Jaslok Hospital and Research Centre,
In Greek mythology, there was once a great warrior called Achilles. When he was a small baby, the Gods told his mother to dip him in river Styx as this would make him completely safe from any harm or injury. The mother held him up by his heels and dipped him completely in the river. As Achilles grew up he became renowned as a fearless warrior and the fable grew that nobody could ever defeat him as nothing could ever injure him! Until one day, another famous warrior called Paris shot a poisoned arrow which hit Achilles in his heel. This was the part of the body that had been held in the mother's hand when she had dipped him in the river and therefore was not safe from harm. The poisoned arrow did kill Achilles. From that day onwards, any vulnerable aspect of a person, has been called as the "Achilles heel" of that person.
In my opinion, this could well be applied to the feet of any diabetic. We tend to pay so much attention to the long term complications of diabetes like eye, kidney and nerve problems that we overlook the importance of foot care in diabetes. In view of the morbidity, if not mortality, associated with foot problems, this attitude is quite unfortunate, as we shall soon see.
The importance of foot problems in a diabetic should NEVER be underestimated. It should be remembered that second highest cause of foot amputations in our country and this true of many developing countries also are diabetes induced foot problems. 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 still require surgical intervention. The medical and socioeconomic cost to these patients and their families is mind boggling.
This is all the more unfortunate as 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 comes to us? In fact, it has been said, possibly in a lighter vein, that the most important step in the prevention of foot problems is for the doctor to ask the patient to take off the shoes.
I would like to quote a passage from the ancient chronicles. "In the thirty ninth year of his reign Asa was diseased in his feet, and his disease became severe; he sought help from his physicians but died in the forty first year of his reign." (II Chronicles XVI, 12-14). Some authorities regard this quotation as one of the earliest reference to diabetic foot disease and many of the more sceptical ones feel that there is not much more that we can do today about diabetic foot problems as compared to what was done for Asa. This attitude is unfortunate as foot problems in diabetes are preventable provided a few basic instructions are followed and proper care taken. 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 patient reaches home and the small piece of paper is either filed or lost. Even if the patient were to remember his instructions to inspect the feet, does this really mean much to the patient? What is the patient supposed to look for? How is he supposed to look for any problem and how often? How can he care for his feet? What is he supposed to do in case of any problem (and possibly, more important, what is he 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 him some "commandments" to observe.
We all know that diabetic neuropathy is the commonest longterm complication associated with diabetes and I have discussed this separately in another chapter. Here, I will only discuss those aspects that have direct bearing on the foot problem.
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. 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. These are nerves that have many important functions in the body and of these many functions, the ones that are especially relevant to our discussion, are that 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. It should be remembered that it is at the capillary level that the real function of the blood circulation takes place. It is here that the metabolites (oxygen, nutrients, waste products, etc.) are exchanged. The white blood cells and the other body mechanisms to fight off infection come into play at the capillary level. 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.
The inadequate blood supply to the limb may be further compromised by the presence of peripheral vascular disease, which is much more common amongst diabetics than in a non-diabetic. In this condition, the arteries supplying blood to the legs and the feet are narrowed down by the atheroma formation. The earliest symptom of this could pain in the legs whilst walking, Some patients get pain at night when they are lying down but this can be relieved by hanging the foot over the edge of the bed and is increased if the patient gets up and walks around. The feet may feel cold, skin appears dry and parched, the nails lose their lustre and the small amount of hair on the toes may be lost.
I have said previously that the feet of a diabetic with autonomic neuropathy appear warm whilst with peripheral vascular disease, the skin is cold. This may sound confusing but it should be realised that diabetics do not have a clear cut demarcation between those that have only a neuropathy and those that have only peripheral vascular problems. Most of them have varying degrees of both, and the clinical picture would depend upon the relative severity of the two conditions in any individual patient. In any case, neuropathy and vascular disease, in severe forms, presenting in the same patient is dangerous because the patient becomes prone to painless ulcers which are quite resistant to treatment.
Whilst the 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. One could make a point that avoiding or minimising neuropathy and peripheral vascular disease would be the best way of prevent- ing foot complication. I would definitely agree with this and some of these aspects have been covered elsewhere, but often a certain degree of nerve involvement is usually present in most people with diabetes and efforts to correct this have not proved to be too successful.
I would now like to take the discussion further and discuss ways and means to avoid trauma and infection in a foot already prone to complications.
Before we discuss these methods, there is one small aspect that I would like to clear up. There are some who feel that rigorous foot care is only important for those patients who are at special risk for getting serious foot complications. I thoroughly disagree with such an attitude and feel that all people with diabetes should have an intensive schedule of foot care, as it is not possible to clearly predict which patient is prone to serious problems and importantly, at what point of symptoms do we say that this particular patient should now have a more intensive foot care. At the same time, there are patients who are more prone to this problem and would need a much more specialised care and attention.
