AN IMPLANTABLE MECHANICAL URINARY SPHINCTER - A NEW NONHYDRAULIC DESIGN CONCEPT

Objectives. We present data concerning an artificial implantable mecha nical urinary sphincter that was designed to eliminate the inherent pr oblems of the current hydraulic artificial urinary sphincter (American Medical System [AMS] 800). Our goal was to design a sphincter that cr eates urethral compression similar to the AMS 800 but creates the forc e without the use of fluid, thereby eliminating as much as 50% of the reoperations seen with the AMS 800, which occur because of fluid-relat ed malfunctions. Methods. An implantable artificial mechanical sphinct er consisting of a compressive coil encompassed in a polytetrafluoroet hylene sheath was devised and tested in 6 live mongrel dogs to establi sh compressive force Versus bladder pressure data, so as to provide da ta to create a mechanical sphincter for use in humans. Results. A dire ct relationship between bladder leakage pressure and cable tension for ce was demonstrated in ail 6 experimental animals, thereby creating a mathematical equation that can be used by mechanical engineers to desi gn a mechanical sphincter for use in humans. Conclusions. This study d emonstrated that a mechanical urinary sphincter can be created that wi ll provide continence and eliminate the problems associated with the h ydraulic aspect of the AMS 800. In doing so, nearly 50% of the reopera tions seen with the current AMS 800 can be eliminated, thereby improvi ng the quality of life of patients for whom an artificial urinary sphi ncter is indicated. (C) 1998, Elsevier Science Inc. All rights reserve d.