How does untreated pad lead to the loss of a leg? make sure to mention the specific arteries of the leg.

Gangrene: Gangrene requiring amputation of part of the leg occurs when there is total loss of blood flow to tissue caused by blockage in a portion of a leg artery. The blockage may occur in small branches of the tibial artery, popliteal artery or higher up in the large femoral arteries or iliac arteries. The higher up in the leg that blockage occurs, the more extensive is the damage.

Poor circulation: Peripheral artery disease results from atherosclerosis of the blood vessels supplying your lower extremities. The main arteries of the legs are the internal and external iliacs and popliiteal arteries. The smaller and narrower blood vessels are occluded first.If you have plaque in your arteries which severely impedes blood flow the tissue can die ( gangrene) and eventually lead to amputation.