/vision, verticality); and, control of dynamics (gait, proactive).

Applying this analysis to IS, it would be reasonable to exclude deficits in cognitive processing from the focus of rehabilitative approaches, as no such deficits have been observed to occur consistently in IS populations in the literature.

While biomechanics influences balance in IS, treatment of biomechanics alone does not appear to resolve balance deficits.  De Abreu et al commented on the effect of surgical treatment on postural control, and their findings suggested that the balance control deficits they observed in their population were more likely due to sensory issues rather than biomechanical [91].  This is further supported by papers on the effect of bracing on balance [92-94]; there is no immediate effect of bracewear on balance control strategies, and influencing spinal biomechanics alone does not appear to resolve the functional deficits in IS patients; the paper on bracing and balance by Chow et al suggests that the action of a TLSO may aggravate rather than reduce these deficits by adding biomechanical constraints to the spine, reducing its ability to react in dynamic conditions: “[B]racing may affect balance function by limitation of the trunk motion between the thoracic and sacral spine, which may in turn restrict the ability of the trunk to contribute to the maintenance of balance.”

The role of movement strategies could be considered to play a role in IS, particularly with reactive and anticipatory strategies.  An example of a voluntary movement strategy could be the motion that occurs in the ankles as the subject stands on a firm surface and compensates for postural sway.  While AIS patients have greater amounts of postural sway in a standing position [95,96], there is no clinical or scientific evidence to suggest that they exhibit an increased risk of falling, suggesting that the voluntary movement strategies are not impaired, or that the impairment is so minimal that compensatory mechanisms are able to adapt and prevent measurable functional deficits.  In either scenario, it is unlikely that rehabilitation of voluntary movement strategies would be productive.

Reactive and anticipatory (or predictive) strategies, in contrast, typically take place only in unstable conditions or after perturbations.  In IS patients, both reactive and anticipatory strategies show earlier onset and prolonged activation of muscles, particularly on the concave side [97].  As these deficits are measurable, and functionally this increased muscle activity creates a reduction the efficiency of the body’s ability to maintain an upright posture, rehabilitation on compliant surfaces and/or with perturbation could be considered worthy of further research.

Deficits in sensory integration have been measured and documented to occur in IS, particularly in the integration of vestibular signals [98].  While the exact cause of this vestibular impairment is not yet known, if the vestibular system is intact and capable of rehabilitation, specific exercise-based approaches to vestibular rehabilitation have been shown to be effective in improving balance in other populations with documented vestibular dysfunction [99-101]; this could be considered sufficient evidence to explore the effect of vestibular rehabilitation in patients with IS to determine if these vestibular integration deficits are reversible.

One etiologic theory for AIS postulates that one of the reasons why AIS develops more predominantly in females rather than males has to do with the timing of the maturation of the proprioceptive systems in regards to the onset of the growth spurt [102].  Some evidence suggests that the proprioceptive processing systems of adolescents are not fully developed [88] and that adolescents, given only proprioceptive cues, cannot effectively control their postural orientation, and so tend to rely more upon visual cues [103].  While deficits in postural control can be observed in AIS populations even when vision is not inhibited, these deficits do worsen when only proprioceptive feedback is allowed [15-17], suggesting that rehabilitation performed in the absence of visual cues may be of benefit in AIS.

Abnormalities in gait are a common finding in AIS; so much so that they could be used as a diagnostic factor [104].  Typically noted are decreased pelvis, hip, and shoulder mobility, as well as increased muscle activation and energy expenditure [105].  These findings are present in mild scoliosis, and become more severe as the deformity progresses [104].  Conflicting results are reported post-surgery, with no significant differences observed between anterior or posterior approaches [105-107].  Bracing appears to further reduce mobility in the shoulders and pelvis [108].  Neither intervention affects energy expenditure [105,108].  While there is no research on the effect of exercise-based approaches to gait rehabilitation in scoliotic populations, there is evidence suggesting that backwards-walking can improve balance in school-age children [109].  It has not been researched if similar results would occur within a scoliotic population.

Applying this information in a clinical environment, it would appear that strategies aimed at rehabilitating anticipatory/reactive movement strategies, performed either with postural feedback or body schema awareness to address vestibular deficits or under visual deprivation to stimulate proprioceptive function, may be a promising beginning in functional rehabilitation approaches to AIS.  It may also be of interest to explore whether backwards-walking or other types of gait therapy could have a beneficial effect upon gait and/or balance in AIS.

