Development of urethral occlusive techniques for restoration of urinary continence.

Three models of an artificial sphincter for treatment of urinary incontinence are described. Each of the models shares the two basic features of a cuff that encircles the urethra and a totally implantable hydraulic system for volitionally inflating the cuff to control the flow of urine. The models differ in the means by which pressure in the cuff is maintained below safe operating limits. In one model, pressure is regulated by a pressure-relief valve. This model has a clinical success rate of 66 percent over 5 years. The success rate has been increased by improvements in mechanical design, surgical technique, and patient selection. In another model, cuff pressure is regulated by means of a balloon which inflates at constant pressure as fluid is pumped into the balloon and cuff simultaneously to occlude the urethra. In the third model, pressure is also controlled by a balloon. To void, fluid is pumped from the cuff into the balloon. It then automatically flows back to the cuff through a fluid resistance to reestablish continence. Clinical trials of the balloon-regulated models are currently in progress.