THE ANGIOSOMES OF THE FOREARM - ANATOMIC STUDY AND CLINICAL IMPLICATIONS

The angiosome concept was introduced in 1987 by Taylor and Palmer. The ir anatomic study correlated the blood supply to the skin from the nam ed segmental or distributing ''source'' arteries with their supply to the underlying muscles, tendons, nerves, and bones. Although this inve stigation encompassed the body, there were areas where the supply to i ndividual tissues was not examined in detail. The present study, there fore, examines one of these regions where certain Voids in our knowled ge still exist-the forearm. Ten upper limbs from fresh cadavers were s tudied over an 18-month period after perfusing each with a radiopaque lead oxide mixture. The arterial supply to the skin and the bones of t he forearm, together with that of a total of 200 muscles, was examined . The contribution to each was defined by dissection, by metal clip ta gging of vessels, by radiography, and by mapping the branches with col ored pins coded to match the respective source arteries. In the case o f the muscles, a subtraction technique was used whereby the bones of t he extremity were replaced with radiolucent balloons to obtain an unob scured picture of the forearm vasculature. Then the muscles were remov ed one by one from the muscle mass and x-rayed again. In this way, the angiosomes in the forearm, provided by the brachial, radial, ulnar, a nd interosseous arteries, were defined. Similarly, the contribution fr om each angiosome to the skin, to each muscle, and to the radius and t he ulna was identified and the territories were color-coded to match t hese source arteries. Results showed that in most cases the connection s between adjacent angiosomes occurred within tissues, not between the m. The skin, the bones, and most muscles received branches from the so urce arteries of at least two angiosomes, thus revealing one of the im portant anastomotic pathways by which the circulation is reconstituted in those cases where a source artery is interrupted by disease or tra uma. Several muscles, however, were supplied within one angiosome. Thi s helps explain the variable clinical pictures seen in cases where the circulation is interrupted, such as that which occurs in a Volkmann's ischemic contracture. Finally, this anatomic study provides further i nformation to help design various flaps from the forearm for local or free transfer. In the case of muscles, the supply to most from multipl e angiosomes allows for refinements whereby a portion only of a muscle can be used. Similarly, this anatomic information reveals the pathway by which the supply to remaining muscle groups is reconstituted when one of the source arteries is harvested with a skin flap, a muscle, or part thereof.