scholarly journals Biaxial Mechanical Assessment of the Murine Vaginal Wall Using Extension–Inflation Testing

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Kathryn M. Robison ◽  
Cassandra K. Conway ◽  
Laurephile Desrosiers ◽  
Leise R. Knoepp ◽  
Kristin S. Miller
Keyword(s):  
Structure Function ◽  
Soft Tissues ◽  
Local Stress ◽  
Normal Structure ◽  
Biomechanical Properties ◽  
Pelvic Organ ◽  
Vaginal Wall ◽  
Tissue Properties ◽  
Curve Fit

Progress toward understanding the underlying mechanisms of pelvic organ prolapse (POP) is limited, in part, due to a lack of information on the biomechanical properties and microstructural composition of the vaginal wall. Compromised vaginal wall integrity is thought to contribute to pelvic floor disorders; however, normal structure–function relationships within the vaginal wall are not fully understood. In addition to the information produced from uniaxial testing, biaxial extension–inflation tests performed over a range of physiological values could provide additional insights into vaginal wall mechanical behavior (i.e., axial coupling and anisotropy), while preserving in vivo tissue geometry. Thus, we present experimental methods of assessing murine vaginal wall biaxial mechanical properties using extension–inflation protocols. Geometrically intact vaginal samples taken from 16 female C57BL/6 mice underwent pressure–diameter and force–length preconditioning and testing within a pressure-myograph device. A bilinear curve fit was applied to the local stress–stretch data to quantify the transition stress and stretch as well as the toe- and linear-region moduli. The murine vaginal wall demonstrated a nonlinear response resembling that of other soft tissues, and evaluation of bilinear curve fits suggests that the vagina exhibits pseudoelasticity, axial coupling, and anisotropy. The protocols developed herein permit quantification of biaxial tissue properties. These methods can be utilized in future studies in order to assess evolving structure–function relationships with respect to aging, the onset of prolapse, and response to potential clinical interventions.

scholarly journals Assembled Cell-Decorated Collagen (AC-DC) bioprinted implants mimic musculoskeletal tissue properties and promote functional recovery

2021 ◽  
Author(s):  
Kyle W Christensen ◽  
Jonathan Turner ◽  
Kelly Coughenour ◽  
Yas Maghdouri-White ◽  
Anna A Bulysheva ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Functional Recovery ◽  
Cross Sections ◽  
Soft Tissues ◽  
Biomechanical Properties ◽  
Permanent Disability ◽  
Tissue Properties ◽  
Musculoskeletal Tissue ◽  
Strength And Stiffness

Musculoskeletal tissue injuries, including the damage and rupture of ligaments and tendons, and volumetric muscle loss (VML), are exceptionally commonplace and often lead to permanent disability and deformation. We developed an advanced biomanufacturing platform producing cellularized collagen microfiber implants to facilitate functional repair and regeneration of musculoskeletal soft tissues. This Assembled Cell-Decorated Collagen (AC-DC) bioprinting process rapidly and reproducibly forms 3D implants using clinically relevant cells and strong, microfluidic extruded collagen fibers. Quantitative analysis showed that the directionality and distribution of cells throughout AC-DC implants mimic the cellular properties of native musculoskeletal tissue. AC-DC bioprinted implants further approximate or exceed the strength and stiffness of human tendons and ligaments and exceeded the properties of commonplace collagen hydrogels by orders of magnitude. The regenerative potential of AC-DC implants was also assessed in vivo in a rodent VML model. A critically sized muscle injury in the hindlimb was created and repaired, and limb torque generation potential was measured over 12 weeks. Both acellular and cellular implants were found to promote functional recovery compared to the unrepaired group, with AC-DC implants containing therapeutic muscle progenitor cells promoting the highest degree of recovery. Histological analysis and automated image processing of explanted muscle cross-sections revealed increased total muscle fiber count, median muscle fiber size, and increased cellularization for injuries repaired with cellularized implants. These studies introduce the tremendous potential of an advanced bioprinting method for generating tissue analogs with near-native biological and biomechanical properties with the potential to repair numerous challenging musculoskeletal injuries.

