Comparing the mechanical properties of a self‐expandable metallic stent for colorectal obstruction: Proposed measurement method of axial force using a new measurement machine

Objectives Colorectal stenting is widely performed using self‐expandable metallic stents (SEMSs), but the mechanical properties have not been evaluated. Therefore, we conducted an in vitro study to evaluate the mechanical properties of colorectal SEMSs. Methods Eighteen individual types and sizes of uncovered SEMSs were evaluated for their mechanical properties. Radial force was measured using a measurement machine. Axial force (AF) was measured by two methods: a conventional manual method and a new method using a measurement machine. The correlation of these two methods was evaluated. We also proposed an “AF zero border” that was defined as the angle at which the torque force disappeared. Results Radial force versus diameter curves and AF versus angle curves were influenced by the structure and the size of each stent. There was excellent correlation of AFs measured by the new and conventional manual method (y = 21.434x, R = 0.881, P