The importance of foot problems in people with diabetes should NEVER be underestimated. It should be remembered that second highest cause of foot amputations in our country. Moreover, if one were to see the number of indoor patients in any specialised diabetic clinic or hospital, one would find more than half are there because of some foot problem. These are also patients who need to stay in the hospital the longest and whilst with excellent management, we are able to save many feet, a significant number of these patients may be left with significant morbid deformities. The medical and socioeconomic cost to these patients and their families is mind boggling.
Due to the fact that there are usually definite precipitating factors, a vast number of the foot problems are preventable!
The vast majority of foot problems occur in those with insensitive feet, possibly without adequate circulation and are PRECIPITATED by infection, injury, or both. Due to the fact that there are usually definite precipitating factors, a vast number of the foot problems are preventable! Even if they do occur, it is possible to "catch" them at the earliest so that the management is simpler and the morbidity minimal, if any.
The tragedy is that many of us do not pay adequate attention to the feet of our patients. How often do we instruct patients to examine feet daily and even take the trouble to show them how this should be done? For that matter, how often do we insist that the feet of the patient be examined every time they come to us?
Unfortunately even in specialised institutions which may pay attention to foot problems, the patient either gets some rapid oral instructions about foot care or may even be given a small slip of paper detailing briefly the instructions. Whilst, this may be better than doing nothing, it still does not solve the problem, because more often than not, the oral instructions are forgotten by the time the patients reached home and the small piece of paper is either filed or lost. Even if the patient were to remember the instructions to inspect the feet, does this really mean much to the patient? What is the patient supposed to look for? How are they supposed to look for any problem and how often? How can they care for the feet? What are they supposed to do in case of any problem, and possibly, more important, what are they NOT supposed to do!
Before we discuss the "do's and don'ts" about foot care, it would be worthwhile to consider briefly some of the mechanisms which predispose the patient to foot problems. This would allow us to instruct the patient in a much more rational manner rather than just giving some "commandments" to observe.
Predisposing factors for limb-threatening lower extremity infections and ulcerations include neuropathy, macrovascular and microvascular impairments, as well as decreased resistance to infection, which is often referred to as immunopathy.
Nerve damage in diabetes affects the sensory, motor, and, the often forgotten, autonomic fibers.
Involvement of the sensory nerves going to the feet brings about many varied symptoms and signs but many patients have a marked reduction in the pain sensations and a significant number of the patients go on to have insensitive feet, and are incapable of feeling any type of sensation. The patient may not feel any pain or other uncomfortable sensations. Therefore, often they may not be aware of any the presence of any injury or infection until these may have progressed to a severe stage, or they are pointed out by a relative or the doctor. Thus it may not be possible to detect the presence of any injury or infection at a stage when management may be a lot easier.
Although diabetic neuropathy more commonly affects the sensory nerves, the motor nerves may also be involved. Motor neuropathy causes muscle weakness, atrophy, and paresis. The motor nerves which innervate the small muscles of the feet help in maintaining the shape and the "arches" of the foot. When these nerves are affected, there is a wasting of the small muscles of the feet and this may change the configuration of the foot. The toes may become “cocked” up and the area of the sole near the heads of the metatarsals comes to bear most of the weight of the body. This is made worse by changes taking place in the small joints of the foot due to diabetic nerve and bone damage. The change in the normal architecture of the foot accompanied by a decrease in the sensitivity is one of the most important predisposing factor in diabetic foot disease.
One aspect of neuropathy that is rarely given its due is the autonomic nerve involvement. They regulate the blood supply to the limbs, determine sweating and also maintain the normal texture of the skin. When these nerves are affected in diabetes, it may lead to a reduction or even a complete absence of sweating in the feet and the lower legs. A reduction in sweating causes the outer layers of the skin to become dry and this makes the skin of the feet, especially the skin on the soles of the feet, to become brittle, liable to develop cracks which may form entry points for infecting bacteria. The skin also loses its ability to stretch and therefore any change in the shape of the feet also tends to cause the development of breaks and cracks in the skin.
In some people, the clinical picture may be completely reversed. With the skin showing excessive sweating. This again leads to the skin becoming “soggy” and macerated, thus, making it more prone to injuries and allowing for easy entry of bacteria.
