Which is the most common material used for grafting below inguinal aeries?

For blockage fuher down the leg either a femoral popliteal or femoral distal procedure may be performed. Long saphenous vein is the graft of choice which may be used with its valves destroyed by a special valve cutting instrument or reversed so that the valves do not interfere with the bold flow. Ref: Schwaz's Principles of Surgery, 9th Edition, Chapter 23; Surgical Talk: Revision in Surgery By Andrew Goldberg, Page 238; Mastery of Vascular and Endovascular Surgery By Gerald B. Zelenock, Page 417