Dynamic Forces in the SFA and Popliteal Artery During Knee Flexion

T he superficial femoral artery (SFA) lies largely within the adductor canal, where it is surrounded by a double layer of fascia of the firm muscles of the thigh. After passing the adductor hiatus, the termination of the adductor canal, the SFA becomes known as the popliteal artery and enters the soft fatty tissue of the popliteal fossa. The SFA is hypothesized to undergo dramatic nonpulsatile deformations in the adductor canal, including axial compression and extension, radial compression, bending, and torsion. Because the SFA is largely untethered compared to the iliac and femoral arteries, which are tethered by the hypogastric arteries and the profunda femoris and the popliteal artery, which is tethered by the genicular arteries, the SFA is thought to be very susceptible to these deformations.1 Atherosclerosis commonly develops in the SFA. Scholten and coauthors found 72% of the femoropopliteal occlusions in their study at the level of the adductor canal hiatus (Figure 1).2 Wood and coauthors showed that the adductor canal is a region with low wall shear stress (WSS), which is associated with atherogenesis.3 Bypass surgery is the definitive solution for patients with atherosclerotic lesions of the SFA, but this invasive intervention is associated with long hospitalization and higher morbidity and mortality rates. Therefore, particularly in early-stage and short lesions, endovascular therapy is recommended in SFA disease cases. Recently introduced self-expanding nitinol stents have shown improved patency results for femoropopliteal revascularization;4-7 however, nitinol stent fractures in the SFA occur in 8% to 28% of cases and may cause complications, such as restenosis, pseudoaneurysm, perforation of the vessel, and embolism in the stent.8-12 Longer stents, and especially multiple overlapping stents, which are often required by the long diffuse atherosclerotic lesions of the SFA, are associated with a higher stent fracture rate.8 Furthermore, Iida et al proved that nitinol stent fracture was more frequent in patients who walked more than Dynamic Forces in the SFA and Popliteal Artery During Knee Flexion