Oral Presentation Track 16: Reproductive Biomechanics 16.6. Penile Mechanics and Hemodynamics Abstract: 5360 Citation: Journal of Biomechanics 2006; Vol. 39 Suppl. 1, page S346
A three-dimensional model of the penis for analysis of tissue stresses during erection
E. Linder-Ganz1, A. Gefen1, J. Chen2, D. Elad1 1 Department of Biomedical Engineering, Tel Aviv University, Israel 2 Department of Urology, Tel Aviv Medical Center, Israel Approximately half of the males between the ages of 40-70 years suffer from erectile dysfunction. Since adequate mechanical interactions in the penis are necessary for developing functional erection it is important to analyze mechanical stresses in the erect penis. Recent publications demonstrated many of the mechanical characteristics of the structural elements of the penis, but the models were limited to the geometry of a two-dimensional cross-section. In this work we developed a three-dimensional model that allowed for structural analysis of normal erection as well as a variety of erectile dysfunction conditions. The model was constructed from the Visible Human digital anatomical database and included the skin, deep and superficial fascia, tunica albuginea, corpus cavernosa and the corpus spongiosum. The mechanical properties of each tissue component were extracted from our previous works. Stresses and deformations during penile erection were analyzed by implementing the model into the commercial finite elements solver of Nastran. Penile erection was simulated by simultaneously raising blood pressure in the three corporal bodies and weighing the counteracting tractions by trabecular smooth muscle stretching, which produced effective erectile pressure of 6.3 kPa (~47 mmHg). In a patient with diabetes the collagen-rich tissues (e.g., tunica albuginea and deep fascia) were stiffened by a factor of 3. Simulations of a normal erection, from tumescence to rigidity demonstrated maximal von Mises stresses in the tunica albuginea and deep fascia of 120 kPa and 95 kPa, respectively. The corresponding stresses in the diabetic patient were 10% and 5% higher, respectively. In the diabetic tunica albuginea and deep fascia larger areas were exposed to maximal stresses. This rise in mechanical stresses, though mild, may further decrease blood perfusion in the penis, which, in turn, may further deteriorate the erectile dysfunction condition.