A novel unembalmed human cadaveric limb model for assessing conformational changes in self-expanding nitinol stents in the popliteal artery

To develop an unembalmed human cadaveric lower limb model as a more realistic environment for testing self-expanding nitinol stents. We studied conformational changes and strain induced by knee flexion in nitinol stents deployed in the popliteal artery (PA).

One Lifestent® each was deployed into one limb of four cadavers (control group), while the contralateral leg received a different stent (Absolute®, Protégé Everflex®, Supera®, and Gore Viabahn®). The limbs were mounted on a quasi-static knee rig (QKR) and X-ray imaging was performed at pre-defined knee flexion angles. A least-squares solution to the equation of a circle was used to assess radius of curvature at flexion points (FP), and nominal strain was calculated for each stented artery.

There were differences but also some similarities in conformational changes seen in the various stents. Knee flexion produced at least two FP in all stents. The mean radius of curvature decreased with increasing degrees of flexion but more so in distal (main) than proximal (accessory) FP (22 mm vs. 11 mm) in all stents. Supera® stent had the greatest relative radii of curvatures, and Absolute® stent had the highest strain value in comparison to the contralateral PA as the control group.

This study describes a novel human cadaveric limb model for testing self-expanding nitinol stents implanted in the PA. Several parameters of conformational change in the stented PA such as FP formation, FP translocation and strain induced by axial compression were described. These may be useful for developing new stents for the PA location.