title: Measurement of radial and axial forces of biliary self-expandable metallic stents.
abstract: BACKGROUND
  Efforts to understand the properties of self-expandable metallic stents (SEMSs) through their mechanical properties have progressed. Among them, radial force (RF) is well known as an expanding force, but axial force (AF) has not been measured before. Correlations of these properties to clinical results are not well known.
  
  
  OBJECTIVE
  We measured RF and AF of 14 different SEMSs and discussed the results in terms of clinical implications.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Measurement of RF and AF of 14 different covered and uncovered SEMSs.
  
  
  METHODS
  RF was measured with an RF measurement machine manufactured by Machine Solution, and AF was measured with in-house equipment.
  
  
  RESULTS
  Measurements of RF in the process of expansion showed characteristic patterns closely related to the structures and materials of SEMSs. Results of AF measurement can be classified into 3 groups: high, medium, and low AF, depending on the type of SEMS. AF decreased with an increase of the length of stents. A plot of RF against AF revealed 3 distinguished RF/AF combinations and indicated the importance of understanding the properties by not only RF or AF individually but also by RF/AF combination.
  
  
  CONCLUSIONS
  In vitro study using measurement equipment.
  
  
  CONCLUSIONS
  It was demonstrated that a combination of RF and AF is more effective than RF or AF individually in understanding the clinical implications of SEMSs. More work is needed to correlate mechanical properties with clinical results by designing model experiments.
authors.affiliation: Department of Gastroenterology, Faculty of Medicine, University of Tokyo, Tokyo, Japan. isayama-tky@umin.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Isayama
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Nakai
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Toyokawa
authors.forename: Osamu
authors.initials: O
authors.lastname: Togawa
authors.forename: Chimyon
authors.initials: C
authors.lastname: Gon
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Ito
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yashima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yagioka
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kogure
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasaki
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Arizumi
authors.forename: Saburo
authors.initials: S
authors.lastname: Matsubara
authors.forename: Natsuyo
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Naoki
authors.initials: N
authors.lastname: Sasahira
authors.forename: Kenji
authors.initials: K
authors.lastname: Hirano
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsujino
authors.forename: Nobuo
authors.initials: N
authors.lastname: Toda
authors.forename: Minoru
authors.initials: M
authors.lastname: Tada
authors.forename: Takao
authors.initials: T
authors.lastname: Kawabe
authors.forename: Masao
authors.initials: M
authors.lastname: Omata
mesh_terms: D001652:Bile Ducts / Q000601:surgery*; D019245:Compressive Strength; D006801:Humans; D008670:Metals; D011474:Prosthesis Design; D015607:Stents; D013718:Tensile Strength
chemical_list: D008670:Metals