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.

Mechanical Properties and Related Histological Alterations of Engineered Tendons In Vivo

2005 ◽  
Vol 288-289 ◽  
pp. 11-14 ◽  
Author(s):  
Ting Wu Qin ◽  
Shujiang Zhang ◽  
Zhi Ming Yang ◽  
Xiang Tao Mo ◽  
Xiu Qun Li
Keyword(s):  
Mechanical Properties ◽  
Collagen Synthesis ◽  
Biomechanical Properties ◽  
Biomechanical Test ◽  
Histological Alterations ◽  
Normal Tendon ◽  
Tendon Cells ◽  
Biomechanical Stimulation

The purpose of this research is to find out the interaction between histological alterations and mechanical properties of engineered tendon implanted in situ. Defects of 0.5cm-1.0cm were made at deep flexor tendons by surgical procedure. Engineered tendons using degradable scaffolds polyglytic acid (PGA) mesh and tendon cells were implanted to repair the defects. Chickens were killed respectively at 2 weeks, 4 weeks, 6 weeks, and 8 weeks after surgery. The implants were taken out for histological examination, biomechanical test, and collagen synthesis assay. The results showed that after surgery the PGA scaffolds degraded fast and took precedence of collagen synthesis. There were not enough amount and maturation of the collagen fibers of the new tendon at 2-8 weeks after surgery. The biomechanical properties of new tendons were less than those of the normal tendon. Therefore, it is necessary to construct engineered tendons with better degradation rate of scaffolds and suitable biomechanical stimulation so that more collagen synthesis and better biomechanical properties of new tendons can be developed early after implantation.

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.

An in Situ Dual Indentation and Optimization Method to Determine Mechanical Properties of Articular Cartilage

2007 ◽  
Author(s):  
Jonathan E. Pottle ◽  
J.-K. Francis Suh
Keyword(s):  
Articular Cartilage ◽  
Stress Relaxation ◽  
Structural Integrity ◽  
Reaction Force ◽  
Model Parameters ◽  
Unconfined Compression ◽  
Confined Compression ◽  
Practical Applications

The efficacy of the biphasic poroviscoelastic (BPVE) theory [1] in constitutive modeling of articular cartilage biomechanics is well-established [2–4]. Indeed, this model has been used to simultaneously predict stress relaxation force across confined compression, unconfined compression, and indentation protocols [2,3]. Previous works have also demonstrated success in simultaneously curve-fitting the BPVE model to reaction force and lateral deformation data gathered from stress relaxation tests of articular cartilage in unconfined compression [4]. However, a potential limitation of practical applications of such a successful model is seen in some commonly-employed mechanical testing methods for articular cartilage, such as confined compression and unconfined compression. These methods require the excision of a disk of cartilage from its underlying subchondral base, which likely would compromise the structural integrity of the tissue, causing swelling and curling artifacts of the sample [5]. Indentation represents a testing protocol that can be used with an intact cartilage layer. This results in a specimen more closely resembling cartilage in vivo. Using an agarose gel construct, our previous study [6] has demonstrated that a unique set of the six BPVE model parameters of a soft tissue can be determined readily from in situ dual indentation method using stress relaxation and creep viscoelastic protocols. The objective of the current study is to validate the efficacy of this technique as a means to determine the BPVE material parameters of articular cartilage.

scholarly journals Compressional Optical Coherence Elastography of the Cornea

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 111
Author(s):  
Manmohan Singh ◽  
Achuth Nair ◽  
Salavat R. Aglyamov ◽  
Kirill V. Larin
Keyword(s):  
Rabbit Model ◽  
Biomechanical Properties ◽  
Clinical Applications ◽  
Optical Coherence ◽  
Collagen Crosslinking ◽  
Corneal Collagen Crosslinking ◽  
Corneal Biomechanical Properties ◽  
Corneal Collagen

Assessing the biomechanical properties of the cornea is crucial for detecting the onset and progression of eye diseases. In this work, we demonstrate the application of compression-based optical coherence elastography (OCE) to measure the biomechanical properties of the cornea under various conditions, including validation in an in situ rabbit model and a demonstration of feasibility for in vivo measurements. Our results show a stark increase in the stiffness of the corneas as IOP was increased. Moreover, UV-A/riboflavin corneal collagen crosslinking (CXL) also dramatically increased the stiffness of the corneas. The results were consistent across 4 different scenarios (whole CXL in situ, partial CXL in situ, whole CXL in vivo, and partial CXL in vivo), emphasizing the reliability of compression OCE to measure corneal biomechanical properties and its potential for clinical applications.

