Basin of Attraction and Limit Cycle Oscillation Amplitude of an Ankle-Hip Model of Balance on a Balance Board
In this study, a three degree-of-freedom model for a human balancing on a balance board (BB) was developed. Analysis of the model revealed the BoAs and the amplitude of the LCOs. Results show that physical parameters (time-delays and feedback control gains) have a large impact on the size of the BoA and the amplitude of the LCOs. Particularly, the size of the BoA increases when balancing on a rigid surface and decreases when either proprioceptive or combined visual and vestibular (V&V) feedback gain is too high. With respect to the LCOs, it is shown that they emerge from both the subcritical and supercritical HBs and i...
Source: Journal of Biomechanical Engineering - July 31, 2019 Category: Biomedical Engineering Source Type: research

Rear-Impact Neck Whiplash: Role of Head Inertial Properties and Spine Morphological Variations on Segmental Rotations
This study was designed to investigate the role of variations in spine morphology and head inertia properties on cervical spine segmental rotation in rear-impact whiplash loading. Vertebral morphology is rarely considered as an input parameter in spine finite element (FE) models. A methodology toward considering morphological variations as input parameters and identifying the influential variations is presented in this paper. A cervical spine FE model, with its morphology parametrized using mesh morphing, was used to study the influence of disk height, anteroposterior vertebral depth, and segmental size, as well as variati...
Source: Journal of Biomechanical Engineering - July 31, 2019 Category: Biomedical Engineering Source Type: research

Dynamics of the Tracheal Airway and Its Influences on Respiratory Airflows: An Exemplar Study
Respiration is a dynamic process accompanied by morphological changes in the airways. Although deformation of large airways is expected to exacerbate pulmonary disease symptoms by obstructing airflow during increased minute ventilation, its quantitative effects on airflow characteristics remain unclear. Here, we used in vivo dynamic imaging and examined the effects of tracheal deformation on airflow characteristics under different conditions based on imaging data from a single healthy volunteer. First, we measured tracheal deformation profiles of a healthy lung using magnetic resonance imaging (MRI) during forced exhalatio...
Source: Journal of Biomechanical Engineering - July 31, 2019 Category: Biomedical Engineering Source Type: research

How Stapes Ankylosis and Fracture Affect Middle Ear Dynamics: A Numerical Study
Numerical models of the human middle ear have been developed throughout the last 30  years, for different purposes. While several types of pathologies have been studied, stapedial disorders were seldomly explored. This papers aims to clarify how stapes fracture and some forms of stapes ankylosis, such as stapedial tendon (ST) ossification, augmented pyramidal eminence (PE) and bo ny bar presence, affect the sound transmission through the middle ear. In addition, the stapes dynamics is also analyzed by means of total displacement and first principal strain. For the purpose of the study, first, a three-dimensional fin...
Source: Journal of Biomechanical Engineering - July 31, 2019 Category: Biomedical Engineering Source Type: research

On the Relative Impact of Intraluminal Thrombus Heterogeneity on Abdominal Aortic Aneurysm Mechanics
Intraluminal thrombus (ILT) is present in the majority of abdominal aortic aneurysms (AAA) of a size warranting consideration for surgical or endovascular intervention. The rupture risk of AAAs is thought to be related to the balance of vessel wall strength and the mechanical stress caused by systemic blood pressure. Previous finite element analyses of AAAs have shown that ILT can reduce and homogenize aneurysm wall stress. These works have largely considered ILT to be homogeneous in mechanical character or have idealized a stiffness distribution through the thrombus thickness. In this work, we use magnetic resonance imagi...
Source: Journal of Biomechanical Engineering - July 31, 2019 Category: Biomedical Engineering Source Type: research

Characterization of Ankle Kinematics and Constraint Following Ligament Rupture in a Cadaveric Model
This study suggests that if patients demonstrate primarily an increased laxity in internal ro tation, the damage has solely occurred to the ATFL; however, if the constraint is reduced across multiple motions, there is likely damage to both ligaments. Higher loads in the Achilles suggest that it is overloaded after the injury; hence, targeting the calf muscles in rehabilitation exercises may reduce patients' pain. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - July 31, 2019 Category: Biomedical Engineering Source Type: research

