bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intimal Hyperplasia — Development and Regression in Response to Fluid Shear
Authors: Berceli Scott A. , Clowes Alexander W. 
Published: December 2021

Abstract
The long-term success of autogenous and prosthetic bypass grafts is dictated by the development and subsequent progression of intimal hyperplasia. While recent advances in vascular biology continue to improve our understanding of the mechanisms which control this process, available clinical therapies which treat or slow its progression have yet to be identified. Among the factors which influence the development of intimal hyperplasia are the physical forces exposed to bypass conduits. As initially described by Glagov et al. (1988) and confirmed by multiple other investigators, the biology of the hyperplastic response is modulated by the imposed fluid shearing forces While our ability to modulate the local hemodynamics of bypass conduits is limited, an understanding of how these forces govern the healing response can serve as a basis for future pharmacological therapies. In our laboratory we have employed a primate model to understand the influence of shear stress on the development of intimal hyperplasia in PTFE grafts.
Artery as a Pressure Vessel: Correlation Between Stress Concentration and Pathology
Authors: Thubrikar Mano J. , Robicsek Francis 
Published: December 2021

Abstract
Arterial disease most often can be classified in one of two categories — aneurysm and atherosclerosis. Interestingly enough these diseases affect the artery only at certain locations rather than the whole organ, i.e., the diseases have predilection for certain sites. Furthermore, some of the sites are common to both the diseases and at some sites, not so infrequently, the diseases occur together one preceding the other.
Computational Modeling of Platelet Aggregation
Authors: Fogelson Aaron , Yu Haoyu 
Published: December 2021

Abstract
Platelet aggregation is an essential component of normal hemostasis and pathological thrombosis. It involves complex, dynamic, often competitive, mechanical and chemical interactions among platelets, fluid, and vessel wall, the balance among which determines whether and to what extent aggregate growth occurs and persists. It is very difficult in a laboratory setting to measure more than a few quantities of interest, and usually only at a few spatial locations or a few times. From such measurements, it is very hard to piece together a coherent picture of the dynamics. Further it is very difficult to control more than a couple of the players involved. Mathematics, by contrast, is well suited for studying the evolution of a complex system, and for precisely controlling the inputs into the system. It can provide a wealth of temporal and spatial detail about the interactions taking place. It allows for extraction of ‘essential’ elements of the complex system, and through study of the behavior of the simplified system can provide insight into the workings of the true biological system. It thus complements more traditional experimental approaches. But the mathematical study of platelet aggregation presents its own substantial challenges, among them how to handle the mechanical interactions between fluid and platelets, platelets and other platelets, and platelets and vessels walls. This talk is addressed at ways to meet these challenges.
Acoustically Modulated Speckle Imaging of Soft Tissue
Authors: Kirkpatrick Sean J. , Jacques Steven L. 
Published: December 2021

Abstract
Previous research has demonstrated the usefulness of employing laser speckle and dynamic optical coherence measurements in medical imaging. For example, Briers (1993) discussed speckle fluctuations to detect movement within tissue and Zimnyakov et al., (1997) described a camera system that uses speckle fluctuations to monitor tissue structure. Speckle metrology has been used to evaluate displacements and strains in biological hard tissues, such as bone, particularly in the vicinity of implants (Shelton and Kate, 1991). Kirkpatrick and Brooks (1998) demonstrated a speckle technique for directly evaluating strain rates in cortical bone.
Thermal Modification of Collagen
Authors: Torzilli Peter A. , Wall Michael S. , Deng Xiang-Hua , O’Brien Stephen J. , Warren Russell F. 
Published: December 2021

Abstract
Shoulder capsular (collagen) shrinkage has recently been advocated as a therapeutic modality in a select group of patients with multidirectional instability. Tissue shrinkage is a function of temperature and time. This relationship was studied and two models were derived to describe the relationship mathematically for shrinkage and mechanical properties.
Isotonic Biaxial Loading: An Economic, Versatile Method for the Study of Fibroblast-Populated Collagen Gels
Authors: Holmes Jeffrey W. , Borg Thomas K. 
Published: December 2021

