Ulcers are skin wounds that are slow to heal and are classified in four stages, according to which layers of skin are broken through.
Those stages and their characteristics are:
- Stage 1 – characterized by a reddening over bony areas. The redness on the skin does not go away when pressure is relieved.
- Stage 2 – characterized by blisters, peeling or cracked skin. There is a partial thickness skin loss involving the top two layers of the skin.
- Stage 3 – characterized by broken skin and sometimes bloody drainage. There is a full thickness skin loss involving subcutaneous tissue (the tissue between the skin and the muscle.)
- Stage 4 – characterized by breaks in the skin involving skin, muscle, tendon and bone and are often associated with a bone infection called osteomyelitis.
People get foot ulcers for four major reasons:
- Neuropathic – loss of sensation in the feet.
- Arterial – due to poor blood flow to the lower extremity. This type of ulcer can be very painful and is usually found on the tips of toes, lower legs, ankle, heel and top of the foot. It can very easily become infected.
- Venous – This type of ulcer is due to compromised veins. It is commonly seen around the inside of the ankle and are slow to heal.
- Decubitus – This type of ulcer is caused by excessive prolonged pressure on one area of the foot. The most common place to see this type of ulcer is in a person confined to bed and they occur on the backs of the heels.
Foot ulcers are typically found in diabetics.
As prominent metatarsal heads on the plantar or bottom of the foot are subjected to increased pressure, the skin begins to become callused. The callused skin can be subjected to shear forces that cause a separation between the layers of the skin, which fill with fluid and become contaminated and infected. The result is a foot ulcer.
"Contact casts" are sometimes applied to the diabetic foot to relieve the bony prominent areas of pressure, allowing ulcers are to heal.