Arin M. Ellingson
Bio: Arin M. Ellingson is an academic researcher from University of Minnesota. The author has contributed to research in topics: Intervertebral disc & Medicine. The author has an hindex of 12, co-authored 31 publications receiving 378 citations. Previous affiliations of Arin M. Ellingson include American Physical Therapy Association & Mayo Clinic.
TL;DR: Routine MRI sequences are not adequate in detecting early changes in degeneration and fails to correlate with pain or improve patient stratification, so quantitative T2* mapping is a sensitive quantitative method capable of detecting changes associated with disc degeneration.
Abstract: Study Design. Experimental correlation study design to quantify features of disc health, including signal intensity and distinction between the annulus fibrosus and nucleus pulposus, with T2* magnetic resonance imaging (MRI) and correlate with the functional mechanics in corresponding motion segments. Objective. Establish the relationship between disc health assessed by quantitative T2* MRI and functional lumbar mechanics. Summary of Background Data. Degeneration leads to altered biochemistry in the disc, affecting the mechanical competence. Clinical routine MRI sequences are not adequate in detecting early changes in degeneration and fails to correlate with pain or improve patient stratification. Quantitative T2* relaxation time mapping probes biochemical features and may offer more sensitivity in assessing disc degeneration. Methods. Cadaveric lumbar spines were imaged using quantitative T2* mapping, as well as conventional T2-weighted MRI sequences. Discs were graded by the Pfirrmann scale, and features of disc health, including signal intensity (T2* intensity area) and distinction between the annulus fibrosus and nucleus pulposus (transition zone slope), were quantified by T2*. Each motion segment was subjected to pure moment bending to determine range of motion (ROM), neutral zone (NZ), and bending stiffness. Results. T2* intensity area and transition zone slope were significantly correlated with flexion ROM (P = 0.015; P = 0.002), ratio of NZ/ROM (P = 0.010; P = 0.028), and stiffness (P = 0.044; P = 0.026), as well as lateral bending NZ/ROM (P = 0.005; P = 0.010) and stiffness (P = 0.022; P = 0.029). T2* intensity area was also correlated with lateral bending ROM (P = 0.023). Pfirrmann grade was only correlated with lateral bending NZ/ROM (P = 0.001) and stiffness (P = 0.007). Conclusion. T2* mapping is a sensitive quantitative method capable of detecting changes associated with disc degeneration. Features of disc health quantified with T2* predicted altered functional mechanics of the lumbar spine better than traditional Pfirrmann grading. This new methodology and analysis technique may enhance the assessment of degeneration and enable greater patient stratification for therapeutic strategies. Conclusion. Level of Evidence: N/A
TL;DR: The screws designed specifically for osteoporotic bone showed significantly larger insertion torque compared with the standard screw design irrespective of insertion technique, and much of the variability in pullout failure and stiffness was explained by bone mineral density.
TL;DR: T2*MRI assessment of disc health is a clinically viable tool showing promise as a biomarker for distinguishing degenerative changes and strong correlations highlight T2* MRI's ability to predict the biochemical and mechanical health of the disc.
TL;DR: This was the first study to quantify ROM in a single group of spinal motion segments at four independent laboratories with varying pure moment systems and supported the hypothesis that given a well-described test method, independent laboratories can produce similar biomechanical outcomes.
TL;DR: The results of this study indicate that lateral bending may be more apt to detect the subtle changes associated with degeneration, without being masked by associated changes of surrounding stabilizing structures.
Abstract: Understanding spinal kinematics is essential for distinguishing between pathological conditions of spine disorders, which ultimately lead to low back pain. It is of high importance to understand how changes in mechanical properties affect the response of the lumbar spine, specifically in an effort to differentiate those associated with disc degeneration from ligamentous changes, allowing for more precise treatment strategies. To do this, the goals of this study were twofold: (1) develop and validate a finite element (FE) model of the lumbar spine and (2) systematically alter the properties of the intervertebral disc and ligaments to define respective roles in functional mechanics. A three-dimensional non-linear FE model of the lumbar spine (L3-sacrum) was developed and validated for pure moment bending. Disc degeneration and sequential ligament failure were modelled. Intersegmental range of motion (ROM) and bending stiffness were measured. The prediction of the FE model to moment loading in all three planes of bending showed very good agreement, where global and intersegmental ROM and bending stiffness of the model fell within one standard deviation of the in vitro results. Degeneration decreased ROM for all directions. Stiffness increased for all directions except axial rotation, where it initially increased then decreased for moderate and severe degeneration, respectively. Incremental ligament failure produced increased ROM and decreased stiffness. This effect was much more pronounced for all directions except lateral bending, which is minimally impacted by ligaments. These results indicate that lateral bending may be more apt to detect the subtle changes associated with degeneration, without being masked by associated changes of surrounding stabilizing structures.
