The development and evolution of artificial urethral sphincters.

This history and evolution of mechanical devices designed to achieve urinary continence are reviewed. The following devices were studies: Foley clamp, Kaufman prosthesis, Giori, Summers and Rosen sphincters, Gruneberger and Cleveland Clinic magnetic designs, Craggs sphincter and the AMS family of sphincters (AMS 721, AMS 761, AMS 742 (A, B, C), AMS 792, AMS 800). The design of active hydraulic devices is discussed in more detail. This review analyses the problems relating to the application of pressure and the presence of foreign material around the urethra. 'Volume set' devices are universally unsuccessful and detrimental for urethral integrity as opposed to 'pressure set' hydraulic sphincters (e.g. AMS 800). The implications for the design of artificial implants are discussed.