|
Functional and Accommodative Foot Orthoses
A prescription foot orthosis is an in-shoe
brace which is designed to correct for abnormal foot and lower
extremity function (the lower extremity includes the foot, ankle, leg,
knee, thigh and hip). In correcting abnormal foot and lower extremity
function, the prescription foot orthosis reduces the strain on injured
structures in the foot and lower extremity, allowing them to heal and
become non-painful. In addition, prescription foot orthoses help
prevent future problems from occurring in the foot and lower extremity
by reducing abnormal or pathological forces acting on the foot and
lower extremity. A prescription foot orthosis is more commonly known by
the public as a "foot orthotic". Podiatrists
prescribe two main types of prescription foot orthoses for their
patients, accommodative orthoses and functional foot orthoses. Both
types of prescription foot orthoses are used to correct the foot plant
of the patient so that the pain in their foot or lower extremity will
improve so that normal activities can be resumed without pain. However,
accommodative and functional foot orthoses are generally made using
different materials and may not look or feel the same. Both types of
prescription foot orthoses are nearly always prescribed as a pair to
allow more normal function of both feet [similar to having both the
left and right wheels of a car realigned in a front end alignment]. Accommodative Foot Orthoses Accommodative
foot orthoses are used to cushion, pad or relieve pressure from a
painful or injured area on the bottom of the foot. They may also be
designed to try to control abnormal function of the foot. Accommodative
orthoses may be made of a wide range of materials such as cork,
leather, plastic foams, and rubber materials. They are generally more
flexible and soft than functional foot orthoses. Accommodative orthoses
are fabricated from a three dimensional model of the foot which may be
made by taking a plaster mold of the foot, stepping into a box of
compressible foam, or scanning the foot with a mechanical or optical
scanner. Accommodative orthoses are useful in the treatment of painful calluses on the bottom of the foot, diabetic foot ulcerations,
sore bones on the bottom of the foot and other types of foot pathology.
The advantages of accommodative orthoses are that they are relatively
soft and forgiving and are generally easy to adjust in shape after they
are dispensed to the patient to improve comfort. The disadvantages of
accommodative orthoses are that they are relatively bulky, have
relatively poor durability, and often need frequent adjustments to
allow them to continue working properly. Functional Foot Orthoses Functional
foot orthoses are used to correct abnormal foot function and, in so
doing, also correct for abnormal lower extremity function. Some types
of functional foot orthoses may also be designed to accommodate painful
areas on the bottoms of the foot, just like accommodative foot
orthoses. Functional foot orthoses may be made of flexible, semi-rigid
or rigid plastic or graphite materials. They are relatively thin and
easily fit into most types of shoes. They are fabricated from a three
dimensional model of the foot which may be made by taking a plaster
mold of the foot, stepping into a box of compressible foam, or scanning
the foot with a mechanical or optical scanner. Functional
foot orthoses are useful in the treatment of a very wide range of
painful conditions of the foot and lower extremities. Big toe joint and
lesser toe joint pain, arch and instep pain, ankle pain and heel pain
are commonly treated with functional foot orthoses. Since abnormal foot
function causes abnormal leg, knee and hip function, then functional
foot orthoses are commonly also used to treat painful tendonitis and
bursitis conditions in the ankle, knee and hip, in addition to shin
splints in the legs. The advantages of functional foot orthoses are
that they are relatively durable, infrequently require adjustments and
more likely to fit into standard shoes. The disadvantages are that they
are relatively difficult to adjust and relatively firm and less
cushiony. Foot and Lower Extremity Biomechanics The study of the mechanical nature of the foot and lower extremity is called biomechanics.
It is a specialized branch of science that uses the mechanical
principles of physics to study the motions and forces on the human
body. Podiatrists receive specialized, in-depth training during their
four years of medical training on how the movements and forces in the
foot affect the movements and forces in the rest of the lower
extremity, and how the movements and forces in the lower extremity
affect the movements and forces in the foot. No other medical specialty
has this in-depth training, which is necessary to understand lower
extremity pathology as it relates to the biomechanics of foot function.