The autonomic nerves are also responsible for regulating the blood supply to the feet and this supply is affected when the nerves are involved. Surprisingly, feet that are affected with autonomic neuropathy may appear warm and have been shown to have an increased blood supply. This increase in the warmth leads many to mistakenly feel that the circulation in the limb is adequate. This is definitely not the true situation. It is known that although the total blood going to the leg and feet may have increased, most of this blood is shunted directly from the small arteries to the veins, bypassing the capillaries. Therefore, although the total quantity of blood flow to the feet may appear to increase in diabetic neuropathy, this is of no real use and one could say that in practical terms there is a lack of blood supply to the feet.
Autonomic dysfunction (and denervation of dermal structures) also results in loss of skin integrity, which provides an ideal site for microbial invasion.
This can be further compromised by the presence of peripheral vascular disease, which is much more common amongst diabetics than in a non-diabetic.
|Warm with intact pulses||Pulseless, not warm|
|Diminished sensation||Usually diminished sensation|
|Ulceration, usually on tips of toes and plantar surfaces under metatarsal heads||Ulceration, often on margins of foot, tips of toes, heels|
|Local necrosis||Necrosis or gangrene|
|Oedema||Critical ischaemia, foot pink, painful, pulseless, and often cold|
Whilst nerve involvement and the peripheral vascular disease predispose to foot problems, there is usually seen a “trigger” or precipitating factor. This can be trauma, or infection or both. Therefore, the focus in preventing serious foot complications would aim at efforts to avoid trauma and infection to the feet or in the least, diagnose their presence in the very early stages so that adequate measures can be taken at a time when management of the patient would be simpler.
|Precipitating causes of foot ulceration and infection|
Friction in ill fitting or new shoes
Whilst all patients should have intensive foot care education, there are certain categories of patients who are more at risk of having foot problems and would need a much more specialised care and attention.
|Patients With High Risk|
|a) Patients who walk barefoot.|
|b) Patients with diabetic neuropathy.|
|c) Patients with significant peripheral vascular disease.|
|d) Patients who smoke or use tobacco in any form.|
|e) Those with a foot deformity such as claw toes and hallux valgus.|
|f) Diabetics with a history of previous ulcers or foot infections.|
|g) Patients with abnormal gait.|
|h) Those with significant skin and nail infections or deformitoes.|
|i) Blind/partially sighted persons.|
|j) Elderly patients ; especially those living alone.|
|k) Diabetics with chronic renal failure.|
|l) Patients with a high alcohol intake.|
The prognosis for the second limb is poor in those who have had an amputation of the contra lateral limb.
A comprehensive foot exam assesses skin, circulation, and sensation. The test can be done during a routine clinic visit.
Inspection of the feet of the patient can be one of the most important aspects when screening for diabetic foot problems. In fact, the most important step in the prevention of foot problems is for the doctor to ask the patient to take off their footwear!
The presence of dry or excessively moist, skin, hair and nail abnormalities, corns, calluses, bunions, warts, foot deformities, heel spurs, flat arches, hammer toes, etc., are all pointers to an increased propensity for foot problems. Occasionally, one may be surprised to find an injury or infections which the patient may have been completely unaware of.
The footwear should also be examined, not only to see if it is appropriate, but often one may find jutting nails which again the patient is unaware of due to the loss of sensations in the feet.
After a detailed history which must include questions about numbness or tingling in the limbs, the most important aspect of grading diabetic neuropathy from foot ulceration point of view is to assess the degree of nerve involvement.
The testing is usually done by testing if the patient can feel the pain of a pin prick or the touch of a cotton wool or the vibration of a tuning fork. These are perfectly useful and time honoured techniques. However, the problems with testing sensation with a pin prick, cotton wool or tuning fork is that every doctor does it in a slightly different way. It is very difficult to standardize the procedures and the results. To overcome these problems, two other methods are often used :
In recent times, it is felt as much information can be obtained by the use of the monofilament test. Consequently, biothesiometry is rarely carried, or even required, in the vast majority of cases.
A standardized filament is pressed against part of the foot. When the filament bends, its tip is exerting a pressure of 10 grams (therefore this monofilament is often referred to as the 10gram monofilament). If the patient cannot feel the monofilament at certain specified sites on the foot, he/she has lost enough sensation to be at risk of developing a neuropathic ulcer. The monofilament has the advantage of being cheaper than a biothesiometer, but to get results which can be compared to others, the monofilament needs to be calibrated to make sure it is exerting a force of 10 grams.
Do not apply to an ulcer site, callous , scar or necrotic tissue.
|The circles represent the places on the foot to test with the monofilament.|
|Consider feet to be “at risk” if patient cannot feel the 10gm monofilament at any of the sites marked.|
Here again, a detailed history often suffices. If a person has intermittent 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 there is any mottling 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. At the same time, one must remember that in patients with severe autonomic neuropathy, as we have discussed above, the peripheral arteries may be well filled, but the tissues may be ischemic as the blood bypasses the capillaries. Well filled and prominent veins on the dorsum of the feet especially when the patient is lying down flat is a clue to this possibility.
