The human vertebral column serves as the primary protection system to the main spinal cord nerves. By studying a model of how each vertebra reacts under a force applied at different postures would provide valuable information to future medical studies. There is not a standard technique available yet that can be applied to each human. By modeling of the spine using free body diagrams to create equations of motion and using computer software to simulate the lumbar region, the result would allow us to study how the forces and stresses would relate. In addition, this will provide a more precise analysis for vertebral column under different postures. Since each vertebra has a different shape and mass, the model of the spine should be represented using lumped mass, and the tissue and disc surrounding the body of the vertebrae will be represented by spring and dampers. The equations developed is solved using a MATLAB code which plots displacements, while the software, Patran, would output plots of displacement using finite element analysis. With two different modeling approaches, we will be able to determine how different loadings on the spine would affect its deformations.
ABSTRACT: This thesis describes two different, but complementary modeling tasks for the human spine. Methodologies for modeling and simulation of the motion of the human spine vary dramatically in complexity. While providing detailed stress and strain field representations, full finite element modeling of the human spine can be computationally expensive. Alternatively, nonlinear multibody dynamics representations are often used because of their simplicity. These formulations employ rigid models of vertebrae interconnected via conventional mechanical joints. However, it is well documented that inter-vertebral motion can depart significantly from conventional mechanical joint constraints. We present an identification methodology that employs a relaxation technique in which joint mechanical properties are represented via a probability measure. In addition we describe an effort to obtain accurate three-dimensional models of the human spine. These efforts are motivated by considering scoliosis. Scoliosis is defined as abnormal lateral curvature of the spine. It is usually considered as a three-dimensional deformity, because axial rotation will always accompany the lateral curvature. The correction of the deformity is required when the patient risks severe deformity. A three-dimensional spine model is constructed and a computer simulation tool is provided.
Substantial strides are being made in fields supporting human spaceflight, making re-usable and robust flight systems for missions to new and exciting destinations. However, the human body is not capable of withstanding long-duration spaceflight, which involves gravitational unloading as well as extreme loading conditions. In the dynamic loading environment projected on space missions, the potential for injury will likely be high due to the creation of irreversible changes to the musculoskeletal system. Therefore, the specific goals of this research were to (1) determine the appropriate material models to simulate gravitational unloading, (2) determine the loading and boundary conditions in the simulation of gravitational unloading, and (3) investigate the response of the whole human spine under several representative gravitational unloading test cases. A high fidelity computational model and simulation of the space adapted whole human spine was generated and validated for the purpose of investigating the mechanical integrity of the spine in crewmembers during exploratory space missions. Simulation of intervertebral disc poro-hyperelastic response to mechanical unloading was conducted through the application of boundary conditions to approximate the osmotic conditions of the system. Morphology of this gravitational unloading spine model was compared to a control terrestrial-based finite element model. Additionally, the morphology of the lumbar spine was compared to a validation data set generated from head down tilt bed rest studies, a ground-based analog of human spaceflight, and spaceflight experiments. The results were compared to tissue injury limits to implicate bone micro-fractures and intervertebral disc herniations, indicating potential locations of injuries. Five test cases were conducted to offer an overview of the influence of certain boundary and loading conditions on the gravitational unloading responses of the system. Simulations captured straightening of the spinal column under gravitational unloading, a result observed in some of the experimental investigations into this phenomenon. Each intervertebral disc exhibited a swelling response, increasing in height. Unavailability of controlled experimental studies with a large number of subjects created a validation data set with large standard deviations. Injury limits for annular tears were exceeded in the lower cervical and upper thoracic spine and bony micro-fractures occurred throughout the spine on each of the investigated test cases. Additionally, the influence of certain boundary conditions on the deformed shapes of the spinal column was determined. This work offers the first complete review of spaceflight-induced changes in spinal morphology to date. A full derivation of the constitutive equations for poro-hyperelastic materials is presented, offering the framework for the development and implementation of higher fidelity formulations of biphasic swelling as it relates to biological tissues. Additionally, this whole spine finite element model is presented as the only investigation of the spine to long duration gravitational unloading, with a time duration longer than those in diurnal simulations. It is also the only investigation into the response of the whole spine to an analog of spaceflight gravitational unloading. This thorough gravitational unloading study offers a tool that can be used to conduct more robust investigations of human spaceflight.
The 41st Annual International Conference of the IEEE EMBS, took place between July 23 and 27, 2019, in Berlin, Germany. The focus was on "Biomedical engineering ranging from wellness to intensive care." This conference provided an opportunity for researchers from academia and industry to discuss a variety of topics relevant to EMBS and hosted the 4th Annual Invited Session on Computational Human Models. At this session, a bevy of research related to the development of human phantoms was presented, together with a substantial variety of practical applications explored through simulation.
In this research, a spinal toolbox, for modeling lumbar spine, was built which contains different types of models (i.e. spinal element, Ligaments, discs, and beam models) to be used for specific loading cases.
Biomechanics of the Spine encompasses the basics of spine biomechanics, spinal tissues, spinal disorders and treatment methods. Organized into four parts, the first chapters explore the functional anatomy of the spine, with special emphasis on aspects which are biomechanically relevant and quite often neglected in clinical literature. The second part describes the mechanics of the individual spinal tissues, along with commonly used testing set-ups and the constitutive models used to represent them in mathematical studies. The third part covers in detail the current methods which are used in spine research: experimental testing, numerical simulation and in vivo studies (imaging and motion analysis). The last part covers the biomechanical aspects of spinal pathologies and their surgical treatment. This valuable reference is ideal for bioengineers who are involved in spine biomechanics, and spinal surgeons who are looking to broaden their biomechanical knowledge base. The contributors to this book are from the leading institutions in the world that are researching spine biomechanics. - Includes broad coverage of spine disorders and surgery with a biomechanical focus - Summarizes state-of-the-art and cutting-edge research in the field of spine biomechanics - Discusses a variety of methods, including In vivo and In vitro testing, and finite element and musculoskeletal modeling