Personalized Design of Functional Gradient Bone Tissue Engineering Scaffold
The porous structure of the natural bone not only has the characteristics of lightweight and high strength but also is conducive to the growth of cells and tissues due to interconnected pores. In this paper, a novel gradient-controlled parametric modeling technology is presented to design bone tissue engineering (BTE) scaffold. First of all, the method functionalizes the pore distribution in the bone tissue, and reconstructs the pore distribution of the bone tissue in combination with the pathological analysis of the bone defect area of the individual patient. Then, based on the reconstructed pore distribution, the Voronoi...
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

Inhibition of Contraction Strength and Frequency by Wall Shear Stress in a Single-Lymphangion Model
The phasic contractions of collecting lymphatic vessels are reduced in strength and occur at diminished frequency when a favorable pressure difference and the resulting antegrade flow create large fluid shear stresses at the luminal surface. This paper describes a minimal phenomenological model of this mechanism that is applied to a previously validated numerical model of a phasically contracting lymphangion. The parameters of the inhibition model are quantitatively matched to observations in isolated segments of rat lymphatic vessel, first for mesenteric lymphatics then for thoracic duct, and outcomes from the numerical m...
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

Two Closely Spaced Aneurysms of the Supraclinoid Internal Carotid Artery: How Does One Influence the Other?
The objective of this study was to use image-based computational fluid dynamics (CFD) techniques to analyze the impact that multiple closely spaced intracranial aneurysm (IAs) of the supra-clinoid segment of the internal carotid artery (ICA) have on each other's hemodynamic characteristics. The vascular geometry of fifteen (15) subjects with 2 IAs was gathered using a 3D digital subtraction angiography clinical system. Two groups of computer models were created for each subject's vascular geometry: both IAs present (model A) and after removal of one IA (model B). Models were separated into two groups based on IA separation...
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

Human Disc Nucleotomy Alters Annulus Fibrosus Mechanics at Both Reference and Compressed Loads
Nucleotomy is a common surgical procedure and is also performed in ex vivo mechanical testing to model decreased nucleus pulposus (NP) pressurization that occurs with degeneration. Here, we implement novel and noninvasive methods using magnetic resonance imaging (MRI) to study internal 3D annulus fibrosus (AF) deformations after partial nucleotomy and during axial compression by evaluating changes in internal AF deformation at reference loads (50  N) and physiological compressive loads (∼10% strain). One particular advantage of this methodology is that the full 3D disc deformation state, inclusive of both in-pla...
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

A Validated, Specimen-Specific Finite Element Model of the Supraspinatus Tendon Mechanical Environment
This study establishes a rigorously validated specimen-specific (both geometry and material properties) computational model using novel surface strain measurements for the use in investigating the function of the supraspinatus tendon and to ultimately predict the propagation of supraspinatus tendon tears based on the tendon's mechanical environment. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

A Primary Computational Fluid Dynamics Study of Pre- and Post-TEVAR With Intentional Left Subclavian Artery Coverage in a Type B Aortic Dissection
The impact of left subclavian artery (LSA) coverage during thoracic endovascular aortic repair (TEVAR) on the circulatory system is not fully understood. Here, we coupled a single-phase non-Newtonian model with fluid –structure interaction (FSI) technique to simulate blood flow in an acute type B aortic dissection. Three-element Windkessel model was implemented to reproduce physiological pressure waves, where a new workflow was designed to determine model parameters with the absence of measured data. Simulatio ns were carried out in three geometric models to demonstrate the consequence of TEVAR with the LSA coverage;...
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

Fracture Mechanism and Fracture Toughness at the Interface Between Cortical and Cancellous Bone
This study observed that J integral of corticellous bone is higher than the cortical bone since more energy is required for plastic deformation of corticellous bone due to crack branches and slowdown at the interface between cortical and cancellous bone. (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