Reliability Investigation of Tissue Resonator Indenter Device

2010 ◽  
Author(s):  
Ming Jia ◽  
Jean W. Zu ◽  
Alireza Hariri
Keyword(s):  
Mechanical Properties ◽  
Soft Tissue ◽  
Soft Tissues ◽  
Tissue Properties ◽  
University Of Toronto ◽  
In Vivo Measurements ◽  
Disease Diagnostics ◽  
Working Principle ◽  
The University

Knowledge of tissue mechanical properties is widely required by medical applications, such as disease diagnostics, surgery operation, simulation, planning, and training. A new portable device, called Tissue Resonator Indenter Device (TRID), has been developed for measurement of regional viscoelastic properties of soft tissues at the Bio-instrument and Biomechanics Lab of the University of Toronto. As a device for soft tissue properties in-vivo measurements, the reliability of TRID is crucial. This paper presents TRID’s working principle and the experimental study of TRID’s reliability with respect to inter-reliability, intra-reliability, and the indenter misalignment effect as well. The experimental results show that TRID is a reliable device for in-vivo measurements of soft tissue mechanical properties.

scholarly journals Analysis of expansion within a pressure inflated section of an urethral stricture model

2021 ◽  
Vol 7 (2) ◽  
pp. 578-581
Author(s):  
Ashish Bhave ◽  
Knut Möller
Keyword(s):  
Element Model ◽  
Biomechanical Properties ◽  
Sensor Data ◽  
Bottom Surface ◽  
Tissue Properties ◽  
Simplified Approach ◽  
Sensor Actuator ◽  
Sensor Model ◽  
New Sensors

Abstract The Urethra is a long tubular structure in the genitourinary tract and serves important functions. Researchers have experimented with some approaches to model the urethra and to analyse its biomechanical properties. However, experiments to model the in-vivo behaviour of urethra with strictures is not thoroughly explored. To analyse the in-vivo urethral properties and specifically for supporting treatment of strictures, a new inflatable sensor-actuator system is being developed. The capabilities of this sensor shall be evaluated in simulations which require appropriate modelling of the human male urethra with strictures. This forms a part of the identification procedure for a variety of urethra conditions and geometries, which in turn forms a basis for inverse modelling. As an initial simplified approach, an axisymmetric Finite Element model was generated that resembled the urethra incorporating a stricture region. An ideal actuator with sensor elements exerting a pressure on inner wall of this urethra was simulated. Three circumference measurement zones within the sensor height (top surface, centre and bottom surface) were implemented. The resulting pressure-extension (circumferential) responses were determined at these measurement zones. The sensor was placed at different lengths within this urethral tube and inflated and the pressure-extension responses were noted. It was found that depending on the position of the sensor-actuator, the extension of tissue can vary. The possible factors for this variation were the finite length of the actuator as well as the influence of tissue properties around the measurement zones. This is important information for the interpretation of sensor data to be gained by the current development. It was possible to generate datasets based on an ideal sensor model, that proved helpful in the evaluation of biomechanical tissue properties in healthy and stricture conditions. This indicates simulations are a versatile and prospective way to test new sensors prior to real experiments.

scholarly journals In vivo measurement of the biomechanical properties of plantar soft tissues under simulated gait conditions

2012 ◽  
Vol 5 (S1) ◽  
Author(s):  
Daniel Parker ◽  
Glen Cooper ◽  
Stephen Pearson ◽  
David Howard ◽  
Gillian Crofts ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Biomechanical Properties ◽  
In Vivo Measurement

Biomechanical Comparison of Abdominal Wall Hernia Repair Materials

2008 ◽  
Author(s):  
Daniel V. Boguszewski ◽  
Nathaniel A. Dyment ◽  
Denis L. Bailey ◽  
Jason T. Shearn ◽  
David L. Butler
Keyword(s):  
Hernia Repair ◽  
Soft Tissues ◽  
Abdominal Wall Hernia ◽  
Biomechanical Properties ◽  
Abdominal Hernia ◽  
Test Procedures ◽  
Synthetic Materials ◽  
Repair Materials ◽  
Biomechanical Comparison

Complications following abdominal hernia repair include infection, mechanical failure, adhesion, and hernia recurrence [1,2]. Mesh materials require less revision surgery and reduce patient morbidity compared to when fascia is harvested [1,3]. Biologic meshes have lower infection rates and less adhesion than synthetic materials, but are more expensive [1]. In order to determine how these materials will function in vivo, it is important to simulate aspects of the actual conditions to which the material might be subjected after surgery. Previous studies have examined how different types of fascia, synthetic materials, and extracellular matrix materials responded to tests that mimic the in vivo state [3–6]. Suture retention testing has been used to compare the performance of human fascia versus possible substitutes [4]. Ball burst testing has been instrumental in understanding the biomechanical properties of different soft tissues and replacement materials by simulating biaxial forces associated with physiological loading conditions [5–7]. This objective of this was to determine which material might be most optimal for use in hernia repair. We hypothesize that biologic mesh materials will exhibit more optimal mechanical properties than synthetic materials when exposed to these test procedures.

