Examination of diabetic foot ulcers
When we examine a new diabetic foot ulcer, we have to do this in a structured manner to ensure that we do not miss anything. The points below are key elements to examining a diabetic ulcer. Most healthcare providers should be able to perform these. Remember: always look at both feet- not only the foot with the ulcer!
Diabetic ulcers aren't sterile, and you will usually find a variety of pathogenic bacteria in these ulcers. This means that you don't have to use sterile gloves for examining a diabetic foot ulcer. But you should work in an aseptic manner. Use a facemask and single-use, non-sterile gloves. Protect your work clothes with an apron.
At the end of the chapter, we will give you an example of using the TIMES principle to describe a diabetic foot ulcer.
How long has the patient had diabetes? How is it treated, and how well is it regulated? What is the HbA1c?
Does the patient have any other diabetic complications - i.e.neuropathy, renal disease, heart disease, or eye symptoms?
Does the patient have other medical conditions?
Medication list, including traditional treatments?
Does the patient smoke or use other nicotine products?
How did the ulcer start? What was the likely cause? Bad fitting shoewear? Check the patient's shoes!
How long has the ulcer prevailed?
Has the patient had ulcers before? In the same area of the foot?
Is the ulcer painful? Is the patient using pain medication?
Who has treated the ulcer so far, and what dressings were used?
Has the patient been using any form of off-loading devices?
Has the patient been on antibiotics?
Quick neurological examination
Does the patient have signs of sensory neuropathy? Do a monofilament test or a tuning-fork test.
Does the patient have signs of autonomic neuropathy? Typical signs may be an unusually warm foot with swelling or dry skin.
Signs of motoric neuropathy? In diabetic patients, deformities of the feet are often caused by motor neuropathy.
Figure 1 Testing for sensory neuropathy is essential for examining a diabetic foot. If the patient has sensory neuropathy, this tells you that the patient usually does not feel pain from the ulcer and will not necessarily adhere to off-loading advice. It is a factor for poor prognosis and means that you should provide extra good follow-up. If you do not have access to a 10g monofilament- use a fishing line of equivalent thickness. Please refer to our chapter on " Using a Monofilament" under Practical Skills in the main menu.
Quick vascular examination
Palpate the dorsal foot artery and the artery behind the medial malleolus. If there are palpable pulses, then most likely, the arterial circulation is not too bad.
Use a handheld doppler to do an ankle-brachial index (ABI) if available. The ABI can be unreliable in some people with diabetes because of calcified and thus stiff arteries. However, this does not mean that an ABI is useless for diabetic patients, as some caregivers think. If you have a handheld doppler available, you should certainly take an ABI of all your diabetic patients. If you measure an ABI of 0,8, for example, the true ABI is 0,8 or less. Check our chapter on ABI as to how to perform this procedure correctly.
If available, do a toe pressure measurement as well. This will allow you to measure the microcirculation of the foot and is often a more reliable measurement in diabetic patients.
A vascular examination should also include asking the patient about pain. Patients with ischemic pain will often say that it helps to keep the feet hanging down and that they even may sleep with their feet hanging over the bedside. Be aware, however, that patients with sensory neuropathy may not feel ischemic pain.
As a rule of thumb, all diabetic patients with a foot ulcer and an ABI of 0,8 or less and higher than 1,3 should be referred to a vascular surgeon to check if reperfusion is indicated. At some centers, all diabetic foot patients, regardless of what the ABI is, are examined by a vascular surgeon! That is really the way to go when you have these resources available. Also, in western countries, many patients are first referred to a vascular specialist when gangrene is apparent. We want to get the patient to a vascular specialist before the condition of the foot is catastrophic. While diabetic ulcers in younger patients often are purely neuropathic and often have adequate arterial circulation, the issue with poorly perfused ulcers is mainly a phenomenon of elderly diabetic patients. As populations get older, we see an alarming rise in patients with diabetic foot ulcers who need to be evaluated by vascular surgeons.
However, the reality for most patients in Africa is that any form of reperfusion technique is not a realistic option. In these situations, you have to make sure that all other measures like offloading and avoiding infections are taken care of as well as possible.
Video 1 Palpating the pulses of the foot. copyright motivation australia
Figure 2 Using a handheld doppler to evaluate the anklel-brachial index (ABI). Please also refer to our chapter on how to perform an ABI correctly if you are not familiar with this procedure.
