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 , 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. 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. Until the excessive pronation is corrected with custom-made,
flexible orthotic supports, 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. 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 Instabilit
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,and many chronic
and sub-clinical problems remote from the feet and legs improve when
their postural support is fine-tuned.
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. Early intervention with custom-made orthotics is best.
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. 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.
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.
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 syndrome can develop when gait abnormalities continue.
Recurrent Subluxations
Because a smooth and symmetrical gait is tied so closely to proper
vertebral function, 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 orthotics is frequently indicated to
restore balance and provide a level pedal foundation. Orthotics are of special value in cases where
excessive foot pronation and arch collapse have been observed. conditions.