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.
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.
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.
Lets say someone has a brachial pressure of 120mmHg and an ankle pressure of 96mmHg
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.
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.
If necessary, the following tests should be considered:
All these investigations may not be necessary in every patient and the range of investigations should be individualised.
In so far as foot complications are concerned, prevention is still the best policy. It is absolutely essential that the feet of all the patients be examined for the presence of any problems which may predispose the patient to foot infections.
If present, these MUST be treated before, rather than after, a foot infection develops.
Corns and calluses are thick layers of skin caused by too much rubbing or pressure on the same spot. Corns and calluses can become infected.
Blisters can form if shoes always rub the same spot. Wearing shoes that do not fit or wearing shoes without socks can cause blisters. Blisters can become infected.
Ingrown toenails happen when an edge of the nail grows into the skin. The skin can get red and infected. Ingrown toenails can happen if one cuts into the corners of ones’ toenails when they are trimmed. One can also get an ingrown toenail if your shoes are too tight.
A bunion forms when the big toe slants toward the small toes and the place between the bones near the base of the big toe grows big. This spot can get red, sore, and infected. Bunions can form on one or both feet. Pointy shoes may cause bunions. Bunions often run in the family. Surgery can remove bunions.
Plantar warts are caused by a virus. The warts usually form on the bottoms of the feet and tend to go away without treatment.
Hammertoes form when a foot muscle gets weak. The weakness may be from diabetic nerve damage. The weakened muscle makes the tendons in the foot shorter and makes the toes curl under the feet. This may lead to sores on the bottoms of your feet and on the tops of your toes. The feet can change their shape. Hammertoes can cause problems with walking and finding shoes that fit well. Hammertoes can run in the family. Wearing shoes that are too short can also cause hammertoes.
Dry and cracked skin can happen due to nerve involvement. Dry skin can become cracked and allow germs to enter.
Conversely, excessive sweating can lead to skin which gets macerated and form an entry point for bacteria.
Athlete's foot is a fungus that causes redness and cracking of the skin. It is itchy. The cracks between the toes allow germs to get under the skin. The infection can spread to the toenails and make them thick, yellow, and hard to cut.
All of these foot problems CAN and MUST be taken care of!
The overall risk of an individual developing a diabetic foot ulcer is determined by a combination of factors. In general, the risk is higher if:
|Neuropathy is more severe (because more sensation is lost)|
|Peripheral vascular disease is more severe (because there is less circulation to bring enough oxygen to repair tissue damage)|
|There are coexisting abnormalities of the shape of the foot which make the local effects of neuropathy or vascular disease more severe (because it increases local pressure and callus)|
|The person is unable to practise reasonable self care to maintain general condition of the feet and to prevent trauma (because there are more chances of damaging the feet)|
|The diabetic control is very poor (because of susceptibility to infection and poor wound healing)|
|There is a past history of foot ulceration due to diabetes (because the above factors often persist)|
At the same time, one has to treat any infection at the earliest so that it does not proceed to a more severe form of morbidity. “Nip it in the bud” as they say!
The clinical diagnosis of infection usually consists of three aspects.
(1) Systemic signs of fever and leukocytosis.
(2) Classic signs of inflammation around the ulcer (eg, heat, redness, edema, and pain); and
(3) Presence of purulent discharge from the ulcer;
It should be realized that due to the presence of varying degrees of nerve and arterial involvement, one may not see these “classic” signs. Pain and tenderness may be absent because of neuropathy. The response to injury in skin includes a local vasodilation mediated by sensory nerve fibers, which are impaired in diabetic neuropathy. Intact tissue responds to bacterial infection by increasing blood flow >20-fold in the area around the infection. However, erythema or redness may be absent in the diabetic foot because of the inability of the foot to increase its blood supply in response to infection. Furthermore, it is now established that up to 50% of patients with deep foot infections will not have leukocytosis or fever. Thus, one cannot wait for the classical signs before initiating management in all patients.
