PURPOSE To quantify the deformation behavior of the diseased femoropopliteal segment and assess the change to deformation behavior due to various stent placements. METHODS The length and curvature changes of 6 femoropopliteal segments (the right and left superficial femoral and popliteal arteries) from 3 cadavers were measured in 3-dimensional space based on rotational angiography image data in straight leg and flexed hip/knee (50°/90°) positions before and after placement of nitinol stents of varying type (EverFlex, Misago, and BioMimics 3D) and length (60, 100, and 200 mm) in different locations along the arteries. Three-dimensional centerline data were extracted for the measurements. RESULTS All 6 femoropopliteal cadaver segments displayed signs of peripheral artery disease. Hip/knee flexion resulted in vessel shortening and increases in the mean and maximum vessel curvatures in all cases. Location-specific results of the unstented arteries showed that magnitudes of vessel length and curvature change vary as a function of vessel length. The average shortening of the entire femoropopliteal segment due to flexion was observed at 10.7%±0.7%, which was reduced to 8.1%±0.9% after stent deployment. Average and maximum curvatures of the unstented segment increased due to flexion (average: 0.008±0.002 mm-1 to 0.019±0.006 mm-1, maximum: 0.030±0.009 mm-1 to 0.091±0.045 mm-1). After stent deployment, average and maximum curvatures of the flexed stented segments increased compared with the flexed unstented segments (average: 0.019±0.006 mm-1 to 0.022±0.004 mm-1, maximum: 0.091±0.045 mm-1 to 0.103±0.025 mm-1). The most flexurally stiff stent demonstrated the least ability to axially shorten during flexion of the leg at the knee joint. CONCLUSION The deformation characteristics of the femoropopliteal segment change in the presence of a stent, with the change to the deformation behavior dependent on stent type, stent length, location, flexibility, and intrinsic centerline curvature.
Deformation of the Femoropopliteal Segment: Effect of Stent Length, Location, Flexibility, and Curvature.