Investigation of the Effect of Stent Length and Stent Location on the Deformation Characteristics of the Femoropopliteal Artery After Knee Flexion: A Finite Element Study

Abstract

There are a range of physiological movements such as knee and hip flexion that result in the deformation and loading of the femoropopliteal artery, characterised as axial compression, radial compression, bending and torsion [1]. The SFA is a prevalent location for peripheral arterial disease often requiring percutaneous transluminal angioplasty followed by stenting to restore vessel patency and uncompromised blood flow. Whilst stent placement provides the required scaffolding of the artery, opening up blockages and preventing elastic recoil of the vessel, it alters axial rigidity, changing the way in which the vessel deforms. With extreme stent rigidity and long stent lengths, severe bending can occur in the unstented vessel portions, proximal and distal to the stent. This has been observed in angiographic images of stented vessels that show unstented artery portions bending in an exaggerated manner adjacent to stented regions [2, 3]. It is postulated that due to knee flexion, deformation characteristics of the vessel are changed with extreme curvatures induced, initiating large stresses in the vessel tissue which may contribute to vascular injury, intimal hyperplasia and restenosis [2]. The goal of this work was to determine the effect of stent placement on deformation characteristics of the SFA after knee flexion using an anatomically accurate, three dimensional finite element model of the leg. Deformation characteristics (length change, curvature change and axial twist) that result from knee flexion movements of the stented vessel are quantified and linked with stress and strain levels within the artery for various cases of stent length and location within the femoropopliteal artery.