Mechanical Reliability of AMS 700 CX Improved by Parylene Coating

Introduction: Parylene coating was added to the silicone layers of the American Medical Systems (AMS) 700 controlled expansion (CX) penile prosthesis cylinders in January 2001. The coating was placed on non-tissue contacting silicone surfaces to increase lubricity, reduce friction, and silicone wear

Aim: We compared mechanical reliability of the original and Parylene-enhanced AMS 700 CX in a large single surgical group series.

Methods: Seven hundred seventy-five consecutive patients receiving the AMS 700CX prosthesis (596 first time [virgin] and 179 revisions) were followed for 3 years. Four hundred fourteen received the non-coated model and 361 received the Parylene-coated device. Revision-free survival was estimated using the Kaplan-Meier product limit method and compared using the log-rank test.

Main Outcome Measures: We calculated overall survival from revision for any reason and survival from mechanical problems such as fluid leakage, cylinder, connector or tubing breakage, pump or reservoir defects.

Results: For the entire series (virgin + revised) the 3-year revision free survival for any cause improved from 78.6% for non-coated to 87.4% for the Parylene-coated implants. Freedom from mechanical breakage showed similar improvement from 89.2% for the non-coated to 97.5% for enhanced models.

Conclusions: This study documents that short-term mechanical reliability and survival from revision for any cause is significantly increased with Parylene-coated AMS 700CX cylinders compared with the earlier AMS 700CX model with non-coated cylinders.