Abstract
Studies of collagen gel contraction by embedded fibroblasts have characterized the response of free (unloaded) or isometric (maximally loaded) gels but not the response to intermediate loads. An inexpensive, simple system was devised to isotonically load fibroblast-populated collagen gels using freely hanging weights. This system provided excellent repeatability. Maximal contraction force was estimated at 1 mN per million cells in neonatal rat cardiac fibroblasts, a value that agreed well with reported isometric experiments in fibroblasts from other tissues. The ability to load uniaxially or biaxially and with variable loads will facilitate exploration of the regulation of fibroblast mechanics and biology by stress.
Contractility Affects Stress Fiber Remodeling and Reorientation of the Endothelial Cells in Response to Mechanical Stretching
Authors: Wang James H.-C. , Yin Frank C.-P. 
Published: December 2021

Abstract
Actin cytoskeletal stress fibers are thought to be the major cellular constituents responsible for cell shape and locomotion. As such, stress fiber remodeling likely plays a major role in the cell reorientation responses to mechanical stimuli (Iba and Sumpio, 1991). The assembly and dis-assembly of stress fibers in non-muscle cells are mediated by contractility via the interaction of actin and myosin (Chrzanowska-Wodnicka and Burridge, 1996). Reactive oxygen species (ROS) also play an important role in organization of stress fibers (Hinshaw et al., 1991). Since cyclic stretching can enhance production of certain ROS, including H2O2 (Howard et al., 1997) and H2O2 stimulates, in a time- and dose-dependent manner, myosin light chain (MLC) phosphorylation (Zhao and Davis, 1998), stress fiber remodeling and cell reorientation in response to cyclic stretching should be affected by changes in contractility — including changes in ROS. The roles of these factors have not been carefully examined.
Protein Conformational Changes Under Applied Forces
Authors: Xu Yangqing , Bao Gang 
Published: December 2021

Abstract
Recent studies confirm that stresses, including that due to gravity, tension, compression, pressure, and shear influence cell growth, differentiation, secretion, movement, signal transduction, and gene expression. Yet, little is known about how cells sense the mechanical stresses or deformations, and convert these mechanical signals into biological or biochemical responses. A possible mechno-chemical coupling mechanism involves protein conformational changes under mechanical forces. Our hypothesis is that mechanical forces can cause large changes of the conformation of proteins, which in turn can influence receptor-ligand binding. To test this hypothesis, molecular dynamics simulations and biochemical assays are performed.
The Effect of Motion Path on the Wear Rate of UHMWPE for Orthopaedic Implants
Authors: Sprague Jeff A. , Sauer Willard L. 
Published: December 2021

Abstract
The effect of adding a second axis of motion was investigated for pin-on-disk wear testing of ultra-high-molecular-weight polyethylene (UHMWPE) for orthopaedic implant applications. In addition to linear reciprocation of the UHMWPE or metal disk, axial rotation of the metal or UHMWPE pin was conducted. The added rotation reproduces the cross-shear on the UHMWPE surface that is generated in clinically relevant wear simulator tests and in vivo. The wear rates that result from the multi-axis pin-on-disk tests are significantly higher (one to two orders of magnitude) than those seen in the linear-only tests. This supports the findings of other researchers (Bragdon et al., 1996; McKellop, 1995; Walker et al., 1996; Wang et al. 1997) in that the application of nonlinear motion increases the wear of UHMWPE substantially. This is further validated by the comparison of a hip simulator wear test conducted with three axes of motion — rotation, flexion, and abduction — to a test conducted with two axes of motion — rotation and flexion. The absence of the abduction eliminated a significant degree of nonlinear motion (cross-shear) and, consequently, the wear rate was significantly lower than that seen in the test with abduction.
Effect of Wear on Kinematics of a TKR: A Simulator Comparison of Molded and Machined UHMWPE Tibial Plateaus
Authors: Benson Lisa C. , DesJardins John D. , Schroeder David W. , LaBerge Martine 
Published: December 2021