Figure 3 Gangrene on the big toe of a 90-year-old patient who was first referred three months after debut of the ulcer. She had a ABI of 0,6 and a percutanous transluminal angioplasty (PTA) was performed in local anesthesia. The toe was saved in the "nick of time". The image on the right shows the toe about 4 weeks after PTA. The toe healed completly within 4 months. Without a PTA the toe would have been amputated. At the point of referral the patient also had developed an osteomyelitis in the toe which needed an antibiotic therapy over 6 weeks. This case shows how important it is to refer these patients early to a specialized center.
Examining the foot for deformities and edema
Figure 4 Always inspect both feet to check for swelling or deformities. Many healthcare professionals forget this rule and only focus on the foot with the ulcer. We want our readers to be better than that. Always checking both feet can provide important clues and help prevent future ulcers on the "healthy side." In the image on the left, we see suspicious edema of the left foot. This can be due to infection but can also be a sign of Charcot's foot (we will discuss the latter condition in another chapter). In the right image, we see a severe hallux valgus where the greater toe pushes the second toe in an elevated position. copyright left image: https://commons.wikimedia.org/ wiki/File:Charcot_arthropathy_clinical_examination.jpg Attribution: J. Terrence Jose Jerome, CC BY 3.0
Figure 5 While you are examining the feet you should always also look at the footwear the patient is using. Feel inside the shoes to check for hard edges or even pebbles/other objects that may have fallen into the shoe. Make sure that the shoes have the appropriate length and width. In the examples above, it is evident that the shoes are too narrow at the front of the foot.
Examination of the ulcer(s)
Debriding and probing the ulcer
Before we can evaluate the severity of an ulcer, we have to debride away necrotic tissue. Almost all diabetic ulcers require some initial debridement, sometimes repeated debridements at follow-ups. We usually do this with a scalpel ( the no. 15 blade is excellent for this), a ring curette, and a pair of fine scissors. Good forceps with fine teeth are an invaluable aid here as well. Cheap plastic forceps do not work well here at all.
Figure 6 Important tools for debridement: forceps with fine teeth, sharp scissors, scalpel with no 15 blade, ring curette.
When we hold courses, a very common question we are asked is to what degree nurses or podiatrists can debride a diabetic foot ulcer. There is not a simple answer to this. Firstly this is dependent on the experience of the nurse or podiatrist. Specially trained nurses, for example, can be assigned quite complicated debridements. It will also depend on the resources available where the patient is. If the setting is a remote clinic in the bush, a debridement by less experienced staff is usually better for the patient than no debridement at all.
In many countries, the treatment of diabetic foot ulcers ( including the debridement part) is usually done in specialist clinics. At these clinics, specially trained nurses or podiatrists may do these debridements. In most parts of Africa, clinics specializing in diabetic foot issues are unavailable, and we have to look at workaround solutions. In these parts of Africa, debridements of ulcers are usually done by a medical officer or medical assistant. Some of these healthcare workers are experienced debriders! That being said, we have never seen an ulcer that was debrided too aggressively by a colleague! Never! In all cases, ulcers that were referred to us needed a lot more debridement. Lack of debridement is a big issue in diabetic wound care.
Can you teach debridement by use of videos? We think yes. We have posted several videos on debridement in the chapter " Practical Skills- Debridement." Hopefully, these will give you more confidence to debride a wound thoroughly.
If available, take a picture of the ulcer before and after the debridement. This is important for juridical reasons. Sometimes the debridement leaves behind a big hole in the foot- the patient may blame you for this hole which wasn't so apparent before the debridement. A series of images can help to justify the reason for the debridement.
