Since a significant number of patients do not have suitable autologous saphenous vein for femorodistal bypass, the search for alternative graft material continues. The most commonly used prosthetic material is Polytetrafluoroethylene, however because of the poor patency of these grafts in the below knee position, a variety of techniques have been tried to improve their patency. A series of studies utilizing venous cuffs at the distal anastomosis have showed improved patency of PTFE grafts. We have reviewed the biological basis for graft failure and the literature for possible mechanical explanations.