The concept of diabetic foot was first introduced by Oakley in 1956 and was defined by Catterall in 1972 as a foot with loss of sensation and ischemia due to neuropathy and co-infection.
In 1999, the World Health Organization defined it as an infection, ulcer formation, or deep tissue destruction in the lower extremity of a diabetic patient due to a combination of neuropathy and various degrees of lower extremity vasculopathy.
As the understanding of diabetic foot continues to grow, it has been found that diabetic foot is a group of foot syndrome rather than a single symptom, which should have at least the following elements. First, the patient should be diabetic, and second, there should be adequate tissue dystrophy with ulcer or gangrene formation. After that, patients with diabetic foot should also have lower extremity neurological or vascular lesions, without one of the above three elements, otherwise it cannot be considered as diabetic foot.
The diagnosis of diabetic foot mainly includes the diagnosis of neuropathy and the diagnosis of arterial disease of the lower extremities.
The diagnosis of diabetic foot neuropathy mainly includes electromyography. Diabetes mainly affects the sensory nerves of the lower extremities, but the motor nerves are also often damaged, manifesting as slowed conduction speed, and electromyography can clarify the extent of the lesion and which specific nerve is involved. Second, protective temperature sensory examination, mainly using the water cup method, pouring cool water and warm water into the cup, and then use the wall of the cup to contact the local skin, so that the patient to judge the hot and cold sensation, this method is qualitative examination. Third, protective nociceptive examination, also using a relatively sharp needle, needling the local skin of the lower limb or leg to determine the patient’s sensation of pain, this method belongs to qualitative examination. Fourth, tuning fork vibration sensory examination, is a semi-localized examination of the sensation of deep tissue. Fifth, nylon monofilament pressure sensory examination, the examination is made perpendicular to the foot and the nylon monofilament is bent to produce momentary pressure, if the patient cannot feel the presence of nylon monofilament in any part, it indicates the loss of pain sensation and suggests the risk of diabetic foot ulcer.
The diagnosis of diabetic foot lower limb artery disease mainly includes: 1 , touching the arterial pulsation of the foot, touching the arterial pulsation of the foot is a simple, economical and practical examination method, using food paper and middle paper to touch the patient’s dorsalis pedis artery and posterior carotid artery pulsation, if both through pulsations are palpable, the possibility of severe ischemia of the foot is relatively small, if the pulsations of both of the above arteries are absent, then the N artery should be further and femoral artery to initially determine the site of stenosis.
It is a very valuable index reflecting the blood pressure and vascular status of the lower limbs, and is widely used because of its simplicity and sensitivity. The normal ratio is 1.0-1.4, and a ratio of less than 0.9 is considered mild ischemia, 0.5-0.7 moderate ischemia, and if the ratio is less than 0.5 is considered severe ischemia, and patients with severe ischemia are prone to ulceration and gangrene of the lower limbs.
Third, transcutaneous oxygen partial pressure measurement, transcutaneous oxygen partial pressure measurement can reflect the state of microcirculation of the foot, but also reflects the state of peripheral arterial blood supply, normal human dorsal foot skin oxygen partial pressure should be higher than 40 mm Hg, if the measured value is lower than 30 mm Hg, indicating the existence of local ischemia. If it is below 20 mm Hg, the ulcer of the foot is difficult to heal and surgical vascular surgery is needed to improve the blood supply.
Fourth, lower extremity vascular ultrasound Doppler examination, this method is a common means to check the narrowing of the lower extremity blood vessels, the location of plaque lesions and blood flow conditions. It is often used clinically as a reference for the degree and severity of ischemia in the lower extremities, but the shortcoming is that the human factor is more influential. Compared with ankle-brachial pressure index and transcutaneous partial pressure of oxygen, its sensitivity and specificity in determining foot ischemia are not as good as the latter.
V. Arterial digital subtraction angiography. This method can directly display the morphology and direction of the diagnostic vessels, so that the tissue structure and lesion sites are more clearly displayed, which can be used for the objective assessment of the patient’s amputation risk, and can be an important basis for interventional treatment and vascular bypass surgery, and is the gold standard for lower extremity vascular examination and diagnosis.
Clinical assessment of the diabetic foot. The main purpose is to understand the severity of the diabetic foot, the possible development trend and outcome of the lesion, and to guide the clinical treatment plan according to the assessment results, which is an important procedure in the diagnosis and treatment of diabetic foot.
The clinical condition assessment of diabetic foot includes three parts, namely history, physical examination and auxiliary examination.
History taking includes the taking of general medical history and the taking of foot specialist history.
The general medical history should be taken to understand the duration of diabetes, glycemic control, cardiovascular, renal and retinopathy complications, and past treatment, as well as the patient’s lifestyle, smoking, alcohol consumption and current medication.
The history of foot specialist includes previous trauma sites, causes of formation, trauma treatment history, improvement and recurrence status, whether combined with foot edema and morphological changes of joints.