Do Pulmonary Cavity Shapes Influence Lung Function?
Distribution of lung tissue within the chest cavity is a key contributor to delivery of both blood and air to the gas exchange regions of the lung. This distribution is multifactorial with influences from parenchyma, gravity, and level of inflation. We hypothesize that the manner in which lung inflates, for example, the primarily diaphragmatic nature of normal breathing, is an important contributor to regional lung tissue distribution. To investigate this hypothesis, we present an organ-level model of lung tissue mechanics, which incorporates pleural cavity change due to change in lung volume or posture. We quantify the ch...
Source: Journal of Biomechanical Engineering - July 30, 2019 Category: Biomedical Engineering Source Type: research

Assessing the Disturbed Flow and the Transition to Turbulence in the Arteriovenous Fistula
The arteriovenous fistula (AVF) is the main form of vascular access for hemodialysis patients, but its maintenance is very challenging. Its failure is mainly related to intimal hyperplasia (IH), leading to stenosis. The aim of this work was twofold: (i) to perform a computational study for the comparison of the disturbed blood dynamics in different configurations of AVF and (ii) to assess the amount of transition to turbulence developed by the specific geometric configuration of AVF. For this aim, we reconstructed realistic three-dimensional (3D) geometries of two patients with aside-to-end AVF, performing a parametric stu...
Source: Journal of Biomechanical Engineering - July 27, 2019 Category: Biomedical Engineering Source Type: research

Instability of Incompatible Bilayered Soft Tissues and the Role of Interface Conditions
Mechanical stability analysis is instructive in explaining biological processes like morphogenesis, organogenesis, and pathogenesis of soft tissues. Consideration of the layered, residually stressed structure of tissues, requires accounting for the joint effects of interface conditions and layer incompatibility. This paper is concerned with the influence of imposed rate (incremental) interface conditions (RICs) on critical loads in soft tissues, within the context of linear bifurcation analysis. Aiming at simplicity, we analyze a model of bilayered isotropic hyperelastic (neo-Hookean) spherical shells with residual stresse...
Source: Journal of Biomechanical Engineering - July 27, 2019 Category: Biomedical Engineering Source Type: research

Indirect Traumatic Optic Neuropathy Induced by Primary Blast: A Fluid –Structure Interaction Study
Current knowledge of traumatic ocular injury is still limited as most studies have focused on the ocular injuries that happened at the anterior part of the eye, whereas the damage to the optic nerve known as traumatic optic neuropathy (TON) is poorly understood. The goal of this study is to understand the mechanism of the TON following the primary blast through a fluid –structure interaction model. An axisymmetric three-dimensional (3D) eye model with detailed orbital components was developed to capture the dynamics of the eye under the blast wave. Our numerical results demonstrated a transient pressure elevation in ...
Source: Journal of Biomechanical Engineering - July 27, 2019 Category: Biomedical Engineering Source Type: research

Flow Dynamics in the Aortic Arch and Its Effect on the Arterial Input Function in Cardiac Computed Tomography
This study employs computational modeling in a patient-specific aorta to investigate mixing and dispersion of contrast in the aortic arch (AA) and to compa re the TDCs in the coronary ostium and the descending aorta. Here, we examine the validity of the use of TDC in the descending aorta as a surrogate for the AIF. Computational fluid dynamics (CFD) was used to study hemodynamics and contrast dispersion in a CTA-based patient model of the aorta. Variat ions in TDC between the aortic root, through the AA and at the descending aorta and the effect of flow patterns on contrast dispersion was studied via postprocessing of the ...
Source: Journal of Biomechanical Engineering - July 15, 2019 Category: Biomedical Engineering Source Type: research

On the Influence of the Shoulder Kinematic Chain on Joint Kinematics and Musculotendon Lengths During Wheelchair Propulsion Estimated From Multibody Kinematics Optimization
In this study, shoulder kinematics and MT lengths obtained from four shoulder kinematic chains (open-loop thorax-clavicle-scapula-humerus (M1), closed-loop with contact ellipsoid (M2), scapula rhythm from regression equations (M3), and a single ball-and- socket joint between the thorax and the humerus (M4) were compared. Right-side shoulder kinematics from seven subjects were obtained with 34 reflective markers and a scapula locator using an optoelectronic motion capture system while propelling on a MWC simulator. Data were processed based on the four models. The results showed the impact of shoulder kinematic chains on al...
Source: Journal of Biomechanical Engineering - July 13, 2019 Category: Biomedical Engineering Source Type: research

