There are three main types of chronic wounds: venous ulcers, diabetic ulcers, and pressure ulcers.

Venous ulcers:
Venous ulcers usually occur in the legs, account for the majority of chronic wounds, and mostly affect the elderly. They are caused by improper function of tiny valves in the veins that normally prevent blood from flowing backward. The dysfunction of these valves impedes the normal circulation of blood in the legs, causing tissue damage and impaired wound healing.

Diabetic ulcers:
Diabetic patients are particularly susceptible to developing ulcers. People with advanced diabetes have a diminished perception of pain in the extremities due to nerve damage, and therefore may not initially notice small scratches or bruises on their legs and feet. Diabetes also impairs the immune system and damages capillaries. Repeated injury, compounded by impaired healing, can cause even the smallest cut or bruise to become dangerously infected.

Peripheral Arterial Disease:
Diabetics are also 2-4 times more likely than healthy individuals to have peripheral arterial disease (PAD), a term that covers an array of medical problems caused by obstruction of the large arteries in the arms or legs. A more severe form of PAD is critical limb ischemia (CLI), a leading cause of lower limb amputations. The Angiogenesis Foundation estimates that 1.4 million people in the United States have CLI, with an estimated 350,876 new cases diagnosed each year.¹ Smoking, high cholesterol, and high blood pressure are also significant risk factors for PAD and CLI.

Pressure ulcers:
Pressure ulcers comprise the third main type of chronic wounds. These typically occur in people who are bedridden or whose mobility is severely limited. Pressure ulcers are caused by a loss of blood circulation that occurs when pressure on the tissue is greater than the pressure in capillaries, thereby cutting off circulation. Parts of the body that are particularly susceptible to pressure ulcers include the heels, shoulder blades, and sacrum (the triangular bone at the base of the spine forming the posterior of the pelvis).