THE ACCURACY OF DUPLEX ULTRASONOGRAPHY IN THE PLANNING OF SKIN FLAPS IN THE LOWER-EXTREMITY

The septocutaneous perforators represent one of the major sources of t he blood supply to the skin of the lower extremity. Despite several we ll-described anatomic accounts, the location of lower leg septocutaneo us perforators, as they originate from each of the three main infrapop liteal vessels in the leg, remains inconsistent as a result of individ ual anatomic variations. With the aid of duplex ultrasonography (color Doppler imaging), preoperative: mapping and size determination of the se perforators can be provided. The skin paddle can then be designed t o lie exactly over these perforators, ensuring blood supply to the ski n paddle. The location and distribution of medial septocutaneous perfo rators in the leg, which originate from the posterior tibial artery, w ere mapped using anatomic dissections (29 lower extremities). These fi ndings were then compared with duplex ultrasonograhic data in 9 living volunteers (18 lower extremities). The medial septocutaneous perforat ors were chosen for this study because they course directly over the p osterior tibial artery, making their location difficult to assess with standard Doppler techniques. The hand-held Doppler is incapable of di stinguishing flow originating from the perforators versus the posterio r tibial artery. No Significant difference existed between cadaver and duplex distributions. ''Large'' perforator vessels (>1 mm outer diame ter) were evenly distributed with a central tendency at 140 to 150 mm from the medial malleolus. The distribution of ''small'' perforator ve ssels (<1 mm outer diameter) was skewed. Fifty percent were found with in 80 mm of the medial malleolus and the remainder spread proximally i n the leg. Accurate knowledge of underlying vessels, based on noninvas ive anatomic findings, will allow safer and more reliable design of fa sciocutaneous flaps. The results of our study indicate that duplex ult rasonography should be useful in imaging and locating vascular perfora tors preoperatively.