Abstract
The wear and mechanical performance of identically designed total knee replacement (TKR) tibial bearing surfaces, which differed only in manufacturing process, were evaluated using a Stanmore KC Four Station Knee Joint Simulator. The first group utilized Co-Cr-Mo alloy femoral components with ultra-high molecular weight polyethylene (UHMWPE) tibial bearings processed by direct compression molding. The second group was identical to the first, except that the UHMWPE components were machined from a compression molded sheet. The implant alignment and testing conditions were identical for both series, with a 1 Hz standardized force-controlled walking cycle being employed for a duration of 3 million cycles. Gravimetric wear and surface roughness of the UHMWPE components were quantified every 1 million cycles. Measures of implant mechanics and kinematics were quantified every 0.1 million cycles. Results show that molded UHMWPE exhibited less wear (12 mg/million cycles) and no changes in kinematics. Moreover, the higher rate of wear (18 mg/million cycles) in the machined components was correlated with a statistically significant change in implant kinematics.
Three-Dimensional Lubrication Model of an Artificial Hip Joint With Gait Analysis
Authors: Meyer Donna M. , Tichy John A. 
Published: December 2021

Abstract
The development of the hip prosthesis is a result of extensive collaboration between the medical and engineering fields. Although the technology to replace ailing human joints with artificial replicas is quite advanced, these remarkable advances require additional attention. In particular, extending the service life of a hip prosthesis is a primary consideration. An artificial hip joint may require revision surgery due to a number of contributions, one of which is extensive wear. Within the first few years following hip implantation, high amounts of wear particles form due to the contact of the articulating surfaces. The amounts of wear debris generated is a function of the material combinations of the rubbing surfaces of the joint, the amount of lubrication present in the joint during activity and the types and levels of activity.
Mechanical Degradation of Retrieved UHMWPE Tibial Components Characterized by the Small Punch Test
Authors: Kurtz S. M. , Jewett C. W. , Kalinowski A. , Rimnac C. M. , Edidin A. A. 
Published: December 2021

Abstract
Miniature specimen testing techniques are necessary to characterize the mechanical behavior of UHMWPE components for total joint replacement after sterilization, shelf aging, and implantation. The small punch test has been shown to reproducibly characterize virgin and in vitro aged UHMWPE. The first goal of this study was to demonstrate the feasibility of applying this technology to UHMWPE components after retrieval from the human body. Six short-term retrievals of the same tibial design were characterized with the intent of comparing the mechanical behavior of conventional and enhanced UHMWPE having an extended chain crystalline morphology. Statistically significant relationships were observed between damage scores and the small punch test metrics of initial load, ultimate load, and work to failure. The results of this study support the hypothesis that the in vivo performance of tibial bearings is related to the large deformation mechanical behavior of UHMWPE.
Rotational Stiffness Adjustability of a Prototype Foot/Ankle Prosthesis
Authors: Quesada Peter M. , Hays John A. , Pitkin Mark R. , Colvin James M. 
Published: December 2021

Abstract
Mechanical testing was conducted for a prototype prosthetic foot/ankle component to assess the potential for being able to adjust dynamic rotational stiffness of the prototype in a simple but quantitative manner. The tested prototype has been dubbed the rolling joint ankle (RJA) prosthesis. The RJA prototype design is based on a concept in which rotational stiffness is lower with the ankle position closer to neutral, and increases as ankle rotation moves away from neutral. Adjustment of the RJA prototype’s stiffness involved systematic tightening and loosening of two set screws. Two sets of mechanical testing were conducted at each of three different loading rates to evaluate repeatability of rotational stiffness and to examine the effects of loading rate on RJA stiffness.
Effects of Mechanical Loading and Interstitial Fluid Pressure on Bone Remodeling
Authors: Turner Charles H. 
Published: December 2021

