Diabetic foot – specific anatomical and functional changes in foot tissues caused by metabolic disorders in patients with decompensated diabetes mellitus. Signs of diabetic foot are pain in the legs, hyperkeratosis and skin cracks, distal limb deformity, ulcerative defects and necrosis of soft tissues, in severe cases – gangrene of the foot or lower leg. Diagnosis of diabetic foot syndrome includes external examination, determination of various types of sensitivity, dopplerography and angiography of vessels, radiography of the feet, microbiological examination of the contents of ulcers, etc. Treatment of diabetic foot requires a comprehensive approach: normalization of the level of glycemia, unloading of the affected limb, local treatment of ulcerative defects, antibiotic therapy; in severe lesions – surgical methods are used.
Meaning
Diabetic foot syndrome in endocrinology is understood as a complex of microcirculatory and neurotrophic disorders in the distal parts of the lower extremities, leading to the development of ulcerative necrotic processes of the skin and soft tissues, bone and joint lesions. Changes that characterize a diabetic foot usually develop 15-20 years after the onset of diabetes mellitus. This complication occurs in 10% of patients, another 40-50% of patients with diabetes are at risk. At least 90% of diabetic foot cases are associated with type 2 diabetes mellitus.
Currently, the organization of care for patients with diabetic foot is far from perfect: in almost half of cases, treatment begins at late stages, which leads to the need for limb amputation, disability of patients, and an increase in mortality.
Causes
The main pathogenetic links of diabetic foot syndrome are angiopathy, neuropathy and infection. Prolonged uncorrectable hyperglycemia in diabetes mellitus causes specific vascular changes (diabetic macroangiopathy and microangiopathy), as well as peripheral nerves (diabetic neuropathy). Angiopathies lead to a decrease in the elasticity and patency of blood vessels, an increase in blood viscosity, which is accompanied by a violation of innervation and normal trophic tissues, loss of sensitivity of nerve endings.
Increased glycosylation of proteins causes a decrease in joint mobility, which entails simultaneous deformation of the limb bones and a violation of the normal biomechanical load on the foot (diabetic osteoarthropathy, Charcot’s foot). Against the background of altered blood circulation, reduced sensitivity and protective function of tissues, any, even minor injury to the foot (small bruise, scuffs, cracks, micro-cuts) leads to the formation of long-term non-healing trophic ulcers. Ulcerative foot defects are often infected with staphylococci, colibacteria, streptococci, anaerobic microflora. Bacterial hyaluronidase loosens the surrounding tissues, contributing to the spread of infection and necrotic changes that cover subcutaneous fat, muscle tissue, bone-ligamentous apparatus. When ulcers are infected, the risk of developing an abscess, phlegmon and gangrene of the limb increases.
Despite the fact that the potential danger of developing diabetic foot exists in all patients with diabetes mellitus, the high-risk group includes people with peripheral polyneuropathy, atherosclerosis of blood vessels, hyperlipidemia, coronary artery disease, hypertension, alcohol and smoking abusers.
The risk of deep damage in diabetes mellitus is increased by local tissue changes – the so-called small problems of the feet: ingrown toenail, fungal nail lesions, skin mycoses, corns and calluses, cracked heels, insufficient hygiene of the feet. The cause of these defects may be incorrectly selected shoes (excessively narrow or tight). Reducing the sensitivity of the limb does not allow the patient to feel that the shoes are too pressing, rubbing and injuring the foot.
Classification
Taking into account the predominance of one or another pathological component, there are ischemic (5-10%), neuropathic (60-75%) and mixed – neuroischemic (20-30%) forms of diabetic foot. In the ischemic form of diabetic foot, a violation of the blood supply to the limb is predominant due to damage to large and small vessels. Ischemic syndrome occurs with pronounced persistent edema, intermittent lameness, pain in the legs, rapid fatigue of the legs, skin pigmentation, etc.
Neuropathic diabetic foot develops when the nervous system of the distal extremities is affected. Signs of a neuropathic foot are dry skin, hyperkeratosis, anhidrosis of the extremities, a decrease in various types of sensitivity (thermal, pain, tactile, etc.), deformities of the bones of the foot, flat feet, spontaneous fractures.
With a mixed form of diabetic foot, ischemic and neuropathic factors are equally pronounced. Depending on the severity of the manifestations during the diabetic foot syndrome , the stages are distinguished:
0 – high risk of developing diabetic foot: there is a deformity of the foot, calluses, hyperkeratosis, but there are no ulcerative defects 1 – stage of a superficial ulcer limited to the skin 2 – stage of a deep ulcer involving skin, subcutaneous fat, muscle tissue, tendons, but without bone damage 3 – stage of a deep ulcer with bone damage 4 – stage of limited gangrene 5 – stage of extensive gangrene.
Symptoms
Ischemic form
In the debut, the ischemic form of diabetic foot syndrome is manifested by pain in the legs when walking, rapid fatigue of the legs, intermittent lameness, followed by persistent swelling of the foot. The foot is pale and cold to the touch, pulsation on the arteries of the foot is weakened or absent. Against the background of pale skin, areas of hyperpigmentation are often visible.
Typically, the presence of calluses, long-term non-healing cracks on the fingers, heels, lateral surface of the I and V metatarsophalangeal joints, ankle. In the future, painful ulcers develop in their place, the bottom of which is covered with a black-brown scab. Copious exudation is atypical (dry skin necrosis).
