Book of Abstracts 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization

In this edition, the two events will run together as a single conference, highlighting the strong connection with the Taylor & Francis journals: Computer Methods in Biomechanics and Biomedical Engineering (John Middleton and Christopher Jacobs, Eds.) and Computer Methods in Biomechanics and Biomedical Engineering: Imaging and Visualization (JoãoManuel R.S. Tavares, Ed.). The conference has become a major international meeting on computational biomechanics, imaging andvisualization. In this edition, the main program includes 212 presentations. In addition, sixteen renowned researchers will give plenary keynotes, addressing current challenges in computational biomechanics and biomedical imaging. In Lisbon, for the first time, a session dedicated to award the winner of the Best Paper in CMBBE Journal will take place. We believe that CMBBE2018 will have a strong impact on the development of computational biomechanics and biomedical imaging and visualization, identifying emerging areas of research and promoting the collaboration and networking between participants. This impact is evidenced through the well-known research groups, commercial companies and scientific organizations, who continue to support and sponsor the CMBBE meeting series. In fact, the conference is enriched with five workshops on specific scientific topics and commercial software.info:eu-repo/semantics/draf

Scoliosis Analog Model for the Evaluation of Bracing Technology

Thoracolumbar braces are commonly used to treat Adolescent Idiopathic Scoliosis (AIS). Braces serve to reduce and prevent progression of the spinal curve by applying corrective forces. The magnitude and direction of these corrective forces applied by the brace to the spine remain unknown. Additionally the brace fitting process involves making alterations to the brace that affect its corrective force capacity. The objective was to design and validate an analog model of a mid-thoracic single curve scoliotic deformity for quantifying structural properties of the brace and the force response of the brace on the spine. This model was used to investigate the effects of strap-related brace design alterations. Additionally, the model was customized and demonstrated to be representative of a clinical case study. A novel mechanically-equivalent analog model of the AIS condition was designed and developed to simulate up to 40 degrees of spinal correction. The linkage-based model was used in conjunction with a biorobotic testing platform to test a scoliosis brace. Measurements of the force components applied to the model and angular displacement of the linkage assembly were used to calculate the brace structural stiffness properties. The brace was tested using two types of straps (Velcro and buckle) applied in various configurations and compared to an unconstrained configuration and rigidly constrained configuration to demonstrate the capacity of the model to study brace design alterations. Calculated stiffness was expressed as a resistive force relative to the angular change of the linkage system. Addition of either strap type significantly increased the stiffness values relative to the unconstrained configuration. An optimal brace radial stiffness was achieved with three Velcro straps, i.e., there was no significant stiffness gained by adding a fourth strap. For the case of the buckle straps, no significant stiffness gain occurred when more buckle straps were added. Structural properties provide a means to compare bracing technology and better understand design features. The testing of design alterations, i.e. variable strap configurations, show a measureable difference in brace force response and structural properties between each configuration. Also, interpretation of the measured force components revealed that the brace applied inward and upward forces to the spine. A novel scoliosis analog model and testing assembly were developed to provide first time measures of the forces applied to the spine by a thoracolumbar brace. In addition to quantifying brace structural properties, this test assembly could be used as a design and testing tool for scoliosis brace technology

Injury and Skeletal Biomechanics

This book covers many aspects of Injury and Skeletal Biomechanics. As the title represents, the aspects of force, motion, kinetics, kinematics, deformation, stress and strain are examined in a range of topics such as human muscles and skeleton, gait, injury and risk assessment under given situations. Topics range from image processing to articular cartilage biomechanical behavior, gait behavior under different scenarios, and training, to musculoskeletal and injury biomechanics modeling and risk assessment to motion preservation. This book, together with "Human Musculoskeletal Biomechanics", is available for free download to students and instructors who may find it suitable to develop new graduate level courses and undergraduate teaching in biomechanics

Development of ultrasound to measure deformation of functional spinal units in cervical spine

Neck pain is a pervasive problem in the general population, especially in those working in vibrating environments, e.g. military troops and truck drivers. Previous studies showed neck pain was strongly associated with the degeneration of intervertebral disc, which is commonly caused by repetitive loading in the work place. Currently, there is no existing method to measure the in-vivo displacement and loading condition of cervical spine on the site. Therefore, there is little knowledge about the alternation of cervical spine functionality and biomechanics in dynamic environments. In this thesis, a portable ultrasound system was explored as a tool to measure the vertebral motion and functional spinal unit deformation. It is hypothesized that the time sequences of ultrasound imaging signals can be used to characterize the deformation of cervical spine functional spinal units in response to applied displacements and loading. Specifically, a multi-frame tracking algorithm is developed to measure the dynamic movement of vertebrae, which is validated in ex-vivo models. The planar kinematics of the functional spinal units is derived from a dual ultrasound system, which applies two ultrasound systems to image C-spine anteriorly and posteriorly. The kinematics is reconstructed from the results of the multi-frame movement tracking algorithm and a method to co-register ultrasound vertebrae images to MRI scan. Using the dual ultrasound, it is shown that the dynamic deformation of functional spinal unit is affected by the biomechanics properties of intervertebral disc ex-vivo and different applied loading in activities in-vivo. It is concluded that ultrasound is capable of measuring functional spinal units motion, which allows rapid in-vivo evaluation of C-spine in dynamic environments where X-Ray, CT or MRI cannot be used.2020-02-20T00:00:00

Human lumbar spine biomechanics: study of pathologies and new surgical procedures

