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Foot Ulcers
posted 04/05/04
What is it?
A foot ulcer is an open sore on the foot. Some foot ulcers are a superficial,
shallow, red crater that involves only the surface skin. Other foot ulcers are
very deep and produce a crater that extends through the full thickness of the
skin, sometimes involving tendons, bones and other deep structures. In
vulnerable individuals, especially those with diabetes or poor circulation, even
a small foot ulcer may become infected if it is not treated quickly and
effectively. If this local infection is allowed to progress, it can evolve into
an abscess (a localized pocket of pus), an area of cellulitis (infection of soft
tissue), osteomyelitis (bone infection) or gangrene. In persons with diabetes, a
seemingly simple foot ulcer is the initial problem in approximately 85 percent
of severe foot infections that ultimately require amputation of some part of the
lower limb.
Foot ulcers are especially common in people who have one or more of the following health problems:
 | Peripheral neuropathy. In peripheral neuropathy (nerve damage in the extremities), the nerves that normally detect sensations in the feet can no longer warn about pain or discomfort. As a result, even tight-fitting shoes can trigger a foot ulcer by simply rubbing on a portion of the foot that has become numb to the sensation. Persons with peripheral neuropathy may not be able to "feel" it when they've stepped on something sharp or when they have an irritating pebble in their shoe. They can significantly injure their feet and never know it, unless they routinely examine their feet for sites of injury. Unfortunately, many elderly individuals and diabetics with vision problems cannot see their feet well enough to perform even this simple foot examination. Failure to detect early skin damage is one reason why elderly individuals with peripheral neuropathy develop foot ulcers more than nine times more often than those with normal foot sensation. |
| Circulatory problems.
Any illness that decreases circulation to the feet can
cause foot ulcers by cutting off the foot's blood supply, which deprives cells
of oxygen, making the skin more vulnerable to injury and slowing the foot's
ability to heal. Persons are at especially high risk of foot ulcers if the
circulation in their leg arteries is reduced because of atherosclerosis, a
disease that is triggered by fatty deposits of cholesterol within the walls of
arteries. |
| Abnormalities in the bones or muscles of the feet. Any condition that distorts the normal anatomy of the foot can lead to foot ulcers, especially if the foot is forced into shoes that cannot accommodate the foot's altered shape. Diabetics are at an especially high risk of foot abnormalities that can lead to foot ulcers. Long-standing, poorly controlled diabetes can cause nerve and muscle problems that can lead to claw foot (muscle contractions that produce a clawlike position of the toes) and increase the risk of fractures and dislocations of the foot bones. |
Persons with diabetes have a particularly high risk of developing foot ulcers, because poorly controlled diabetes is often complicated by the triple risk factors of neuropathy, circulatory problems and a gradual development of structural abnormalities in the feet. Among the estimated 16 million diabetics living in the United States, approximately 15 percent will eventually develop an ulcer involving either the foot or ankle. Without prompt and proper treatment, this ulcer may become so severe that it requires hospital treatment or even amputation.
In addition to diabetes, other medical conditions that increase the risk of foot ulcers include:
| Atherosclerosis.
This condition can involve poor circulation to the legs. |
| Hereditary motor and sensory
neuropathy. This inherited form of neuropathy can
affect sensation and movement in the feet, causing muscle weakness in the
feet, foot ulcers and other symptoms. This condition affects 36 in every
100,000 Americans, with symptoms beginning during the late teens or early
twenties. |
| Raynaud's disease. This mysterious condition causes sudden episodes of decreased circulation in the fingers and toes. During these episodes, the fingers and toes initially turn blue as the blood supply diminishes, then turn red again as the circulation returns to normal. Raynaud's disease tends to strike women aged 20 to 40, and its cause is unknown. |
Also, in relatively rare cases, a foot ulcer may be unrelated to these risk factors and illnesses. For example, an isolated foot ulcer in a person who has no underlying health problems may potentially be a site of skin cancer, especially squamous cell carcinoma.
Symptoms
A foot ulcer looks like a red crater in the skin, usually located on the sole of
the foot or between the toes. In many cases, this crater is surrounded by a
well-defined border of thickened, callused skin, especially if it has been
present for a fairly long time. In severe ulcers, the red crater may be deep
enough to expose foot tendons or bones.
If the nerves to the foot are functioning normally, the ulcer will be painful. If not, the patient may not know that the ulcer is there, particularly if the ulcer is located on a less obvious portion of the foot. In debilitated or elderly patients, a relative or caregiver may first notice the problem when the ulcer becomes infected, drains pus and develops a foul odor.
What your doctor looks for
After reviewing your symptoms, your doctor will ask whether you have diabetes or
any other illness that can cause nerve damage or circulatory problems in your
feet. If you have diabetes, your doctor will want to know how long you've been
diabetic, the type of medication you use and how well your blood sugar has been
controlled. Your doctor will ask about whether you have other diabetic
complications, especially ones that involve your eyes or kidneys.
