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Foot Examination

Infection of the Foot Diabetic Neuropathy Charcot's Arthropathy Peripheral Vascular Disease Foot Examination Foot Care What sort of help is needed

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Uncontrolled diabetes for several years can result in damage to the nerves in the feet causing tingling, numbness, burning or pain that usually begins at the tips of the toes / fingers and over a period of time gradually spreads upward. In due course you could lose sensation in the affected limbs (neuropathy) which places you at a high risk of injuries. You may develop certain high pressure points in the feet where the skin gets thickened (callus). Moreover, you may not feel where you are stamping and you may not feel pain from injuries or sore spots on your feet. These areas can become ulcers and can break open the skin to various infections. Left untreated, this severe damage might require toe, foot or even leg amputation.

Make sure to check your feet regularly so that you can treat minor injuries before they become infected. This is especially important for people with diabetes, who tend to heal more slowly due to concomitant decreased blood flow to the feet. Please remember that cigarette smoking is very harmful and can lead to nerve damage and reduce blood flow to feet.

 HOW DOES DSDSC TAKES CARE OF YOUR FEET

Doctors at DSDSC examines your feet for any visual evidence of neuropathy (dry skin, callus, dilated veins) or incipient ischaemia; nail deformity or damage. He then grades diabetic neuropathy from foot ulceration point of view by assessing the degree of loss of sensation in the feet. He usually do this by testing if you can feel the pain of a non-traumatic pin-prick / the touch of a cotton wool / the touch pressure sensation of a 10-g monofilament / the vibration of a tuning fork. A biothesiometer is an option for quantitative assessment (cut-off point for ulcer
risk >25 volts).

Testing with a non-traumatic pin-prick

Testing with a cotton wool

Monofilament testing

Testing with a tuning fork

 

Testing vibration sensation with a biothesiometer: A probe is applied to part of the foot, usually on the big toe. The probe can be made to vibrate at increasing intensity by turning a dial. The person being tested indicates as soon as he/she can feel the vibration and the reading on the dial at that point is recorded. The biothesiometer can have a reading from 0 to 50 volts. The reading is low in young normal individuals (ie.they are very sensitive to vibration). As we get older, the biothesiometer reading becomes progressively higher. From experience, it is known that the risk of developing a neuropathic ulcer is much higher if a person has a biothesiometer reading greater than 25 volts, if the high reading cannot be explained by age.

Overall if a person has a high biothesiometer reading (eg. 40 volts) and cannot feel the monofilament, there is a high risk of developing neuropathic ulceration. For these individuals, intensive footcare education is required. On the contrary, if a person has a low biothesiometer reading (eg.10 volts) and can feel the monofilament, the risk of neuropathic ulcer is low, especially if none of the other risk factors are present. For these individuals, only simple footcare advice is required.

 

How to tell if the peripheral vascular disease is severe enough to predispose to foot ulceration ?

Palpation of foot pulses (dorsalis pedis and posterior tibial) and capillary return time; Doppler ankle:brachial pressure ratio (<0.9 for occlusive vascular disease) may be used where pulses are diminished to quantify the abnormality.

  • If a person has claudication or rest pain (especially the latter), there is sufficiently severe peripheral vascular disease to predispose to vascular ulceration.

  • If a person has no claudication or rest pain, then one relies on physical examination and, if necessary, investigations to determine the risk.

  • Looking at the feet to see if they are purplish in colour and feeling them to see if they are cold give important clue that the circulation may be impaired.

If pulses in the foot can be clearly felt, the risk of foot ulceration due to vascular disease is small. Pictures showing the anatomical positions of the dorsalis pedis and the posterior tibial arteries.

Taking the temperature of the foot

Palpation of the posterior tibial pulse

Palpation of the dorsalis pedis artery pulse

In most cases, looking at the feet and palpating the foot pulses are all that is required to assess the risk of vascular ulceration. When the foot pulses are very weak or not palpable, then it is necessary to carry out "non-invasive vascular tests" to assess the risk.

