The amount of work accomplished by the feet is astounding. If a 150-pound person
walks just one mile during the day (about 2,600 steps for most people), the feet
have cumulatively borne 390,000 pounds, or 195 tons of weight. Despite the incredible
amount of work the feet have to do to transport us from place to place, we compromise
their effectiveness and comfort by wearing overly tight shoes that create a number
of minor problems, and by engaging in activities that expose them to undue stress.
This article discusses several minor foot problems.
Blisters
Blisters are a common problem, occurring in any location where the skin has been
subjected to sustained friction. Swinging an ax, for instance, will cause blisters
on hands unused to the activity. On the feet, blisters occur at locations where
the shoe fits poorly, allowing shearing forces or friction to occur during walking,
running, or jumping. The most common locations are the toes, balls of the foot,
and back of the heel.[1] The uncomplicated blister is a round or oval
lesion in which the epidermal layers have separated and the interior area is filled
with clear fluid. The raised skin is known as the roof, while the lower area is
the floor of the blister. Occasionally, pharmacists will see patients who continued
to engage in activity as the blister formed, allowing blood to enter the fluid,
creating a "blood blister." In one study of West Point cadets undergoing basic
training, risk factors for blister formation included use of smokeless tobacco,
flat feet, illness within the past year, lack of previous military experience,
and ethnicity (African-Americans were at lower risk than others).[2]
Some physicians advise leaving the blister intact, allowing the epidermal layers
of the floor to mature and become less sensitive to infection. Others advise piercing
the roof with a sterile needle and gently expressing the fluid inside. This has
two benefits: it reduces the pain and it allows the roof to connect with the base,
where it may readhere for a short period, thereby reducing the pain and helping
prevent infection.
Shoe pads may be helpful in preventing blisters. The patient whose blister has
already ruptured through loss of the roof may discover that a collodion-based
product such as New-Skin placed over the exposed skin will provide some relief.
Corns
The corn is a raised hyperkeratosis with a central core. Its etiology is friction
of the toe against the shoe or against another toe, which tends to occur when
the patient chooses shoes that are too tight. The patient with the condition known
as hammertoe frequently has corns on the upper part of the deformed toes.[4]
When corns are located between the toes, they are usually softer in texture. Those
located on all other areas of the toes are harder to the touch when palpated.
Regardless of location, as the patient ambulates, pressure against the corn causes
it to press against the skin and nerve endings, which results in pain.
The corn serves no useful function, and can be effectively eliminated without
consequences. However, the patient should avoid drastic methods of removal such
as the dangerous razor-bladed implements popularly sold as "corn planes." In addition,
such devices as pumice stone and corn files should generally be avoided. The safest
and most effective nonprescription intervention is the use of salicylic acid in
the form of plasters, disks, or collodions. Before use of salicylic acid, the
patient should soak the corn for five minutes. This increases the ability of salicylic
acid to macerate the skin, allowing it to slowly erode the corn. Collodions such
as Freezone should be applied once or twice daily for up to two weeks by applying
one drop at a time to the corn. Plasters such as Mediplast and disks or pads such
as the extensive line of Dr. Scholl's Corn Removers (e.g., Dr. Scholl's Soft Corn
Removers, Dr. Scholl's Ultra-Thin Corn Removers) are applied and removed as directed,
usually after 48 hours. Application may be repeated every 48 hours for up to two
weeks. Padding and protective cushioning may also be used to relieve discomfort.
Calluses
The etiology of the callus is identical to that of the corn -- namely, pressure
or friction against the skin. However, the callus is a diffuse thickening of the
skin overlying the area where pressure has been applied. Any type of pressure
can cause calluses if it is sustained for a prolonged period of time. For instance,
repeated use of an engraving tool can cause a set of hand calluses where the tool
exerts pressure against the epidermis.
In the case of the foot, weight-bearing areas such as the heels and balls of the
feet are most prone to developing calluses. The risk of callus formation is increased
when patients wear shoes that allow the heel to move during ambulation, increasing
the shear forces. Patients should be instructed to wear shoes that have a snug
fit for the heel.
