Diabetic Foot Ulcer Treatment

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Diabetic Foot Ulcer Treatment
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Medical Therapy


Preventive strategies

The major focus of current diabetic foot care is prevention. Preventive strategies combine patient education, prophylactic skin and nail care, and protective footwear. Foot-specific, individualized patient education is the most important element of a comprehensive diabetic foot program. Low-risk individuals must wear nonconstrictive shoes. Soft leather or athletic footwear decreases the risk of tissue breakdown from direct pressure (see Image 2). Cushioned stockings are helpful, and white socks make identification of skin breakdown easier, especially in individuals with impaired vision. Nails should be cut transversely to decrease the risk of an ingrown toenail. Once a problem arises, the patient is instructed to seek medical attention immediately. Often, the earliest sign of infection is slowly increasing blood sugars and insulin requirement.

When applied to diabetic populations, the above strategies have been shown to markedly decrease the rates of DFU and LEA. Patient education materials are available through the American Orthopaedic Foot and Ankle Society, the American Diabetes Association, the American Podiatric Medical Association, and the National Institutes of Health (NIH) web site Feet Can Last a Lifetime.

When individuals progress to a higher degree of risk, they require accommodative footwear and prophylactic skin and nail care. Depth-inlay, soft leather, Oxford-laced shoes with accommodative pressure and custom-made shear-dissipating foot orthoses (insoles) have been shown to appreciably decrease the development of DFUs. The complexity and individualized nature of the shoes and custom-made foot orthoses vary with the magnitude of deformity and loss of protective sensation. Calluses should be pared to decrease the incidence of shear-mediated ulcer formation. Trained professionals should perform skin and nail care in these individuals.

Ulcer treatment

The first step in the treatment of a patient with diabetes who has a foot ulcer is medical management of the systemic diabetes. Many individuals with diabetes are malnourished due to chronic renal disease or chronic infection. Many are also immunocompromised. Once the systemic condition of the patient is optimized, specific attention can be directed to the foot ulcer.

Ulcers can be neuropathic or ischemic. Neuropathic ulcers are caused by pressure or by shear forces. Once the ulcer is unroofed and the necrotic tissue is debrided, the soft-tissue base reveals healthy granulation tissue. If the ulcer is unroofed and the tissue at the base is necrotic, the ulcer is likely to be ischemic. A vascular surgeon should evaluate patients with ischemic ulcers to determine if the limb can be salvaged. A risk-benefit analysis then can then be performed to determine whether treatment should entail limb salvage, amputation, or a combination of both. If the ulcer is neuropathic, noninvasive vascular testing is in order in the absence of palpable pedal pulses.

From a practical standpoint, vascular surgery consultation is warranted only when the patient is symptomatic with ischemic pain or a nonhealing ulcer. Ischemic ulcers generally require angioplasty or vascular bypass surgery to achieve wound healing. Neuropathic ulcers require debridement of nonviable or infected tissue, combined with local wound care and offloading.

Wet-to-dry wound care does not promote wound healing because dry wounds desiccate. This allows potential wound-healing cells to die and opportunistic infection to propagate. Dry wounds should be kept moist with saline-soaked dressings or hydrocolloid gels. Wounds that produce massive quantities of exudative material should be treated with absorbent materials (calcium alginate) and dressings while the wound is kept moist. Growth factor gels have been shown to promote wound healing in wounds with reasonable wound-healing potential.

Offloading distributes weight-bearing pressure over a larger surface area and provides an interface to decrease shear forces. Elimination of weight bearing is generally not required. The optimal offloading device is the total contact cast (TCC). This device acts to dissipate weight-bearing and shearing loads by eliminating foot or ankle motion, using an interface material to distribute pressure and shear forces. Venous swelling is lessened by the compression effect of the cast. When the ulcer shows appreciable improvement, foot care can be simplified with prefabricated walking braces that have a plantar weight-bearing surface lined with Plastazote or other pressure-dissipating materials (see Image 3). When the swelling decreases or when ankle immobilization is not necessary, healing shoes can be used (see Image 4).

