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Mechanical failure of the American Medical Systems Ultrex inflatable penile prosthesis: before and after 1993
Aaron J Milbank1, Drogo K Montague, Kenneth W Angermeier
1Urological Institute, Department of Biostatistics and Epidemiology, Cleveland Clinic Foundation, Cleveland, Ohio, USA.
Purpose:
The 700 Ultrex (American Medical Systems, Minnetonka, Minnesota) is the only penile prosthesis capable of length and girth expansion. Early experience with the 700 Ultrex showed an increased mechanical failure rate compared with the 700CX, mostly secondary to cylinder failure. In 1993 the Ultrex cylinders were modified. We examined the performance of the Ultrex device before and after modification.
Materials And Methods:
We compared our results with the Ultrex prosthesis before (group 1) and after (group 2) the 1993 modification. We implanted 239 devices from October 1989 to December 1999. A total of 26 patients have died. Followup was obtained on the results of 137 of the remaining 213 implants (64%), including 85 pre-modification devices in 85 patients and 52 post-modification devices in 51, via a mailed questionnaire, telephone survey or chart review. The questionnaire and survey included a 5-point satisfaction scale. Groups 1 and 2 were compared in regard to 3 end points, namely cylinder, mechanical and overall failure.
Results:
Followup was less than 1 to 136 months (median 92, 25th to 75th percentiles 43 to 108) in group 1 and less than 1 to 92 months (median 46, 25th to 75th percentiles 21 to 75) in group 2. The 5-year Kaplan-Meier estimates of overall, mechanical and cylinder survival in groups 1 and 2 were 64.7%, 70.7% and 80.2%, and 77.7% (p = 0.23), 93.7% (p = 0.017) and 96.2% (p = 0.008), respectively. Overall satisfaction was similarly high in groups 1 and 2 (mean 3.9 and 4 points).
Conclusions:
On long-term followup the 1993 modification of the Ultrex cylinders appears to have significantly decreased the propensity of cylinder failure of the pre-modification device.