Experimental and Computational Modeling of Joint and Ligament Mechanics

2004 ◽  
Vol 20 (4) ◽  
pp. 450-474 ◽  
Author(s):  
Richard E. Debski ◽  
Shon P. Darcy ◽  
Savio L-Y. Woo
Keyword(s):  
Computational Models ◽  
Soft Tissues ◽  
Experimental Studies ◽  
Complex Loading ◽  
External Loading ◽  
Spring Model ◽  
Loading Conditions ◽  
Rehabilitation Protocols ◽  
Force Moment

Quantitative data on the mechanics of diarthrodial joints and the function of ligaments are needed to better understand injury mechanisms, improve surgical procedures, and develop improved rehabilitation protocols. Therefore, experimental and computational approaches have been developed to determine joint kinematics and the in-situ forces in ligaments and their replacement grafts using human cadaveric knee and shoulder joints. A robotic/universal force-moment sensor testing system is used in our research center for the evaluation of a wide variety of external loading conditions to study the function of ligaments and their replacements; it has the potential to reproduce in-vivo joint motions in a cadaver knee. Two types of computational models have also been developed: a rigid body spring model and a displacement controlled spring model. These computational models are designed to complement and enhance experimental studies so that more complex loading conditions can be examined and the stresses and strains in the soft tissues can be calculated. In the future, this combined approach will improve our understanding of these joints and soft tissues during in-vivo activities and serve as a tool to aid surgical planning and development of rehabilitation protocols.

Modeling of a Dynamic Knee Simulator With Advanced PID Controller to Evaluate Joint Loading Conditions

2014 ◽  
Author(s):  
Fallon Fitzwater ◽  
Amber Lenz ◽  
Lorin Maletsky
Keyword(s):  
Computational Models ◽  
Total Joint Replacement ◽  
External Loading ◽  
Loading Conditions ◽  
Dynamic Simulations ◽  
Knee Simulator ◽  
Joint Loads ◽  
External Loads

In-vitro dynamic knee simulators allow researchers to investigate changes in natural knee biomechanics due to pathologies, injuries or total joint replacement. The advent of the instrumented tibia, which directly measures knee loads in-vivo, has provided a wealth data for various activities that in-vitro studies now aim to replicate [1, 2]. Dynamic knee simulators, such as the Kansas Knee Simulator (KKS), achieve these physiological loads at the joint by applying external loads to either bone ends or musculature. Determining the external loading conditions necessary to replicate activity specific joint loads, obtained from instrumented tibia data, during dynamic simulations are calculated using computational models.

The Effect of Muscle Loading on Internal Mechanical Parameters of the Lumbar Spine: A Finite Element Study

2011 ◽  
Author(s):  
Benjamin C. Gadomski ◽  
John Rasmussen ◽  
Christian M. Puttlitz
Keyword(s):  
Annulus Fibrosus ◽  
Critical Role ◽  
Complex Loading ◽  
Tissue Level ◽  
Mechanical Parameters ◽  
Loading Conditions ◽  
Additional Stability ◽  
Muscle Loading ◽  
Pure Moment

The human spine experiences complex loading in vivo; however, simplifications to these loading conditions are commonly made in computational and experimental protocols. Pure moments are often used in cadaveric preparations to replicate in vivo loading conditions, and previous studies have shown this method adequately predicts range of motion behavior (1, 2). It is unclear what effect pure moment loading has on the tissue-level internal mechanical parameters such as stresses in the annulus fibrosus and facet contact parameters. Recent advances in musculoskeletal modeling have elucidated previously unknown quantities of the musculature recruitment patterns such as times, forces, and directions. The advancements are especially relevant in cases of surgical intervention because the spinal musculature has been reported to play a critical role in providing additional stability to the spine when defects such as discectomy and nucleotomy are involved (2). Thus, the aim of the study was to determine the importance of computational loading conditions on the resultant global ranges of motion, as well as the tissue-level predictions of annulus fibrosus stresses, and facet contact pressures, forces, and areas.

Development and Verification of a Dynamic TKR Model

2002 ◽  
Author(s):  
Jason P. Halloran ◽  
Anthony J. Petrella ◽  
Paul J. Rullkoetter
Keyword(s):  
Finite Element ◽  
Contact Mechanics ◽  
Dynamic Loading ◽  
Soft Tissues ◽  
Dynamic Models ◽  
Total Joint Replacement ◽  
Fe Model ◽  
Loading Conditions ◽  
Dynamic Loading Conditions

The success of current total knee replacement (TKR) devices is contingent on the kinematics and contact mechanics during in vivo activity. Indicators of potential clinical performance of total joint replacement devices include contact stress and area due to articulations, and tibio-femoral and patello-femoral kinematics. An effective way of evaluating these parameters during the design phase or before clinical use is via computationally efficient computer models. Previous finite element (FE) knee models have generally been used to determine contact stresses and/or areas during static or quasi-static loading conditions. The majority of knee models intended to predict relative kinematics have not been able to determine contact mechanics simultaneously. Recently, however, explicit dynamic finite element methods have been used to develop dynamic models of TKR able to efficiently determine joint and contact mechanics during dynamic loading conditions [1,2]. The objective of this research was to develop and validate an explicit FE model of a TKR which includes tibio-femoral and patello-femoral articulations and surrounding soft tissues. The six degree-of-freedom kinematics, kinetics and polyethylene contact mechanics during dynamic loading conditions were then predicted during gait simulation.

