"Muha J. Local wound care in diabetic foot complications: aggressive risk management and ulcer treatment to avoid amputation. Postgrad Med 1999;106(1):97-102"

"oot infection is the most common reason for hospitalization among diabetic patients, accounting for up to 25% of admissions (1,2). Regrettably, less than 14% of patients admitted for diabetic foot complications receive adequate lower extremity evaluation (3,4), and when foot ulcers do develop, one in five of these patients eventually has to undergo amputation (1,2). It has been estimated that with appropriate knowledge of risk factors and treatment by a multidisciplinary team, up to 85% of foot and leg amputations in diabetic patients could be prevented (3,4). "

" In addition, aggressive management of diabetic foot complications is important in terms of healthcare expenditures. In 1990, the average cost per lower extremity amputation was $57,300, whereas the cost to achieve primary healing in an ulcer with osteomyelitis was $26,000 (4). "

" Early identification of risk factors for diabetic foot ulcer and initiation of proper treatment reduce the occurrence of complications, including the need for amputation. Several factors contribute to ulceration in diabetic patients (5). Among the most common are neuropathy, structural deformity or limited joint mobility, previous history of ulceration or amputation, and poor glucose control (3,5). Effects of these risk factors are cumulative. However, neuropathy or ischemia does not cause spontaneous ulceration. Rather, the combination of high risk and an environmental hazard, often involving pressure that ultimately leads to tissue damage, form the basis for ulceration (6). The triad of peripheral neuropathy, vasculopathy, and susceptibility to infection is the classic high-risk scenario for amputation. "

" Neuropathy permits moderate repetitive stress on the foot to go unnoticed, ultimately resulting in ulceration in many cases. Therefore, determining the point at which loss of protective sensation develops, and thus the risk of injury increases, is important (7). McNeely and associates (8) and other experts define loss of protective sensation as the inability to perceive testing with a 5.07 Semmes-Weinstein nylon monofilament standardized to deliver a 10-g force. "

" Structural deformity and limited joint mobility increase peak plantar pressures and often result in callus formation. If a callus persists or pressure is not resolved in patients with neuropathy, an ulcer is likely to develop. "

" Complete evaluation of the lower extremities is vital when undertaking treatment of a diabetic foot ulcer, starting with the cause of the problem. Clinical assessment should include the ulcer's appearance, the presence of any local or systemic infection, the degree of neuropathy and peripheral vascular disease, and the patient's metabolic status. "

" Location is important in evaluating the cause of a diabetic foot ulcer. Usually, plantar ulcers are the result of moderate repetitive stress underneath a prominent metatarsal head or sesamoid bone. Medial, lateral, and digital ulcers are often the result of pressure from shoes overlying such osseous abnormalities as bunions and hammer toes. "

" Ulcers should be measured or photographed for monitoring of wound progression. The base should be described in terms of tissue type (ie, granular, fibrotic, or necrotic), and wound margins should be examined for hyperkeratosis, maceration, and undermining. The presence of serous or purulent drainage or odor should be noted. Surrounding tissues should be inspected for edema, erythema, cellulitis, warmth, and fluctuance. "

" The ulcer should be explored with a blunt probe to determine its depth and to check for abscess and sinus tract. All hyperkeratotic, fibrotic, and necrotic tissue should be debrided so involvement of underlying structures (eg, tendon, joint capsule, bone) can be ascertained. "

" The presence and extent of infection directly affect morbidity. In some instances, serious infection provokes only a mild systemic response in diabetic patients, and the resultant minimal fever and leukocytosis can be misleading. "

" Identifying ischemia in patients with diabetic foot complications can be more difficult than expected, because diabetes masks ischemia. Inactivity and neuropathy may disguise claudication and pain at rest, and arteriovenous shunting may limit pallor and coolness. The foot may be pink and warm and have normal capillary refill but at the same time have insufficient blood flow to heal an ulcer (9). "

" An indication of the vascular status of the foot can be derived according to the presence or absence of dorsal-pedal and posterior-tibial pulses. Hair growth on the top of the foot and toes and vigorous capillary refill are signs of good blood flow. "

