Stresses in the normal and diabetic human penis following implantation of an inflatable prosthesis.

The prevalence of impotence in diabetes mellitus ranges as high as 75%. The implantation of an inflatable penile prosthesis (IPP) is frequently carried out to restore erectile function. However, clinical studies have demonstrated that severe post-implantation penile pain during erection is a common complication in diabetic men. A biomechanical model of the penis/prosthesis complex is developed, based on cross-sectional anatomy, to simulate the internal stress distribution due to interaction of the prosthesis with both normal and diabetic penile tissues. The material properties of the model components are adopted from experimental data. The model is solved by using commercial finite-element software for a characteristic inflation loading of the penile prosthesis. Elevated structural stresses during erection are found in the dorsal aspect of the tunica albuginea (normal 5.1-31.5 kPa, diabetic 5.1-70 kPa post-implantation). Following IPP implantation, stresses in the diabetic penis are almost as twice as high as those in the normal one and can cause a painful sensation owing to nerve stimulation or to ischaemia in regions of compressed vascular tissue.