Biomechanical Properties of Abdominal Organs In Vivo and Postmortem Under Compression Loads

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Jacob Rosen ◽  
Jeffrey D. Brown ◽  
Smita De ◽  
Mika Sinanan ◽  
Blake Hannaford
Keyword(s):  
Surgical Procedures ◽  
Biomechanical Properties ◽  
Model Parameters ◽  
Loading Conditions ◽  
Tissue Properties ◽  
Surgical Simulators ◽  
Surgical Tools ◽  
Abdominal Organs

Accurate knowledge of biomechanical characteristics of tissues is essential for developing realistic computer-based surgical simulators incorporating haptic feedback, as well as for the design of surgical robots and tools. As simulation technologies continue to be capable of modeling more complex behavior, an in vivo tissue property database is needed. Most past and current biomechanical research is focused on soft and hard anatomical structures that are subject to physiological loading, testing the organs in situ. Internal organs are different in that respect since they are not subject to extensive loads as part of their regular physiological function. However, during surgery, a different set of loading conditions are imposed on these organs as a result of the interaction with the surgical tools. Following previous research studying the kinematics and dynamics of tool/tissue interaction in real surgical procedures, the focus of the current study was to obtain the structural biomechanical properties (engineering stress-strain and stress relaxation) of seven abdominal organs, including bladder, gallbladder, large and small intestines, liver, spleen, and stomach, using a porcine animal model. The organs were tested in vivo, in situ, and ex corpus (the latter two conditions being postmortem) under cyclical and step strain compressions using a motorized endoscopic grasper and a universal-testing machine. The tissues were tested with the same loading conditions commonly applied by surgeons during minimally invasive surgical procedures. Phenomenological models were developed for the various organs, testing conditions, and experimental devices. A property database—unique to the literature—has been created that contains the average elastic and relaxation model parameters measured for these tissues in vivo and postmortem. The results quantitatively indicate the significant differences between tissue properties measured in vivo and postmortem. A quantitative understanding of how the unconditioned tissue properties and model parameters are influenced by time postmortem and loading condition has been obtained. The results provide the material property foundations for developing science-based haptic surgical simulators, as well as surgical tools for manual and robotic systems.

scholarly journals Reverberant Shear Wave Elastography: A Multi-Modal and Multi-Scale Approach to Measure the Viscoelasticity Properties of Soft Tissues

2021 ◽  
Vol 8 ◽  
Author(s):  
Juvenal Ormachea ◽  
Fernando Zvietcovich
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Acoustic Waves ◽  
Guided Waves ◽  
Soft Tissues ◽  
Ex Vivo ◽  
Surface Acoustic Waves ◽  
Shear Wave Elastography ◽  
Biomechanical Properties

There are a variety of approaches used to create elastography images. Techniques based on shear wave propagation have received significant attention. However, there remain some limitations and problems due to shear wave reflections, limited penetration in highly viscous media, requirements for prior knowledge of wave propagation direction, and complicated propagation in layers where surface acoustic waves and guided waves are dominant. To overcome these issues, reverberant shear wave elastography (RSWE) was proposed as an alternative method which applies the concept of a narrow-band diffuse field of shear waves within the tissue. Since 2017, the RSWE approach has been implemented in ultrasound (US) and optical coherence tomography (OCT). Specifically, this approach has been implemented in these imaging modalities because they are similar in image formation principles and both share several approaches to estimate the biomechanical properties in tissues. Moreover, they cover different spatial-scale and penetration depth characteristics. RSWE has shown promising results in the elastic and viscoelastic characterization of multiple tissues including liver, cornea, and breast. This review summarizes the 4-year progress of the RSWE method in US and OCT. Theoretical derivations, numerical simulations, and applications in ex vivo and in vivo tissues are shown. Finally, we emphasize the current challenges of RSWE in terms of excitation methods and estimation of biomechanical parameters for tissue-specific cases and discuss future pathways for the in vivo and in situ clinical implementations.

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