Smania et al described the neurophysiological basis of the rehabilitation of AIS; the authors concluded that neural control could play an important role in postural rehabilitation [110].  Romano et al described a spinal straightening reflex that occurred when AIS patients were placed on an unstable surface [111].  In this paper, the effect was small and difficult to predict; nevertheless, it suggests that there may be a way to improve spinal alignment through activation of the body’s own reactive balancing mechanisms.

If patterns in how certain configurations of scoliosis react to specific combinations of stimuli can be identified, this may provide insight into opportunities for neurophysiological rehabilitation of scoliosis.

Whole-Body Vibration (WBV) Therapy

WBV therapy is currently being researched for its effect upon postural control and other balance-related parameters, particularly in the elderly population and in patients with neurodegenerative disorders.  While no definitive conclusions can yet be drawn, WBV therapy may be effective in improving balance and mobility in some populations [112,113].  Using WBV therapy to influence postural control and balance in AIS patients is a novel concept which has not been explored in the literature.  The intended goal of incorporating WBV with the described exercise and neuromuscular rehabilitation protocols is to add an additional perturbation to enhance balance training, facilitate motor-sensory feedback communication between the brain and body, and to increase EMG activation of the targeted muscle groups.  It is important to note that concerns have been raised that certain WBV therapy products may exceed established safe limits for WBV exposure [114]; this is the primary reason for the specific settings (30 Hz, 0.3 G’s) utilized in the CLEAR protocols; to ensure patient safety, especially in a pediatric population.  Evidence suggests that 30 Hz is also the ideal frequency for increasing EMG amplitudes with vibration exercise [115].  Data regarding the effect of specific vibratory settings remains inconclusive to-date; however, many studies that investigate the effect of WBV therapy on balance, postural control, neuromuscular performance, and the skeletal system utilize frequencies in the vicinity of 30 Hz [116].

Conclusion

The described method is based upon five tenets which are based on clinical experience and anatomical and physiological research.

Research on spinal intervertebral disc biomechanics suggests that motion is designed to occur in the spine and that cyclic repetitive loading and unloading, through the process of osmosis and imbibition, may positively influence disc function.

Paraspinal muscle imbalances are well-documented to occur in scoliosis, and evidence indicates they are linked to the risk of progression.  Some exercises designed for scoliosis patients have the ability to activate specific muscle groups in an asymmetrical fashion.  Therapeutic stretches are also commonly used to rehabilitate hypertonic muscles; these stretches can similarly be done in an asymmetrical manner.

Ligaments are not purely a mechanical structure, but also play a role in posture, proprioception and sensory integration.  Ligamentous abnormalities are well-documented to occur in scoliosis patients, and may be linked to problems with sensory integration.  Rehabilitation of documented impairments is the desired goal, but initially the poorly-functioning ligaments must be identified and injury/aggravation of any existing issues avoided.

If a sensorimotor integration disorder is involved in the etiopathogenesis and/or progression of idiopathic scoliosis, approaches such as vestibular rehabilitation, balance training exercises, and whole-body vibration (WBV) therapy are currently being investigated for their effect in improving function in populations with vestibular impairment; it may be worth the effort of further research to determine if these approaches may be of benefit in the management of IS.

The likelihood of a successful treatment outcome for the person living with scoliosis increases when scoliosis-specific approaches are applied.  Evidence does not support diversified full-spine CMT for mild cases of scoliosis.  In the same manner that scoliosis-specific exercises are more likely to be of benefit in the management of IS, more specific applications of CMT may be worthy of further investigation to determine if the same principle applies.

The CLEAR Institute scoliosis treatment method aims to treat disc problems through motion, muscle imbalances through exercises and stretching, spinal biomechanics through specialized CMT procedures, and neuromuscular function through balance exercises and WBV therapy.  It focuses upon the inclusion of functional, cosmetic, and quality-of-life indices alongside radiographic measurements.  It is intended to provide an evidence-based option to scoliosis patients who wish to self-select chiropractic treatment for their condition.  Quantitative research is needed to evaluate its effectiveness.