This is most easily done by measuring what is called the Ankle Brachial Index. It is as easy as having blood pressure checked although a simple hand held Doppler machine is required for this. The following steps are involved :

 Taking blood pressure in the arm. This is called the brachial pressure because the artery being measured is the brachial artery

 Taking blood pressure in the ankle. This is called the ankle pressure because either of the two arteries in the ankle can be measured.

 

Taking brachial pressure

Taking ankle pressure

The arteries in the ankles are calcified due to diabetes (blue arrows)

A couple of examples for the calculation of the ankle brachial index.

Lets say someone has a brachial pressure of 120mmHg and an ankle pressure of 132mmHg.

  • Ankle brachial index = 132 / 120 = 1.1

Lets say someone has a brachial pressure of 120mmHg and an ankle pressure of 96mmHg

  • Ankle brachial index = 96 / 120 = 0.8

The following can be used as a guide to interpreting results of ankle brachial index:

Normal 0.9 - 1.2 Risk of vascular foot ulcer is small
Definite vascular disease 0.6 - 0.9 Risk of vascular ulcer moderate and depends on other risk factors
Severe vascular disease Less than 0.6 Risk of vascular foot ulcer very high

Sometimes the arteries in the ankles are calcified due to diabetes (blue arrows). This makes measurement of blood pressure at the ankle unreliable. In this situation, more information is obtained by measuring pressure at the toe. As a guide, a toe brachial index less than 0.5 indicates the presence of peripheral vascular disease

A duplex scan. When it has already been established that there is significant vascular disease, a duplex scan can be performed to locate the blockage and assess its severity. A duplex scan is a combination of an ultrasound test and a Doppler test and is again non-invasive.

Overall, if a person has good strong foot pulses the risk of developing a vascular ulcer is small. In doubtful cases, measurement of ankle brachial index gives useful information.

What are the abnormalities of foot shape which make the effects of neuropathy or vascular disease worse ?

Like any other part of the body, our feet can have some minor variations in shape from one another
 

Bunions

High Instep

Sometimes, the foot shape abnormality is part of the diabetic neuropathy or other disease processes. Some of the abnormalities are :

  • Clawed toes
  • Rocker bottom
  • Abnormal toe nails

Clawed toes occur as a result of imbalance of the muscles in the feet due to diabetic neuropathy. This increases pressure at the tip or apex of the toes. In the presence of neuropathy, these sites become ulcer prone.

Rocker bottom deformity occurs due to Charcot's joint which is a complication of diabetic neuropathy

Toe nails can become infected, thickened and deformed

Clawed toes

Rocker bottom deformity with neuropathic ulcer

Abnormal Toe nails

Poor diabetic control

Poor diabetic control increases infection and impairs wound healing. Although it is not possible to be absolutely clear cut, by and large it is the person with very poor control (eg. HbA1c greater than 10%), that is most at risk. Therefore even if diabetic control cannot be made excellent, it is worthwhile improving it to a level that is not "very bad". Also remember that even excellent diabetic control by itself will not be able to completely prevent foot problems once severe neuropathy or peripheral vascular disease is established. Other preventive and treatment strategies are still important.

Poor compliance to self care instruction

What a person can do for himself or herself to prevent foot disease is outlined in another section (Foot care for those at high risk of developing an ulcer). Needless to say, assuming all the other factors remain the same, the more care that is taken to prevent foot trauma and to improve foot hygiene, the more chance there is to avoid foot ulceration. Some of the problems due to poor foot care are :

  • Maceration between the toes which can lead to infection
  • Very dry skin with cracks predisposing to infection

Maceration

Very dry skin

Is Type 1 or Type 2 diabetes more likely to lead to foot problems ?

Children or young adults with Type 1 diabetes are not at great risk of diabetes related foot problems in the early years as their nerves and blood vessels will not have been severely affected by diabetes. They should be encouraged to play sports or undertake the activities they normally do. There is no reason to stop any activity after being diagnosed with diabetes for fear that it might hurt the feet. As the duration of diabetes becomes longer (eg. greater than 10-15 years) and the person becomes older (eg older than 40-50 years), progressively more care is required.

People with Type 2 diabetes can get foot problems even soon after diagnosis because they might have diabetes for a long time without knowing. Circulation and nerve function are also not as good in older people.

 

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Last modified: 04/22/18