Repositioning the Human Body Lower Extremity FE Model

Jani, Dhaval; Chawla, Anoop; Mukherjee, Sudipto; Goyal, Rahul; Nataraju, V.

doi:10.4271/2009-01-0922

Cited by 9 publications

(7 citation statements)

References 19 publications

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“…However, despite the constant progress in the development of Hill-type muscle models, they remain sensitive to parameter variations [7][8][9][10] and can be prone to numerical instability [11]. In the context of finite element (FE) models, further challenges are presented by the models' inherent deformability, which can cause joints to shift or dislocate during repositioning simulations required to adjust the model's posture [12][13][14]. As a result, the physiological validity of the predicted kinematic responses and internal forces is highly dependent upon the correct calibration of muscle parameters and, in the case of FE models, the structural integrity of their internal skeletal structure.…”

Section: Introductionmentioning

confidence: 99%

Using muscle-tendon load limits to assess unphysiological musculoskeletal model deformation and Hill-type muscle parameter choice

Nölle,

Wochner,

Hammer

et al. 2024

Preprint

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Musculoskeletal simulations are a useful tool for improving our understanding of the human body. However, the physiological validity of predicted kinematics and forces is highly dependent upon the correct calibration of muscle parameters and the structural integrity of a model’s internal skeletal structure. In this study, we show how ill-tuned muscle parameters and unphysiological deformations of a model’s skeletal structure can be detected by using muscle elements as sensors with which modelling and parameterization inconsistencies can be identified through muscle and tendon strain injury assessment. To illustrate our approach, two modelling issues were recreated. First, a model repositioning simulation using the THUMS AM50 occupant model version 5.03 was performed to show how internal model deformations can occur during a change of model posture. Second, the muscle material parameters of the OpenSim gait2354 model were varied to illustrate how unphysiological muscle forces can arise if material parameters are inadequately calibrated. The simulations were assessed for muscle and tendon strain injuries using previously published injury criteria and a newly developed method to determine tendon strain injury threshold values. Muscle strain injuries in the left and right musculus pronator teres were detected during the model repositioning. This straining was caused by an unphysiologically large gap (12.92 mm) that had formed in the elbow joint. Similarly, muscle and tendon strain injuries were detected in the modified right-hand musculus gastrocnemius medialis of the gait2354 model where an unphysiological reduction of the tendon slack length introduced large pre-strain of the muscle-tendon-unit. The results of this work show that the proposed method can quantify the internal distortion behaviour of musculoskeletal human body models and the validity of Hill-type muscle parameter choice via strain injury assessment. Furthermore, we highlight possible actions to avoid the presented issues and inconsistencies in literature data concerning the material characteristics of human tendons.

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Section: Introductionmentioning

confidence: 99%

Using muscle-tendon load limits to assess unphysiological musculoskeletal model deformation and Hill-type muscle parameter choice

Nölle,

Wochner,

Hammer

et al. 2024

Preprint

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“…The repositioned models usually report degraded mesh quality and rely on manual corrections thereafter to rectify the distortions. Besides, a fundamental-level problem is that the resulting kinematics is not guaranteed to be anatomically correct ( Jani et al, 2009 ) because the HBM lacks part of the necessary kinematical constraints from connective tissues. Researchers have turned to kinesiology for answers.…”

Section: Introductionmentioning

confidence: 99%

Can we reposition finite element human body model like dummies?

Tang

Zhou

Shen

et al. 2023

Front. Bioeng. Biotechnol.

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Rapidly repositioning finite element human body models (FE-HBMs) with high biofidelity is an important but notorious problem in vehicle safety and injury biomechanics. We propose to reposition the FE-HBM in a dummy-like manner, i.e., through pose parameters prescribing joint configurations. Skeletons are reconfigured along the trajectories inferred from model-specific bone geometries. We leverage differential geometry to steer equidistant moves along the congruent articulated bone surfaces. Soft tissues are subsequently adapted to reconfigured skeletons through a series of operations. The morph–contact algorithm allows the joint capsule to slide and wrap around the repositioned skeletons. Nodes on the deformed capsule are redistributed following an optimization-based approach to enhance element regularity. The soft tissues are transformed accordingly via thin plate spline. The proposed toolbox can reposition the Total Human Body Model for Safety (THUMS) in a few minutes on a whole-body level. The repositioned models are simulation-ready, with mesh quality maintained on a comparable level to the baseline. Simulations of car-to-pedestrian impact with repositioned models exhibiting active collision-avoidance maneuvers are demonstrated to illustrate the efficacy of our method. This study offers an intuitive, effective, and efficient way to reposition FE-HBMs. It benefits all posture-sensitive works, e.g., out-of-position occupant safety and adaptive pedestrian protection. Pose parameters, as an intermediate representation, join our method with recently prosperous perception and reconstruction techniques of the human body. In the future, it is promising to build a high-fidelity digital twin of real-world accidents using the proposed method and investigate human biomechanics therein, which is of profound significance in reshaping transportation safety studies in the future.

