Flexions of the popliteal artery: dynamic angiography

Stenting of popliteal artery (PA) with self-expandable stents is a therapeutic option in selected patients with arterial disease. Fractures of these stents may occur, and they are thought to be related to development of hinge points (HPs) secondary to knee flexion. However, it remains obscure how movements of the knee affect the morphology of the PA and where HPs occur.

To describe the morphologic changes of the PA during knee flexion and their relationship with bone structures using dynamic angiography (DA).

All DA procedures performed in our institution between February 2000 and July 2003 were reviewed. Dynamic angiography consisted of a static phase (during which the knee was bent at 100 degrees) and a dynamic phase (during which the leg was passively extended to total extension following opacification of the PA).

Sixty-three PAs in 57 patients with arterial disease were evaluated. In 62 PAs (98.2%), presence of an HP was identified and the pre-HP and post-HP segments also were defined. HPs were never observed at the level of the knee joint line. We developed a geometric model to establish a relationship of proximity between a bone structure and the HP. The HP was the main and most acute angled curve observed during knee flexion. Accessory flexions (AFs) were observed when the knee was bent in 46 PAs (73%). Presence of AFs was associated with high blood pressure (p < 0.01).

We identified HPs of the PA as the main curve observed during knee flexion as well as a large number of AFs. DA appears to be a useful diagnostic tool for obtaining the most accurate morphologic information about the PA during knee flexion.