Venous ulcers are sores that develop after veins in the legs have  been damaged. These ulcers penetrate deep into the skin. Venous ulcers affect  approximately 1% of the worlds population.  Venous ulcers have a high  prevalence and are more common in women than in men and are the most frequent  causes of lower extremity ulcers. Approximately 70 percent of all leg ulcers are venous ulcers.

Venous ulcers are  usually located over the medial malleolus (gaiter area), and recurrence at the  same location is common. The borders of the ulcers are generally irregular,  flat, or slightly steep. Risk factors for development of these ulcers include  a history of leg injury, obesity, phlebitis, a family history of varicose  veins, types of employment or activities that require standing or sitting for  long periods, deep venous thrombosis, and previous varicose vein surgery. 

Symptoms of lower extremity venous ulcers include swelling and  aching of the legs, often late in the day, which may improve with elevation of  the limbs. Pain is a common complaint. Associated signs and symptoms may include dependent edema, varicose veins, a reddish-brown color, and purpura  caused by erythrocyte extravasation with subsequent deposition of hemosiderin.  Eczematous changes with redness, scaling, and pruritus (also known as venous  dermatitis) are common and may be caused or worsened by topical liquid  medications.

Characteristics of Venous ulcers:

• Located below the knee,  most often on the inner part of  the ankles. 

• Relatively painless  unless infected. 

• The borders of the ulcer appear as though they have been ‘punched out’

• Associated with aching,  swollen lower legs that feel more  comfortable when elevated.  

• Surrounded by mottled  brown or black staining and/or dry,  itchy and reddened  skin.

Most of venous leg  ulcers occur because the valves connecting the  superficial and deep  veins are not functioning properly. Superficial and deep vein systems are  connected to  each other by veins that have one-way valves.  These  valves normally  ensure that blood flows from the superficial veins to  the deep system. Failure of these valves causes blood to flow from  the  deep veins back out to the superficial ones - a major cause of varicose   veins. When you walk or exercise, the calf  muscles push venous  blood back to the heart. 

Venous insufficiency refers to  improper  functioning of the one-way valves in the veins. Veins drain  blood from the  feet and lower legs uphill to the heart. Two mechanisms  assist this uphill  flow, the calf muscle pump which pushes blood towards  the heart during  exercise, and the one-way valves which prevent the flow  of blood back  downhill. Faulty valves and impaired calf pumping action  result in pooling of  blood around the lower part of the leg to just  below the ankle. The increased  venous pressure causes fibrin deposits  around the capillaries, which then act  as a barrier to the flow of  oxygen and nutrients to muscle and skin tissue.  The death of tissue  cells leads to the ulceration.