Evaluating Plastic Deformation and Damage as Potential Mechanisms for Tendon Inelasticity Using a Reactive Modeling Framework
In this study, we evaluated these potential mechanisms of tendon inelasticity by using a recently developed reactive inelasticity model (RIE), which is a structurally inspired continuum mechanics framework that models tissue inelasticity based on the molecular bond kinetics. Using RIE, we formulated two material models, one specific to plastic deformation and the other to damage. The models were independently fit to published macroscale experimental tensile tests of rat tail tendons. We quantified the inelastic effects and compared the performance of the two models in fitting the mechanical response during loading, relaxat...
Source: Journal of Biomechanical Engineering - July 13, 2019 Category: Biomedical Engineering Source Type: research

Evaluation of Force Sensing Resistors for the Measurement of Interface Pressures in Lower Limb Prosthetics
Understanding the pressure distributions at the limb-socket interface is essential to the design and evaluation of prosthetic components for lower limb prosthesis users. Force sensing resistors (FSRs) are employed in prosthetics research to measure pressure at this interface due to their low cost, thin profile, and ease of use. While FSRs are known to be sensitive to many sources of error, few studies have systematically quantified these errors using test conditions relevant to lower limb prosthetics. The purpose of this study was to evaluate FSR accuracy for the measurement of lower limb prosthetics interface pressures. T...
Source: Journal of Biomechanical Engineering - July 13, 2019 Category: Biomedical Engineering Source Type: research

Development and Assessment of a Microcomputed Tomography Compatible Five Degrees-of-Freedom Knee Joint Motion Simulator
Currently available knee joint kinematic tracking systems fail to nondestructively capture the subtle variation in joint and soft tissue kinematics that occur in native, injured, and reconstructed joint states. Microcomputed tomography (CT) imaging has the potential as a noninvasive, high-resolution kinematic tracking system, but no dynamic simulators exist to take advantage of this. The purpose of this work was to develop and assess a novel micro-CT compatible knee joint simulator to quantify the knee joint's kinematic and kinetic response to clinically (e.g., pivot shift test) and functionally (e.g., gait) relevant loadi...
Source: Journal of Biomechanical Engineering - July 13, 2019 Category: Biomedical Engineering Source Type: research

Embolus Analog Trajectory Paths Under Physiological Flowrates Through Patient-Specific Aortic Arch Models
Atrial fibrillation (AF) is the most common irregular heartbeat among the world's population and is a major contributor to cardiogenic embolisms and acute ischemic stroke (AIS). However, the role AF flow plays in the trajectory paths of cardiogenic emboli has not been experimentally investigated. A physiological simulation system was designed to analyze the trajectory patterns of bovine embolus analogs (EAs) (n  = 720) through four patient-specific models, under three flow conditions: steady flow, normal pulsatile flow, and AF pulsatile flow. It was seen that EA trajectory paths were proportional to the perce...
Source: Journal of Biomechanical Engineering - July 13, 2019 Category: Biomedical Engineering Source Type: research

In Vivo Layer-Specific Mechanical Characterization of Porcine Stomach Tissue Using a Customized Ultrasound Elastography System
This paper presents in vivo mechanical characterization of the muscularis, submucosa, and mucosa of the porcine stomach wall under large deformation loading. This is particularly important for the development of gastrointestinal pathology-specific surgical intervention techniques. The study is based on testing the cardiac and fundic glandular stomach regions using a custom-developed compression ultrasound elastography system. Particular attention has been paid to elucidate the heterogeneity and anisotropy of tissue response. A Fung hyperelastic material model has been used to model the mechanical response of each tissue la...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