" The ankle-brachial index is unreliable in diabetic patients because of medial calcinosis of vessels, so tests that do not rely on vessel-wall compressibility (eg, Doppler echocardiography, pulse-volume waveforms) may be more suitable. The toe-pressure index is more reliable than the ankle-brachial index because digital vessels are less susceptible to calcinosis. Transcutaneous oxygen pressure measurements are also useful in diabetic patients. "

" Successful treatment of diabetic foot ulcers relies on reducing or eliminating pressure, resolving infection, correcting ischemia (10), and maintaining an environment that promotes wound healing. When an ulcer fails to heal, it is likely that one or more of these objectives have not been met. Close follow-up is critical for assessing patient response to treatment. "

" Relief of pressure on the ulcer along with rest and elevation of the limb should be started immediately. Foot ulcers do not heal in neuropathic patients who continue to walk on the affected foot without taking some protective measures. Ideally, patients should keep weight totally off the limb with use of crutches, a walker, or a wheelchair with a foot extension. Complete bed rest may be necessary in recalcitrant cases. "

" When staying off the limb is not feasible, improper or ill-fitting footwear should be replaced with "healing" sandals (eg, canvas, sling-back design, hooks-and-loops top closure that adjusts to foot's shape) or special shoes (eg, containing a shock-absorbent insole made especially for insensitive feet). Diabetic patients who qualify under Medicare Part B may be eligible for coverage of some therapeutic footwear (see box below). Knowledge of these benefits may encourage patients with financial concerns to obtain appropriate protective footwear. "

" Total-contact casts have been considered the "gold standard" for treatment of neuropathic ulcers in ambulatory diabetic patients because they distribute pressure over the total foot surface. However, they are often impractical. Recently, certain removable walking casts have been found to be as effective as total-contact casts in reducing pressure at ulcer sites (11). "

" In some instances, because of an underlying osseous prominence (eg, metatarsal head, sesamoid bone, bunion, hammer toe), reducing external pressure is not sufficient to accomplish healing. Early surgical intervention to correct the deformity may be prudent in these cases. In patients with adequate blood supply, correction of the underlying osseous abnormality usually results in ulcer resolution when more conservative care has failed. "

" Most diabetic foot infections are polymicrobial, so aerobic and anaerobic cultures should be done and initial therapy started with a broad-spectrum antibiotic. Cultures from superficial tissue are of little value; cultures from tissue deep in the ulcer base are more reliable for identifying the true pathogens (12). Antibiotic coverage can then be tailored according to culture and sensitivity results and clinical response. (See the "

" As mentioned, the wound should be thoroughly debrided and probed. Systemic symptoms may not improve without adequate wound debridement. Any pus should be drained. Use of full-strength topical solutions and antiseptics (eg, povidone-iodine) should be avoided because these agents can be cytotoxic. "

" In deep ulcers, osteomyelitis may be present. If bone is visible or palpable within the ulcer, the specificity for osteomyelitis is about 85% (13). In most cases of deep ulcer, radiographs should be ordered to evaluate the lesion for osteomyelitis, foreign body, and subcutaneous gas. Other imaging methods (eg, various leukocyte scans, magnetic resonance imaging, computed tomography) may be useful in determining the presence and extent of osteomyelitis and in ruling out Charcot's disease. "

" When osteomyelitis is found, aggressive debridement of devitalized bone is needed. All infected bone and any underlying osseous prominence, which may be the cause of the ulceration, should be removed. Antibiotic therapy is chosen on the basis of bone biopsy results. Controversy exists regarding the duration of intravenous antibiotic treatment of osteomyelitis. However, most experts agree that adequate osseous resection reduces the duration of needed antibiotic therapy and possibly the hospital stay. Given the complexity of osteomyelitis and the impaired metabolism of diabetic patients, consultation with an infectious disease specialist may be helpful. "

" A useful drug-delivery system in diabetic patients with osteomyelitis is implantation of antibiotic-impregnated polymethyl methacrylate beads (14) (figure 1). This method can achieve therapeutic local levels of antibiotic, despite poor tissue perfusion, while avoiding serum concentrations that increase the likelihood of side effects. These characteristics are important in patients with impaired renal or hepatic function. "

" Ischemia is the only factor that, in itself,
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