The Rear Tip Extender for Inflatable Penile Prostheses: Introduction of "Rigidity Factor" and Review of the Literature.

INTRODUCTION: Rear tip extenders (RTEs) are often used in penile prosthesis surgery, and their value and use have varied with the evolution of penile prostheses.

AIM: To review the literature addressing RTEs and to introduce a new term, rigidity factor, which quantifies the ratio of inflatable to non-inflatable component of the cylinders.

METHODS: The urologic literature was reviewed for all mention of RTEs. In addition, literature regarding penile prostheses was explored for mention of RTEs.

MAIN OUTCOME MEASURE: A search on PubMed for "rear tip extender" resulted in 17 publications. These publications were reviewed, and references were also explored for related publications.

RESULTS: The history of the development of RTEs, complications associated with the use of RTEs, and current practices in the use of RTEs are all discussed. In addition, recent publications regarding RTEs were examined in detail. RTEs were introduced in the 1980s to improve mechanical survival of prostheses. They were thought to decrease input tubing wear. Although the trend recently has been to place more rear tips, evidence has surfaced suggesting a link to increased need for reoperation with additional RTEs. In addition, we believe that increased length of RTEs can decrease erectile quality. Rigidity factor, defined as the ratio of the live (inflatable) portion of cylinder to the total cylinder length, can be used to quantify the effect of RTE on erectile strength. However, the effects of RTEs on biomechanical properties of the penis when fully inflated are still not fully understood.

CONCLUSION: The use of RTEs is a relatively underexplored area of penile prosthesis placement. Further laboratory and in vivo work will allow for a better understanding of the optimal role of RTEs in penile prosthesis surgery. Thirumavalavan N, Cordon BH, Gross MS, et al. The Rear Tip Extender for Inflatable Penile Prostheses: Introduction of "Rigidity Factor" and Review of the Literature. Sex Med Rev 2019;XX:XXX-XXX.