Venous bypass drainage of the small saphenous vein in the neurovascular pedicle of the sural flap:Anatomical study and clinical implications

Background: Little is known about the necessary dimensions of the neurovascular pedicle of the sural flap for inclusion of the concomitant bypass veins of the small saphenous vein to secure sufficient retrograde venous flow. Therefore, the authors evaluated the anatomical basis for venous outflow of the sural flap and were able to give recommendations as to the necessary pedicle width for the flap to be transferred safely.Methods: The collateral bypass pathway of the small saphenous vein was studied in five formalin-preserved cadaver legs. The authors evaluated the usefulness of duplex sonography to visualize the venous collateral system of the small saphenous vein in five legs of healthy volunteers.Results: The pedicle width necessary to bypass the small saphenous vein ranged from 1.4 to 3.1 cm in the human cadavers and 0.09 to 1.5 cm in the duplex group. In both groups, only one side, medial or lateral to the small saphenous vein, was responsible for a total proximal-to-distal bypass. The opposite side partly bypassed the vein. Ultrasonography alone without Doppler was sufficient to visualize this variable suprafascial venous network.Conclusion: Preoperative evaluation of the venous system through duplex sonography is essential to localize on which side the bypass veins are present, making it possible to decrease the width of the pedicle without interfering with the reliability of the sural flap.