Fluid –Structure Interaction and In Vitro Analysis of a Real Bileaflet Mitral Prosthetic Valve to Gain Insight Into Doppler-Silent Thrombosis
Prosthetic valve thrombosis (PVT) is a serious complication affecting prosthetic heart valves. The transvalvular mean pressure gradient (MPG) derived by Doppler echocardiography is a crucial index to diagnose PVT but may result in false negatives mainly in case of bileaflet mechanical valves (BMVs) in mitral position. This may happen because MPG estimation relies on simplifying assumptions on the transvalvular fluid dynamics or because Doppler examination is manual and operator dependent. A deeper understanding of these issues may allow for improving PVT diagnosis and management. To this aim, we used in vitro and fluid &nd...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

The Effects of Personalized Versus Generic Scaling of Body Segment Masses on Joint Torques During Stationary Wheelchair Racing
In this study, athlete-specific mass segment inertial parameters of the head and neck, torso, upper arm, forearm, hand, thigh, shank, and feet for five elite wheelchair athletes were calculated using dual-energy X-ray absorptiometry (DXA) scans. These were compared against commonly used anthropometrics parameters of data presented in the literature. A computational biomechanical simulation of wheelchair propulsion using the upper extremity dynamic model inopensim assessed the sensitivity of athlete-specific mass parameters using Kruskal –Wallis analysis and Spearman correlations. Substantial between-athlete body mass...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

Anchor Hole Placement for Bankart Repairs and Its Interaction With Variable Size Hill –Sachs Defects-Minimizing Risk of Glenoid Rim Fractures
This study used finite element modeling techniques to investigate the risk of fracture of the glenoid rim in relation to variable sized Hill–Sachs defects impacting on the anterior glen oid edge with suture anchor holes placed in varying positions. The distribution of Von Mises (VM) stresses and the factor of safety (FOS) for each of the configurations were calculated. The greatest peak in VM stresses was generated when the glenoid was loaded with a small Hill–Sachs lesion. The V M stresses were lessened and the FOS increased (reducing likelihood of failure) with increasing size of the Hill–Sachs lesion. ...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

The Effects of Personalized Versus Generic Scaling of Body Segment Masses on Joint Torques During Stationary Wheelchair Racing
In this study, athlete-specific mass segment inertial parameters of the head and neck, torso, upper arm, forearm, hand, thigh, shank, and feet for five elite wheelchair athletes were calculated using dual-energy X-ray absorptiometry (DXA) scans. These were compared against commonly used anthropometrics parameters of data presented in the literature. A computational biomechanical simulation of wheelchair propulsion using the upper extremity dynamic model inopensim assessed the sensitivity of athlete-specific mass parameters using Kruskal –Wallis analysis and Spearman correlations. Substantial between-athlete body mass...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

Fluid –Structure Interaction and In Vitro Analysis of a Real Bileaflet Mitral Prosthetic Valve to Gain Insight Into Doppler-Silent Thrombosis
Prosthetic valve thrombosis (PVT) is a serious complication affecting prosthetic heart valves. The transvalvular mean pressure gradient (MPG) derived by Doppler echocardiography is a crucial index to diagnose PVT but may result in false negatives mainly in case of bileaflet mechanical valves (BMVs) in mitral position. This may happen because MPG estimation relies on simplifying assumptions on the transvalvular fluid dynamics or because Doppler examination is manual and operator dependent. A deeper understanding of these issues may allow for improving PVT diagnosis and management. To this aim, we used in vitro and fluid &nd...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

Anchor Hole Placement for Bankart Repairs and Its Interaction With Variable Size Hill –Sachs Defects-Minimizing Risk of Glenoid Rim Fractures
This study used finite element modeling techniques to investigate the risk of fracture of the glenoid rim in relation to variable sized Hill–Sachs defects impacting on the anterior glen oid edge with suture anchor holes placed in varying positions. The distribution of Von Mises (VM) stresses and the factor of safety (FOS) for each of the configurations were calculated. The greatest peak in VM stresses was generated when the glenoid was loaded with a small Hill–Sachs lesion. The V M stresses were lessened and the FOS increased (reducing likelihood of failure) with increasing size of the Hill–Sachs lesion. ...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