Video 1 An example of the importance of de-roofing areas with callus to reveal what is underneath. In diabetic foot ulcers, you should never be afraid to remove suspicious areas with hard ( or soft) skin. Copyright: woundcarewindow
Video 1 An example of the debridement of a minor diabetic foot ulcer. The video shows how to debride not only the ulcer edges themselves but also the hyperkeratotic skin surrounding the ulcer. We find that a sharp ring curette is the best tool for this. It is not uncommon to get small bruises when debriding, which can bleed ( as seen in the video). These are usually not a problem and normally heal well. Copyright: woundcarewindow
Video 3 Another excellent video by Wound Care Window, USA. In this video, we see the debridement of a severe foot ulceration. We have picked this particular video because it demonstrates well where the surgeon is careful with the debridement when he reaches a layer with slight bleeding. Some may react to the way the surgeon uses his fingers to palpate the bottom of the ulcer. However, your fingers are an excellent tool for evaluating a wound bed. In this particular case, the surgeon removes most of the necrotic tissue and schedules the patient for vascular treatment the next day. In Africa, however, vascular treatment will be non-existing for most patients, and the best thing you can do there is to get the wound as clean as possible copyright: woundcarewindow.com
Many patients with diabetic foot ulcers also have sensory neuropathy. This means that many of these patients will not feel pain when you debride the wound. Be aware that some diabetic patients have a form of sensory neuropathy where nerves are over-sensitive, and the patient may feel a lot of pain when we are debriding. It can help to apply a topical analgesic gel (lidocaine/xylocaine gel or pilocarpine cream) into the ulcer and let it dwell there for at least 15-20 minutes. Sometimes we may have to inject a local anesthetic around the ulcer area. Remember that it is also helpful to provide the patient with oral pain medication like paracetamol + codeine about 45-60 minutes before the procedure. Please refer to our separate chapter on that topic under the menu " Important."
NB! If the patient has completely dry eschar and signs of poor arterial circulation, it may be best not to debride. This rule is certainly true in pure arterial ulcers - if you start to debride away dry eschar in these patients, it will usually give you more trouble than you had before. The best practice here is to get the patient referred to a vascular specialist. As a vascular specialist will not be an option for many African patients, the only choice is to wait and see. In some cases, the dry eschar can fall off within some months ( sometimes up to a year), revealing healed skin beneath.
It can be challenging to decide what to do when it comes to dry eschar in diabetic patients. In patients who only have an arterial disease and not diabetes simultaneously, the rule of not debriding dry eschar is quite absolute. However, in diabetic patients with concomitant arterial disease, the situation is not as clear-cut. What appears to be dry eschar will often reveal pus underneath the eschar leading to osteomyelitis. In diabetic patients, there may be only a few or no tell-tale signs to show us that there is actually an infection going on beneath the dry eschar.
As a general rule for diabetic foot ulcers: if the patient has the resources and access to a vascular intervention, we should preferably not debride the dry eschar until the arterial circulation has been improved - for example, by using modern endovascular methods. As this treatment option is unavailable to most patients in Africa, the safest choice is usually to debride the dry eschar. Removing the dry eschar in diabetic patients will give us better control to monitor the healing process and prevent infection. In diabetic patients, the dry eschar is like a time bomb; it may go off at any time, and it is usually better to defuse it by removing the eschar. In bedridden patients or patients with little mobility/ severe concomitant disease, it is often better to treat the ulcers palliatively and not remove dry eschar.
Most diabetic patients with dry eschar on the toes also have sensory neuropathy, and the debridement is often painless. If the patient has an intact sensory function, you will have to anesthetize the toe. Be aware that injecting large volumes of local anesthetic into a toe where the arterial circulation is already impaired can lead to even more gangrene! We usually avoid injecting a local anesthetic into the toes of all patients with poor arterial circulation! It is far safer to do an ankle block or a popliteal block. If you do not have the skills to do an ankle block and have no choice other than a ring block of the toe, use only small amounts of local anesthetic - usually only about 2 ml are required on each side of the toe.
Figure 7 Dry eschar on the first and third toe. The patient has diabetes but also poor arterial circulation. International best practice guidelines advise that a vascular specialist treat these patients before attempting a debridement of the necrotic tissue. In most parts of Africa, vascular treatment is not available to the patients, and you will have to decide whether to debride or see what happens. In our experience, dry eschar in diabetic patients are time-bombs, and at some point in time, they inadvertently lead to infection of the bone beneath. We tend to debride these early to "de-fuse" the situation and to have control over what is happening beneath. Again, this rule applies to patients with diabetes + arterial disease. In patients who only have arterial disease and no diabetes, we tend to keep the dry eschar in place and wait and see.
