Three areas in urology currently rely upon the use of prostheses: artificial urinary sphincter for urinary incontinence, penile prosthesis for erectile dysfunction, and testicular prosthesis for congenital or acquired absent testis.
Artificial urinary sphincter
Normally, the sphincter is in the closed state: the cuff is filled with contrast/saline, compressing the urethra to ensure continence. For voiding, the cuff is opened temporarily, causing the cuff fluid to flow out into the pressure-regulating balloon. While the patient voids, fluid spontaneously returns to the cuff through a delayed-fill resistor until the pressure within the regulating balloon and cuff equalizes, closing the sphincter. The balloon regulates pressures within the cuff during periods of increased abdominal and bladder pressure, thus limiting the incidence of stress incontinence. In addition, the pump allows long-term deactivation of the sphincter if the patient needs to undergo a urethral instrumentation or procedure.
The most common indications for using an AUS are in patients suffering from post-prostatectomy incontinence and in those with neurogenic bladder. Together, these two indications account for more than 75% of all procedures performed.1
Post-prostatectomy incontinence. Nearly 100,000 radical prostatectomies are performed annually in the United States, and one of the associated complications is postoperative stress urinary incontinence (SUI). Varying degrees of incontinence may range from insignificant leakage to the continuous use of pads. While some series have reported an incidence of SUI as low as 0.4%,1 it is believed that the incidence as reported may be higher: 8% to 77%.2
Incontinence necessitating treatment also may occur after surgery for benign prostatic enlargement in up to 2% of cases.1 In such patients, an initial 6 to 12 months of conservative treatment is advisable because a majority of cases resolve to complete urinary control. However, after this period, some form of surgical intervention may be necessary. Haab et al3 showed an average decrease in pad usage from 2.75 to 0.97 pads per day following AUS placement after a mean 7.2 years of follow-up. Eighty percent of the men had a socially acceptable level of continence, at less than one pad per day, and patients reported an overall satisfaction level of 4.1 on a scale of 1 to 5 (5 being extremely satisfied).
Satisfaction rates with the AUS continue to be good.4,5 In a recent publication, Simon et al reviewed data on 47 men undergoing an AUS implant between 1990 and 2003 for a variety of indications. At a mean 3 years of follow-up, over 95% were satisfied with their device.4