FREE FILLET LEG FLAP

Templeton KJ, Toby EB (University of Kansas Medical Center, Kansas City, Kansas, 66160).

Occasionally, large sarcomas are resectable only with an amputation. When local soft tissues are extensively involved with a tumor of this magnitude, the use of standard flap closure may be precluded, and other techniques, such as free tissue transfer, are required. Reconstruction of such a soft tissue defect after hemipelvectomy may be accomplished with a free fillet leg flap.

Case: A 73-year-old woman presented with a pathologic fracture through a cartilagenous lesion, arising in the proximal femur. Biopsy was consistent with chondrosarcoma. MRI demonstrated extensive soft tissue involvement of the neurovascular bundle, hip adductors, abductors, and quadriceps. It was felt that due to extensive bone and soft tissue involvement, a wide margin could not be obtained while retaining a functional limb. Further, none of the standard local flaps would be available. Therefore, a hemipelvectomy with free leg flap was planned. A posterior approach was made to the popliteal fossa, and the popliteal vessels were dissected free before initiating the hemipelvectomy, to decrease the warm ischemia time of the flap. Upon conclusion of the dissection, the hemipelvectomy was completed with the last maneuver being ligation of the external iliac vessels. A flap was then created by removing the tibia and its periosteum. The fibula was left intact to decrease the total operative time. The fillet flap consisted of the entire soft tissue of the lower extremity including skin as well as muscles from the anterior, posterior, and lateral compartments. End-to-end anastomoses were performed of the external iliac to the popliteal vessels. The fibula was positioned to provide support to the pelvic contents.

Rarely, all local soft tissues, or the vessels that supply it, are unavailable for reconstruction of a hemipelvectomy defect. The free fillet leg flap provides an option for coverage. Unlike other free tissue transfers, this flap has no donor site morbidity since it is part of the amputated specimen. Compared to previous reports, the technique described here modifies this procedure to address concerns with warm ischemia time of the flap as well as total operative time. First, with the exception of the initial dissection of the popliteal vessels, there is no added time factor involved with this flap because the majority of the dissection is done on the back table while the soft tissue at the resection site is addressed.

Secondly, retaining the fibula makes for an easier and more rapid dissection in the lower leg. Since there is considerable vascularity emanating from the peroneal artery, which is in close proximity to the fibula, retaining the fibula also avoids damage to the vascularity of the flap, allowing for rapid healing and less potential for wound necrosis. We also found the retaining the fibula provided some structural support to the flap, avoiding redundant, sagging soft tissue.