A three-dimensional model of the penis for analysis of tissue stresses during normal and abnormal erection

Approximately half of the males between the ages of 40 and 70 suffer erectile dysfunction. Because adequate mechanical interactions in the penis are necessary for functional erection it is important to analyze stresses in the erect penis. Previous penis models were limited to simplified or two-dimensional geometry. Here we developed a three-dimensional model for structural analysis of normal erection as well as erections of a penis with substantial asymmetry of the corporal bodies, and Peyronie's disease. The model was constructed based on anatomical images and included skin, tunica albuginea, corpus cavernosa, and spongiosum. The mechanical behavior of the tunica and skin were assumed to be three-dimensional-orthotropic, and other tissues as well as Peyronie's plaque was taken as linear elastic. Stresses and deformations during erection were analyzed using a commercial finite elements (FE) solver. Erection was simulated by raising blood pressure in the corporal bodies to 100 mmHg. The tunica was found to be the most highly loaded tissue in the erect penis. Peak von Mises stresses in the healthy tunica, tunica of the asymmetric corpora model, and tunica with Peyronie's disease were 114 kPa, 167 kPa, and 830 kPa, respectively. The angles of distortion of the penis with respect to the vertical axis were approximately 4.5 degrees and approximately 2 degrees , for the asymmetric and Peyronie's cases, respectively. The model's ability to determine internal stresses in the erect penis offers a new point of view on the mechanical factors involved with erection, and enables us to relate these data with different penile pathologies.