Development of in silico models to guide the experimental characterisation of penile tissue and inform surgical treatment of erectile dysfunction

A review of the experimental methods and results of testing the mechanical properties of Tunica Albuginea

The present work provides a comprehensive review of the literature on the mechanical properties and existing human tunica albuginea tissue testing methods. Assessments were completed on papers reporting experimental values of Young's modulus, tensile strength, puncture strength, stiffness, toughness, and strain at the ultimate tensile strength (UTS). A high degree of variability in the reported experimental values was found; Young's modulus ranged from 5 MPa to 118 MPa, and tensile strength went from 1.1 MPa to 6.1 MPa. A comparison of the variability of the reported experimental values for puncture strength, stiffness, toughness, and strain at the UTS could not be completed due to a lack of experimental results. This review discusses the pathophysiology and surgical treatment of erectile dysfunction and Peyronie's disease, variability in the existing reported mechanical properties, the impact of the variability of mechanical properties on in silico models and explores the absence of a standardised testing method as a possible reason for the variable in results. Finally, this work attempts to provide suggestions for standardising future mechanical testing of the tunica albuginea through minimising and reporting freeze/thaw cycling, noting the proximal/distal region of the cadaver tunica sample, reporting the orientation (o'clock position) of the cadaver tunica sample, and testing the cadaver tunica samples in bi-axial tension. Ultimately, standardising the testing methodologies of the tunica albuginea will provide higher confidence in reported mechanical property values.