This thesis aims to shed light on the process that undergoes the lumbar spine as a result of intervertebral disc degeneration and different lumbar surgeries, paying special attention on the main risk factors and how to overcome them. Low back pain is the leading musculoskeletal disorder in all developed countries generating high medical related costs. Intervertebral disc degeneration is one of the most common causes of low back pain. When conservative treatments fail to relieve this pain, lumbar surgery is needed and, in this regard, lumbar fusion is the \textquotedblleft gold standard\textquotedblright technique to provide stability and neural decompression.Degenerative disc disease has been studied through two different approaches. An in-vivo animal model was reproduced and followed-up with MRI and mechanical testing to see how the water content decreased while the stiffness of the tissue increased. Then, degeneration was induced in a single disc of the human lumbar spine and the effects on the adjacent disc were investigated by the use of the finite element models. Further on, different procedures for segmental fusion were computationally simulated. A comparison among different intersomatic cage designs, supplemented with posterior screw fixation or placed in a stand-alone fashion, showed how the supplementary fixation drastically decreased the motion in the affected segment increasing the risk of adjacent segment disease more than a single placed cage. However, one of the main concerns regarding the use of cages without additional fixation is the subsidence of the device into the vertebral bone. A parametric study of the cage features and placement pointed to the width, curvature, and position as the most influential parameters for stability and subsidence.Finally, two different algorithms for tissue healing were implemented and applied for the first time to predict lumbar fusion in 3D models. The self-repairing ability of the bone was tested after simple nucleotomy and after instrumentation with internal fixation, anterior plate or stand-alone intersomatic cage predicting, in agreement with previous animal and clinical studies, that instrumentation may be not necessary to promote segmental fusion. In particular, the intervertebral disc height was seen to play an important role in the bone bridge or osteophyte formation.To summarize, this thesis has focused in the main controversial issues of intervertebral disc degeneration and lumbar fusion, such as degenerative process, adjacent segment disease, segment stability, cage subsidence or bone bridging. All the models described in this thesis could serve as a powerful tool for the pre-clinical evaluation of patient-specific surgical outcomes supporting clinician decisions. This thesis aims to shed light on the process that undergoes the lumbar spine as a result of intervertebral disc degeneration and different lumbar surgeries, paying special attention on the main risk factors and how to overcome them. Low back pain is the leading musculoskeletal disorder in all developed countries generating high medical related costs. Intervertebral disc degeneration is one of the most common causes of low back pain. When conservative treatments fail to relieve this pain, lumbar surgery is needed and, in this regard, lumbar fusion is the \textquotedblleft gold standard\textquotedblright technique to provide stability and neural decompression. Degenerative disc disease has been studied through two different approaches. An in-vivo animal model was reproduced and followed-up with MRI and mechanical testing to see how the water content decreased while the stiffness of the tissue increased. Then, degeneration was induced in a single disc of the human lumbar spine and the effects on the adjacent disc were investigated by the use of the finite element models. Further on, different procedures for segmental fusion were computationally simulated. A comparison among different intersomatic cage designs, supplemented with posterior screw fixation or placed in a stand-alone fashion, showed how the supplementary fixation drastically decreased the motion in the affected segment increasing the risk of adjacent segment disease more than a single placed cage. However, one of the main concerns regarding the use of cages without additional fixation is the subsidence of the device into the vertebral bone. A parametric study of the cage features and placement pointed to the width, curvature, and position as the most influential parameters for stability and subsidence. Finally, two different algorithms for tissue healing were implemented and applied for the first time to predict lumbar fusion in 3D models. The self-repairing ability of the bone was tested after simple nucleotomy and after instrumentation with internal fixation, anterior plate or stand-alone intersomatic cage predicting, in agreement with previous animal and clinical studies, that instrumentation may be not necessary to promote segmental fusion. In particular, the intervertebral disc height was seen to play an important role in the bone bridge or osteophyte formation. To summarize, this thesis has focused in the main controversial issues of intervertebral disc degeneration and lumbar fusion, such as degenerative process, adjacent segment disease, segment stability, cage subsidence or bone bridging. All the models described in this thesis could serve as a powerful tool for the pre-clinical evaluation of patient-specific surgical outcomes supporting clinician decisions. <br /

MAGNETIC FORCES IN ORTHODONTICS

BACKGROUND: Pneumococcus is a major human pathogen and the polysaccharide capsule is considered its main virulence factor. Nevertheless, strains lacking a capsule, named non-typeable pneumococcus (NT), are maintained in nature and frequently colonise the human nasopharynx. Interest in these strains, not targeted by any of the currently available pneumococcal vaccines, has been rising as they seem to play an important role in the evolution of the species. Currently, there is a paucity of data regarding this group of pneumococci. Also, questions have been raised on whether they are true pneumococci. We aimed to obtain insights in the genetic content of NT and the mechanisms leading to non-typeability and to genetic diversity. RESULTS: A collection of 52 NT isolates representative of the lineages circulating in Portugal between 1997 and 2007, as determined by pulsed-field gel electrophoresis and multilocus sequence typing, was analysed. The capsular region was sequenced and comparative genomic hybridisation (CGH) using a microarray covering the genome of 10 pneumococcal strains was carried out. The presence of mobile elements was investigated as source of intraclonal variation. NT circulating in Portugal were found to have similar capsular regions, of cps type NCC2, i.e., having aliB-like ORF1 and aliB-like ORF2 genes. The core genome of NT was essentially similar to that of encapsulated strains. Also, competence genes and most virulence genes were present. The few virulence genes absent in all NT were the capsular genes, type-I and type-II pili, choline-binding protein A (cbpA/pspC), and pneumococcal surface protein A (pspA). Intraclonal variation could not be entirely explained by the presence of prophages and other mobile elements. CONCLUSIONS: NT circulating in Portugal are a homogeneous group belonging to cps type NCC2. Our observations support the theory that they are bona-fide pneumococcal isolates that do not express the capsule but are otherwise essentially similar to encapsulated pneumococci. Thus we propose that NT should be routinely identified and reported in surveillance studies