Angiosomes of the Leg: Anatomic Study and Clinical Implications

In 1987, Taylor and Palmer introduced the angiosome concept. This anatomical study defined the three-dimensional vascular territories supplied by source arteries and veins to each tissue layer between the skin and the bone. This report, however, was an overview investigation and did not study each region of the body in fine detail. In 1996, Inoue and Taylor studied the angiosomes of the forearm in much greater detail. They showed, among other findings, that the zone between the angiosomes, formed by reduced caliber (choke) vessels or similar caliber (true) anastomotic arteries, occurred usually within tissues, especially the muscles, not between them. This study focuses on the same region in the lower limb to draw a comparison and to fill certain voids in our knowledge--the leg. Twelve lower limbs from fresh cadavers were investigated over a 2-year period after perfusing each with a mixture containing radio-opaque lead oxide. The anatomy of the arterial supply to the skin, the muscles, and the periosteum of the bones of the leg was examined. The contribution to each tissue was defined by dissection, by metal clip tagging of vessels, by radiography, and by mapping the branches with colored pins, coded to match the respective source arteries. A subtraction technique was used to study the muscles whereby the bones of the limb were replaced with radiolucent balloons to obtain an unobscured picture of the vasculature of the leg. The muscles were then segregated one by one from the muscle mass and x-rayed again. Next, cross-section studies were made in two legs to complete the three-dimensional picture, tracing the branches from the source arteries to each layer. Finally, the contribution to each tissue from the popliteal, sural, anterior tibial, posterior tibial, and peroneal vessels were color coded to match these source arteries, thus defining the angiosomes of the leg. Results, as in the forearm, showed that in most cases the connections between adjacent angiosomes occurred within tissues, not between them. The skin, the bones, and most muscles received branches from two or more angiosomes, thus revealing one of the important anastomotic pathways through which the circulation is reconstituted when a source artery is interrupted by disease or trauma. Notably, however, the muscles of the anterior compartment of the leg were supplied from one angiosome. This finding, coupled with the anatomy of the rigid fascial compartments of the leg, helps explain the variable clinical pictures and syndromes seen in cases in which the circulation is compromised or interrupted. Finally, this anatomical study adds further information to help design or redesign flaps in the leg for local or free transfer. Similarly, the information reveals the pathways through which the supply to the remaining tissues is reconstituted when one of the source arteries is harvested with a free flap, especially when multiple tissues are included in the transplant.