Diabetic foot is one of the most serious and costly complications among patients diagnosed with Diabetes mellitus. According to Nalini Singh, David G. Armstrong and Benjamin A. Lipsky, 4% to 10% of the total diabetic population have at least one-foot ulcer and 25% of all diabetics will suffer from a foot ulcer in their lifetime(1).
Without proper management, these ulcers become quite frequently infected, causing a great morbidity, increasing financial costs tremendously and is most commonly the first step leading to lower extremity amputation(2). A prompt and effective management of Diabetic Foot ulcers by specialized and trained medical professionals is essential. However, our focus in this article is on prevention, taking the necessary steps to avoid reaching that point.
Why do Diabetic Foot ulcers occur? There are a number of causative factors, which, Peripheral Neuropathy is the most prominent one. Peripheral neuropathy is defined as the impaired protective sensation on the skin of the patient’s feet, and the consequent vulnerability to physical and thermal trauma increases the risk of foot ulcers. Peripheral neuropathy is estimated to affect more than 50% of diabetic people(3). Another causative factor is increased plantar pressure due to both limited joint mobility and foot deformities that are developed over time due to muscular atrophy(1, 3). This atrophy can also be caused by Peripheral Neuropathy which doesn’t affect just the superficial protective sensation, but also the muscular function and sympathetic innervation. In this case, sweat glands can be affected causing extreme skin dryness, increasing the risk of ulceration. In short, it affects several nerve fibres with completely different functions and therefore different consequences.
There is a contributing factor that is mandatory to address in order to provide proper ulceration prevention: Peripheral vascular disease, also known as ischemia, decreases the healing capacity of patients and making them more susceptible to other skin infections such as tinea pedis or onychomycosis in toenails(4). Peripheral Vascular disease, along with severe infection, is the most direct cause of lower limb amputation.
The first step in prevention is the risk categorization of the patient. In order to achieve this, we need to adhere to the following well-defined protocols
- Collect the patient’s history: years of diabetes evolution, previous ulceration, previous amputation, previous education, bare-foot walking habits, frequent shoe-wear used, access to healthcare, etc. Presence of subjective symptoms such as tingling or needle pain, burning sensation in feet, unjustified lower limb pain (these symptoms especially important their presence at night) claudication (presence of sharp pain on the calf after some distance walked that makes the patient stop), hot-cold sensation in foot/legs.
- Clinical examination: Presence of foot and toes deformities (hammer-toe, bunions, too high arch, collapsed arch, convex foot dorsum, etc.) Assessment of ankle joint range of motion. Assessment of patient’s gait.
- Screening for loss of protective sensation: nerve conduction studies are considered the gold standard for Peripheral Neuropathy diagnosis. However, we can perform other techniques in the clinic that are faster, cheaper and non-invasive. The most frequently used instrument for detecting neuropathy is the 10g of a force of a 5.0. Inability to perceive the explored points with the monofilament is associated with clinically significant large-fibre neuropathy and a lack of capacity to perceive painful stimuli on the foot(5). Other instruments used for assessing neuropathy are tuning fork and Biothensiometer. A tuning fork is an instrument which applies simple vibration and it is applied to bone prominences. An impaired sensation is considered when the patient stops feeling the vibration although the explorer still feels it, or of course if the patient doesn’t feel it at all. Biothensiometer is a handheld device that assesses the vibration perception threshold. The explorer will evaluate this time at what voltage level patient starts feeling the vibration.
- Screening for Peripheral Vascular Disease: Palpation of pedal pulses is a recommended practice; however, it is dependent on the explorer’s skills. (Dorsal and Tibialis posterior arteries are palpated) The most accepted value to assess the vascular status of the patient is the Arterial-Brachial-Index (ABI) which is the ratio of systolic blood pressure in the ankle to that in the brachial artery. An ABI of 0.9 or less is suggestive of peripheral vascular disease, while higher than 1.1 may represent a falsely elevated pressure caused by arterial calcification(4).
- Screening for Plantar pressure: a pressure platform is a highly accurate and useful tool in order to measure barefoot plantar pressure. It doesn’t only identify those anatomical areas where the loading and ground forces are elevated more than normal, but also will analyze the patient’s gait pattern. The combination of all this data input will result on an objective analysis of the risk of developing a pressure wound in specific areas of the foot, therefore this accurate information can be used in order to design a specific, accurate customized treatment with the necessary modifications in order to normalize plantar pressure.
Once all this clinical data has been collected we can categorize patients according to risk (using International Working Group on the Diabetic Foot risk categorization(6)and the follow-up plan recommended according to each case and applying the recommended actions in the table below.