Chronic wounds are wounds that do not heal in an orderly set of stages and in a predictable amount of time the way most wounds do; they persist for weeks, months, or years. Chronic wounds often occur in people with conditions such as diabetes, poor circulation, or an immune system disorder. They can also be caused by pressure, friction, or trauma. Common types of chronic wounds include pressure ulcers, venous ulcers, and diabetic foot ulcers.