In Vivo Layer-Specific Mechanical Characterization of Porcine Stomach Tissue Using a Customized Ultrasound Elastography System
This paper presents in vivo mechanical characterization of the muscularis, submucosa, and mucosa of the porcine stomach wall under large deformation loading. This is particularly important for the development of gastrointestinal pathology-specific surgical intervention techniques. The study is based on testing the cardiac and fundic glandular stomach regions using a custom-developed compression ultrasound elastography system. Particular attention has been paid to elucidate the heterogeneity and anisotropy of tissue response. A Fung hyperelastic material model has been used to model the mechanical response of each tissue la...
Source: Journal of Biomechanical Engineering - July 11, 2019 Category: Biomedical Engineering Source Type: research

Dr. Y. C. Fung's Contributions to Biomechanics, Bioengineering, and Humanity: Warmest Celebration for a Magnificent Centenarian
Professor Y. C. Fung has made superb contributions to science, engineering, and humanity through his research and its applications, as well as his words and deeds. By setting the highest standards of rigor and excellence, training many outstanding students and their students, and providing his exemplary leadership, Dr. Fung has made tremendous impacts that spread across the world and transcend time. He established the foundations of biomechanics in a variety of living tissues, including the lung, the heart, blood vessels, blood cells, ureter, intestine, skin, as well as other organs and tissues. Through his vision of the p...
Source: Journal of Biomechanical Engineering - July 10, 2019 Category: Biomedical Engineering Source Type: research

Special Issue: A Tribute to Dr. Y. C. Fung
This September we celebrate the 100th birthday of Professor Y. C. Fung, the Father of Biomechanics. There are multiple events organized in the biomechanics and biomedical engineering communities in honor of Professor Fung, including the YC Fung symposium at the Summer Biomechanics, Bioengineering and Biotransport Conference (SB3C2019) in Seven Spring, PA in June and the YC Fung symposium at San Diego, CA in September. A special issue has been published by theJournal of Medical Biomechanics [1]. The ASMEJournal of Biomechanical Engineering organized this special issue titled “Special Issue: A Tribute to Dr. Y. C Fung,...
Source: Journal of Biomechanical Engineering - July 10, 2019 Category: Biomedical Engineering Source Type: research

Three-Dimensional Kinematic Coupling of the Healthy Knee During Treadmill Walking
Accurate joint kinematics plays an important role in estimating joint kinetics in musculoskeletal simulations. Biplanar fluoroscopic (BPF) systems have been introduced to measure skeletal kinematics with six degrees-of-freedom. The purpose of this study was to model knee kinematic coupling using knee kinematics during walking, as measured by the BPF system. Seven healthy individuals (mean age, 23  ± 2 yr) performed treadmill walking trials at 1.2 m/s. Knee kinematics was regressed separately for the swing and stance phases using a generalized mixed effects model. Tibial anterior translati...
Source: Journal of Biomechanical Engineering - May 23, 2019 Category: Biomedical Engineering Source Type: research

Machine Learning-Based Pre-Impact Fall Detection Model to Discriminate Various Types of Fall
In this study, a robust pre-impact fall detection model was developed to classify various activities and falls as multiclass and its performance was compared with the performance of previous developed models. Twelve healthy subjects participated in this study. All subjects were asked to place an inertial measuring unit module by fixing on a belt near the left iliac crest to collect accelerometer data for each activity. Our novel proposed model consists of feature calculation and infinite latent feature selection (ILFS) algorithm, auto labeling of activities, and application of machine learning classifiers for discrete and ...
Source: Journal of Biomechanical Engineering - May 13, 2019 Category: Biomedical Engineering Source Type: research

Thermodynamic Theory and Experimental Validation of a Multiphase Isochoric Freezing Process
Freezing of the aqueous solutions that comprise biological materials, such as isotonic physiological saline, results in the formation of ice crystals and the generation of a hypertonic solution, both of which prove deleterious to biological matter. The field of modern cryopreservation, or preservation of biological matter at subfreezing temperatures, emerged from the 1948 discovery that certain chemical additives such as glycerol, known as cryoprotectants, can protect cells from freeze-related damage by depressing the freezing point of water in solution. This gave rise to a slew of important medical applications, from the ...
Source: Journal of Biomechanical Engineering - May 13, 2019 Category: Biomedical Engineering Source Type: research