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“…[8][9][10] This implies that repositioning of body regions or the entire HBM may be required for analysis of different impact scenarios; however, in current methods the focus has been on retaining mesh quality, while the stresses and strains generated within the tissues from repositioning are not included in subsequent impact analyses.Studies have been undertaken regarding repositioning techniques for finite element HBM, and most have focused on producing anatomically correct postures for the models while retaining finite element mesh quality. [11][12][13][14][15][16] During repositioning, the original configuration of the HBM (eg, seated driving position or neutral posture) are morphed into desired configurations (eg, nonneutral postures such as a head-turned posture), which may be necessary for vehicle safety simulations. The response to deformation including crash induced injury predictions are then assessed using the repositioned configuration of the model.…”

mentioning

confidence: 99%

“…Mesh smoothing techniques were used to improve the mesh quality when they encountered element distortions during the repositioning process. 5,12 The lower extremity of the total human model for safety model has been repositioned using dynamic finite element simulations from an occupant posture to a standing pedestrian posture by restraining the upper leg and applying a force to the tibia while rotating the lower leg between 5 and 6 degrees. 17 Besides long simulation times and the large number of iterations, the geometry defined contacts and imposed boundary conditions determined the anatomical accuracy and mesh quality of the repositioned model.…”

mentioning

confidence: 99%

“…Studies have been undertaken regarding repositioning techniques for finite element HBM, and most have focused on producing anatomically correct postures for the models while retaining finite element mesh quality. [11][12][13][14][15][16] During repositioning, the original configuration of the HBM (eg, seated driving position or neutral posture) are morphed into desired configurations (eg, nonneutral postures such as a head-turned posture), which may be necessary for vehicle safety simulations. The response to deformation including crash induced injury predictions are then assessed using the repositioned configuration of the model.…”

mentioning

confidence: 99%

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On the importance of retaining stresses and strains in repositioning computational biomechanical models of the cervical spine

Boakye‐Yiadom

Cronin

2017

Numer Methods Biomed Eng

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Human body models are created in a specific posture and often repositioned and analyzed without retaining stresses that result from repositioning. For example, repositioning a human neck model within the physiological range of motion to a head-turned posture prior to an impact results in initial stresses within the tissues distracted from their neutral position. The aim of this study was to investigate the effect of repositioning on the subsequent kinetics, kinematics, and failure modes, of a lower cervical spine motion segment, to support future research at the full neck level. Repositioning was investigated for 3 modes (tension, flexion, and extension) and 3 load cases. The model was repositioned and loaded to failure in one continuous load history (case 1), or repositioned then restarted with retained stresses and loaded to failure (case 2). In case 3, the model was repositioned and then restarted in a stress-free state, representing current repositioning methods. Not retaining the repositioning stresses and strains resulted in different kinetics, kinematics, or failure modes, depending on the mode of loading. For the motion segment model, the differences were associated with the intervertebral disc fiber reorientation and load distribution, because the disc underwent the largest deformation during repositioning. This study demonstrated that repositioning led to altered response and tissue failure, which is critical for computational models intended to predict injury at the tissue level. It is recommended that stresses and strains be included and retained for subsequent analysis when repositioning a human computational neck model. | INTRODUCTION AND BACKGROUNDRecently, extensive efforts are being made with automotive crash simulations and computational models to address occupant safety challenges, such as out-of-position scenarios, using advanced finite element human body models (HBM). [1][2][3][4] These models incorporate representations of soft and hard tissues including bones surrounded by muscles, tendons, and ligaments such as the total human model for safety, human models for safety (HUMOS2), and the HBMs developed by the global human Received: 20 September 2016 Revised: 29 May body models consortium (GHBMC). [5][6][7] Although these HBMs have demonstrated new potential to evaluate injuries at the tissue level, they are often created in a specific position such as a seated driving posture and therefore must be morphed or repositioned to other important postures such as standing in the case of a pedestrian, or may be repositioned to investigate postural effects for specific body regions such as the neck or thorax. 3,4 In addition, integrating an occupant HBM with a vehicle model may require considering different positions of the HBMs compared to the standardized positions of the models. [8][9][10] This implies that repositioning of body regions or the entire HBM may be required for analysis of different impact scenarios; however, in current methods the focus has been on retaining mesh quality,...

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Repositioning the Human Body Lower Extremity FE Model

Cited by 9 publications

References 19 publications

Using muscle-tendon load limits to assess unphysiological musculoskeletal model deformation and Hill-type muscle parameter choice

Using muscle-tendon load limits to assess unphysiological musculoskeletal model deformation and Hill-type muscle parameter choice

Can we reposition finite element human body model like dummies?

On the importance of retaining stresses and strains in repositioning computational biomechanical models of the cervical spine

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