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Richard E. Ernst - One of the best experts on this subject based on the ideXlab platform.
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Giant Circumferential Dyke Swarms: Catalogue and Characteristics
Springer Geology, 2018Co-Authors: Kenneth L. Buchan, Richard E. ErnstAbstract:Giant Circumferential dyke swarms have a primary geometry that is quasi-circular or quasi-elliptical. Examples and possible examples described previously or identified in this study have outer diameters that range from ~450 to ~2500 km. There has been little study of these features. Here, we present a global catalogue of giant Circumferential dyke swarms and discuss their characteristics. All of the identified giant Circumferential swarms are of mafic composition. Many, but not all, are associated with a roughly coeval giant radiating dyke swarm whose focus is at or near the centre of the Circumferential system. As giant radiating swarms are usually interpreted to focus above mantle plume centres and form a key component of the plumbing system of large igneous provinces (LIPs), it is likely that giant Circumferential swarms linked to radiating systems are also plume and LIP related. The largest giant Circumferential swarms have diameters comparable to the diameters postulated for the flattened heads of plumes that have risen from the core-mantle boundary, suggesting that they may be associated with the outer edge of a flattening or flattened mantle plume head. Smaller giant Circumferential swarms could be linked with small plumes from the mid-mantle or with the edge of a magmatic underplate above a plume head. Giant Circumferential dyke swarms on Earth may be analogues of coronae on Venus and similar features on Mars. Coronae are large tectono-magmatic features that typically consist of a quasi-circular or quasi-elliptical graben-fissure system and associated topography (central uplift or depression, and circular rim or moat). In some instances, they are linked to a giant radiating graben-fissure system and LIP-scale volcanism. Both radiating and Circumferential graben on Venus and Mars have been interpreted to be underlain by dykes.
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a giant Circumferential dyke swarm associated with the high arctic large igneous province halip
Gondwana Research, 2018Co-Authors: Kenneth L. Buchan, Richard E. ErnstAbstract:Abstract In this study, we identify a giant Circumferential mafic dyke swarm associated with the 135–75 Ma High Arctic Large Igneous Province (HALIP). Previously, a HALIP giant radiating mafic dyke swarm, with portions scattered across the Canadian high Arctic islands, northern Greenland, Svalbard and Franz Josef Land, was recognized in a pre-drift plate tectonic reconstruction of the Arctic region. The radiating swarm has been interpreted to focus above a mantle plume responsible for HALIP magmatism. The newly-recognized HALIP giant Circumferential swarm has a centre that is near the focus of the HALIP radiating system, and hence, is likely related to the HALIP plume. Elements of the Circumferential swarm are located in each of the four regions where the radiating system is found. The Circumferential swarm has a quasi-circular or slightly elliptical geometry, an outer diameter of ~1600 km and an arc of ~220°. It is one of the largest giant Circumferential dyke swarms recognized on Earth, and could be linked to the outer edge of the flattening plume head. It is also the first such swarm to have been identified by means of a plate tectonic reconstruction. Although giant Circumferential dyke swarms appear to be relatively rare on Earth, possible analogues are common on Venus and are also found on Mars. On Venus giant circular or elliptical tectono-magmatic features, termed coronae, are characterized by an annulus of graben or fissures and prominent topography. Some coronae include a radiating graben-fissure system. Both radiating and Circumferential graben may be underlain by dykes. If so, coronae could be analogues for terrestrial giant Circumferential dyke swarms such as observed in the case of the HALIP.
Cody E. Bünger - One of the best experts on this subject based on the ideXlab platform.