Regression Models for the Erector Spinae Muscle Mass (ESMM) Cross-Sectional Area: Asymptomatic Populations
The objective is to perform morphological analyses and then provide regression models to estimate the ESMM CSA of an individual with his/her subject characteristics. Thirty-five subjects (13 females and 22 males) without low back pain (LBP) history were included in this magnetic resonance imaging (MRI) study. Axial-oblique scans of low back region were used to measure the ESMM CSA. Subject demographics and anthropometrics were obtained and regressed over the ESMM CSA. Best-subset regression analyses were performed. Lean body mass (LBM) and the ankle, wrist, and head indexes were the most frequent predictive variables. Regr...
Source: Journal of Biomechanical Engineering - May 13, 2019 Category: Biomedical Engineering Source Type: research

Relative Motion Between the Helmet and the Head in Football Impact Test
Approximately 1.6 –3.8 million sports-related traumatic brain injuries occur each year in the U.S. Researchers track the head motion using a variety of techniques to study the head injury biomechanics. To understand how helmets provide head protection, quantification of the relative motion between the head and the helmet is necessary. The purpose of this study was to compare helmet and head kinematics and quantify the relative motion of helmet with respect to head during experimental representations of on-field American football impact scenarios. Seven helmet-to-helmet impact configurations were simulated by propelli...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

The Phan-Thien and Tanner Model Applied to the Lubrication of Knee Prostheses
This work aims to provide a contribution to determine a proper model for the study of fluid film lubrication for the reduction of knee prostheses failure due to polyethylene wear. The Phan-Thien and Tanner (PTT) rheological law and the elastic deformation of the articular surfaces were considered in this modeling. The governing equations were solved numerically for different geometries and different Weissenberg numbers. The lubrication approximation applied to the PTT rheological law leads to an expression for the apparent viscosity similar to the Cross model. The results attest the importance of considering the non-Newton...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Computational Modeling of Developing Cartilage Using Experimentally Derived Geometries and Compressive Moduli
During chondrogenesis, tissue organization changes dramatically. We previously showed that the compressive moduli of chondrocytes increase concomitantly with extracellular matrix (ECM) stiffness, suggesting cells were remodeling to adapt to the surrounding environment. Due to the difficulty in analyzing the mechanical response of cells in situ, we sought to create an in silico model that would enable us to investigate why cell and ECM stiffness increased in tandem. The goal of this study was to establish a methodology to segment, quantify, and generate mechanical models of developing cartilage to explore how variations in ...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Cholesterol-Dependent Modulation of Stem Cell Biomechanics: Application to Adipogenesis
Cell mechanics has been shown to regulate stem cell differentiation. We have previously reported that altered cell stiffness of mesenchymal stem cells can delay or facilitate biochemically directed differentiation. One of the factors that can affect the cell stiffness is cholesterol. However, the effect of cholesterol on differentiation of human mesenchymal stem cells remains elusive. In this paper, we demonstrate that cholesterol is involved in the modulation of the cell stiffness and subsequent adipogenic differentiation. Rapid cytoskeletal actin reorganization was evident and correlated with the cell's Young's modulus m...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Bridging Finite Element and Machine Learning Modeling: Stress Prediction of Arterial Walls in Atherosclerosis
In this study, we develop a parametric model to generate arterial geometries and accumulate a database of 12,172 2D finite element simulations modeling the hyperelastic behavior and resulting stress distribution. The arterial wall composition mimics vessels in atherosclerosis –a complex cardiovascular disease and one of the leading causes of death globally. We formulate the training data to predict the maximum von Mises stress, which could indicate risk of plaque rupture. Trained deep learning models are able to accurately predict the max von Mises stress within 9.86% error on a held-out test set. The deep neural net...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

