Mechanical comparative analysis of stents for colorectal obstruction

Abstract

The goal of this work is the mechanical comparison of different types of stents for colorectal obstructions. We consider self-expanding and balloon-expanding stents made of two different materials such as stainless steel and shape memory NiTi alloy. The mechanical parameters are expansion rate, shortening, radial compression resistance, longitudinal and perimetral adaptability, and buckling resistance. This analysis results in a better understanding of global mechanical behavior and also allows better design and device selection for colonic lesions.

Study of the Behavior of a Bell-Shaped Colonic Self-Expandable NiTi Stent under Peristaltic Movements

“…The stent geometry analyzed in this paper corresponds to the prototype proposed by the same authors in [11, 14]. It is a self-expanding stent with diamond cell type and bell-shaped profile with longitudinal variable radial strength.…”

“…A laser-cutting technique was used to obtain a strut width of 400  μ m and variable strut length from 6.15 mm to 16 mm (Figure 1(a)). The final bell-shaped stent was obtained by plastic deformation process at cryogenic conditions and posterior thermal annealing treatment [11, 14] (Figure 1(b)). A more detailed explanation about the whole process including thermal treatments can be found in [14] for a preliminary design.…”

“…Recent technologic advances have seen the advent of stents that expand to greater diameters and have increased flexibility, facilitating placement across tortuous paths and more angulated strictures, like those encountered in the colon [11–13]. Stents must be capable of exerting a radial pressure on the bowel wall stenosed, allowing bolus transit, while keeping good flexibility to adapt well to the walls and prevent migration or obstruction.…”

Evidence-Based Recommendations on Colorectal Stenting: A Report from the Stent Study Group of the Korean Society of Gastrointestinal Endoscopy

“…These features represent factors to consider when selecting the stent model; however, there is not enough evidence to demonstrate whether these factors could affect the clinical outcomes of patients 44-55…”

Finite element simulation. Applications in Orthopaedics and Traumatology

“…The use of materials with shape memory and superelastic behaviour like NiTi for the manufacture of orthopedic splints is a possibility with great expectations for the future. The experience of the authors in the design of other devices based on the NiTi alloy Lahoz et al, 2002;Domingo et al, 2005;Domingo et al, 2006), makes it possible to carry out the proposed design of a finger splint for the treatment of the contracture in flexion of the PIP joint. About the material, NiTi is an equiatomic alloy of nickel and titanium (commercially known as Nitinol), discovered in the U.S.…”