Probing the ulcer
After the wound has been debrided, we should explore it more by probing it. Probing helps us see how deep the ulcer is, whether there is undermining, and whether we can feel exposed bone somewhere in the wound bed. There are special probes made of metal with a round tip at the end. Remember that these need to be re-sterilized between each patient. There are single-use probes with soft foam tips and a centimeter ruler on the pin, but these are often surprisingly expensive. We often use an iv cannula ( without the needle) to probe wounds. Iv cannulas are usually readily available and cheap. Of course, you have to use a new one for each patient.
When we probe the ulcer, we try to feel if we can feel exposed bone - this is the so-called " probe to bone test." If you can feel exposed bone, this does not necessarily mean that the patient has osteomyelitis. However, it means that we cannot rule out osteomyelitis and should take a plain x-ray film to look for signs of a bone infection. If the bony area is smooth and covered by periosteum ( the outer layer of the bone), there is usually not a bone infection. If we can feel an eroded bone surface, this is more indicative of a bone infection. To determine whether a bone infection is present or not is very important. It will determine whether the patient needs antibiotics and how long these need to be administered. Remember that a foot ulcer will never heal if untreated osteomyelitis lurks beneath it!
Figure 8 Different tools which can be used to probe a wound Left: A single-use plastic probe with centimeter markings and a soft tip Middle: A metal probe with a round tip. This can be sterilized and used indefinitely. Right: Iv-cannulas are very useful to probe wounds. Obviously, you need to remove the sharp needle first.
Figure 9 Here, a metal probe with a round tip is used to probe the wound. Remember that it needs to be sterilized for every patient.
Are there signs of infection?
It is particularly important to be vigilant about infections in diabetic foot ulcers because infection is not always apparent. In diabetic patients, the classical signs of infection like redness ( rubor), increased temperature of the skin around the ulcer ( color), or pain (dolor) can be absent!. Sometimes a foul smell may be the only sign of infection, and at other times a purulent discharge may be the only hint of an infection. A foul smell does not necessarily mean that the patient has an infection! It usually means that there is too much necrotic tissue in the wound and that the ulcer needs debridement and not necessarily antibiotics.
We have often been fooled by areas with hyperkeratosis where a small abscess was actually hiding beneath this.
Never underestimate the severity of a diabetic foot infection. It is usually deeper than you think, and the condition can worsen severely overnight. Today's manageable situation can be an amputation case within a few days.
Ideally, diabetic foot infections should be handled by experts and should be referred as an emergency to specialist care. Where this is not available, you will have to manage it yourself. While we, in general, are reserved to using antibiotics routinely in chronic wounds, this does not apply to diabetic ulcers. Here the threshold for starting a course of antibiotics is much lower. We are not saying that all diabetic ulcers should be treated with antibiotics. However, if there are signs of infection, antibiotics are almost always warranted. Before prescribing antibiotics, you should always take a sample for bacterial culturing. See also our chapter on " microbiological samples." In infected diabetic foot ulcers, it is quite common to change the antibiotic regimen once the culture sample has been analyzed. Remember to check them as soon as you see the lab report and inform the patient if you have to switch to another type of antibiotic treatment. Not rarely do the lab reports show several strains of bacteria simultaneously, and it can be a challenge to pick the right antibiotic treatment. We routinely confer with specialists in infectious medicine when we get lab results showing a mix of different bacteria.
Remember that we do not advise using topical antibiotics in infected wounds. It is, unfortunately, a widespread practice to do so and a hard habit to break. Firstly, if there is an infection of the soft tissues surrounding the ulcer, topical antibiotics will not do much good. As you may be aware, topical antibiotics are considered a risk for developing resistant bacterial strains. The truth is that topical antibiotics probably are less of a risk of developing resistant strains than systemic antibiotics. When you administer systemic antibiotics - all of the bacteria in your body " get a taste" of that particular antibiotic. So the risk of resistance developing is high. When using topical antibiotics in a wound, we only target the bacteria in the wound. So why are topical antibiotics not recommended after all? The issue is that if topical antibiotics were recommended, " everybody" would have a low threshold for using them. The " abuse" of topical antibiotics would be significant, and in return, this would lead to a high resistance developing. As we mentioned earlier, if there is an infection in the tissues surrounding the ulcer, it is highly unlikely that topical antibiotics will be effective. In conclusion: if you have signs of infection in a diabetic foot ulcer, you should use systemic antibiotics. If you want to lower the bacterial concentrations in an ulcer, povidone-iodine is better than topical antibiotics.