A Triphasic Analysis of Indentation on Articular Cartilage

1999 ◽  
Author(s):  
D. N. Sun ◽  
X. E. Guo ◽  
W. M. Lai ◽  
V. C. Mow
Keyword(s):  
Articular Cartilage ◽  
Biomechanical Properties ◽  
Joint Surface ◽  
Specimen Preparation ◽  
Experimental Configuration ◽  
Indentation Experiment ◽  
Articulating Surface ◽  
Non Destructive

Abstract The indentation experiment is one of the most frequently used methods for studying biomechanical properties of articular cartilage. This experimental configuration is attractive because it does not require special specimen preparation [1,2]. Indentation can be performed on an articulating surface with the cartilage attached on the bone, a condition resembling closer to the physiologic and anatomic condition than compression of osteochondral plugs excised from the joint surface. It provides a non-destructive method to determine the variation of cartilage properties over the joint surface and has a potential for in vivo applications of determining mechanical and electrochemical properties of articular cartilage. Numerous theoretical and numerical analyses of indentation on articular cartilage have been performed and used to calculate the in situ mechanical material constants (Ha, k, v) of the tissue [e.g., 1–3].

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.

Use of Robotic Manipulators to Study Diarthrodial Joint Function

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Richard E. Debski ◽  
Satoshi Yamakawa ◽  
Volker Musahl ◽  
Hiromichi Fujie
Keyword(s):  
Surrounding Tissue ◽  
External Loading ◽  
Loading Conditions ◽  
Joint Function ◽  
Diarthrodial Joint ◽  
Injury Mechanisms ◽  
Diarthrodial Joints ◽  
Robotic Testing

Diarthrodial joint function is mediated by a complex interaction between bones, ligaments, capsules, articular cartilage, and muscles. To gain a better understanding of injury mechanisms and to improve surgical procedures, an improved understanding of the structure and function of diarthrodial joints needs to be obtained. Thus, robotic testing systems have been developed to measure the resulting kinematics of diarthrodial joints as well as the in situ forces in ligaments and their replacement grafts in response to external loading conditions. These six degrees-of-freedom (DOF) testing systems can be controlled in either position or force modes to simulate physiological loading conditions or clinical exams. Recent advances allow kinematic, in situ force, and strain data to be measured continuously throughout the range of joint motion using velocity-impedance control, and in vivo kinematic data to be reproduced on cadaveric specimens to determine in situ forces during physiologic motions. The principle of superposition can also be used to determine the in situ forces carried by capsular tissue in the longitudinal direction after separation from the rest of the capsule as well as the interaction forces with the surrounding tissue. Finally, robotic testing systems can be used to simulate soft tissue injury mechanisms, and computational models can be validated using the kinematic and force data to help predict in vivo stresses and strains present in these tissues. The goal of these analyses is to help improve surgical repair procedures and postoperative rehabilitation protocols. In the future, more information is needed regarding the complex in vivo loads applied to diarthrodial joints during clinical exams and activities of daily living to serve as input to the robotic testing systems. Improving the capability to accurately reproduce in vivo kinematics with robotic testing systems should also be examined.

Assessment of a Novel Technique for In-Vivo Investigation of Joint Cartilage Deformation Characteristics

2007 ◽  
Author(s):  
Ion Robu ◽  
Janet L. Ronsky ◽  
Richard Frayne ◽  
Ayman H. Habib
Keyword(s):  
Biomechanical Properties ◽  
Morphological Properties ◽  
Elastic Behavior ◽  
Unconfined Compression ◽  
Indentation Tests ◽  
Magnetic Resonance Imaging Mri ◽  
Cadaveric Knee

Cartilage is characterized by unique biomechanical and morphological properties. These properties are dictated mainly by the visco-elastic behavior of the interstitial matrix. Attempts to quantify the biomechanical properties of cartilage have been based on in-vitro confined and unconfined compression experiments and indentation tests, in-situ measurements of intact cadaveric knee joint specimens under loading using Magnetic Resonance Imaging (MRI), numerical modeling, or in-vivo techniques such as those applying arthroscopic indentation or loading with MR imaging.

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.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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