Foot Symptoms Caused by Systemic Disorders

Systemic disorders can cause foot symptoms (see Table 56-4). Ischemic disorders and neuropathy, particularly if related to diabetes, increase the risk of developing life- and limb-threatening foot infections. Various arthritides, including RA, osteoarthritis, and crystal-induced arthritides, are common causes of foot pain and foot deformities in the elderly.

Peripheral arterial disease: Peripheral arterial disease commonly affects the legs and feet. Symptoms include exertional pain (claudication), edema, skin color changes, coldness, burning, numbness, hair loss, and ulcers. Nail changes, especially thickening and onychomycosis, occur as peripheral arterial disease advances. Poor circulation diminishes the ability to combat infection, and even the slightest cut or bruise may result in ulcers or gangrene. Tobacco use should be minimized, and other risk factors should be controlled. Vascular surgery (eg, arterial bypass procedures) may decrease risk of complications.

Diabetes Mellitus: Diabetes mellitus tends to cause neuropathy as well as ischemia. Consequently, patients have symptoms such as paresthesias, motor weakness, numbness, burning, and cramping, as well as symptoms of ischemia. Skin may be dry and scaly. Diabetes affects small blood vessels, impairing healing and increasing risk of infection.

Patients are prone to ulcers. Using an acidic OTC corn remedy may cause skin sloughing and soft-tissue destruction and may precipitate both neurotrophic and vascular ulceration. Patients with decreased plantar sensation to pinprick are at highest risk of ulcers, especially on the weight-bearing surfaces of the foot. Such ulcers are usually painless, and patients may not be aware of them. Any foot ulcer may lead to infection, osteomyelitis, and gangrene.

Closely controlling plasma glucose and controlling risk factors for peripheral arterial disease may help prevent ulcers. Shoes should be leather and lightweight and have a wide toe box, a soft rocker-bottom sole, a padded tongue, and an Achilles pad. Calluses should be debrided. Patients at highest risk of ulcers require frequent evaluation by a podiatrist or physician (ie, every 6 mo for patients with sensory neuropathy, every 3 mo for patients with sensory neuropathy plus peripheral arterial disease, every 1 to 3 mo for patients with a previous foot ulcer). Patients with ulcers require daily wound care, custom-made orthoses, and sometimes casting or patellar-tendon-bearing bracing. Vascular or wound surgery may also be necessary.

RA: RA may cause progressive stiffening of the joints, which may lead to deformity and ankylosis. Periods of rest from weight bearing are essential. Shoes must be modified to accommodate painful plantar areas. A custom-made orthopedic shoe is particularly helpful. Local injection of a corticosteroid helps alleviate pain in foot joints, as do oral NSAIDs and analgesics. Surgery should be considered when conservative therapy is ineffective.

This topic was last updated May 2006.