General Computational Model for Human Musculoskeletal System of Spine

A general computational model of the human lumbar spine and trunk muscles including optimization formulations was provided. For a given condition, the trunk muscle forces could be predicted considering the human physiology including the follower load concept. The feasibility of the solution could be indirectly validated by comparing the compressive force, the shear force, and the joint moment. The presented general computational model and optimization technology can be fundamental tools to understand the control principle of human trunk muscles

Biomechanics of foetal movement.

© 2015, AO Research Institute. All rights reserved.Foetal movements commence at seven weeks of gestation, with the foetal movement repertoire including twitches, whole body movements, stretches, isolated limb movements, breathing movements, head and neck movements, jaw movements (including yawning, sucking and swallowing) and hiccups by ten weeks of gestational age. There are two key biomechanical aspects to gross foetal movements; the first being that the foetus moves in a dynamically changing constrained physical environment in which the freedom to move becomes increasingly restricted with increasing foetal size and decreasing amniotic fluid. Therefore, the mechanical environment experienced by the foetus affects its ability to move freely. Secondly, the mechanical forces induced by foetal movements are crucial for normal skeletal development, as evidenced by a number of conditions and syndromes for which reduced or abnormal foetal movements are implicated, such as developmental dysplasia of the hip, arthrogryposis and foetal akinesia deformation sequence. This review examines both the biomechanical effects of the physical environment on foetal movements through discussion of intrauterine factors, such as space, foetal positioning and volume of amniotic fluid, and the biomechanical role of gross foetal movements in human skeletal development through investigation of the effects of abnormal movement on the bones and joints. This review also highlights computational simulations of foetal movements that attempt to determine the mechanical forces acting on the foetus as it moves. Finally, avenues for future research into foetal movement biomechanics are highlighted, which have potential impact for a diverse range of fields including foetal medicine, musculoskeletal disorders and tissue engineering

Musculoskeletal modelling of the human cervical spine for the investigation of injury mechanisms during axial impacts

This is the final version. Available from Public Library of Science via the DOI in this record.All relevant data are available at Figshare [https://figshare.com/projects/SILVESTROS_PLOS_ONE_SUPPORTING_DOCUMENTS/58280] and musculoskeletal models and relevant project information is available on the OpenSim SimTK repository [https://simtk.org/projects/csibath].Head collisions in sport can result in catastrophic injuries to the cervical spine. Musculoskeletal modelling can help analyse the relationship between motion, external forces and internal loads that lead to injury. However, impact specific musculoskeletal models are lacking as current viscoelastic values used to describe cervical spine joint dynamics have been obtained from unrepresentative quasi-static or static experiments. The aim of this study was to develop and validate a cervical spine musculoskeletal model for use in axial impacts. Cervical spine specimens (C2-C6) were tested under measured sub-catastrophic loads and the resulting 3D motion of the vertebrae was measured. Specimen specific musculoskeletal models were then created and used to estimate the axial and shear viscoelastic (stiffness and damping) properties of the joints through an optimisation algorithm that minimised tracking errors between measured and simulated kinematics. A five-fold cross validation and a Monte Carlo sensitivity analysis were conducted to assess the performance of the newly estimated parameters. The impact-specific parameters were integrated in a population specific musculoskeletal model and used to assess cervical spine loads measured from Rugby union impacts compared to available models. Results of the optimisation showed a larger increase of axial joint stiffness compared to axial damping and shear viscoelastic parameters for all models. The sensitivity analysis revealed that lower values of axial stiffness and shear damping reduced the models performance considerably compared to other degrees of freedom. The impact-specific parameters integrated in the population specific model estimated more appropriate joint displacements for axial head impacts compared to available models and are therefore more suited for injury mechanism analysis.Rugby Football Union (RFU) Injured Players Foundatio

Recent trends, technical concepts and components of computer-assisted orthopedic surgery systems: A comprehensive review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.Web of Science1923art. no. 519

COMBINED MUSCULO-SKELETAL MULTI-BODY DYNAMICS/FINITE ELEMENT ANALYSIS OF SEVERAL ERGONOMICS AND BIO-MECHANICS PROBLEMS

Within this thesis, two ergonomics (i.e. seating comfort and long-distance driving fatigue problems) and two structural bio-mechanics (i.e. femur-fracture fixation and radius-fracture fixation) problems are investigated using musculo-skeletal multi-body dynamics and finite element computational analyses. Within the seating comfort problem analyzed, a complete-body finite element model is constructed and used to assess the effect of seat geometry and seating posture on the feel of comfort experienced by a seated human. Within the long-distance driving fatigue problem, musculo-skeletal analysis is employed to assess the extent of fatigue experienced by a driver through the evaluation of level of activity of his/her various muscles. Within the femur-fracture fixation problem, physiologically realistic loading conditions associated with active daily activities (i.e. cycling) are employed within a finite-element frame work to assess fracture fixation performance and durability of the implant. Within the radius-fracture fixation problem, the analysis developed within the femur-fracture fixation problem is further related to indicate the effects of other types of loadings (associated with additional daily activities) and improved biological and structural material model are employed. For all cases studied in the present work, relevant experimental data are used to validate the computational procedure employed

