Anterograde Intra-Arterial Urokinase Injection for Salvaging Fibular Free Flap
A 57-year-old male patient came to our attention for squamous cell carcinoma on his mouth floor with cervical and mandibular metastases. Wide glossectomy with intergonial mandibular ostectomy, and sequential reconstruction using fibular osteomyocutaneous free flap were planned. Initially, extended radical neck dissection was performed by head and neck surgeons. When the patient's tongue and mandible were completely exposed, severe dysmorphism and adhesion were observed in the surrounding soft tissue ().\nThe left fibular osteomyocutaneous free flap was elevated, which included the part of the fibular bone for mandibular reconstruction and a skin paddle measuring 8 cm×18 cm for reconstructing the floor of the mouth (). Three osteoseptocutaneous perforators, which were identified by Doppler preoperatively, supplying the skin paddle and the lateral part of the soleus muscle, were included in the elevated flap. Before the fibular free flap was transferred, an ostectomy of the fibular bone to the neo-mandible was carried out using a reciprocating saw and reconstruction plate (). The peroneal artery, with a diameter of 1.5 mm, was anastomosed in an end-to-end fashion to the well-matched right lingual artery. The warm ischemic time from flap division to initial arteriorrhaphy was 1 hour. After the arteriorrhaphy, the flap was pale, and neither color improvement nor venous return was observed after the completion of the anastomosis. A localized exploration of the anastomoses was initially performed, showing that the anastomotic junction was patent. Although a topical application of papaverine and lidocaine was done, the blood supply was not recovered. Warm saline irrigation for more than 30 minutes was also useless. To seek a solution, an arterial re-anastomosis was performed, followed by repeated applications of these anti-spasmodic agents, which still gave a negative result. Assessment of vessel patency by Doppler and a milking test was performed, and the arterial anastomotic junction was carefully observed. Thrombectomy and systemic heparin administration were not performed because simple clot or small amounts of clot were absolutely not encountered by the milking test. Although the pedicle had sufficient arterial filling, the flap was still pale with no recovery of venous return within the surgical field. We confirmed there was no technical error. As the arterial anastomosis was definitely patent, microvascular thromboses of the donor vessels under nonvisible area were clinically suspected (). As the ischemic time was becoming prolonged, a subjective test such as intraoperative angiography could not be carried out. After ruling out many possible causes of flap ischemia, the decision was made to use a thrombolytic agent as the last resort.\nTwo stitches at the arterial anastomotic site were released, and a bolus of 100,000 units of urokinase was infused once anterogradely through a 26-gauge angiocatheter. Within one minute after the application of urokinase, the arterial flow and venous return were restored. Improvement of the flap's color was noted and the urokinase solution gushed out through the flap vena comitans (). Arterial blood reperfusion was performed for over 2 hours. Finally, venorrhaphy was performed with a peroneal vein and right thyroidal vein. There were no further problems nor systemic effects of the thrombolysis and no other treatment was required. The flap survived with a follow-up of 11 months (). We have concluded that vibrating injuries of the reciprocating saw during flap fabrication and insetting might have been the cause of the microvascular thromboses.