Determination of Real Time In-Vivo Cartilage Contact Deformation in the Ankle Joint

2007 ◽  
Author(s):  
Guoan Li ◽  
Lu Wan ◽  
Michal Kozanek
Keyword(s):  
Computational Models ◽  
Ex Vivo ◽  
Loading Conditions ◽  
Contact Deformation ◽  
Normal Cartilage ◽  
Physiological Loading ◽  
Contact Data ◽  
Biomechanical Responses

Knowledge of in-vivo articular cartilage contact deformation is critical for understanding normal cartilage function and the etiology of osteoarthritis (2,8). This knowledge is also instrumental for design of ex-vivo experiment to investigate the chondrocyte mechanotransductions under physiological loading conditions (7). Further, in-vivo cartilage contact data is necessary for validation of 3D computational models used to predict biomechanical responses of the articular joints (1,5). However, due to the complexity of in-vivo joint loading conditions as well as the complicated joint geometry, little information is available on in-vivo cartilage deformation in literature (9). In-vivo cartilage deformation as a function of loading history has not been delineated.

scholarly journals Deformation of Transvaginal Mesh in Response to Multiaxial Loading

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
William R. Barone ◽  
Katrina M. Knight ◽  
Pamela A. Moalli ◽  
Steven D. Abramowitch
Keyword(s):  
Computational Model ◽  
Complex Loading ◽  
Pelvic Organ ◽  
Synthetic Mesh ◽  
Transvaginal Mesh ◽  
Complication Rates ◽  
Multiaxial Loading ◽  
Loading Conditions ◽  
In Vivo Loading

Synthetic mesh for pelvic organ prolapse (POP) repair is associated with high complication rates. While current devices incorporate large pores (>1 mm), recent studies have shown that uniaxial loading of mesh reduces pore size, raising the risk for complications. However, it is difficult to translate uniaxial results to transvaginal meshes, as in vivo loading is multidirectional. Thus, the aim of this study was to (1) experimentally characterize deformation of pore diameters in a transvaginal mesh in response to clinically relevant multidirectional loading and (2) develop a computational model to simulate mesh behavior in response to in vivo loading conditions. Tension (2.5 N) was applied to each of mesh arm to simulate surgical implantation. Two loading conditions were assessed where the angle of the applied tension was altered and image analysis was used to quantify changes in pore dimensions. A computational model was developed and used to simulate pore behavior in response to these same loading conditions and the results were compared to experimental findings. For both conditions, between 26.4% and 56.6% of all pores were found to have diameters <1 mm. Significant reductions in pore diameter were noted in the inferior arms and between the two superior arms. The computational model identified the same regions, though the model generally underestimated pore deformation. This study demonstrates that multiaxial loading applied clinically has the potential to locally reduce porosity in transvaginal mesh, increasing the risk for complications. Computational simulations show potential of predicting this behavior for more complex loading conditions.

Grand Challenge Competition: A Parametric Numerical Model to Predict In Vivo Medial and Lateral Knee Forces in Walking Gaits

2012 ◽  
Author(s):  
Christopher B. Knowlton ◽  
Markus A. Wimmer ◽  
Hannah J. Lundberg
Keyword(s):  
Knee Joint ◽  
Computational Models ◽  
Soft Tissues ◽  
Numerical Models ◽  
Contact Forces ◽  
Grand Challenge ◽  
Total Knee Replacements ◽  
Lateral Contact ◽  
Total Knee

Numerical models are necessary to estimate forces through the knee joint during activities of daily living. However, the numerous muscles and soft tissues crossing the knee joint result in a computationally indeterminate problem. The recent availability of measured contact force data from telemeterized total knee replacements (TKRs) has given researchers the chance to validate models, but telemeterized TKRs represent only a few patients with a specific implant type. Computational models remain necessary to bridge the gap between the small instrumented patient population with a particular implant and larger patient populations executing various activities. Abstracted gait data from another lab tests the versatility of any model to accurately predict forces of TKR patients performing a variety of gaits with disparate implant types. In this study, we calculate and examine the differences between medial and lateral contact forces in level walking and medial thrust gait trials from a freely provided dataset1.