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, hammertoes, 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 loss of sensation in the feet. This 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.
Testing with a pin prick
Testing with a cotton wool
Testing with 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 :
Testing vibration sensation with a biothesiometer. This measures the vibration sense but in recent times, it is felt as much if not better 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. The use of the monofilament test is simple and gives a great deal of information and should be routinely carried out by any doctor treating patients with diabetes.
In this test, 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.
In view of the importance of this test, it is described in more detail below.
Sensation threshold screening using a 10 gram monofilament (also known as Semmes-Weinstein monofilament)
|1. Use the 10g monofilament to test sensation.|
|2. The sites to be tested are indicated on the foot diagram below.|
|3. Apply the filament perpendicular to the skin's surface ( see Diagram A).|
|4. The approach, skin contact and departure of the monofilament should be approximately 1.5 seconds duration.|
|5. Apply sufficient force to allow the filament to bend ( see Diagram B)|
|6. Do not allow the filament to slide across the skin or make repetitive contact at the test site.|
|7. Randomise the order and timing of successive tests.|
|8. 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 your feet to be "at risk" if you 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.
|Pictures showing the anatomical positions of the dorsalis pedis and the posterior tibial arteries.|
|Palpation of the dorsalis pedis artery pulse||Palpation of the posterior tibial 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.
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.
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.
The routine use of a simple point based PROTOCOL allows delineation of patients with high, or increasing risk, for the development of foot problems.
Simple Protocol For Judging Potential For Foot Problems
|(Basic Point Based Protocol)|
|Paraesthesia||no (0)||yes (2)|
|Hypoesthesia||no (0)||yes (4)|
|Anaesthesia||no (0)||yes (6)|
|Veins on dorsum of foot||empties normally on lying flat (0)|
|Distended on lying flat (3)|
|Distended on leg elevation to 45 (6)|
|H/O intermittent claudication||no (0)||moderate (3)||severe (6)|
|H/O rest pain||no (0)||moderate (3)||severe (6)|
|H/O nocturnal leg pain||no (0)||moderate (3)||severe (6)|
|Peripheral pulses||normal (0)||feeble (4)||absent (6)|
|Filling time after blanching of nail beds By pinching (in seconds)||< 5(0)||5-10(1)||11-15(2)||>15(4)|
|Skin and Nail Changes:|
|Skin:cold/dry/thickened/atrophic/shining/loss of hair||no(0)||yes(2)|
|Nails: thickened/ingrown/ fungal infections||no(0)||yes(2)|
|Presence of corns||no(0)||yes(2)|
|Presence of calluses||no(0)||yes(2)|
|Based on the points scored, patients are classified into categories A to E with increasing risk for developing foot problems.|
|A < 5;||B 5-10;||C 11-15;||D 15-20;||E >20;|
The treatment of diabetic neuropathy as well as the peripheral vascular dysfunction is discussed in their respective chapters. In so far as foot complications are concerned, prevention is still the best policy in so far as foot complications in a person with diabetes is concerned.
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 for use by a diabetic. These really afford no protection against trauma and as far as I am concerned their use is as good as going out barefoot. 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. For those who are too vain to accept anything but the latest in the fashionable trend, one statement which I have found to be quite effective is to tell them "Think how fashionable you would look if you lost a foot by not taking care". Not that the problem of vanity is the sole prerogative of women, I have come across many men with the same attitude and have used the same argument with telling effect.
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.
The "break" of the shoe, should correspond to the widest part of the patient´s foot (typically at the metatarsophalangeal joints). Heel-to-ball length is as different from person to person as is heel-to toe length and should be taken into account when sizing shoes.
Many patients feel that such spacious shoes make them look awkward and have a tendency to choose shoes that are a size too small. I usually 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. I insist that this be done for both 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.
I have said that the 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. I also advise that the 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. I usually advise the patients to keep two pairs of shoes so that the other pair can be comfortably worn in an emergency. I also advise them to get some new shoes much before they would need to be worn regularly. These shoes can be then worn at home every day for a short while so that they would get gradually broken in and so could be worn regularly when the old shoes finally wear off. Similarly, many of us have the tendency to wear out the shoes completely and only change them when the soles of the shoes have given way completely. This is obviously a wrong practice as torn soles provide no protection and may be as good or bad as wearing no shoes at all!
If these simple guidelines are followed, the chances of preventing serious foot problems from developing would be very bright. Many patients may feel that I am 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, I really feel 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!