The Hydroflex penile prosthesis: a test case for the introduction of new urological technology

The AMS Hydroflex* penile prosthesis was introduced for commercial distribution in 1985 but 5 years later this device was no longer available on the United States market. In an attempt to understand why this device, which initially enjoyed substantial popularity, was abruptly withdrawn from the market, patients who underwent implantation at the University of Wisconsin were interviewed and a critical analysis of the Food and Drug Administration approval process of medical devices was performed. An AMS Hydroflex penile prosthesis was implanted in 17 patients (mean age 57.7 years, range 27 to 84 years). The followup period ranged from 37 to 73 months with a mean of 58 months, and 3 patients died within that time. Of the remaining patients 10 (71%) were satisfied with the device in the first months after implantation but only 6 (43%) were satisfied at the time of followup, 9 (64%) were more satisfied with sexual relationships after receiving the prosthesis and 7 (50%) found the prosthesis simple to operate. Mechanical failure was noticed by 11 patients (79%), of whom 5 (45%) underwent further surgery. Classification of medical devices started with the enactment of the Medical Device Amendment to the Federal Food, Drug and Cosmetic Act, May 28, 1976. All medical devices that were in commercial distribution at that time were classified in 3 regulatory control categories depending upon the degree of regulation necessary to assure safety and effectiveness of each device. Before May 28, 1976 no approved application was necessary for marketing medical devices, and the Food and Drug Administration has variable amounts of information about safety and effectiveness of the different devices marketed prior to that date. Since May 1976 approved applications have been mandated for new or significantly changed devices. The specific process by which the Hydroflex prosthesis, as well as other medical devices, is approved is critically reviewed.