title: An implantable mechanical urinary sphincter: a new nonhydraulic design concept.
abstract: OBJECTIVE
  We present data concerning an artificial implantable mechanical urinary sphincter that was designed to eliminate the inherent problems of the current hydraulic artificial urinary sphincter (American Medical System [AMS] 800). Our goal was to design a sphincter that creates urethral compression similar to the AMS 800 but creates the force without the use of fluid, thereby eliminating as much as 50% of the reoperations seen with the AMS 800, which occur because of fluid-related malfunctions.
  
  
  METHODS
  An implantable artificial mechanical sphincter consisting of a compressive coil encompassed in a polytetrafluoroethylene sheath was devised and tested in 6 live mongrel dogs to establish compressive force versus bladder pressure data, so as to provide data to create a mechanical sphincter for use in humans.
  
  
  RESULTS
  A direct relationship between bladder leakage pressure and cable tension force was demonstrated in all 6 experimental animals, thereby creating a mathematical equation that can be used by mechanical engineers to design a mechanical sphincter for use in humans.
  
  
  CONCLUSIONS
  This study demonstrated that a mechanical urinary sphincter can be created that will provide continence and eliminate the problems associated with the hydraulic aspect of the AMS 800. In doing so, nearly 50% of the reoperations seen with the current AMS 800 can be eliminated, thereby improving the quality of life of patients for whom an artificial urinary sphincter is indicated.
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Elliott
authors.forename: G W
authors.initials: GW
authors.lastname: Timm
authors.forename: D M
authors.initials: DM
authors.lastname: Barrett
mesh_terms: D000818:Animals; D004285:Dogs; D005260:Female; D008297:Male; D011474:Prosthesis Design; D016741:Urinary Sphincter, Artificial