In addition to questions about your medical history, your doctor will ask about your podiatric history, including any foot surgery, foot trauma or previous foot ulcers. Finally, your doctor will ask about your routine foot care practices and the type of shoes that you usually wear. These questions are asked because poor foot hygiene and poorly-fitting shoes can increase the risk of foot ulcers in susceptible individuals.
Diagnosis
In most cases, your doctor can tell that you have a foot ulcer by simply looking
at your foot, but this is only the beginning of the diagnostic process. Your
doctor must also determine:
| How deep the ulcer is |
| Whether there is an infection |
| Whether that infection has progressed to cellulitis or
osteomyelitis |
| Whether you have any underlying foot abnormalities, circulatory problems or neuropathy that will either interfere with healing or increase the risk that the ulcer will recur |
Your doctor will begin by asking you to walk, because your gait may uncover knee and ankle abnormalities that can cause ulcers by distorting the pressure distribution on the soles of your feet. Next, your doctor will examine both of your feet for obvious structural problems, such as claw foot or fallen arches. To check for neuropathy, your doctor will either touch your foot with a Semms-Weinstein monofilament or use a more complex testing device such as a biothesiometer or a tactile circumferential discriminator. Your doctor will also assess the circulation in your legs and feet by feeling your pulses and noting whether your feet are pink and warm. If your pulses are diminished, then your doctor may order Doppler flow studies to assess your circulation, or he or she may refer you to a vascular surgeon for further evaluation.
Finally, your doctor will examine the ulcer itself, probing it to see how deep it is and checking for exposed tendons, bone fragments or signs of cellulitis. Depending on the depth of your ulcer and any signs of infection, your doctor will classify the ulcer as grade 1 (superficial), grade 2 (deeper, down to tendon or bone), grade 3 (abscess or osteomyelitis present) or grade 4 or 5 (gangrene present). To help in the overall assessment, your doctor may also order bacterial cultures of the ulcer (to check for infection), blood tests, foot X-rays (to check for osteomyelitis) or more complex magnetic resonance imaging (MRI) or bone scans.
Expected duration
The duration of a foot ulcer depends on its grade, its treatment, and the blood
circulation to the area. In persons with good circulation and good medical care,
a superficial grade 1 ulcer can sometimes heal in as little as five to six
weeks. Deeper grade 2 ulcers may take 12 to 20 weeks to heal.
Prevention
Persons at risk for foot ulcers, especially those with diabetes, can probably
prevent about half of them by routinely examining their feet and following good
foot hygiene practices. The following strategies may help:
| Examine every part of your feet every day. If necessary,
use a mirror to check the heel and sole. If your vision is not good, ask a
relative or caregiver to examine your foot. |
| Practice good foot hygiene. Wash your feet every day with
mild soap and warm water. Dry thoroughly, especially between the toes, and
apply moisturizing lotion. |
| Wear well-fitting shoes and soft, absorbent socks. Always
check your shoes for foreign objects and rough areas before you put them on.
Change your socks immediately if they become wet or sweaty. |
| Trim your toenails straight across with a nail clipper or
emery board. |
| If you have corns or calluses, ask your doctor about how to care for them. Your doctor may determine that these problems are best treated in his or her office or refer you to a podiatrist. |
Treatment
If you have good circulation in your foot, the doctor will treat your grade 1 or
2 foot ulcer with debridement (trimming away of diseased tissue), together with
careful removal of any nearby callused skin. The doctor will then apply a
dressing and prescribe specialized footwear to relieve pressure on the ulcerated
area. This specialized footwear may be a total contact cast, a postoperative
walking shoe with a special lining or a fully enclosed healing shoe. The process
of debridement, callus removal and dressing changes will be repeated over a
period of weeks or months - as long as it takes for your ulcer to heal
completely. A "growth factor" gel containing becaplermin (Regranex) may be
applied to the ulcer to speed the healing process. Once healing is done, your
doctor will prescribe special footwear to relieve pressure on vulnerable areas
of your feet. This special footwear will help prevent your ulcer from recurring.
Grade 3 to 5 foot ulcers are treated in the hospital, usually with surgery and parenteral antibiotics (antibiotics given as injections or intravenous infusions).
In addition, patients with poor circulation may need either percutaneous transluminal balloon angioplasty or an arterial bypass graft to correct blood flow problems in their leg arteries. Without these procedures, circulation to the injured foot may be too poor to allow the ulcer to heal properly.
Innovative treatments. To supplement the traditional treatment approach, innovative "bioengineered skin" may soon be approved by the Food and Drug Administration as a way to speed the treatment of diabetic foot ulcers.
When to call your doctor
If you have diabetes or suffer from poor circulation or peripheral neuropathy,
examine your feet every day. If you see an area of redness, swelling, bleeding,
blisters or any other abnormality, call your doctor promptly.
Prognosis
In patients with grade 1 or 2 foot ulcers, the prognosis for healing is good
if blood circulation to the foot is adequate. By using the best wound care
methods available, most ulcers should heal within 12 weeks. Unfortunately, about
30 percent of healed ulcers recur, particularly in patients who do not wear
specialized footwear prescribed by their doctor.
Source: LifeScan: Johns Hopkins University, Updated March 2004.
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