Second, physical examination. Patients must undergo a complete foot examination at each visit and receive a complete lower extremity examination every six months or at least once a year. A detailed record should be made in the medical record.
The most important physical examination is the skin examination of the foot. The order of foot examination is generally right foot first, then left foot, including dorsal, plantar, medial, lateral, root, ankle and intertubercular. Focus on the skin, calluses, toenails, edema, deformed joint movement, etc.
Thin, shiny, wrinkled skin with subcutaneous tissue atrophy suggests functional ischemia. Dry cracked skin and marked varicose veins suggest the presence of neuropathy. Ulcers are signs of skin breakdown, and attention should be paid to the site and depth of the ulcer, whether the skin around the ulcer is combined with redness and swelling, and the condition of the secretion. Corns or calluses are transitional hyperplasia of the keratinized layer, mostly in areas of weight and friction, and excessive development of both should be avoided, which may be a precursor to the formation of ulcers. Bleeding within the callus is an important early change in ulcer formation. Toenails, thickened toenails are very common in diabetic patients and inappropriate growth or trimming can cause damage and ulcer formation. Toenails that turn yellow and darken may indicate the presence of a hematoma under the foot and a risk of ulceration and infection. Swelling and deformity of the foot are also predisposing factors for ulcer formation. Swelling can be unilateral or bilateral and can be caused by factors such as heart failure, secondary diabetic kidney damage, hypoproteinemia, and impaired lymphatic return. formation. A change in foot color with a reddening of the foot is most commonly caused by cellulitis intertwined toe, severe ischemia, dermatitis or eczema. Bluish color of the foot indicates possible heart failure, chronic lung disease, venous insufficiency, etc. Black color of the foot may be local tissue necrosis, either wet gangrene or dry gangrene, suggesting local blood circulation disorders.
Third, laboratory tests, laboratory tests include fasting school or random blood glucose, glycosylated hemoglobin, routine blood count, blood sedimentation, C-reflective protein, and traumatic secretion culture problems in diabetic patients.
Screening tools are valuable when performing clinical condition assessment of the diabetic foot to grade the risk level of the diabetic foot, detect foot lesions early, intervene promptly and effectively, prevent progression and progression and reduce the risk of forced amputation of the patient.
The diabetic foot risk grading system and the follow-up flat rate, grade 0 indicates normal and should be followed up once a year. Grade 1 indicates a diabetic foot with peripheral neuropathy and loss of protective sensation and should be followed up at least once a year. Grade 2 indicates a diabetic foot patient with combined neuropathy, joint deformity, and peripheral arterial disease, and should be followed up at least quarterly. Grade III indicates a history of previous ulcers and amputations in patients with diabetic foot and should be followed up at least monthly.
The appropriate grading of foot ulcers is based on a comprehensive examination, and grading is the first step in the treatment of diabetic foot. There are many grading systems for diabetic foot, the most commonly used being the Wagner system and the Texas grading system, etc. The following is a brief description of the characteristics of each of these two grading systems.
The Wagner system is the most commonly used grading system, which classifies diabetic foot into grade 0, grade 1, grade 2, grade 3, grade 4, and grade 5, with a total of 6 grades, of which grade 0 indicates the presence of diabetes and risk factors for foot ulcers, and no ulcers at present. Grade 1 indicates the presence of superficial ulcers and no sensory ulcers in diabetic foot patients. Grade 2 indicates the presence of a deeper ulcer, combined with soft tissue infection, and no infection of abscess or bone tissue. Grade 3 indicates the presence of deep ulcers with abscesses or osteomyelitis. Grade 4 indicates the presence of limited gangrene in the diabetic foot. Grade 5 indicates total foot gangrene. Of these, grades 0, 1, and 2, which are related to the depth of the ulcer, grade 3 refers to infection, and grades 4 and 5 have ischemia and tissue necrosis; the lower the grade, the better the treatment outcome, and the higher the grade, the greater the risk of amputation may be.
Texas grading, firstly, is divided into 0, 1, 2 and 3 according to the depth of the ulcer, and each level is divided into A, B, C and D according to whether there is a combination of infection and ischemia. Texas has 16 conditions, taking into account both etiology and extent, noting that infection or ischemia may develop even before ulcer formation, and is more instructive than the Wagner classification in evaluating wound severity and predicting limb preservation. In general, patients with Texas grade 2 and 3 stage D are difficult to treat non-operatively.
In conclusion, diabetic foot is one of the major chronic complications of diabetes mellitus. It is characterized by a long course, difficult to cure, high economic burden, and high disability rate, posing a serious threat to the quality of life and prognosis of diabetic patients.
The factors that determine the prognosis of diabetic foot are complex, but early and timely diagnosis and assessment of the condition as well as effective intervention and treatment with multidisciplinary records are important clinical guidelines for effective prevention of diabetic foot.