Multi-Scale Vertebral-Kinematics Based Simulation Pipeline of the Human Spine With Application to Spine Tissues Analysis

This study developed an analytical tool for understanding spine tissues’ behavior in response to vertebral kinematics and spine pathology over a range of body postures. It proposed a novel pipeline of computational models based on predicting individual vertebral kinematics from measurable body-level motions, using musculoskeletal dynamics simulations to drive the vertebrae in corresponding spine FEMs. A reformulated elastic surface node (ESN) lumbar model was developed for use in MSD simulations. The ESN model modifies the lumbar spine within an existing MSD model by removing non-physiological kinematic constraints and including elastic IVD behavior. The model was scaled using subject-specific anthropometrics and validated to predict in vivo vertebral kinematics and IVD pressures during trunk flexion/extension. The ESN model was integrated into a novel simulation pipeline that automatically maps it to a kinematics-driven FEM (KD-FEM). The KD-FEM consisted of lumbar vertebrae scaled to subject-specific geometries and actuated by subject-specific vertebral kinematics from the ESN model for different activities. The pipeline was validated for its ability to predict in vivo IVD pressures at L4-L5 level during flexion and load carrying postures. A detailed multi-layered multi-phase lumbar canal FE model was integrated into the KD-FEM to quantify risks to canal tissues due to vertebral kinematics and progressive canal narrowing (stenosis). This enabled distinct computation of proposed stenosis measures, including cerebrospinal fluid pressure, cauda equina deformation and related stresses/pressure/strains, among others. Model outputs included measures during flexion and comparison of three clinically relevant degrees of progressive stenosis of the bony vertebral foramen at L4 level

A Computer Simulation Model of The Human Head-Neck Musculoskeletal System

Objective. The objective of this research was to develop a muscle-driven biomechanical model of the human head-neck system that could be used to simulate neck movements under muscle control. This model can further be modified to enable input from an external stimulus, such as EMG data. Summary of background data. Utilizing computer aided design (CAD) and dynamic simulation software programs, the Joint Implant Biomechanics Laboratory at The University of Tennessee Health Science Center developed a virtual model of the human cervical spine to simulate the in vitro biomechanical experiments. This in vitro model did not include any muscle components and was unable to simulate any active muscle contribution to head-neck movement. However, the model served well as a platform from which to develop a dynamic musculoskeletal head-neck model that could include muscle involvement. Methods. The development of the current head-neck model was based on a previous in vitro model of the sub-axial cervical spine that was developed within the rigid body dynamic simulation program, Visual Nastran 4D. Interconnecting joints, including intervertebral discs, facet joints, ligaments, and the C0-C1-C2 complex, were defined. The primary neck muscles for axial rotation, lateral bending, extension, and flexion movements were defined, respectively. For each specific movement, the model was driven by muscle length control using three different muscle sets: (1) all the inclusive primary muscles (“All muscles” mode), (2) only the primary muscles during a concentric contraction (“Concentric contraction muscles only” mode), and (3) only the primary muscles during an eccentric contraction (“Eccentric contraction muscles only” mode). The simulation results obtained from these three modes were compared to the in vivopublished data. Results. Simulation results from the muscle model for axial rotation and flexion were comparable to the in vivo data in each of the three muscle mode sets. For extension and lateral bending movement, only the results from the “All muscles” mode matched the in vivo data. There were no significant translations that occurred in the upper cervical spine region, which was in agreement with the published literature. Concluding discussion. A computational model of the human head-neck musculoskeletal system was developed that simulated the dynamic motion response under physiologic head movements. The motion-driven model provided excellent replication of in vivo vertebral kinematics. A similar response occurred for the muscle-driven model when the groups on both sides were activated. Although there was no significant involvement of the extensor muscles during flexion, the forward flexor muscles played an important role during extensional head movement. In the future, the model can be used to explore muscle control strategies within the “Virtual Muscle” program to simulate EMG muscle force activation conditions

Dynamics simulation of human box delivering task

Thesis (M.S.) University of Alaska Fairbanks, 2018The dynamic optimization of a box delivery motion is a complex task. The key component is to achieve an optimized motion associated with the box weight, delivering speed, and location. This thesis addresses one solution for determining the optimal delivery of a box. The delivering task is divided into five subtasks: lifting, transition step, carrying, transition step, and unloading. Each task is simulated independently with appropriate boundary conditions so that they can be stitched together to render a complete delivering task. Each task is formulated as an optimization problem. The design variables are joint angle profiles. For lifting and carrying task, the objective function is the dynamic effort. The unloading task is a byproduct of the lifting task, but done in reverse, starting with holding the box and ending with it at its final position. In contrast, for transition task, the objective function is the combination of dynamic effort and joint discomfort. The various joint parameters are analyzed consisting of joint torque, joint angles, and ground reactive forces. A viable optimization motion is generated from the simulation results. It is also empirically validated. This research holds significance for professions containing heavy box lifting and delivering tasks and would like to reduce the chance of injury.Chapter 1 Introduction -- Chapter 2 Skeletal Human Modeling -- Chapter 3 Kinematics and Dynamics -- Chapter 4 Lifting Simulation -- Chapter 5 Carrying Simulation -- Chapter 6 Delivering Simulation -- Chapter 7 Conclusion and Future Research -- Reference