The exact cause of venous ulcers is not certain, but they are thought to arise when venous valves that exist to prevent backflow of blood do not function properly, causing the pressure in veins to increase [REF].
Wounds of the distal lower extremities arising from causes not directly related to venous insufficiency (e.g., scratch, bite, burn, or surgical incision) may ultimately fail to heal if underlying (often undiagnosed) venous disease is not properly addressed.