Therefore, the podiatrist is the most qualified medical specialist to
diagnose and treat foot pathology. Understanding
the biomechanics of the foot and lower extremity is of critical
importance when the mechanism of an injury must be determined to decide
on a appropriate treatment plan for the patient. In addition,
biomechanics plays an important part in the planning for corrective
surgery for injuries, such as tendon ruptures or bone fractures, or for
the surgical correction of deformities of the foot, such as hammertoes, bunions, or heel spurs.
As a result of the podiatrist's training and expertise in biomechanics,
they will often prescribe either functional or accommodative orthoses
as part of their treatment plan. In many instances, an orthosis will be
all that is required for the successful treatment of foot or lower
extremity pathology. In most instances, however, an orthosis will be
prescribed along with other therapies, such as stretching or
strengthening exercises, oral or injectable medications, and specific
types of shoes, in order to insure the fastest healing for the patient. The Process of Prescribing Foot Orthoses In
order to design and fabricate a prescription foot orthosis, the
podiatrist must perform a biomechanical examination of the foot and
lower extremities. Angular measurements are taken of the toes, foot,
ankle, knees and hip to determine the amount and level of any
structural or functional deformities. This examination is done while
the patient is on an examining table and also while standing. The
podiatrist will also do a walking and/or running gait analysis of the
patient to determine how their foot and lower extremity functions
during these activities. Abnormalities from the biomechanical
examination and gait examination are noted in the patient's chart for
future consideration in the design and fabrication of the prescription
foot orthosis. The podiatrist then next must make
a three dimensional model of the patient's feet in order to make a
prescription foot orthosis. This is done by either applying plaster
splints to the patient's foot, by having the patient step into a box of
compressible foam, or having the foot scanned by a mechanical or
optical scanner. The resultant three-dimensional model of the foot is
then used along with a detailed orthosis prescription from the
podiatrist to have the prescription foot orthoses made for the patient.
Most podiatrists have a specialty podiatric orthosis laboratory make
their orthoses while some podiatrists make their own prescription foot
orthoses. Advantages and Disadvantages of Prescription Foot Orthoses The
advantages of prescription foot orthoses are many. First of all, they
are custom made for each foot of each patient, so that each foot
orthosis will only fit one foot correctly. In addition, since they fit
so exactly to the persons foot, they can be made with relatively rigid,
durable materials with a minimal chance of discomfort or irritation to
the patients foot. Prescription foot orthoses also have a much greater
potential to effectively and permanently treat painful conditions, all
the way from the toes to the lower back, since they are designed
specifically for an individualﾒs biomechanical nature. For example, in children, prescription foot orthoses are used to prevent abnormal development of the foot due to flatfoot
or intoeing or outtoeing disorders. In athletes, prescription foot
orthoses are used to allow the athlete to continue training and
competing without pain. And in most adult patients, prescription foot
orthoses are used to allow more normal daily activities without pain or
disability. One disadvantage to prescription foot orthoses is
that they are relatively expensive when compared to store bought
over-the-counter foot inserts. Even though the over-the-counter inserts
do help some people with mild symptoms, they do not have the potential
to correct the wide range of symptoms that prescription foot orthoses
can since they are made to fit a person with an "average" foot shape. In
this fashion, prescription foot orthoses may be considered to be
analogous to prescription eyeglasses. Over-the-counter eyeglasses may
work for some people since they are made to correct for the average
eye. However, over-the-counter eyeglasses will almost never work as
well as prescription eyeglasses. Prescription foot orthoses, since they
are custom made to each foot of a patient, are almost always more
corrective and comfortable than over-the-counter foot inserts, even
though over-the-counter inserts do work for some people.
Back to Top
|