During the ischemic form of diabetic foot, there are 4 stages: a patient with the first stage can painlessly walk about 1 km; with the second – about 200 m; with the third – less than 200 m, in some cases pain occurs at rest; the fourth stage is characterized by critical ischemia and necrosis of the toes, leading to gangrene of the foot or lower leg.
Neuropathic form
The neuropathic form of diabetic foot can occur by the type of neuropathic ulcer, osteoarthropathy and neuropathic edema. Neuropathic lesion develops in the areas of the foot that are subject to the greatest pressure – between the phalanges of the fingers, on the thumb, etc. Here calluses are formed, dense areas of hyperkeratosis, under which an ulcer is formed. With a neuropathic ulcer, the skin is warm and dry; scuffs, deep cracks, painful ulcers with hyperemic, edematous edges are found on the foot.
Osteoarthropathy or Charcot’s foot, as a form of diabetic foot, is characterized by the destruction of the bone-articular apparatus, which is manifested by osteoporosis, spontaneous fractures, swelling and deformation of the joints (more often knee). With neuropathic edema, interstitial fluid accumulates in the subcutaneous tissues, which further aggravates the pathological changes in the feet.
For various types of neuropathic forms of diabetic foot, it is typical to preserve pulsation on the arteries, decreased reflexes and sensitivity, painless ulcerative necrotic lesions of tissues with a significant amount of exudate, localization of ulcers in places of increased stress (on the fingers, on the sole), specific deformities of the foot (hook-shaped, hammer-shaped fingers, protruding bone heads).
Diagnostics
Patients with a high risk of developing diabetic foot should be observed not only by an endocrinologist-diabetologist, but also by a podiatrist, vascular surgeon, orthopedist. An important role in identifying changes is assigned to self–examination, the purpose of which is to detect signs characteristic of a diabetic foot in time: skin discoloration, the appearance of dryness, swelling and pain, finger curvature, fungal lesions, etc.
Diagnosis of diabetic foot involves the collection of anamnesis with clarification of the duration of diabetes mellitus, examination of the feet with determination of the ankle-shoulder index and reflexes, assessment of tactile, vibration and temperature sensitivity. Special attention in diabetic foot syndrome is paid to laboratory diagnostic data – indicators of blood glucose, glycosylated hemoglobin, cholesterol, lipoproteins; the presence of sugar and ketone bodies in the urine.
In the ischemic form of diabetic foot, ultrasound of the vessels of the lower extremities, radiopaque angiography, peripheral CT arteriography are performed. If osteoarthropathy is suspected, radiography of the foot is performed in 2 projections, X-ray and ultrasound densitometry. The presence of an ulcerative defect requires obtaining the results of back-sowing of the separated bottom and the edges of the ulcer on the microflora.
Treatment
The main approaches to the treatment of diabetic foot are: correction of carbohydrate metabolism and blood pressure, unloading of the affected limb, local wound treatment, systemic drug therapy, if ineffective – surgical treatment. In order to optimize the level of glycemia in type 1 diabetes, the insulin dose is adjusted; in type 2 diabetes, the patient is transferred to insulin therapy. Beta–blockers, ACE inhibitors, calcium antagonists, diuretics are used to normalize blood pressure.
In the presence of purulent-necrotic lesions (especially in the neuropathic form of diabetic foot), it is necessary to provide a mode of unloading the affected limb by restricting movement, using crutches or a wheelchair, special orthopedic devices, insoles or shoes. The presence of ulcerative defects in diabetic foot syndrome requires systematic wound treatment – excision of necrotic tissues, bandages using antibacterial and antiseptic agents, laser treatment. It is also necessary to remove calluses, corns, areas of hyperkeratosis around the ulcer in order to reduce the load on the affected area.
Systemic antibiotic therapy for diabetic foot syndrome is carried out with drugs of a wide spectrum of antimicrobial action. As part of the conservative therapy of diabetic foot, preparations of a–lipoic acid, antispasmodics (drotaverine, papaverine), hemodialysate of calf serum, infusion of solutions are prescribed.
Severe lesions of the lower extremities that are not amenable to conservative treatment require surgical intervention. In the ischemic form of diabetic foot, endovascular dilation and stenting of peripheral arteries, thromboembolectomy, popliteal bypass surgery, arterialization of the veins of the foot, etc. are used. In order to close large wound defects, skin plastic surgery of the ulcer is performed. According to the indications, deep purulent foci (abscesses, phlegmons) are drained. With gangrene and osteomyelitis, the risk of amputation / exarticulation of fingers or feet is high.
Forecast
Wound defects in diabetic foot do not respond well to conservative therapy, require long-term local and systemic treatment. With the development of foot ulcers, amputation is required in 10-24% of patients, which is accompanied by disability and an increase in mortality from developing complications. The problem of diabetic foot dictates the need to improve the level of diagnosis, treatment and medical examination of patients with diabetes mellitus.
Prevention
Prevention of diabetic foot syndrome provides for mandatory monitoring of blood glucose levels at home, regular monitoring by a diabetologist, compliance with the required diet and medication regimens. It is necessary to abandon the wearing of tight shoes in favor of special orthopedic insoles and shoes, to carry out careful hygienic care of the feet, perform special exercises for the feet, avoid injury to the lower extremities.
Patients with diabetic foot should be monitored in specialized departments or offices. Special foot care, atraumatic manipulations and local treatment are organized by a specialist podiatrist.