Removal of the callus is complicated by two factors. First, unlike the corn, which
serves no purpose, the callus protects underlying skin from the continued friction
that caused it. Second, the callus is rarely painful because it has no central
core that pushes against underlying tissues with each step. For these reasons,
removal is purely cosmetic in most cases and actually exposes newer, softer skin
beneath. It is preferable to allow the calluses to remain in place as long as
they are not troublesome. The person who ignores this advice and removes all callused
skin from the soles of the feet with the products known as callus reducers or
callus files may experience pain when he or she walks on the newly exposed nonhornified
surfaces of the feet. It will take a while for the calluses to regrow and again
shield the feet.
Calluses may occasionally, however, be so thick that they cause pain upon ambulation.[5]
In these cases, reduction may be necessary. Since it involves removal of tissue,
a preferable method of reduction would be through a visit to a podiatrist or a
physician. Professionals are aware that judicious use of a rotary sanding tool
is useful for callus removal. Removal is halted if the area begins to feel warm,
or if drainage is visible from any callus fissures. Dust particles will also change
texture from a large amount of thick particles to a small amount of fine powdery
substance as the procedure approaches its end. The skin should feel thinner and
smoother to the touch when appropriate reduction is completed. Calluses may fissure
or crack open. In these cases, a physician/podiatrist visit is advisable to ensure
that the area has not become infected.
Ingrown Toenails
Ingrown toenails occur when the nail turns in its growth and grows into the skin.
This painful condition can be caused by improper cutting or shoes with inappropriately
tight toe boxes. Patients should be instructed to cut their toenails straight
across, without tapering the sides.
No nonprescription product or device can reverse this condition safely. Some patients
attempt to excise the toenail themselves with nonsterile scissors, but this may
leave a section of nail imbedded in the skin, allowing it to serve as a nidus
for infection. In all cases, patients should instead be advised to visit a podiatrist
or physician for appropriate care.
Tennis Toe
Tennis players may develop a set of hematomas under the nails of the first or
second toe, accompanied by nail bed injuries or jammed joints. The cause is rapid
charging toward the net followed by a sudden stop, which forces the toe into the
toe box.[3] The condition is more common in older players and in those
who wear shoes with a small, tight toe box. Playing on a synthetic court induces
more tennis toe than play on a grass or clay court. A podiatrist may penetrate
the nail to decompress the hematoma to relieve the pain, which is often severe.
Taping the affected toe to the adjacent toe may help to prevent injury, as well
as wearing shoes with rigid soles to minimize stress on the interphalangeal joints.
Tired Feet
It is axiomatic that people who are required to stand long hours (such as pharmacists)
are more prone to foot problems. Various foam/cloth insoles or orthotics are available
to help cushion the feet. Some are fairly shallow, while others are moderately
thick. While a greater thickness can yield more comfort, the patient must be sure
that the product does not cause excess pressure against the top of the shoe and
create a blister. Gel-filled, air-filled, and fluid-filled insoles are also available.
However, "magnetized" insoles have no proven therapeutic value and should not
be recommended.
In addition to using insoles, patients may gain comfort for their tired feet with
a post-workday soaking in warm Epsom salts or any of several commercially available
foot soaks.
The Black Heel Syndrome
Runners may approach pharmacists for help with an irregular hemorrhage on the
heel known as the black heel syndrome. This rare condition appears as a crop of
dark brown to black macules that are irregular in pattern.[1] The typical
location is the sole of the foot or the edges of the heels. Black heel syndrome
reflects tearing of superficial blood vessels when the runner subjects the foot
to a sudden shearing force. It can mimic more serious conditions such as melanoma.
However, efficient questioning can uncover the causal running history. Black heel
syndrome causes no discomfort and subsides in a relatively short period of time.
If the patient wishes to avoid it entirely, the pharmacist may suggest use of
an anti-shearing insole, or use of felt linings or other padding materials inside
the shoe. Paddings for feet and shoes are usually backed with adhesive, so they
may be placed on the foot or directly inside the shoe at the points of maximal
friction. They may be made of lamb's wool, latex foam, or cotton flannel.
References
King MJ. Dermatologic problems in podiatric sports medicine. Clin Podiatr
Med Surg 1997;14(4):511-524.