Figure 10 In general, topical antibiotic ointments and creams have no place in treating diabetic foot ulcers. They are not effective enough to treat infections in these types of ulcers. Uncritical, widespread use of topical antibiotics has led to an increase in bacterial resistance. If there are signs of infection in a diabetic foot ulcer, systemic antibiotics should be used.
Describing a diabetic foot ulcer using the TIMES acronym
Once we have gone through all the steps above and have looked more closely at the ulcer, we can attempt to describe what we have seen. It is advisable to do this in a structured manner. The TIMES acronym is a helpful tool to help you describe what the wound looks like. The letters in the acronym stand for the following:
T (Tissue): How does the tissue within the wound bed look? Is it made of healthy granulating tissue? Is there necrotic tissue? A slimy layer?
I ( Inflammation/Infection): Does the wound appear inflamed or even infected? Note that it is sometimes difficult to differentiate between these two conditions.
M ( Moisture): This refers to the exudate coming from the wound. Is there much exudate, or does the wound appear to be dry? What is the color of the exudate? Is it smelly?
E ( Edge): By " edge," we mean the immediate wound edge. Is it a sharp edge or irregular? Is there undermining? Are there signs of skin ingrowth at the edges? Are there signs of maceration?
S( Surrounding skin): What is the skin like surrounding the ulcer? Is it dry and flaky? Are there signs of dermatitis or rashes?
Let us try to apply the TIMES acronym using the ulcer in the image below as an example. Obviously, this is not easy to do from a picture alone, as we cannot probe the ulcer to check for undermining, etc., but it will be a useful exercise nonetheless.
Figure 11 An example of using the TIMES acronym concerning the image above.
T (Tissue): Granulation tissue, some hypertrophy of granulation in the center
I (Inflammation/Infection): no apparent signs of inflammation or infection ( remember that this is hard to determine from a picture alone. Remember that signs of infection are not always evident in diabetic patients, especially with dark skin.
M (Moisture): To evaluate the exudate amounts, we need to be able to take a look at the old dressing. Judging from the amount of moisture damage at the skin edges, we would expect there to be a fair amount of exudate.
E (Edges) The skin edges are pretty sharp, and we cannot determine the extent of undermining from the image. Most diabetic foot ulcers have some undermining. The skin edges are macerated from excessive moisture.
S (Surrounding skin): We see some hyperpigmentation in the skin immediately surrounding the ulcer, indicating that there has been some inflammation ( or even infection) here previously. Some dry skin at the back of the heel, but mostly the skin looks quite fine.
Diabetic foot ulcer classification systems
While the TIMES acronym is a useful tool to describe the appearance of a wound it is not really a suitable tool to grade a diabetic foot ulcer according to the severity of the condition.
Many classifications systems have been developed to describe the severity of a diabetic foot ulcer. The most known classifications are the Wagner Classification and the University of Texas Classification System. Other popular classifications systems are PEDIS and SINBAD.
We are not going into a lengthy discussion about the advantages/disadvantages of each classification system. You will find many articles about this on the internet. If you are embarking upon doing research on diabetic foot ulcers it is important to look at other similar studies and see which classification systems they used. This will make it easier to compare your results with others.
We like the PEDIS classification ourselves. It was developed by the IWGDF ( International Working Group on the Diabetic Foot) and is a user-friendly classification. It is ideal for practitioners with a lower level of experience.
Table 1 The PEDIS classification system. Example: If the patient has critical limb ischemia, a 2cm2 ulcer down to the bone, loss of sensation but no signs of infection, then the total score is: 2+2+1 + 0 =5
Figure 12 MD+Calc has provided you with an easy-to-use online calculator for scoring diabetic foot ulcers using the PEDIS system. The results show you a probability of the ulcer healing within six months and the risk of amputation. Click on the image above to get to the calculator. Give it a try, put in some values, and check the results.
Once you have examined the patient's foot and the ulcer, you will have to ask yourself the following questions:
Can I treat this patient myself, or should I refer the patient to a more specialized facility? If I have to refer the patient- how quickly should this happen?
Does the patient need referral to a vascular surgeon? Is this a realistic option for the patient?
Does the patient need special orthotics to heal the wound, or can you manage with more simple offloading techniques?