Abstract
Mechanical loading clearly affects bone remodeling (by remodeling, I refer to the process of removal and replacement of bone tissue rather than bone shape changes). Bone remodeling is minimal under normal physiological conditions, but becomes elevated under disuse or extreme overuse (Figure 1). In each case, the mechanism for elevated remodeling is probably quite different. Elevated bone remodeling in overuse is probably caused by microdamage accumulation in the bone tissue. Microdamage causes site-directed bone remodeling [1,2], preceded by osteocyte apoptosis [3]. Conversely, elevated bone remodeling in disuse is not due to tissue microdamage but probably diminished tissue perfusion. In bone subject to disuse, osteocytes show signs of hypoxia within three days and remodeling becomes elevated a few days later [4]. Therefore elevated bone remodeling is preceded by osteocyte distress regardless of whether it is caused by disuse or overuse, suggesting that osteocytes play an important role in the signal cascade leading to elevated bone remodeling. Osteocytes form a highly interconnected network within the bone matrix which has signal processing capabilities, yet is unclear how osteocytes process information, e.g., microdamage. In this paper some effects of disuse and overuse on bone remodeling are discussed with the goal of outlining the key mechanical parameters important for bone remodeling.
Strain Amplification in the Bone Mechanosensory System
Authors: You Lidan , Cowin Stephen C. , Weinbaum Sheldon 
Published: December 2021

Abstract
In this work we suggest a mechanism whereby the bone deformation driven flow of bone fluid through the glycocalyx surrounding an osteocytic cell process in its canaliculus will lead to strains in the cell process membrane which are many times those in the whole bone. We shall describe a mechanism whereby the low magnitude of the strain applied to the whole bone (0.1% to 0.3%) is amplified by nearly two orders of magnitude at the membrane of the cell process. The possibility of this strain amplification depends upon the values of the certain physical and biological parameters. These parameters include the elastic constants of the cell membrane, the elastic constants of the fibers that constitute the glycocalyx. the pre-tension in the fibers and cell membrane, the permeability of bone fluid through the glycocalyx, the physical dimensions of the cell process, the canaliculus, the fibers and fiber spacing of the glycocalyx.
The model employed is an interactive micro-macro mechanical model. It was analyzed numerically. The micro model is a detailed model of the structure and contents of a canaliculus and the macro model is poroelasticity. A mechanical loading range from 1 MPa to 20 MPa at different frequencies, 1Hz to 20Hz, were considered. We calculated the ratio of the drag force on the fibers to the shear force on the osteocyte membrane in a canaliculus and found that the drag force is at least 50 times larger than the shear on the cell membrane. We also calculated the strain al the membrane, as well as the strain amplification ratio, and found that the strain amplification ratio reached a maximum value of 65 for this loading range. Thus the proposed mechanism amplifies the strain applied to the whole bone when it is experienced at the osteocyte process membrane.
The Dependence of the Elastic Constants of Cancellous Bone Upon Volume Fraction
Authors: Yang Guoyu , Cowin Stephen C. , Kabel Jesper , Odgaard Anders , van Rietbergen Bert , Huiskes Rik 
Published: December 2021

Abstract
A simple and explicit representation for the anisotropic elastic constants of human cancellous bone was determined using a new method of analysis on a data base consisting of 141 human cancellous bone specimens. The method of analysis shows that human cancellous bone has orthotropic elastic symmetry at the 95% confidence level and it also provides expressions for all the orthotropic elastic constants as functions of the volume fraction of solid only; no stereological measures of trabecular architecture are involved. This result should be employed to improve the in vivo evaluation of cancellous bone stiffness and strength from a standard clinical test.
Kinematic and Kinetic Analyses in Full-Body Asymmetric Lifting
Authors: Li Yi-Chun , Lavender Steven A. , Natarajan Raghu N. , Andersson Gunnar B. J. , Amirouche Faird M. L. 
Published: December 2021

