20: Ulcers

Ayman Grada, Tania Phillips

Abstract:

Ulcers are skin injuries that result in complete absence of the epidermis. They result from a diverse range of underlying diseases. Because they frequently reflect the presence of underlying disease states, accurate diagnosis is imperative. This chapter reviews cutaneous ulcers with an emphasis on diabetic ulcers, pressure ulcers, vasculitic ulcers, arterial ulcers, pyoderma gangrenosum, and surgical site infections.

Key terms:

diabetic ulcers

pressure ulcers

vasculitic ulcers

arterial ulcers

pyoderma gangrenosum

surgical site infections

Chapter outline

Diabetic Ulcers
Pressure Ulcers
Vasculitis Ulcers
Venous Ulcers
Pyoderma Gangrenosum
Surgical Site Wound Infection

Diabetic ulcers

Diabetic wounds are multifactorial in etiology. Patients with long-standing diabetes develop polyneuropathy, which creates sensory, motor, and proprioceptive abnormalities and can lead to insensate skin and foot deformities. Combined with vascular disease and immunosuppression, patients have a high risk for trauma, subsequent ulceration, and infection. Most diabetic foot ulcers (DFUs) result from peripheral neuropathy (60%–70%), peripheral vascular disease (15%–20%), or a combination of both (15%–20%). Approximately 2% to 3% of all patients with diabetes will develop a DFU in a given year, and 10% to 25% of all patients with diabetes will develop at least one DFU in their lifetime. Approximately 50% to 60% of patients with a DFU have clinical signs of infection at the time of hospital admission. DFU accounts for nearly two-thirds of all nontraumatic amputations performed in the United States.

Clinical features

Symptoms

• Sensory neuropathy results in the loss of protective sensation (as evidenced by an abnormal 10-point monofilament examination). Patients frequently complain of skin burning, numbness, itching, needle-like pain, and paresthesia.
• Autonomic neuropathy results in reduced sweating and dry, scaly feet.
• DFUs are often painless.

Location

• The majority of DFUs originate at sites of pressure, including plantar metatarsal phalangeal joint prominences and the plantar surface of the heel (Fig. 20.1). They can also originate within the toe web spaces.

Clinical findings

• Motor neuropathy leads to difficulty in activating certain extensor muscles, resulting in inadequate pressure distribution and altered foot anatomy, such as hammer toes, claw toes, or a high or flattened arch (Charcot foot).
• The wound often appears punched out with a thick rim of callus.
• Peripheral pulses may be diminished or absent if there is coexisting arterial disease.
• Patients with neuropathy may have altered sensation to light touch, pinpricks, or joint position sense.

Differential diagnosis

The differential includes nondiabetic neuropathic ulcers, arterial ulcers, pressure ulcers, calciphylaxis, venous ulcers, and drug-induced cutaneous necrosis.

Work-up

• Diagnosis is based mainly on history and physical examination. Location and physical characteristics are key.
• A patient with diabetes who has foot calluses should be checked for neuropathy (using nylon monofilament, testing vibration sense, and proprioception).
• Ulcer depth should be assessed by probing for bone with a metal instrument. If the ulcer can be probed to bone, there is a high correlation with osteomyelitis.
• There is a high risk for wound infection in patients with diabetes and classic signs can often be masked. Therefore there should be a lower threshold in putting patients with diabetes on antibiotics if infection is suspected.
• The ankle brachial index (ABI)/toe brachial index (TBI) should be calculated.

• Note that the ABI can be unreliable in DFU because of noncompressible (or partly compressible) arteries.

• If the ABI is high or arterial disease is suspected, the TBI should be measured in the vascular lab.
• Hemoglobin A1c (HbA1c) levels should also be tested.

• Good diabetic control is needed to facilitate healing.

Initial steps in management

• A comprehensive assessment and physical examination of both the patient and wound is critical.
• Tight control of blood glucose levels and lifestyle modifications is often necessary. It is also important to manage other contributing systemic factors, such as hypertension and peripheral arterial disease.

Infection control

Treatment of tinea pedis and onychomycosis will prevent the development of skin cracks and bacterial entry (which can lead to cellulitis). If present, treat concomitant cellulitis or osteomyelitis with the appropriate antibiotics.

Surgical debridement

Surgical (sharp) debridement at frequent intervals has been shown to heal neuropathic wounds more rapidly. Necrotic and callus tissue should be debrided to a healthy bleeding base. This allows for a more thorough examination of the wound and activation of platelets and allows the proliferative phase of healing to begin.

Avoiding repetitive trauma

Patients can avoid repetitive trauma by using mechanical off-loading and pressure relief techniques. These may include adhering to bed rest; using crutches, a walker, or a wheelchair; and wearing therapeutic shoes or sandals (matching the shoe gear to the anatomic alterations). Total contact casting can be a useful first step in managing Charcot foot. Foams and padding can also be used to off-load pressure.

Prevention

Patients should be tested regularly with a 10 g monofilament on the feet. Loss of this sensation increases the risk for undetected injuries, which can lead to amputations.

Prevention is important and involves daily foot inspections, meticulous hygiene, and properly fitting shoes. Advise smoking cessation if applicable because smoking increases the risk for ulcer formation.

Wound dressings are selected based on ulcer appearance and other wound characteristics (e.g., dry, exudative, infected). Ulcer beds should be kept clean and moist (not wet).

Advanced/adjunctive options

• In complicated or recalcitrant cases where there is no evidence of ulcer healing, a few different treatment modalities can be tried. These may include hyperbaric oxygen therapy, skin-equivalent dressings, negative-pressure dressings (e.g., vacuum-assisted closure or VAC dressings), or surgical interventions.

• In terms of skin-equivalent dressings, bilayered skin constructs (such as Apligraf) and bioabsorbable membrane with human fibroblasts (such as Dermagraft) are bioengineered products that act as delivery systems for growth factors and extracellular matrix. Both have been approved by the U.S. Food and Drug Administration (FDA) and are indicated for recalcitrant diabetic foot ulcers that have no exposed muscle, bone, or tendon; are not infected; and have had aggressive debridement.

• Surgical interventions should be made on an individual basis and may involve revascularization to restore arterial perfusion and reduce the risk for amputation; foot/joint revision; wound closure; or coverage by plastic surgery.

Warning signs/common pitfalls

• Good patient care should take a multiprofessional approach, involving primary care, endocrinology, podiatry, and orthopedic and vascular surgery specialists.
• The insensate foot is generally poorly understood by patients; therefore patient education and continuous reinforcement is crucial.
• Liberal moisturizers with emollients, such as unscented petroleum jelly, are recommended to prevent cracking and fissuring of the skin.
• Patients should not attempt to trim calluses or cut their nails on their own, especially if they have impaired vision.
• Patients should never walk barefoot.
• Patients should always check the insides of their shoes before putting them on. Many patients cannot detect a foreign body in their shoe if they have insensate feet.
• Patients should test water temperature with their elbow before taking a bath.
• Exposed bone generally indicates osteomyelitis. Ulcers can become deep, and underlying osteomyelitis should be considered when ulcers do not heal with off-loading therapies.
• Vascular imaging may be helpful, including duplex ultrasonography, computed tomography angiography, or magnetic resonance angiography. Vascular surgical intervention can salvage a limb in many cases.
• Imaging may be helpful, especially if there is a concern for osteomyelitis.
• ABI is unreliable in patients with diabetes and should not be used in these patients to exclude the presence of arterial diseases. ABI can often be falsely elevated because of vessel calcification. In these cases, toe brachial index is helpful because the small toe vessels do not become calcified.
• Biopsy should be done if there is a concern for malignancy.