TL;DR: It is argued that mechanics and biology are interconnected and amplify each other and the proposed disease model explains the comparable efficacy of very different animal models of disc degeneration, but also helps to consider the consequences of therapeutic interventions, either at the cellular, material or mechanical level.
TL;DR: An assessment of the state and historic development of evaluation practices as reported in papers published at the IEEE Visualization conference found that evaluations specific to assessing resulting images and algorithm performance are the most prevalent and generally the studies reporting requirements analyses and domain-specific work practices are too informally reported.
Abstract: We present an assessment of the state and historic development of evaluation practices as reported in papers published at the IEEE Visualization conference. Our goal is to reflect on a meta-level about evaluation in our community through a systematic understanding of the characteristics and goals of presented evaluations. For this purpose we conducted a systematic review of ten years of evaluations in the published papers using and extending a coding scheme previously established by Lam et al. . The results of our review include an overview of the most common evaluation goals in the community, how they evolved over time, and how they contrast or align to those of the IEEE Information Visualization conference. In particular, we found that evaluations specific to assessing resulting images and algorithm performance are the most prevalent (with consistently 80-90% of all papers since 1997). However, especially over the last six years there is a steady increase in evaluation methods that include participants, either by evaluating their performances and subjective feedback or by evaluating their work practices and their improved analysis and reasoning capabilities using visual tools. Up to 2010, this trend in the IEEE Visualization conference was much more pronounced than in the IEEE Information Visualization conference which only showed an increasing percentage of evaluation through user performance and experience testing. Since 2011, however, also papers in IEEE Information Visualization show such an increase of evaluations of work practices and analysis as well as reasoning using visual tools. Further, we found that generally the studies reporting requirements analyses and domain-specific work practices are too informally reported which hinders cross-comparison and lowers external validity.
TL;DR: Whether the loss of nutrients associated with disc degeneration limits the effectiveness of biologic approaches is discussed, and it is indicated that this neglected problem requires investigation if clinical application of such therapies is to succeed.
Abstract: Strategies for the biological repair of intervertebral discs derive from the premise that disc degeneration results from impaired cellular activity and, therefore, that these structures can be induced to regenerate by implanting active cells or providing factors that restore normal cellular activity. In vitro and animal studies using this approach have had some success, but whether this success can be reproduced in degenerate human lumbar discs is unknown. Successful repair requires that the disc cells remain viable and active; they therefore need an adequate supply of nutrients. However, as the disc degenerates, the nutrient supply decreases, thereby limiting cell activity and viability. Current biologic approaches might place additional demands on an already precarious nutrient supply. Here, we discuss whether the loss of nutrients associated with disc degeneration limits the effectiveness of biologic approaches, and indicate that this neglected problem requires investigation if clinical application of such therapies is to succeed.
TL;DR: How identifying the specific mechanisms that operate in the nervous system to produce chronic pain in individual patients could provide the basis for a targeted and rational precision medicine approach to controlling pain is discussed, using chronic low back pain as an example.
TL;DR: Four considerations that abstract comparison are presented that identify issues and categorize solutions in a domain independent manner and provide a process for developers to consider support for comparison in the design of visualization tools.
Abstract: Supporting comparison is a common and diverse challenge in visualization. Such support is difficult to design because solutions must address both the specifics of their scenario as well as the general issues of comparison. This paper aids designers by providing a strategy for considering those general issues. It presents four considerations that abstract comparison. These considerations identify issues and categorize solutions in a domain independent manner. The first considers how the common elements of comparison—a target set of items that are related and an action the user wants to perform on that relationship—are present in an analysis problem. The second considers why these elements lead to challenges because of their scale, in number of items, complexity of items, or complexity of relationship. The third considers what strategies address the identified scaling challenges, grouping solutions into three broad categories. The fourth considers which visual designs map to these strategies to provide solutions for a comparison analysis problem. In sequence, these considerations provide a process for developers to consider support for comparison in the design of visualization tools. Case studies show how these considerations can help in the design and evaluation of visualization solutions for comparison problems.