Engineering analysis of penile hemodynamic and structural-dynamic relationships: Part II - Clinical implications of penile buckling

Purpose: Penile buckling force was analytically described in terms of its constituents. In addition, theoretically-derived buckling force data were compared to clinically measured data and the influence of each constituent on penile buckling force data was assessed. Methods: Using engineering buckling theory for a column, a mathematically-derived penile buckling model was developed which incorporated geometric and hemodynamic data obtained by dynamic infusion pharmacocavernosometry studies in 21 impotent patients (age 43, range 24-62 y) as well as penile tissue mechanical characteristics previously developed (Part I). Results: In 17 of 21 patients the mean difference between theoretically derived and clinically measured buckling force data was 0.33+/-0.25 kg (r=0.96). Factors which increased penile buckling forces were: (1) high intracavernosal pressure values (rigidity was related to pressure in an exponential-like fashion); (2) high penile aspect ratio (D/L) values (relatively large diameter/short length penile geometry) and high flaccid diameter; and (3) high cavernosal expandability values (a measure of the ability of the corpora to approach its erect volume with relatively low intracavernosal pressures). Conclusions: Pressure-volume data (pressure, geometry and tissue characteristics) obtained during erectile function testing have been shown, for the first time, to theoretically predict the magnitude of clinically-measured penile buckling forces.