title: Reliability of cobalt-chromium alloy aneurysm clips after long-term implantations in patients with cerebral aneurysms.
abstract: OBJECTIVE
  Aneurysm clip reliability after long-term implantation in vivo has not been examined. In this study the authors evaluated the mechanical properties and surface elemental composition of Co-Cr alloy aneurysm clips implanted for more than 10 years in patients with cerebral aneurysms.
  
  
  METHODS
  Five aneurysm clips implanted for ruptured or unruptured intracranial aneurysms were retrieved and examined. New aneurysm clips were applied to the regrown aneurysms. The implantation period ranged from 11 to 20 years. Four new and unused aneurysm clips were also examined as controls. The mechanical properties of the clips were tested by measuring their closing force and bending strength. The surface elemental composition of the aneurysm clips was evaluated using x-ray photoelectron spectroscopy. The closing force of the retrieved clips exceeded the minimum force requirement at the time of manufacture. The bending strength was similar between the retrieved and control clips. Chromium oxide was the predominant constituent on the surface of all clips, and its concentration on the retrieved clips was higher than that on the control clips.
  
  
  CONCLUSIONS
  Data in the present study demonstrated that Co-Cr alloy aneurysm clips retain their mechanical properties in vivo for a long time, which indicates the reliability of these clips.
authors.affiliation: Department of Neurosurgery, Iwate Medical University, Morioka, Tokyo, Japan. ootawara-nsu@umin.ac.jp
authors.forename: Yasunari
authors.initials: Y
authors.lastname: Otawara
authors.forename: Miguel M
authors.initials: MM
authors.lastname: Endo
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kubo
authors.forename: Akira
authors.initials: A
authors.lastname: Ogawa
authors.forename: Kouichi
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000368:Aged; D002858:Chromium Alloys; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D006488:Hemostasis, Surgical / Q000295:instrumentation*; D006801:Humans; D002532:Intracranial Aneurysm / Q000601:surgery*; D008875:Middle Aged; D018583:Pliability; D013499:Surface Properties; D013525:Surgical Instruments; D013997:Time Factors
chemical_list: D002858:Chromium Alloys