Why do some
orthotics work, while others do not?
health care practitioners are prescribing an ever-increasing number of
foot orthotics for their patients with limited
and variable results. There are many different types of orthotics with
different approaches and different casting or ordering
methods. Some companies require a foam or plaster cast, while others
require no foot impression at all, to deliver a
biomechanical orthotic for their patient. We will address these issues
and provide an overview as to the rational approach
as to why some orthotics work and others do not.
What is a custom
view is that a custom foot orthotic is an orthotic that is made from a
plaster or foam impression of the foot, in a biomechanical
Why must an orthotic
be made from a biomechanical neutral position?
understand why, one has to understand the gait cycle and continue with
the fundamental biomechanics. Picture the gait
cycle. From careful observation, one can see that the neutral
position comes right after the
heel strike and right after midstance.
The foot and subtalor joint pronates (internal rotation of the limb)
during the first 25% phase of the gait and then begins to
supinate (externally rotate) during the remainder of stance phase of gait.
The foot and the limb are neither pronated
(internally rotated) nor supinated (externally rotated) during this
is neutral so important? An orthotic made from a neutral
position allows the foot and leg to go through the normal range
motion. It can pronate normally and supinate normally. The first 25%
portion of the stance phase of the gate allows for normal
pronation to occur. Knee flexion from an extended knee position is the
main factor for the body to absorb shock (normal pronation).
Internal limb rotation allows for knee flexion. After mid-stance
(neutral) the foot re-supinates (leg externally rotates).
Why do some
orthotics feel harder or uncomfortable if the material was properly
are a number of reasons for this, but more often than not, the orthotic
was made over a cast in the supinated or externally
rotated position. An orthotic made from a supinated cast will not be
tolerated by your patient. This orthotic will not allow your
patient to have full contact phase pronation, which is essential for
normal shock absorption. Your patient may experience knee
pain and/or joint pain. The knee will not be able to flex from an
extended position to allow for internal leg rotation.
you send your cast to your orthotic laboratory, your laboratory must
recognize a supinated, neutral and pronated cast to
fabricate a comfortable and functional orthotic. Our scanning machines
can compensate for casts that are pronated or supinated
and will produce an orthotic that is in neutral position. Your
laboratory must also make these allowances to ensure that your patients
will tolerate their new orthotics.
Why do some
prefabricated orthotics feel good and work adequately?
of prefabricated orthotics afford the patient with a limited amount of
relief. Many prefabs have low arches or very flexible arches
that allow the individual to pronate. Sometimes this approach works,
however this approach is variable with variable results. If, on the
other hand, the arch of the prefab is too high or too rigid, extra
trauma to the body can and will occur.
are different types of orthotics for different biomechanical
conditions. There are indications for soft orthotics, flexible
semi-flexible orthotics and rigid orthotics. If you order an orthotic
without knowing where neutral is, you are chancing a device that may
be intolerable for your patient. There are times when this type of
device may afford your patient with some form of relief, but don't
want your patient to have the best device?
information, call us to arrange a seminar in your area.
265-2248 or (905) 669-5655
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Canadian Orthotics Laboratory