[Silicone ureteral prostheses: results of an experimental study of tolerance and surface conditions over six years, and clinical use for four years (author's transl)].

Two main points of interest are discussed more particularly in this report. Results of the experimental use of spiral prostheses in dogs are presented, studies having been conducted for a period extending over nearly six years, this being longer than any known previous study on this type of prosthesis. Those carried out by the Rhone Poulenc Centre lasted for three years. In this series, four prosthesis were studied for 30 months and two for 70 months. At the same time, the results of the use of straight prostheses in humans over a period of 4 years are also analyzed. Furthermore, the experimental study included a relatively complete ultrastructural study of these prostheses after they had been in contact with the dog's urine for six years, the surface being examined by electron microscopy, and the resulting lipidic deposits analyzed biochemically. The data obtained is used in an attempt to respond to two questions concerning ureteral replacement by silicone prostheses: the effect on the silicone of contact with urine after 6 years, and the possible extension or restriction of use of theses prostheses in humans as a result of the information obtained. The conclusions reached are that the quality of these prostheses has been confirmed and that their valid conception permits continuing clinical application. The indications are limited, however, by reflux and the alterations, even though minimal, appearing on their surface. Lipidic deposits are visible both macroscopically and by electron microscopy, and these could be the starting point for calcaneous incrustation after longer periods of use. Indications should be presently restricted, therefore, to patients with neoplastic lesions.