Most of the foot infections are caused by mulitimicobrial involvement. Thus, empiric treatment should cover Gram- negative aerobic as well as an aerobic organisms. The antibiotic chosen should be bactericiadal as opposed to bacteriostatic. In general, bacteriostatic antibiotics require an intact immune system to function properly. The latter is often compromised in a person with diabetes.
|Selected empirical antibiotic regimens for mild and non–limb-threatening infections|
|Oral agents||Topical agents|
|Cefdinir||Silver powder, gels|
Aminoglycosides should not be used in combination therapy, if possible. In diabetic patients, who may have some degree of underlying nephropathy, the potential toxic effects of these agents is a prime concern, especially since less toxic alternatives are available. In addition, aminoglycosides are inactivated in an acidic environment, such as that found in abscess cavities. They have minimal penetration into bone, thus making them a poor choice for patients with osteomyelitis.
Later, the antibiotic choice would depend on the culture and sensitivity reports.
A patient who presents with mild infection should be closely monitored and if healing does not take place or the conditions worsens, it would be much better to refer the patient to people specializing in managing such problems.
Any person presenting with more serious infections or an abcess or ulcer should immediately be referred to others well versed in this management without wasting precious time.
But coming to the point which was made initially, an ounce of prevention is still better than tons of treatment no matter how advanced these may be!
It is absolutely essential that all of us teach our patients the “Do’s and Don’ts” of foot care!
This is of the utmost importance in order to catch a problem in the earliest stage. But just telling patients that they should inspect their feet is useless. Patients must know what they have to “inspect”! They must search for any breaks in the skin, scalds and burn marks and any redness that may be a sign of infection, any puncture or injury marks, any darkening of the skin, the presence of corns and callus formation. Two areas where he should look very carefully are between toes and at pressure points at the bottom of the feet.
Some patients, especially those that are obese or have joint pains may find it difficult to lift up the feet for a close inspection. They can very easily use a mirror to examine the bottom of the feet. Failing this, a relative would have to be instructed in the means of foot care. Patients who have vision difficulties or are old and infirm would also need the help of a relative. In fact, these are patients who would come into the high risk category so that foot care is all the more important for them.
This may not seem a common problem in our country with the habit of having a daily bath, but some patients are under the mistaken notion that diabetic feet should be kept scrupulously dry at all times so that even when they have a bath, they cover their feet with a plastic bag. This is really absurd unless they have a specific problem for which they have been instructed specifically to keep the feet dry.
In addition to maintaining cleanliness (so important to avoid infection), washing the feet daily helps in the skin regaining some moisture that may be lacking because of the neuropathy. The water that is used to wash the feet should be tepid, neither very hot nor very cold. This means that the patient should always check the temperature of the water before pouring it on the feet Some authorities advise that the temperature of the water should be checked by the hands (if the patient withdraws the hand very rapidly, it is very hot) but I would like to caution about this. The neuropathy may also affect the nerves going to the hands and these too may be relatively insensitive to the heat. I feel that it would be best to check the temperature of the water using the elbows.
There is also a tendency in some patients to soak their feet for a while. This is especially true in those who use bathtubs and many patients who have aching feet use tubs or basins to soak their feet in order to get some relief. Worse still, some put a disinfectant solution in the basin, in the misconception that this will clean the feet better. I feel that one should never soak the feet as this often allows the patients' skin to come into contact with the warm water for far too long. More importantly, this causes the skin to become macerated and such a skin is very prone to act as an entry point for infection. The use of disinfectants should be discouraged because the wrong disinfectant or even a mild one in a strong solution can damage the skin considerably. Similarly, the soap that is used for the bath or the washing of the feet should be a very mild one. I usually recommend that a baby soap of any reputable company should be used. After all, the skin of a diabetic should be treated with as much care and attention as that of a newborn baby.
The practice of using rough stones to scrub the feet, especially the soles should be avoided. It leads to too many small cracks and fissures in the skin.
The towel should be of the soft baby variety. Coarse towels can cause as much damage as the use of stones for scrubbing the feet. The feet should preferably be patted dry rather than be rubbed. Often, many patients give their feet a brisk rub down in the hope that this would improve the circulation. This really does not help and can cause minute breaks in the skin from where infection can enter. Careful attention is to be paid to patting dry the area between the toes as these often tend to remain wet and may macerate.
This is the time that most of the patients should examine their feet. If the feet are very dry, then one may need to apply some mild lubricant like "baby" oil. Conversely, if the skin is moist, then it would be better to apply some mild powder especially between the toes. The point to remember is that the skin should be neither too dry nor too moist and therefore there should be a fine balance between the use of lubricants and powder.