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Circumferential fusion is dominant over posterolateral fusion in a long-term perspective: Cost-utility evaluation of a randomized controlled trial in severe, chronic low back pain
Spine, 2007Co-Authors: Rikke Soegaard, Cody E. Bünger, Terkel Christiansen, Kristian Høy, Søren P. Eiskjaer, Finn B ChristensenAbstract:STUDY DESIGN: Cost-utility evaluation of a randomized, controlled trial with a 4- to 8-year follow-up. OBJECTIVE: To investigate the incremental cost per quality-adjusted-life-year (QALY) when comparing Circumferential fusion to posterolateral fusion in a long-term, societal perspective. SUMMARY OF BACKGROUND DATA: The cost-effectiveness of Circumferential fusion in a long-term perspective is uncertain but nonetheless highly relevant as the ISSLS prize winner 2006 in clinical studies reported the effect of Circumferential fusion superior to the effect of posterolateral fusion. A recent trial found no significant difference between posterolateral and Circumferential fusion reporting cost-effectiveness from a 2-year viewpoint. METHODS: A total of 146 patients were randomized to posterolateral or Circumferential fusion and followed 4 to 8 years after surgery. The mean age of the cohort was 46 years (range, 20-65 years); 61% were females, 49% were smokers, 30% had primary diagnosis of isthmic spondylolisthesis, 35% had disc degeneration and no previous surgery, and 35% had disc degeneration and previous surgery. Eighty-two percent of patients have had symptoms for more than 2 years and 50% were out of the labor market due to sickness. The EQ-5D instrument was applied for the measurement of health-related quality of life and costs (2004 U.S. dollars) were measured in a full-scale societal perspective. Productivity costs were valued by the Friction Cost method, and both costs and effects were discounted. Arithmetic means and 95% bias-corrected, bootstrapped confidence intervals were reported. Nonparametric statistics were used for tests of statistical significance. Comprehensive sensitivity analysis was conducted and reported using cost-effectiveness acceptability curves. RESULTS: The Circumferential group demonstrated clinical superiority over the posterolateral fusion group in functional outcome (P < 0.01), fusion rate (P < 0.04), and number of reoperations (P < 0.01) among others. Cost-utility analysis demonstrated Circumferential fusion dominant over posterolateral fusion, that is, for each QALY gained performing Circumferential fusion, the incremental saving was estimated at U.S. $49,306 (95% confidence interval, $27,183-$2,735,712). Results proved to be strong to various sensitivity analyses; only a differentiated underestimation of patients' need for postoperative household help against the Circumferential approach could alter the dominance; however, still the probability of cost-effectiveness was >0.85 given a threshold for willingness to pay of U.S. $50,000 per QALY. CONCLUSION: Circumferential fusion is dominant over instrumented posterolateral fusion, that is, both being significantly cheaper and significantly better in a long-term, societal perspective.
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Circumferential fusion improves outcome in comparison with instrumented posterolateral fusion long term results of a randomized clinical trial
Spine, 2006Co-Authors: Tina S Videbaek, Rikke Soegaard, Finn B Christensen, Ebbe Stender Hansen, Peter Helmig, Bent Niedermann, Soren P Eiskjœr, Cody E. BüngerAbstract:STUDY DESIGN: Prospective randomized clinical study with a 5- to 9-year follow-up period. OBJECTIVE: The aim of the present study was to analyze the long-term outcome with respect to functional disability, pain, and general health of patients treated by means of Circumferential lumbar fusion in comparison with those treated by means of instrumented posterolateral lumbar fusion. SUMMARY OF BACKGROUND DATA: Circumferential fusion has become a common procedure in lumbar spinal fusion both as a primary and salvage procedure. However, the claimed advantages of Circumferential fusion over conventional posterolateral fusion lack scientific documentation. (The primary report with a 2-year follow-up has been published in Spine in 2002.) METHODS: From April 1996 to November 1999, a total of 148 patients (mean age, 45 years) with severe chronic low back pain were randomly selected for either posterolateral lumbar fusion (titanium Cotrel-Dubousset) or Circumferential lumbar fusion (instrumented posterolateral fusion with anterior intervertebral support by a Brantigan cage). The primary outcome measure was the Dallas Pain Questionnaire (DPQ). The secondary outcome measures were the Oswestry Disability Index, the SF-36 instrument, and the Low Back Pain Rating Scale. All measures assessed the endpoint outcomes at 5 to 9 years after surgery. RESULTS: The available response rate was 93%. The Circumferential group showed a significantly better improvement (P < 0.05) in comparison with the posterolateral group with respect to all four DPQ categories: daily activities, work/leisure, anxiety/depression, and social interest. The Oswestry Disability Index supported these results (P < 0.01). General health, as assessed by means of the SF-36, also showed significantly better physical health (P < 0.01) in the Circumferential group, whereas no significant difference was found with respect to mental health compared with the posterolateral group. The Circumferential group experienced significantly less back pain (P < 0.05) in comparison with the posterolateral group. In regard to leg pain, no significant difference was found. CONCLUSION: Circumferential lumbar fusion demands more extensive operative resources compared with posterolateral lumbar fusion. However, 5 to 9 years after surgery, the Circumferentially fused patients had a significantly improved outcome compared with those treated by means of posterolateral fusion. These new results not only emphasize the superiority of Circumferential fusion in the complex pathology of the lumbar spine but are also strongly supported in all of the validated questionnaires used in the study.
