Ex vivo testing of inflatable penile prosthesis in human cadaveric penis with paired in silico model offering surgical and biomechanical insights

Le résumé fourni par la source

Erectile dysfunction (ED) is the inability to achieve or maintain an erection and affects ~52% of males over 40.1 Implantation of a penile prosthesis is the most common treatment for patients who do not respond well to pharmacological treatments. Various types of penile prostheses are being used to resolve ED.1 The three piece inflatable penile prosthesis (IPP), such as the AMS 700, the Coloplast Titan, and the Rigicon Infla 10 are the most popular penile prostheses.1 Designing medical devices with reliable long-term performance requires preclinical testing in both ex vivo and in silico environments. However, acquiring and testing human penile tissue is challenging (Supplementary Section S4), and animal penile tissues differ substantially from human tissues in both anatomy and mechanical properties.1 Therefore, the development of preclinical models is important for advancing the study of human penile tissue mechanics and evaluating penile prosthesis performance within anatomically relevant conditions.2,3 The objective of this study was to establish a preclinical testing framework by combining ex vivo IPP implantation and inflation testing in a human cadaveric penis with a finite element (FE) model. The model incorporated experimentally derived human penile tissue properties together with implant specifications to predict tissue stress and strain distributions during IPP inflation, providing a computational platform to analyze device–tissue interactions. A fresh human cadaveric penis with a post-mortem time interval of 1–5 days from a donor aged 85 years of age received from ScienceCare, USA. The tissue was received in a frozen state and stored at −20°C. After defrosting at room temperature, the penis was cleaned by removing unwanted tissues in such a way that foreskin, glans and 15 cm penile shaft remained, as shown in Figure S1b. The penis was examined ex vivo by the surgical andrologist and no element of fibrosis, Peyronie’s plaque or chordee were identified. The corpora was sized prior to implantation using a Furlow from the cut proximal end of the corpora to the corporal tips and a 15 cm implant was chosen as appropriate to the measurement. Boston Scientific AMS700™CX with cylinders of 12 mm diameter and 15 cm length, a 100 ml reservoir, and a Momentary Squeeze Pump, was used to be implanted into the cadaveric tissue for the IPP inflation test. An incision was made in the proximal penile cadaveric shaft skin ventrally. A standard 3 cm corporotomy was made in the proximal tunica albuginea and a single pass Furlow dilatation was performed in the corporal smooth muscle to allow implantation of a 15 cm IPP in both corpora. The corporotomies were closed in a standard fashion around the tubing using 0 Vicry suture. A digital barometer was attached into the ex vivo test set-up to measure the inflation pressure. The cylinders inflation within the tissue was visualized using an ultrasound scanner –SIEMENS ACUSON S2000™ – equipped with a 9 L4 linear probe operating at 8 MHz frequency. An image was taken at each pressure increment from 0 to 20 psi and at five different locations through the penis length (Figure S4). The IPP inflation test was conducted in a water bath (PBS, 37°C). The geometry for in-silico modeling (Abaqus 2022) was generated by creating cross-sectional sketches based on photographs of five distinct sections from the cadaveric penis (Figure S2). A 12 mm diameter hole was added to the CC layer to accommodate the IPP cylinders. A pressure of 137 kPa (≈20 psi) was applied to the internal surface of the IPP cylinder, based on specifications from Boston Scientific internal documents. The penile tissue and IPP cylinder properties were adopted from our previous studies,4 see Table S1. Further details of the FE model are included in Supplementary Section S2. Ultrasound image post-processing provided IPP cylinder diameters at different pressures and locations (Figure S3). These data were used to generate pressure–diameter curves describing device inflation in cadaveric tissue. FE simulation results showed good agreement with the ex vivo measurements (Figure S4). After validation, the model was used to evaluate device–tissue interactions during IPP inflation, including tissue displacement, stress, and strain (Figures S5 and S6; Supplementary Section S3). The model incorporates anatomically informed geometry and experimentally derived material descriptions for multiple penile tissue layers and, to our knowledge, represents the most advanced full-penis computational model currently available. Predicted displacement, stress, and strain fields therefore enable relative comparisons across tissue layers, anatomical regions, and inflation pressures rather than exact absolute values. The mechanical responses calculated by the computational model reveal high stress/strain regions. Regions of elevated stress and strain may represent mechanically vulnerable areas that could be more susceptible to tissue compromise during IPP inflation. Reported rupture thresholds of the tunica albuginea4 provide a reference for comparing predicted stress magnitudes. Although definitive clinical thresholds for fibrosis, ischemia, erosion, etc. have not been established in the literature, the identified patterns of mechanical loading may help highlight areas at relatively higher stress and strain and potential risk. Further discussion of the study’s limitations and future directions is provided in Supplementary Section S4. While this study focused on the AMS700, the validated experimental-computational framework is readily extendable to other commercially available IPPs. Future studies can apply this approach to compare different device designs and materials, enabling systematic evaluations of their biomechanical performance. Although this study is preclinical, the validated experimental-computational framework provides clinically relevant insights into device-tissue interactions that are difficult to assess intraoperatively. By identifying regions of elevated stresses and strains and quantifying device expansion and rigidity, the model offers a mechanistic basis for understanding device performance and may support future studies on device selection, surgical planning, and clinical outcomes. In this study, the model validation was performed using data from a single ex vivo human cadaveric penis. As penile geometry, tissue properties, and mechanical response may vary between individuals due to age, health status, and anatomical variability, the predicted stress, strain, and displacement patterns should be interpreted as specimen-specific and mechanistic rather than population-representative. Nevertheless, validation against experimentally measured pressure-diameter responses support the model’s ability to capture the dominant mechanical behavior during IPP inflation. Within this framework, the model provides a useful platform for visualizing and comparing device-tissue interaction patterns. Additional limitations, including the challenges of human tissue acquisition and the need for population- and patient-specific modeling, are discussed in the Supplementary (Section S4). This publication has emanated from research conducted with the financial support of Science Foundation Ireland (SFI) under grant number 12/RC/2278_2 and Boston Scientific Limited (Clonmel). The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Brian Watschke, Evania Mareena, and Thomas Sinnott are employees of Boston Scientific Corporation.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.