Long-term mechanical reliability of AMS 700 series inflatable penile prostheses: comparison of CX/CXM and Ultrex cylinders

Abstract

Purpose: Recently, we have noted an increasing incidence of revisions being performed in patients implanted with the length and girth expanding AMS 700 Ultrex* inflatable penile prosthesis. This observation prompted us to compare the long-term mechanical reliability of the AMS Ultrex inflatable penile prosthesis versus the girth-expanding AMS 700 CX* or CXM* inflatable penile prosthesis in men with organic erectile dysfunction.

Materials and methods: Using chart review, mailed questionnaires and telephone interviews, we obtained accurate followup on 111 of 142 (78.2%) patients with CX/CXM implanted between June 1986 and September 1995, and on 152 of 179 (84.9%) patients implanted with Ultrex between October 1989 and September 1995. The CX/CXM and Ultrex groups were compared with regard to 3 end points: 1) mechanical failure caused by any malfunctioning component, 2) device failure caused by any cylinder complication and 3) cylinder aneurysms/leaks.

Results: Followup ranged from 1.0 to 112.0 months for the CX/CXM group (mean 47.2 months), and 0.7 to 71.5 months for the Ultrex group (mean 34.4 months). CX/CXM versus Ultrex group comparison demonstrated 10 CX/CXM mechanical failures (9.0%) versus 26 Ultrex failures (17.1%), p = 0.001; 5 CX/CXM cylinder complications (4.5%) versus 13 Ultrex cylinder complications (8.6%), p = 0.0292; and 3 CX/CXM cylinder aneurysms/leaks (2.7%) versus 9 in the Ultrex group (5.9%), p = 0.0162. Kaplan-Meier estimates demonstrated significantly decreased mechanical survival in all 3 categories for Ultrex inflatable penile prosthesis versus CX/CXM inflatable penile prosthesis.

Conclusions: Although Ultrex cylinders provide length and girth expansion, Ultrex cylinders exhibit an increased mechanical failure rate at shorter followup compared with CX/CXM cylinders. This increased propensity for Ultrex cylinder problems should be closely monitored.