MMP12 Deletion Preferentially Attenuates Axial Stiffening of Aging Arteries
Arterial stiffening is a hallmark of aging, but how aging affects the arterial response to pressure is still not completely understood, especially with regard to specific matrix metalloproteinases (MMPs). Here, we performed biaxial inflation –extension tests on C57BL/6 mice to study the effects of age and MMP12, a major arterial elastase, on arterial biomechanics. Aging from 2 to 24 months leads to both circumferential and axial stiffening with stretch, and these changes are associated with an increased wall thickness, a decreased i nner radius–wall thickness ratio, and a decreased in vivo axial stretch....
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Effects of Collagenase Type II on Vitreous Humor —An In Situ Rheological Study
We examined thirty-eight porcine eyes using in situ rheological creep tests to measure the mechanical properties of the vitreous humor of the eyes prior to, 1  h and 24 h after the intravitreal injection. Eyes in one group were injected with collagenase type II solution and eyes in the control group were injected with phosphate buffered saline solution (PBS) with calcium and magnesium chloride. Prior to the injection, viscosity and creep compliance in tercept values between both groups were not statistically different. At 1 h and 24 h after the injection, vitreous properties in the eyes from the...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Simulated Tremor Propagation in the Upper Limb: From Muscle Activity to Joint Displacement
Although tremor is the most common movement disorder, there are few noninvasive treatment options. Creating effective tremor suppression devices requires a knowledge of where tremor originates mechanically (which muscles) and how it propagates through the limb (to which degrees-of-freedom (DOF)). To simulate tremor propagation, we created a simple model of the upper limb, with tremorogenic activity in the 15 major superficial muscles as inputs and tremulous joint displacement in the seven major DOF as outputs. The model approximated the muscle excitation –contraction dynamics, musculoskeletal geometry, and mechanical...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Changes in Shear Modulus of the Lumbar Multifidus Muscle During Different Body Positions
The objective of this study is to evaluate localized force production capability in multifidus muscle using ultrasound shear wave elastography (SWE) in healthy individuals. Three different body positions were considered: lying prone, sitting up, and sitting up with the right arm lifted. These positions were chosen to progressively increase multifidus contraction and to minimize body motion during measurements. Shear modulus was measured at the superficial and deeper layers of the multifidus. Repeatability and possible sources of error of the shear modulus measurements were analyzed. Multifidus shear modulus (median (interq...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Using Torque-Angle and Torque –Velocity Models to Characterize Elbow Mechanical Function: Modeling and Applied Aspects
Characterization of muscle mechanism through the torque-angle and torque –velocity relationships is critical for human movement evaluation and simulation. in vivo determination of these relationships through dynamometric measurements and modeling is based on physiological and mathematical aspects. However, no investigation regarding the effects of the mathematical mode l and the physiological parameters underneath these models was found. The purpose of the current study was to compare the capacity of various torque-angle and torque–velocity models to fit experimental dynamometric measurement of the elbow and pr...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Transepidermal Potential of the Stretched Skin
The electrical response of the skin to mechanical stretches is reported here. The electrical potential difference across the epidermis, i.e., transepidermal potential (TEP) of porcine skin samples subjected to cyclic stretching, was measured in real time to observe electrochemical change in epidermal tissue. In addition to a conventional method of TEP measurement for the whole of skin sample, a probe-type system with a fine-needle salt bridge was used for direct measurement of TEP at a targeted local point of the skin. TEP decreased with the increased mechanical stretches, and the change of TEP was found to be mostly occur...
Source: Journal of Biomechanical Engineering - May 6, 2019 Category: Biomedical Engineering Source Type: research

Journal of Biomechanical Engineering: Legacy Paper 2018
TheJournal of Biomechanical Engineering has contributed to biomechanical engineering field since 1977. To honor papers published at least 30  years that have had a long-lasting impact on the field, the Editors now recognize “Legacy Papers.” The journal is pleased to present the following paper as this year's Legacy Paper: (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - May 3, 2019 Category: Biomedical Engineering Source Type: research

2018 Editors' Choice Papers
As part of the Annual Special Issue, the JBME Associate Editors selected the top papers published in the journal during 2018. Those Editors' Choice papers, listed below in chronological order, exemplified both the high quality and the breadth of papers published in the journal. Congratulations to these authors and to all authors whose work appeared in JBME over the past year! (Source: Journal of Biomechanical Engineering)
Source: Journal of Biomechanical Engineering - May 3, 2019 Category: Biomedical Engineering Source Type: research