Diabetic Foot Care Guide (Introduction) http://www.mingyihui.net/article_402.html What is diabetic foot? Diabetic foot refers to the condition where, due to neuropathy, the protective function of the lower extremities in diabetic patients decreases. Large vessel and microvessel diseases cause insufficient arterial perfusion leading to microcirculation disorders, resulting in ulcers and gangrene. Diabetic foot is a serious complication of diabetes, being one of the main reasons for disability or even death in diabetic patients. It not only causes suffering to the patient but also imposes a huge economic burden.
What are the manifestations of diabetic foot? Are there any special symptoms? What are the early symptoms of diabetic foot?
Clinical Manifestations of Diabetic Foot: The clinical manifestations of diabetic foot patients are related to five aspects of lesions: neuropathy, vascular disease, biomechanical abnormalities, formation of lower limb ulcers, and infection.
(1) General manifestations of the feet: Due to neuropathy, the skin of the affected limbs is dry without sweat; the ends of the limbs experience pricking pain, burning pain, numbness, decreased sensation or loss of sensation, presenting a sock-like change, with a feeling of stepping on cotton; due to poor nutrition at the ends of the limbs, muscle atrophy occurs, and the flexor and extensor muscles lose their normal traction tension balance, causing bone depression and bending of interphalangeal joints, resulting in arch foot, hammer toe, claw toes, etc., deformities of the feet. When the bones and joints and surrounding soft tissues of the patient suffer from wear and tear, continued walking can easily lead to bone and joint and ligament injuries, causing multiple fractures and ligament ruptures, forming Charcot joints. X-ray examination often shows bone destruction, and some small bone fragments detach from the periosteum, forming dead bones that affect the healing of gangrene.
(2) Main manifestations of ischemia: Commonly seen are malnutrition of the skin, muscle atrophy, dry skin with poor elasticity, hair loss, reduced temperature, pigmentation, weakened or absent distal artery pulses, and audible vascular murmurs at sites of vascular stenosis. The most typical symptom is intermittent claudication, rest pain, and difficulty in squatting and standing up. When the skin of the affected limb has damage or spontaneously develops blisters followed by infection, it forms ulcers, gangrene, or necrosis.
(3) Diabetic foot ulcers can be classified according to lesion nature into neuropathic ulcers, ischemic ulcers, and mixed ulcers. Neuropathic ulcers: Neuropathy plays a major role in causation, with good blood circulation. This type of foot is usually warm, numb, dry, with less obvious pain, and good foot artery pulsation. Feet with neuropathy can have two outcomes: neuropathic ulcers (mainly occur on the soles) and neuropathic arthropathy (Charcot joints). Purely ischemic foot ulcers, without neuropathy, are rare. Neuroischemic ulcers: These patients have both peripheral neuropathy and peripheral vascular disease. The dorsalis pedis artery pulsation disappears. In these patients, the feet are cool, may be accompanied by rest pain, and have ulcers and gangrene at the edges of the feet.
The occurrence of foot ulcers is commonly seen on the forefoot sole, often caused by repeated mechanical pressure. Due to the disappearance of protective sensation caused by peripheral neuropathy, patients cannot feel this abnormal pressure change, cannot take some protective measures, develop ulcers followed by infections, and ulcers are difficult to heal, eventually leading to gangrene.
3) Grading of diabetic foot: The classic grading method is the Wagner grading method: Grade 0: Feet at risk of developing foot ulcers, with no open lesions on the skin. Grade 1: Superficial ulcers, clinically without infection. Grade 2: Deeper ulcers with infected lesions, often combined with soft tissue inflammation, without abscesses or bone infections. Grade 3: Deep infection, with bone tissue lesions or abscesses. Grade 4: Bone defects, partial toe or foot gangrene. Grade 5: Most or all of the foot gangrene.
In addition to routine physical examinations, diabetic patients should pay special attention to signs of the feet: such as gait, presence of foot deformities like claw feet and hallux valgus, muscle atrophy, calluses; skin temperature, color, and sweating conditions, observing whether there are blisters, cracks, and ulcers; checking the skin's sensitivity to temperature, pressure, and vibration (tuning fork vibration sense); palpating the dorsalis pedis artery for weakened or absent pulsation, hearing vascular murmurs at sites of arterial stenosis; carefully tapping tendon reflexes like knee and ankle reflexes for weakening or absence.
