Leg Reconstruction: Distal Third (Free Flaps)

Clinical Presentation

A 54-year-old White male unfortunately developed a wound dehiscence in the left distal third of his leg after an open reduction and internal fixation for a distal tibial fracture. The distal tibial wound measured 12 × 6 cm with the exposed fracture site, reconstruction plate, and antibiotic beads. The wound was located quite distally and extended to the ankle ( Fig. 46.1 ). Clearly, there was no reliable local option for soft tissue reconstruction of the wound. The plastic surgery service was consulted for a free tissue transfer as a first option for soft tissue reconstruction. The preoperative angiogram showed some atherosclerotic disease of the arteries in the left leg.

Operative Plan and Special Considerations

For this relatively large soft tissue wound in the distal third of the leg extending to the ankle, the primary soft tissue reconstructive option would be a free tissue transfer because there was no reliable local option available to meet the reconstructive need in this case. As most reconstructive plastic surgeons know more and feel comfortable with the anterolateral thigh (ALT) perforator flap, it could be selected to provide a good and reliable soft tissue coverage for this distal tibial open fracture wound. The flap has a long pedicle and can provide a relatively large amount of fasciocutaneous tissue for reliable soft tissue coverage of the wound. As far as selection of recipient vessels for microvascular anastomoses, it has been this author’s preference to select the anterior tibial vessels, if possible, for an end-to-end microvascular anastomosis. In this way, it would be relatively easy to perform microvascular anastomosis with potentially improved patency rate so that a free tissue transfer to the lower extremity might be less complicated. In addition, a preoperative duplex scan is routinely performed to determine which side of the thigh should be selected as a donor site based on the size and blood flow of the perforator identified as well as the amount of intramuscular perforator dissection required.

Operative Procedures

Under general anesthesia with the patient in the supine position, the duplex scan was performed first to identify which side would be better for the ALT perforator free flap donor site. Based on duplex scan findings, there was no obvious perforator on the left side. However, on the right side, there was a single good perforator that measured 1.5 mm in diameter and was about 1.5 cm deep. Anticipated intramuscular dissection was less extensive. Therefore, the intraoperative decision was made to harvest the right ALT perforator flap ( Fig. 46.2 ).

The procedure started by debriding the left distal tibial wound. All colonized tissues were removed. The skin edge was freshened with a blade and the wound was irrigated with Pulsavac. The anterior tibial vessels were exposed as the recipient vessels. The skin incision was extended more laterally and parallel to the lateral tibia. The anterior tibial vessels were identified between the peroneus and anterior tibialis muscles. The anterior tibial artery appeared to be somewhat calcified. After retracting the deep peroneal nerve, both artery and vein were identified and were dissected free. Each vessel was wrapped with a vessel loop.

A 15 × 7 cm skin paddle was marked based on location of the perforator in the right anterolateral thigh. The skin incision was made around the skin paddle through the deep fascia down to the muscle. The subfascial dissection was performed to explore the perforator. During dissection, one major perforator and two small perforators were identified ( Fig. 46.3 ). The space between the rectus femoris and vastus lateralis muscles was opened. The large perforator was followed and gradually dissected free. It traveled through the vastus lateralis muscle and jointed to the descending branch of the lateral circumflex femoral vessels. The vessels were divided distal to the perforator/descending branch junction. The dissection followed the descending branch in a retrograde fashion until it reached the profunda. The pedicle was then divided off the profunda vessel ( Fig. 46.4 ).

The flap was prepared under loupe magnification. Both artery and vein were dissected free from each other. The arterial pedicle was flushed with heparinized saline solution. After that, the pedicle of the flap was ready for microvascular anastomoses. The flap was first inset into the defect and secured with towel clips. The anterior tibial vein was divided distally with hemoclips. The proximal part of it was prepared under the microscope. The anterior tibial artery was also divided distally with hemoclips and further dissection was done to remove all the adventitious tissues under the microscope. The pedicle to the anterior tibial artery was anastomosed with interrupted end-to-end 8-0 nylon sutures. The pedicle to the anterior tibial vein was anastomosed with a 2-mm coupler device in an end-to-end fashion. After all clamps had been removed, the flap appeared to have good arterial inflow and venous outflow.

The flap was inset into the distal leg wound and approximated with adjacent skin with interrupted 3-0 Monocryl sutures in a half-buried horizontal mattress fashion. Prior to the flap inset, a drain was placed under the flap but was kept away from the pedicle vessels. The proximal leg incision was approximated with skin staples ( Fig. 46.5 ).

The flap donor site of the right thigh was closed last. A small portion of divided muscle was approximated with 3-0 Vicryl suture in a figure-of-eight fashion. The deep dermal closure was done with interrupted 2-0 PDS sutures. The skin was closed with 3-0 Monocryl sutures in a running subcuticular fashion.

Follow-Up Results

The patient did well postoperatively without any complications related to the free ALT flap transfer. He was discharged from hospital on postoperative day 10 once he tolerated flap dangling. The drain was removed during subsequent follow-up visits. The reconstruction site over the left distal third of the leg healed well ( Fig. 46.6 ).

Final Outcome

The left distal third of the leg wound after free ALT flap reconstruction healed well with good contour and minimal scarring. The distal tibial fracture site also healed well. No flap debulking procedure was needed. The patient has resumed his normal activities and is being routinely followed by the orthopedic trauma service.

Pearls for Success

A free ALT perforator flap can be a valid reconstructive option as long as the surgeon feels comfortable to perform a perforator flap surgery. The flap is large enough and can be harvested as a fasciocutaneous or cutaneous flap to provide reliable soft tissue coverage in the distal third of the leg. However, the ALT flap dissection can be challenging if the patient is obese and the flap may remain bulky after it heals in the recipient site. Thus, compared with a free muscle flap, a subsequent debulking procedure may be necessary to improve the contour in the distal leg. It has been the author’s preference to perform a preoperative duplex scan routinely to determine the best and easiest site as an ALT flap donor site. Such information is critical because the size, blood flow, and location of a perforator as well as the potential amount of intramuscular dissection for the perforator can be determined. This has made the ALT perforator dissection more predictable and less time-consuming. In addition, because an end-to-end microvascular anastomosis would be easier than an end-to-side anastomosis, the author routinely selects the anterior tibial vessels, if possible, as the recipient vessels for a less complicated microvascular free tissue transfer in the distal leg. After 1 year, flap debulking procedure may be necessary in certain patients to improve leg contour. It can be performed via liposuction followed by a direct excision of excess flap tissue.