A nonlinear-elastic constitutive model for soft connective tissue based on a histologic description: Application to female pelvic soft tissue.

To understand the mechanical behavior of soft tissues, two fields of science are essential: biomechanics and histology. Nonetheless, those two fields have not yet been studied together often enough to be unified by a comprehensive model. This study attempts to produce such model. Biomechanical uniaxial tension tests were performed on vaginal tissues from 7 patients undergoing surgery. In parallel, vaginal tissue from the same patients was histologically assessed to determine the elastic fiber ratio. These observations demonstrated a relationship between the stiffness of tissue and its elastin content. To extend this study, a mechanical model, based on an histologic description, was developed to quantitatively correlate the mechanical behavior of vaginal tissue to its elastic fiber content. A satisfactory single-parameter model was developed assuming that the mechanical behavior of collagen and elastin was the same for all patients and that tissues are only composed of collagen and elastin. This single-parameter model showed good correlation with experimental results. The single-parameter mechanical model described here, based on histological description, could be very useful in helping to understand and better describe soft tissues with a view to their characterization. The mechanical behavior of a tissue can thus be determined thanks to its elastin content without introducing too many unidentified parameters.

Training Significantly Improves Fetoscopy Performance: A Pilot Randomized Controlled Trial.

Background Implementation of complex fetoscopic procedures that included intracorporeal suturing has been limited due to technical difficulties that might be surmounted with adequate training. Evaluating the impact of laparoscopic or fetoscopic training on fetoscopic performance was the aim of this study. Methods To evaluate fetoscopic performance after either laparoscopic or fetoscopic training, subjects were asked to perform four surgeon's square knots fetoscopically prior and post 2 hours of hands-on training. All subjects were medical students and novice in laparoscopic and fetoscopic interventions. Total time, knot stability (evaluated via tensiometer), suture accuracy, knot quality, and fetoscopic performance were assessed. Results Forty-six subjects were included in the study; after simple randomization, 24 were trained fetoscopically and 22 laparoscopically. Both groups had comparable baseline characteristics and improved after training significantly regarding all aspects assessed in this study. Subjects who trained fetoscopically were superior in terms of suturing and knot-tying performance. Conclusion Training significantly improves fetoscopic performance and may indeed be the keystone for future complex fetoscopic interventions. It seems advisable to train rather fetoscopically than laparoscopically resulting in higher suture and knot-tying quality.