The best time to manage the nails is after a bath as the nails are relatively softer at this time. I feel that nails should never be cut by the patient but that he should only file them so that no sharp edge is left. There is no need for cutting the nails very close to the edge or trying to shape them by cutting the side edges inwards. The sharp edge of the scissors tends to cause minute injuries and infection often starts here. Some patients, especially those that have U shaped nails may have a problem with in growing toenails. This should always be managed by a competent doctor and patients should avoid trying to treat such in growing toenails themselves.
Many of the patients we see with serious foot problems seem to have brought it upon themselves by trying to indulge in self doctoring. Some patients when they see a corn or a callus are tempted to take a knife or some other sharp object and try and remove them. Such self-inflicted wounds are often painless and may not be noticed until serious infection has supervened. One should never use any commercial preparation which are available in the market for treating calluses and corns including corn pads and adhesives. In fact, it would be worthwhile to avoid applying any medication to the skin unless it is under medical supervision. Most of the medicines available for applying to the skin may turn out to be too strong for diabetic skin. Strong medicines burn the skin. Patients often use medicines like mercurochrome to treat mild infection or injuries. This is not only too strong but is usually ineffective. The colour of such medications tends to mask the redness that may be the only sign of spreading infection in the absence of any pain sensation.
The best socks to wear are soft cotton ones. These do tend to absorb moisture but this may end up as an advantage in our country where one tends perspire a lot. The socks should not have tight elastic top as this may interfere with the blood circulation to the feet. It may be better, under the circumstances, to allow the top of the socks to be loose even if they have a tendency to roll down a little.
This is one of the most important areas in preventing trauma to the feet, Unfortunately, this is an area where one comes across the most obstinacy. People having diabetes should never walk barefoot. I am against the use of even chappals ( sandals) for use by a diabetic. These really afford no protection against trauma. Unfortunately, many patients refuse to change over from wearing these chappals inspite of all persuation, saying that the use of shoes is not only uncomfortable but goes against their traditional dress style. In such cases, one compromise would be to insist that the chappals should be stitched and not have any nails in them. It is obvious that these patients would need to be extra careful about any injuries that they may get.
Women also rebel against the use of shoes, but this is an argument that does not hold good especially in urban areas where excellent shoes for women are routinely available. Another argument that is used is that the shoes that the doctor feels are good for the feet are not fashionable enough. This may be true in many cases as unfortunately, the arbiters of fashion do not take into consideration the skin condition of a diabetic. At the same time decent looking shoes are available for women which may not be in the height of fashion but are nevertheless quite good looking and suitable for wearing by a diabetic.
Let us now come to the type of shoes that should be worn. They should be made of soft leather rather than of any other synthetic material.
Buy shoes at the end of the day, when the foot is usually at its largest (because of swelling). Shoes will be more accurately and safely sized at that time. All shoes should be sized while the patient is standing since the foot increases in length and width when it is bearing weight. Shoes should be approximately one-half inch longer than the longest digit when sized while the patient is standing.
They should be big enough to accommodate the foot spaciously, especially the front part which should not bunch up the toes.
Many patients feel that such spacious shoes make them look awkward and have a tendency to choose shoes that are a size too small. Advise the patient to make an imprint of their feet on a piece of paper and the shoes that they buy should be broad enough and long enough to completely cover the imprint. This should be done for both the feet Often there may be slight variations in the two feet and what may be all right for one foot may cause the same size shoes to be slightly tight for the other foot. In this case, one would either have to get shoes of different sizes or have shoes specially made for them. This may also have to be done by others who have special problems like cocked up toes, high arches of the feet or other structural deformities.
Shoes should have uppers made of soft leather. The soles of the shoes should also be of leather since rubber (or other synthetic) soles do not offer adequate protection. How often have we seen thorns or nails push right through the rubber soles. Shoes should be stitched rather than nailed together. The soles and the insides of the shoes must be closely examined before the shoes are put on everyday. One would be surprised by what may be sticking out through the soles or even be embedded inside the shoe.
All new shoes even if they are spacious, need breaking in. New shoes should never be worn for more than an hour at a time. What this implies is that one should not wait till the last minute before getting new shoes. Advise patients to keep two pairs of shoes so that the other pair can be comfortably worn in an emergency.
If these simple guidelines are followed, the chances of preventing serious foot problems from developing would be very bright. Many patients may feel that one is being unduly finicky about the need for excellent foot care. But having seen so many patients with serious foot problems and the morbidity associated with this, one would agree that there is no better treatment than prevention. After all, the old saying:
“For want a nail, the shoe was lost;
For want of a shoe, the horse was lost;
For want of a horse, a war was lost.”
……….should not come chillingly true for the patient!