Lower extremity ulcers are wounds or open sores on the legs or feet that do not heal or that keep recurring. These are usually classified as venous, arterial, or diabetic ulcers, depending on their cause. For instance, venous ulcers develop due to damage to veins that prevents effective flow of blood out of the leg. In contrast, arterial ulcers develop due to poor blood flow into the leg, primarily resulting from hardening of the arteries. Standard therapy depends on the type of ulcer being treated and often includes wound cleaning and compressive dressings for venous ulcers, surgical restoration of blood flow for arterial ulcers, and pressure-relieving shoes for diabetic ulcers. In all cases, appropriate wound dressings are used to guard against infection and to maintain a moist environment that facilitates wound healing.