1. Symptoms Initially, patients often experience itchy skin, cold extremities, dull sensation, edema, followed by persistent numbness in both feet like wearing socks, most showing reduced or absent pain sensation, some experiencing needle-like, cutting, or burning pain, worsening at night or when exposed to heat, walking like ducks or using crutches. Some elderly patients have severe histories of limb ischemia, such as intermittent claudication and rest pain.
2. Signs The skin of the lower limbs and feet is dry, smooth, and edematous, with body hair loss, shrinking of the lower limbs and feet. Skin shows scattered blisters, bruises, spots, and pigmentation, with cold extremities. Elevating the legs makes the feet turn white; lowering them turns them purplish-red. Toenails deform, thicken, become brittle, and fall off. Muscle atrophy and poor muscle tone occur. Common foot deformities include sunken metatarsal heads, bent metatarsophalangeal joints, arch feet, hammer toes, and clawed toes. When the dorsalis pedis artery is blocked, the skin of both feet turns purple, with extremely weak or absent pulsation, sometimes vascular murmurs can be heard at sites of vascular stenosis. Sensory perception at the extremities diminishes or disappears, tuning fork vibration sensation disappears, and Achilles reflex is very weak or absent.
When chronic ulcers form on the feet, round penetrating ulcers form under the metatarsal heads on the soles. Sometimes ligament tears, small fractures, bone destruction, and Charcot joints occur. In cases of dry gangrene, the entire foot or toes dry out, shrink, have shiny, thin skin, appear pale pink, and show black dots or spots on the tips of the toes. In wet gangrene, the feet redden, swell, and ulcerate, forming ulcers or abscesses of varying sizes and depths, with skin, vascular, neural, and bone tissue necrosis.
3. Clinically, diabetic foot lesions are divided into six grades based on severity.
4. Based on local manifestations of diabetic foot lesions, they are often categorized into three types: wet gangrene, dry gangrene, and mixed gangrene.
(1) Wet gangrene: More common in younger diabetic patients. Caused by simultaneous obstruction of terminal arteries and veins, microcirculatory disorders, skin trauma, and infection. Lesions mostly occur in the plantar callus area, metatarsal heads, or heels. The degree of lesions varies, ranging from superficial ulcers to severe gangrene. Local skin shows congestion, swelling, and pain. Severe cases present systemic symptoms such as fever, loss of appetite, nausea, abdominal distension, palpitations, oliguria, bacteremia, or toxemia.
(2) Dry gangrene: More common in elderly diabetic patients. Atherosclerosis in the lower limb small and medium arteries, terminal small artery sclerosis, narrowed lumen, thrombosis, and occlusion. However, venous blood flow is not obstructed. Local manifestations include pale, cold feet, with black areas of varying sizes and shapes on the toes, indicating microarterial embolism at the toes, with toe pain. Dry gangrene often occurs on the dorsal side of the foot and toes, sometimes the entire toe or foot turns black, dries out, and shrinks.
(3) Mixed gangrene: Different parts of the same limb simultaneously exhibit dry and wet gangrene. The range of gangrene is larger, involving most or all of the foot, with more severe conditions.
1. Neuropathic diabetic foot presents as local warmth, numbness, dryness, disappearance of pain, and presence of arterial pulsation, leading to neurogenic ulcers (mostly occurring on the soles), Charcot foot, and neurogenic edema. Neuropathic-ischemic type presents as reduced skin temperature, weakened or absent arterial pulsation, rest pain, circumferential foot ulcers, and focal necrotic gangrene.
2. Both types of diabetic foot are prone to infection, with ulcers often becoming portals of bacterial invasion, typically involving multiple microbial infections that rapidly spread to surrounding tissues, eventually affecting the whole body. Tissue destruction caused by infection is the primary reason for amputation.