Dem Simulations in Geotechnical Earthquake Engineering Education

2010 ◽  
Vol 1 (1) ◽  
pp. 61-69
Author(s):  
J. S. Vinod
Keyword(s):  
Engineering Education ◽  
Granular Materials ◽  
Earthquake Engineering ◽  
Laboratory Experiments ◽  
Computational Models ◽  
Complex Loading ◽  
Cyclic Behavior ◽  
Loading Conditions ◽  
Geotechnical Earthquake Engineering ◽  
Element Method

Behaviour of geotechnical material is very complex. Most of the theoretical frame work to understand the behaviour of geotechnical materials under different loading conditions depends on the strong background of the basic civil engineering subjects and advanced mathematics. However, it is fact that the complete behaviour of geotechnical material cannot be traced within theoretical framework. Recently, computational models based on Finite Element Method (FEM) are used to understand the behaviour of geotechnical problems. FEM models are quite complex and is of little interest to undergraduate students. A simple computational tool developed using Discrete Element Method (DEM) to simulate the laboratory experiments will be cutting edge research for geotechnical earthquake engineering education. This article summarizes the potential of DEM to simulate the cyclic triaxial behaviour of granular materials under complex loading conditions. It is shown that DEM is capable of simulating the cyclic behavior of granular materials (e.g. undrained, liquefaction and post liquefaction) similar to the laboratory experiments.

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.

Multilevel Validation of a Male Neck Finite Element Model With Active Musculature

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jeffrey B. Barker ◽  
Duane S. Cronin
Keyword(s):  
Cervical Spine ◽  
Injury Risk ◽  
Muscle Activation ◽  
Computational Models ◽  
Soft Tissues ◽  
Motor Vehicle ◽  
Experimental Studies ◽  
Tissue Level ◽  
Open Loop ◽  
Frontal Impact

Abstract Computational models of the human neck have been developed to assess human response in impact scenarios; however, the assessment and validation of such models is often limited to a small number of experimental data sets despite being used to evaluate the efficacy of safety systems and potential for injury risk in motor vehicle collisions. In this study, a full neck model (NM) with active musculature was developed from previously validated motion segment models of the cervical spine. Tissue mechanical properties were implemented from experimental studies, and were not calibrated. The neck model was assessed with experimental studies at three levels of increasing complexity: ligamentous cervical spine in axial rotation, axial tension, frontal impact, and rear impact; postmortem human subject (PMHS) rear sled impact; and human volunteer frontal and lateral sled tests using an open-loop muscle control strategy. The neck model demonstrated good correlation with the experiments ranging from quasi-static to dynamic, assessed using kinematics, kinetics, and tissue-level response. The contributions of soft tissues, neck curvature, and muscle activation were associated with higher stiffness neck response, particularly for low severity frontal impact. Experiments presenting single-value data limited assessment of the model, while complete load history data and cross-correlation enabled improved evaluation of the model over the full loading history. Tissue-level metrics demonstrated higher variability and therefore lower correlation relative to gross kinematics, and also demonstrated a dependence on the local tissue geometry. Thus, it is critical to assess models at the gross kinematic and the tissue levels.

The in Vivo Elastic Properties of the Plantar Fascia during the Contact Phase of Walking

2003 ◽  
Vol 24 (3) ◽  
pp. 238-244 ◽  
Author(s):  
Amit Gefen
Keyword(s):  
Strain Rate ◽  
Elastic Properties ◽  
Computational Models ◽  
Soft Tissues ◽  
Plantar Fascia ◽  
Contact Forces ◽  
Contact Phase ◽  
Pressure Sensitive ◽  
Excessive Strain

The in vivo elastic properties of the plantar fascia during the contact phase of walking were determined experimentally by integrating a pressure-sensitive optical gait platform with a radiographic fluoroscopy system for recording skeletal motion. In order to calculate the fascia's tension-deformation relation, lateral images of the foot's skeleton that allowed evaluation of the fascia's transient length from the arch-contact to toe-off stages of walking were obtained simultaneously with the vertical foot-ground contact forces. The plantar fascia was shown to undergo continuous elongation from arch-contact to toe-off, reaching a deformation of 9 to 12% between these positions. Rapid elongation of the fascia, at a strain rate of about 0.9±0.1 Sec-1, was observed before and immediately after midstance, while a significantly slower elongation occurred at a strain rate of approximately 0.2±0.1 Sec-1 around push-off and toe-off. The average stiffness of the fascia at the slow-to-moderate walking velocities was 170±45 N/mm, which is similar to reported stiffness values for cadaver fascia specimens. The present technique may be useful for validation of computational models of the soft tissues of the foot as well as for testing the effectiveness of orthoses and shoe types for relieving excessive strain of the fascia in the treatment of plantar fasciitis.

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