The grade 0 foot has no ulcers but is at risk. Treatment involves foot-specific patient education and appropriate footwear. Prefabricated, pressure-dissipating insoles are appropriate. Occasionally, a bony prominence or deformity (eg, bunion, hammertoe) cannot be accommodated by therapeutic footwear. In this situation, removal of the bony prominence (exostectomy) or correction of the deformity is advised to prevent ulceration. As ulcers increase in grade, they require additional treatment. Grade 1 ulcers require debridement of nonviable or infected tissue, local wound care, and offloading. Grade 2 ulcers require debridement, culture-specific antibiotics, local wound care, and more extensive offloading techniques. Grade 3 ulcers require debridement of infected or gangrenous tissue. Partial foot amputation, more complex offloading or non–weight-bearing strategies, and culture-specific parenteral antibiotic therapy are necessary. Grade 4 ulcers require partial or whole foot amputation.

Following wound healing, patients should use offloading permanently. The plantigrade foot can be managed with depth-inlay, soft leather, Oxford-laced shoes and custom-made accommodative foot orthoses. When plantigrade alignment cannot be obtained, an ankle-foot orthosis or surgical reconstruction or stabilization is required.

Persistent or recurrent ulceration

Ulcers that do not heal or that recur in appropriate footwear require careful evaluation. Heel impact or increased forefoot loading can be lessened with a cushioned heel and/or rocker sole modification of the shoe. Consider surgery when accommodative methods are unsuccessful. Increased forefoot loading or ankle equinus (static or dynamic) can be treated with percutaneous Achilles tendon lengthening followed by immobilization in a below-the-knee walking cast for 4-6 weeks. Plastic surgery intervention with rotational flaps or free tissue transfer occasionally is indicated. The key to success in these patients is patient education, accommodative pedorthic footwear, and careful monitoring.

Prescription footwear

The Medicare Therapeutic Shoe Bill of 1993 provides financial support for 1 pair of appropriate inlay-depth shoes and 3 pairs of custom-made foot orthoses yearly for individuals with diabetes. Most insurance carriers have followed their lead with similar guidelines. They have realized that preventive strategies are cost-effective compared with amputation. The certified pedorthist is an essential consultant in providing these devices. The bill requires that both the physician treating the diabetes and the orthopedic surgeon or podiatrist treating the foot sign the prescription.

Charcot foot

Charcot foot is a hypertrophic osteoarthropathy currently seen primarily in patients with diabetes who have peripheral neuropathy. The etiology is neurotraumatic or neurovascular. The traumatic etiology implies fracture or stress fracture without protective sensation. The hypertrophic response results from the inherent motion applied to a nonimmobilized fracture. The vascular etiology implies an abnormal vascular inflow producing bony resorption, bony weakening, and a similar result. Eichenholtz stage 1 is the proliferative phase of the disease. The foot is very swollen, and radiographs are negative for fracture or dislocation. Stage 2 is the period of periarticular fracture or dislocation. Stage 3 is the phase of consolidation or healing.

Treatment historically has been anecdotal, with only recent attempts at a scientific approach. The foot with active disease is immobilized in a non–weight-bearing fashion in a TCC or other prefabricated device. When the process has consolidated, treatment has been accommodative, including with a specialized type of ankle-foot orthosis, the Charcot restraint orthotic walker (CROW). Surgery is advised for bony infection, nonhealing ulcers, or a deformity that cannot be accommodated with a custom orthosis. There has been a trend toward attempted joint fusion in stages 2 and 3 to prevent deformity that would be difficult to accommodate with a shoe-orthotic construct.
Surgical therapy

Amputation

Any discussion of the diabetic foot requires introduction of the concept of function-preserving amputation surgery. Partial and whole foot amputations frequently are necessary as treatment for infection or gangrene. The goal of treatment is the preservation of function, not just the preservation of tissue. Amputation surgery should be the first step in the rehabilitation of the patient. Because most of these individuals are ambulatory, surgical planning should be directed at the creation of a load-bearing terminal end organ that can interface most easily with accommodative footwear, a prosthesis, or a combination of both (ie, prosthosis). The principles that direct construction of a residual limb for weight bearing with a prosthesis should be employed when performing debridement or partial foot amputation.

The major value of partial foot amputation is the potential for the retention of plantar load-bearing tissues, which are uniquely capable of tolerating the forces involved in weight bearing. The soft-tissue envelope should be capable of minimizing these forces. Avoid the use of split-thickness skin grafts in load-bearing areas. Deformity should be avoided as much as possible. Tendo-Achilles lengthening should be used to avoid equinus deformity and increased loading of the residual forefoot in partial foot amputations. Retention of a deformed foot with exposed bony prominence leads only to decreased walking ability and recurrent ulceration.