Evaluating and managing the diabetic foot: An overview

Advances in Skin & Wound Care,  Jan/Feb 2000  by Mulder, Gerit D

• E-mail
• Print
• Link

As many as 20% of diabetic patients will experience foot complications related to diabetes during their lifetime. Foot complications (eg, ulceration, infection, and gangrene) are the most common cause of hospitalization of these patients, with annual health care costs of over $1 billion. The majority of nontraumatic lower extremity amputations in patients with diabetes are the result of complications from ulceration that lead to limb loss.

A thorough evaluation of the lower extremities is important for preventing ulceration or for making treatment decisions subsequent to the presentation of an ulcer. This article outlines the patient and ulcer evaluation, as well as suggests treatment options based on wound depth and status. Algorithms for treating diabetic foot ulcers also are included.

Patient and Ulcer Evaluation

Diabetic foot ulcers are associated with high morbidity and mortality, secondary to the underlying disease pathophysiology and its management. A thorough examination entails an evaluation of multiple systems, including the following:

Neurologic status. Diabetic neuropathy may present as a "stocking glove" paresthesia of the foot, with involvement of the motor, sensory, and autonomic nerves. The patient loses sensation in the foot, resulting in decreased sensitivity to pain, temperature, and pressure. When trauma occurs, the patient may be unaware of tissue damage, inflammation, and infection until an ulcer is apparent. The degree of sensory impairment can be evaluated with the use of a Semmes-- Weinstein monofilament. Instructions for using this monofilament begin on page 39 of this issue.

Vascular status. A high incidence of vascular disease in diabetes may contribute to the development of lower-- extremity ulceration. The lower extremities should be evaluated for signs of vascular insufficiency, including shiny skin, digital redness, dependent rubor, pallor, hair loss, delayed superficial venous plexus filling time, and subcutaneous fat atrophy. Palpable dorsalis pedis and/or posterior tibial pulses are not always indicative of adequate lower-extremity blood flow. Noninvasive vascular testing (eg, toe pressure, pulse volume recording, and transcutaneous oxygen tension) may assist in the evaluation of these patients if there are indications of vascular insufficiency.

Skin and nail status. It is important to note the overall condition of the skin and nails. Tissue discoloration may precede ulceration. Xerosis resulting from anhidrosis can cause cracking and fissures, offering a portal of entry for bacteria. Common nail disorders include onychomycosis (tinea unguium) and onychocryptosis (ingrown toenail).

Wound status. Examination of the ulcer should note the ulcer size, precise anatomic location, stage or grade of the ulcer, appearance of the ulcer base, description of the amount and type of exudate, periwound appearance, exploration of sinus tracts and fistulas, and documentation of bone exposure. Findings should be consistently documented to allow clinicians to track progress of ulcer healing. For information on the general characteristics of diabetic foot ulcers, see Ulcer Characteristics.

Musculoskeletal examination. Many plantar ulcers result from excessive pressure caused by an underlying bony deformity. Reactive callus forms as a result of altered skeletal biomechanics and atrophy of the underlying fat pad. Abnormalities and deformities put the patient at risk for ulceration. Predominant locations of ulcer occurrence are the submetatarsal areas, distal digits, and medial fifth digit.

Diabetic status. A patient who is not in glycemic control is at greater risk for delayed wound healing than is a patient whose blood glucose level is within an acceptable range. A glycosylated hemoglobin test will retrospectively reflect the efficacy of diabetic control (over the past 120 days).

Nutritional status. Malnutrition also is known to affect wound healing and may be measured by determining the albumin level and total lymphocyte count. A serum albumin level less than 3.5 grams/dL and a total lymphocyte count below 1500 cells/cubic mL are indicative of malnutrition. A total protein level greater than 6.2 grams/dL is considered by some clinicians to indicate an adequate nutritional status.

A form is included at the end of this article to assist in documenting the physical examination.

Management Options

Preulceration

Discoloration of the skin may be an indication of a preulcerous condition requiring preventive interventions. The following treatment is suggested:

Debride any callus that may be present. Sharp debridement should be done only by an experienced professional whose licensure and credentials permit him or her to perform this type of debridement.

Use accommodative and pressure-- reducing devices. This may include foam, felt, and custom-molded shoes or special walkers that are intended to off-load or protect potential ulcer sites.

Educate the patient. Instruct the patient on daily inspection of the feet, foot hygiene, selection of proper footwear, and the dangers of self-debridement and use of over-the-counter foot medications. Reinforce the need for continued medical care to prevent ulcer development. See Preventing Diabetic Foot Complications (page38) for more information.