Endovascular therapy is currently considered the primary treatment modality for many patients with peripheral artery disease (PAD). Although the introduction of novel nitinol stents decreased restenosis rates compared to plain balloon angioplasty, restenosis still remains a significant problem in the peripheral arteries. In- stent restenosis, which occurs in up to 30% of the patients subsequent to bare nitinol stent placement, was reported to be associated with stent fractures and arterial wall damage. Stent failures are clearly related with the bending, torsion, and axial motion forces exerted on the femoropopliteal segment during hip and knee flexion.
To understand the causes of restenosis and improve stent designs, an accurate characterization of this mechanical environment is necessary. Therefore, we quantified the in vivo deformations of the popliteal artery during leg flexion in subjects with clinically relevant peripheral artery disease. Rotational angiography has been used to acquired the three-dimensional arterial anatomy with the leg straight and with a flexion of 70°/20° in the knee/hip joints. Results showed that the popliteal artery of patients with symptomatic PAD is exposed to significant deformations during flexion of the knee joint. The severity of calcification directly affects arterial curvature, but not axial strain or twisting angles. These clinical observations are complemented with finite element simulations to evaluate stenting procedures.