The impact of knee joint flexion on infrainguinal vascular grafts: an angiographic study.

Objectives: To characterise the morphologic behaviour of infrainguinal vascular grafts during flexion of the knee.
Design: A prospective angiographic study.
Materials and Methods: In 64 infrainguinal bypass grafts, intravenous digital subtraction angiography was performed within the first postoperative week. Frontal and lateral projection angiograms with the knee joint extended and with a 80-90 degrees flexion were taken. The distal anastomosis of the bypass was performed below-knee in 49 cases (18 in situ veins, 8 reversed veins with an anatomic course, 2 reversed veins with an extra-anatomic course, 4 composite grafts, 15 synthetic grafts with an anatomic course (14 polytetrafluoroethylene (ePTFE), 1 polyurethane), and two synthetic grafts with an extra-anatomic course. Fifteen ePTFE prostheses were implanted in the above-knee position.
Results: Out of 64 cases a total of 16 grafts showed stenotic kinking during flexion: two of the 18 in situ vein grafts, four of the 12 reversed vein grafts implanted with an anatomic course, one of the two reversed vein grafts implanted in an extra-anatomic site, eight of the 15 synthetic grafts crossing the knee, 0 of the two extra-anatomic ePTFE grafts, and one of the 15 cases of above-knee femoropopliteal ePTFE grafts.
Conclusions: Stenotic kinking due to knee flexion can affect all kinds of bypass grafts including vein grafts placed anatomically and above-knee prostheses.