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Inside Spinal Pelvic Stabilizer Research
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As we walk, there is a fine interplay between the movements of the lower extremities and the balancing of the spine. Normal gait causes predictable, repetitive motions to occur from the feet to the head. The accurate timing of the many muscle contractions required during walking and running depends on stimuli from a symmetrical gait. Recent research in several fields has contributed to our appreciation of this complexity. We now understand that excessive foot pronation, whether in one foot or bilaterally, interferes with these carefully orchestrated movements, and causes problems throughout the musculoskeletal system. The effects of excessive pronation on the function of the spine are of particular interest to doctors of chiropractic.

Structural Effects

Pelvic Misalignments

When a foot pronates during the stance phase of gait (Fig. 1), there is a normal inward (medial) rotation of the entire limb and pelvis. In persons who have excessive or prolonged pronation, this twisting movement is accentuated (Fig. 2). The increased rotational forces are transmitted into the pelvis, and especially the sacroiliac joint.1 In response, various compensatory pelvic subluxation complexes develop. These include pelvic tilts (usually anterior or to one side), innominate rotations (usually Postero-Inferior), and other complicated adaptations (Fig. 3). Until the excessive pronation is corrected with custom-made, flexible orthotic supports (Fig. 4), only short-term relief can be achieved with chiropractic adjustments.

Functional Scoliosis
The loss of arch height which occurs with excessive pronation allows the pelvis to drop to the more pronated side during stance and gait.2 The resulting pelvic tilt lowers the sacral base and drops the lowest freely-moveable vertebra. A lateral curvature develops in response to the lack of solid support for the base of the spine. This ‘functional’ scoliosis starts in the lumbar region, but can affect the entire spine. In young patients, this type of curvature disappears when sitting or lying on the exam table. As patients age, the spine becomes less flexible, and functional curves become stiffer and more fixed.

Excessive Lumbar Lordosis
Excessive pronation of both feet often results in bilateral foot flare. In response, the pelvis frequently tilts forward and there is an increase in the lumbar lordosis. Symptoms develop in the compressed posterior vertebral elements, usually causing a ‘facet syndrome.’ In addition to adjustments and corrective postural exercises, custom-made, flexible orthotics are necessary for comprehensive treatment of these conditions.

Postural Instability
One of the interesting facets of excessive pronation is the large variation in response seen from patient to patient. When the gait is affected, the pelvis and spine must compensate in some manner. The specific mechanism each patient uses to adapt to abnormal support from the lower limbs is highly individual. This explains why patients often notice so many areas of improvement when their excessive pronation is corrected with Foot Levelers’ custom-made, flexible Spinal Pelvic Stabilizer Orthotics. Sports performance increases,3-5and many chronic and sub-clinical problems remote from the feet and legs improve when their postural support is fine-tuned.6

Degenerative Changes
Left untreated, all of the structural responses to excessive pronation listed above will eventually progress to joint degeneration. Biomechanical asymmetries transmit abnormal forces and sustained stresses to the joints, resulting in microtrauma, cartilage wear, and osteophytes.7 Early intervention with custom-made orthotics is best. If the patient already has significant degeneration, additional shock absorption will need to be included in the orthotic.

Neurological Effects

Neuromuscular Incoordination
Much of the neurological coordination of the body is based on a balanced, rhythmic gait. The ‘cross crawl’ pattern organizes many fundamental musculoskeletal functions at the spinal cord level. In other words, much of the smooth performance of daily physical activities occurs without the need for conscious thinking or planning. This includes such factors as balance, stability, and center of gravity.8 When this system is interfered with by one or both feet spending too much time in pronation, muscles throughout the body (and around the spine) don’t turn on and shut off in proper sequence. Such interference also increases the work effort for doing simple activities, and increases the consumption of oxygen during normal walking.9

Gait Asymmetry
If the foot and ankle complex is not functioning correctly during the stance phase of gait, this stress is transmitted to the pelvis and spine with every step. Excessive pronation results in abnormal firing of muscles, and in inaccurate proprioceptive nerve impulses. This also interferes with the toe-off phase, resulting in a less-efficient propulsion. Walking with an abnormal gait and poor toe-off causes back pain which can be treated with custom-made foot orthotics.10

Muscle Imbalances
Many chronic myofascial problems can begin with excessive pronation. The gait abnormalities, neurological incoordination, and asymmetrical structural stresses are often compensated by contracting the large stabilizing muscles of the spine. This results in habit patterns with detrimental effects on movement and eventual perpetuation of symptoms. Myofascial trigger points, chronically contracted muscles, and even thoracic
outlet syndrome11 can develop when gait abnormalities continue.

Recurrent Subluxations
Because a smooth and symmetrical gait is tied so closely to proper vertebral function,12 excessive pronation in one or both feet can cause subluxations to recur. When patients don’t respond as expected to chiropractic adjustments, and particularly when we have to adjust the same levels, foot function must be evaluated. The underlying cause in many cases is found to be prolonged pronation.

Treatment Response

Orthotic Support
The use of custom-made, flexible orthotics is frequently indicated to restore balance and provide a level pedal foundation. Yochum demonstrated how a 15.5mm leg length inequality (LLI) could be reduced to just 4mm with the use of Foot Levelers’ custom-made, flexible SPS Orthotics (Figs. 5A & 5B).13 Not only had the pelvic deficiency been markedly reduced, but the right compensatory listing of the lower lumbar spine had also diminished.

Orthotics are of special value in cases where excessive foot pronation and arch collapse have been observed. Foot Levelers’ Elite™ line of SPS Orthotics is the first to offer the both the patented Extreme Gait Cycle System® and the innovative Dynamic Response System™. The unique qualities of the Elite line allow it to have variable degrees of support that work with the individual’s gait cycle, lifestyle, physiology, and conditions.

Adaptation Period
Nearly every person who begins wearing flexible,
custom-made SPS Orthotics for excessive pronation will go through an initial break-in period. That is to be expected. During this time, avoidance of lengthy periods of standing and walking is best, and running should be only gradually re-introduced. General stretching exercises for the spine and pelvis will help eliminate the abnormal muscular patterns, and should be performed daily. Massage therapy can also speed up this adaptation process.

Retraining exercises for balance and coordination can be introduced for athletes and those patients who want to return quickly to complex physical activities. While these recommendations may be difficult for some, those patients who are willing to invest the effort will respond much more rapidly.

Chiropractic Support
It is very important to assess and adjust the pelvis and spine as each patient adapts to wearing SPS Orthotics. Since excessive pronation places abnormal stress in predictable areas (especially the sacroiliac joints and lumbar vertebrae), close evaluation of these regions is needed. However, in light of the postural instability and neurological balance factors discussed above, the entire spine must be checked frequently during the initial adaptation period. In fact, because the upper cervical region is often slow in adapting to the change in posture, it needs to be carefully adjusted. Education of the patient will help to smooth this transition to better foot function and improved spinal alignment.

References