title: Novel characteristics of traction force in biliary self-expandable metallic stents.
abstract: OBJECTIVE
  In recent years, knowledge concerning the mechanical properties of self-expandable metallic stents (SEMS) has increased. In a previous study, we defined traction force and traction momentum and reported that these characteristics are important for optimal stent deployment. However, traction force and traction momentum were represented as relative values and were not evaluated in various conditions. The purpose of the present study was to measure traction force in various situations assumed during SEMS placement.
  
  
  METHODS
  Traction force and traction momentum were measured in non-stricture, stricture, and angled stricture models using in-house equipment.
  
  
  RESULTS
  Stricture and angled stricture models had significantly higher traction force and traction momentum than those of the non-stricture model (stricture vs non-stricture: traction force, 7.2 N vs 1.4 N, P < 0.001; traction momentum, 237.8 Ns vs 62.3 Ns, P = 0.001; angled stricture vs non-stricture: traction force, 7.4 N vs 1.4 N, P < 0.001; traction momentum, 307.2 Ns vs 62.3 Ns, P < 0.001). Traction force was variable during SEMS placement and was categorized into five different stages, which were similar in both the stricture and angled stricture models.
  
  
  CONCLUSIONS
  We measured traction force and traction momentum under simulated clinical conditions and demonstrated that strictures and the angular positioning of the stent influenced the traction force. Clinicians should be aware of the transition of the traction force and should schedule X-ray imaging during SEMS placement.
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Hori
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Hayashi
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Itaru
authors.initials: I
authors.lastname: Naitoh
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Tesshin
authors.initials: T
authors.lastname: Ban
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Miyabe
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Hiromu
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nishi
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Umemura
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Fujita
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Natsume
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Akihisa
authors.initials: A
authors.lastname: Kato
authors.affiliation: Department of Community-Based Medical Education, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ohara
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Joh
mesh_terms: D001660:Biliary Tract Diseases / Q000601:surgery*; D006801:Humans; D055595:Mechanical Phenomena; D008962:Models, Theoretical; D011474:Prosthesis Design; D000069322:Self Expandable Metallic Stents / Q000592:standards*
keywords: mechanical property; self-expandable metallic stent; traction force; traction force transition; traction momentum