Abstract
Biomechanical models had been used to conduct a series of lifting related experiments which were performed to understand different parameters such as asymmetry, lifting speed, load magnitude, lifting techniques, fatigue, etc. These studies were performed either in Bottom-Up or Top-Down models to predict kinematic or kinetic data in each inter-segment joint. Bureau of Labor Statistics (1995) [1] reported that in 1994, 367,424 injuries due to overexertion in lifting had 65% affected the back; 93,325 injuries due to overexertion in pushing or pulling, 52% affected the back; 68,992 injuries due to overexertion in holding, carrying, or truning, 58% affected the back; and totaled across these three categories, 47,861 disorders affected the shoulder [2]. Since lifting activities are whole body motion and each inter-segment joint cannot be treated as individual, the synchronization of all body joints should be considered during lifting tasks. Therefore the whole-body posture, kinematic, and kinetic analyses were included in this study. The whole-body posture analysis included lift duration, peak box velocity and acceleration, and the orientation of the trunk and pelvis segment; the whole-body kinematic analysis contained angular displacement, velocity, and acceleration of all body joints; and the whole-body kinetic analysis consisted of the inertial forces and inertial moment of each body segment, and the local forces and moments of each inter-segment joint.
Biomechancial Stability of an Artificial Cervical Joint
Authors: DiAngelo Denis J. , Davis Champ , Robertson James T. 
Published: December 2021

Abstract
Anterior cervical discectomy with or without fusion is an acceptable surgical method for the treatment of cervical spondylosis or other spinal disc diseases. A spinal device may be used to immobilize the operated/injured region to promote bony fusion. Clinical studies have shown that motion at spinal segments adjacent to a fused region increases over time and may cause adjacent segment problems [Chow et al., 1996; Lee et al., 1988]. Multiple factors have been implicated, including the number of levels fused, health condition, post-operative alignment, and rigid fixation. An alternative approach to fusion surgery of the cervical spine is to restore the motion to the diseased joint using a movable artificial cervical joint (MACJ). The objective of the study was to determine the biomechanical stability of the harvested and instrumented cervical spine tested under physiologic flexion/extension and lateral bending loading mechanics. The instrumented spine consisted of a single level discectomy with subsequent disc replacement using a prototype artificial intervertebral disc implant by the Sofamor Danek Group, Memphis, TN.
Coupled Rigid-Deformable Body Formulation for Analysis of Joint Stress and Deformation During Gait
Authors: Hovey Chad B. , Heegaard Jean H. 
Published: December 2021

Abstract
Analysis of human gait often uses rigid body dynamics to predict joint motions and forces [Andriacchi, et al., 1997]. While these approaches can help identify healthy and pathological human movement, the rigid body assumption does not allow determination of stress and deformation within the joint. This information is desirable not only to help understand the etiology of joint disease, but also for determining how joint replacements will perform once implanted. Finite element analysis, used to determine joint stress and deformation, employs boundary conditions which are intended to simulate physiological conditions [Maxian, et al, 1996]. Because these boundary conditions are defined a priori, it remains unclear as to how well these applied tractions and displacements match what is truly occurring during human motion.
Dynamic Response Analyses of Rabbit Knee Joint
Authors: Kasra M. , Grynpas M. D. , Shirazi-Adl A. 
Published: December 2021

Abstract
The knee joint is a complex nonlinear dynamic system. It is generally known that mechanical factors play an important role in the etiology of knee injuries and diseases such as osteoarthritis. While performing daily activities such as walking, running, and climbing as well as during occupational operations, the joint is exposed to vibrations and multiple impacts. During these activities, according to an individual’s condition (e.g., age, fitness, weight), the joint load and stiffness may reach critical limits initiating or accelerating different knee disorders. This is the case in athletes or workers during occupational activities (1). Therefore, understanding the dynamic characteristics of the knee joint is essential in prediction and prevention of knee disorders as well as in subsequent joint replacement and rehabilitation procedures. There have been very few reported experimental studies investigating the dynamic behavior of the whole knee joint as a dynamic system (2). The objective of this study was to investigate the changes in mechanical properties of the rabbit knee joint under different compressive dynamic loading conditions. Rabbit has frequently been used as an osteoarthritic knee model (3). The data obtained in this study, hence, will also be beneficial in our future studies of osteoarthritic rabbit models.