Knapik JJ, Reynolds K, Barson J. Risk factors for foot blisters during road
marching: Tobacco use, ethnicity, foot type, previous illness, and other factors.
Mil Med 1999;164(2):92-97.
Bylak J, Hutchinson MR. Common sports injuries in young tennis players.
Sports Med 1998;26(2):119-132.
Oliver TP, Armstrong DG, Harkless LB, et al. The combined hammer toe-mallet
toe deformity with associated double corns. Clin Podiatr Med Surg 1996;13(2):263-278.
Lukacs KS. Patient with dystrophic toenails, calluses, and heel fissures:
Skin Care. J Wound Ostomy Continence Nurs 1997;24(4):237-242.
Schissel DJ, Aydelotte J, Keller R. Road rash with a rotten odor. Mil Med
1999;164(1):65-67.
Sidebar: Odorous Feet: Pitted Keratolysis?
The pharmacist is occasionally approached by patients who complain of unacceptable
foot odor. If the patient is someone (e.g., a member of the military on active
duty) whose feet are frequently subjected to moisture, and the foot has a rash
with an unusually foul odor, the problem may be pitted keratolysis.[6]
In this condition, the bacterium Corynebacterium flourishes in warm, wet boots,
causing a rash, usually on the weight-bearing foot surfaces. Lesions are white,
wet plaques with a scalloped border, with pitting of the associated stratum corneum.
This malodorous condition may persist for decades. The condition is not self-treatable.
In one case, twice-daily topical clotrimazole cream and clindamycin solution and
a nightly application of ammonium chloride cleared up a ten-year infection.[6]
Sidebar: Patient Information: Caring for Your Feet
Your feet are marvels of engineering, capable of bearing many tons of weight throughout
the day. Most of the time, they do so without much difficulty. However, there
are several things you should know about shoes to help keep your feet problem-free.
Choosing Shoes
Shoes serve several purposes. They shield your feet from heat and cold, prevent
you from stepping on dangerous objects such as splinters and nails, support the
bones and ligaments of the foot, and cushion your feet when you walk. Therefore,
shoes should contribute to your comfort and protect your feet. They should not
cause injury.
Shoe problems begin with the choice of a particular shoe, which is too often dictated
by fashion rather than comfort and ease. The shape of the foot is essentially
a rectangle. Many women, however, choose short, narrow shoes that are more of
a triangle in shape, with a sharply pointed toe box (the space into which the
toes must fit). These kinds of shoes usually elevate the heel of the foot from
two to five inches, which adds to the problem. With each step the toes are forced
with more pressure into a small area, which places them in an unnatural position.
Over time, the toes may become permanently deformed.
Another mistake people make when purchasing shoes is failing to take into account
the fact that feet vary in size during the day. By the afternoon, for instance,
your feet will have gained some fluid in them due to the force of gravity. It
is best to buy shoes in the late afternoon or at night, when the swelling is at
its maximum point. By doing this, you run the risk of the shoes being looser during
the day, but that is preferable to the more serious problem of having them fit
too tightly. Select shoes that are light, since heavier shoes cause more stress
for the legs and feet. Leather is the best choice, since it is porous, unlike
most synthetic materials. Allow for the fact that thicker socks are worn when
it is cold.
Running or sports shoes should share several characteristics. Studs on the soles
help distribute the shock of the foot hitting the ground. The heel should be raised
through the use of a triangular cushion beneath it, known as the heel wedge. This
wedge should be resilient, to provide a "spring" during sports activity. The middle
of the shoe (midsole) should be flexible so the Achilles tendon does not bear
undue stress. This molded pad at the back of the shoe is important for preventing
irritation of the Achilles tendon at the back of the foot.
Foot Problems
Problems of the foot range from serious conditions that a physician or podiatrist
should examine, such as ankle sprains and toe fractures, to minor and self-treatable
problems, such as blisters, corns and calluses.
Your pharmacist has numerous products for minor foot problems. If you have a question
about the severity of a foot problem and whether a visit to a podiatrist or a
physician is necessary, Consult Your Pharmacist.
W. Steven Pray, Ph.D., R.Ph., Professor of Nonprescription, Products and
Devices,, School of Pharmacy,, Southwestern Oklahoma State University,, Weatherford,
OK
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