Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part I—Clinical implications of penile tissue mechanical properties

Abstract

Purpose: The least investigated physical determinant of penile rigidity has been penile tissue material properties. The goals in this study (Part I) were to define two penile mechanical parameters, cavernosal expandability X and tunical distensibility V_E/V_F, determine their magnitudes in humans and develop an analytical expression for penile volume as a function of these two tissue characteristics and intracavernosal pressure.

Methods: Dynamic infusion pharmacocavernosometry was performed in 21 impotent patients (age 43±19 y) to provide human geometric, hemodynamic and structural data. A mathematically derived model of hemodynamic and structural-dynamic characteristics of penile erection was developed (Parts I, II, III) incorporating penile tissue mechanical qualities.

Results: Cavernosal expandability X provided a measure of the ability to approach maximum volume at relatively low intracavernosal pressures. Tunical distensibility V_E/V_F denoted the maximal erect to flaccid penile volume ratio. The magnitudes of X and V_E/V_F in the study population were 0.04–0.17 mmHg⁻¹ and 1.7–5.0 respectively.

Conclusions: Enabling penile volume to be derived as a function of tissue mechanical characteristics and pressure, allows for penile rigidity to be expressed (in Part II) as a function of pressure, geometry and tissue qualities.