3. The key to diagnosing neuropathic versus neuropathic-ischemic diabetic foot lies in the presence or absence of arterial pulsation. Therefore, checking arterial pulsation is crucial, which is often overlooked. If the posterior tibial artery or dorsalis pedis artery pulsation can be felt, it indicates that ischemia is not severe. If all disappear, it suggests reduced blood circulation. Measuring the pressure index (ankle systolic pressure/arm systolic pressure) helps in judgment. In normal individuals, the ratio is usually >1, while during ischemia, it is 1, ischemia can be excluded, which is important for clinical decision-making because it implies that large vessel disease is not a major factor, thus arterial angiography is unnecessary.
4. However, 5% to 10% of diabetic patients have non-compressive peripheral vascular disease leading to elevated systolic pressure, even in the presence of ischemic lesions. Therefore, diagnosing diabetic feet with unpalpable arterial pulsation but a pressure index greater than 1 is challenging. Sometimes, especially with foot edema, examiners fail to palpate existing arterial pulsations. In such cases, re-examine after Doppler ultrasound localization. If still unpalpable, it might indicate vascular wall calcification, suggesting ischemia exists. Doppler ultrasound blood flow velocity and waveform examination and measurement of toe thumb pressure help diagnosis in such situations.
5. For distal obstructive lesions, Doppler examination shows waveform abnormalities, with normal rapid systolic pulsations and diastolic flow disappearing. As the lesion progresses, waveforms flatten and eventually disappear. Reference indicators for the severity of arterial lesions can be found in relevant books.
6. Measurement of toe systolic pressure requires a dedicated toe cuff and devices capable of measuring toe blood flow, such as laser Doppler or plethysmographs. Toe pressure of 30 mmHg indicates severe ischemia with poor prognosis. Additionally, if transcutaneous oxygen pressure on the dorsum of the foot is <30 mmHg, it also proves severe ischemia.
7. The degree of neuropathy needs to be assessed by checking sensations to needles and cotton, as well as vibration (using a 128 cps tuning fork). Check for symmetrically distributed stocking-like peripheral neuropathy. Absence of knee and ankle reflexes also indicates peripheral neuropathy. Checking autonomic neuropathy is more difficult, judged by skin dryness, fissures, and abnormal sweating.
8. Once neuropathy is confirmed, determining whether protective pain sensation exists is crucial. If absent, the patient is more prone to diabetic foot ulcers. Two clinically valuable examination methods are vibration measurement and nylon filament testing. Manual vibration threshold meters can measure vibration sensation. Note that vibration thresholds increase with age, and measurements must be corrected using data from peers of the same age. Nylon filaments can measure pressure sensation thresholds. If unable to feel a straight pressure equivalent to 10g, it indicates the absence of protective pain sensation.
Clinical Diagnosis and Grading of Diabetic Foot: Diabetic patients with any of the above limb end lesions can be diagnosed with diabetic foot. Based on the severity of the lesions and referring to foreign standards, diabetic foot is divided into 0-5 levels.
Level 0: No open lesions on the skin. Often presents with insufficient blood supply at the extremities, cool skin, purplish-brown color, numbness, stabbing pain, burning pain, delayed or lost sensation, and high-risk foot manifestations such as toe or foot deformities.
Level I: Open lesions on the extremity skin. Superficial ulcers caused by blisters, blood blisters, corns or calluses, frostbite or burns, and other skin injuries, but the lesions have not yet involved deep tissues.
Level II: Infection has invaded deep muscle tissue. Often presents with cellulitis, multiple pus foci, and sinus tract formation, or infection spreading along muscle gaps causing through-and-through ulcers on the sole and dorsum of the foot, with abundant purulent secretions, but no tendon or ligament tissue destruction.
Level III: Destruction of tendon and ligament tissues, fusion of cellulitis forming large abscesses, increased purulent secretions and necrotic tissue, but bone destruction is not yet obvious.
Level IV: Severe infection has caused bone defects, osteomyelitis, and bone joint destruction or pseudo-joint formation. Partial fingers or toes or parts of the hands and feet have developed severe wet or dry gangrene.
Level V: Most or all of the foot is infected or ischemic, leading to severe wet or dry necrosis. The extremities turn black and dry, often involving the ankle joint and leg, generally requiring surgical high-level amputation.
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