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Circumferential lumbar spinal fusion with brantigan cage versus posterolateral fusion with titanium cotrel dubousset instrumentation a prospective randomized clinical study of 146 patients
Spine, 2002Co-Authors: Finn B Christensen, Ebbe Stender Hansen, Soren Peter Eiskjaer, Peter Helmig, Pavel Neumann, Bent Niedermann, Cody E. BüngerAbstract:STUDY DESIGN: A prospective randomized clinical study with a 2-year follow-up period was conducted. OBJECTIVE: To analyze the effects of Circumferential fusion using ALIF radiolucent carbon fiber cages and titanium posterior instrumentation on functional outcome, fusion rate, complications, and lumbar lordosis. SUMMARY OF BACKGROUND DATA: Circumferential fusion has become a common procedure in lumbar spine fusion, both as a primary and salvage procedure. However, the claimed advantages of ALIF plus PLF over conventional PLF lack scientific documentation. METHODS: From April 1996 through November 1999, a total of 148 patients with severe chronic low back pain were randomly selected for either posterolateral lumbar fusion with titanium CD-Horizon (posterolateral group) or Circumferential fusion with a ALIF Brantigan cage plus posterior instrumentation. The Dallas Pain Questionnaire (DPQ), the Low Back Pain Rating Scale (LBPR), and a questionnaire concerning work status assessed their outcomes. RESULTS: Both groups showed highly significant improvement in all four categories of life quality (DPQ) as well as in the back pain and leg pain index (LBPR), as compared with preoperative status. There was a clear tendency toward better overall functional outcome for patients with the Circumferential procedure ( < 0.08), and this patient group also showed significantly less leg pain at the 1-year follow-up evaluation ( < 0.03) and less peak back pain at 2 years ( < 0.04). Sagittal lordosis was restored and maintained in the Circumferential group ( < 0.01). The Circumferential fusion patients showed a higher posterolateral fusion rate (92%) than the posterolateral group (80%)( < 0.04). The repeat operation rate including implant removal was significantly lower in the Circumferential group (7%) ( < 0.009) than in the posterolateral group (22%). CONCLUSIONS: Circumferential lumbar fusion restored lordosis, provided a higher union rate with significantly fewer repeat operations, showed a tendency toward better functional outcome, and resulted in less peak back pain and leg pain than instrumented posterolateral fusion. The clinical perspective of the current study implies a recommendation to favor Circumferential fusion as a definitive surgical procedure in complex lumbar pathology involving major instability, flatback, and previous disc surgery in younger patients, as compared with posterolateral fusion with pedicle screws alone.
Finn B Christensen - One of the best experts on this subject based on the ideXlab platform.
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Circumferential fusion is dominant over posterolateral fusion in a long-term perspective: Cost-utility evaluation of a randomized controlled trial in severe, chronic low back pain
Spine, 2007Co-Authors: Rikke Soegaard, Cody E. Bünger, Terkel Christiansen, Kristian Høy, Søren P. Eiskjaer, Finn B ChristensenAbstract:STUDY DESIGN: Cost-utility evaluation of a randomized, controlled trial with a 4- to 8-year follow-up. OBJECTIVE: To investigate the incremental cost per quality-adjusted-life-year (QALY) when comparing Circumferential fusion to posterolateral fusion in a long-term, societal perspective. SUMMARY OF BACKGROUND DATA: The cost-effectiveness of Circumferential fusion in a long-term perspective is uncertain but nonetheless highly relevant as the ISSLS prize winner 2006 in clinical studies reported the effect of Circumferential fusion superior to the effect of posterolateral fusion. A recent trial found no significant difference between posterolateral and Circumferential fusion reporting cost-effectiveness from a 2-year viewpoint. METHODS: A total of 146 patients were randomized to posterolateral or Circumferential fusion and followed 4 to 8 years after surgery. The mean age of the cohort was 46 years (range, 20-65 years); 61% were females, 49% were smokers, 30% had primary diagnosis of isthmic spondylolisthesis, 35% had disc degeneration and no previous surgery, and 35% had disc degeneration and previous surgery. Eighty-two percent of patients have had symptoms for more than 2 years and 50% were out of the labor market due to sickness. The EQ-5D instrument was applied for the measurement of health-related quality of life and costs (2004 U.S. dollars) were measured in a full-scale societal perspective. Productivity costs were valued by the Friction Cost method, and both costs and effects were discounted. Arithmetic means and 95% bias-corrected, bootstrapped confidence intervals were reported. Nonparametric statistics were used for tests of statistical significance. Comprehensive sensitivity analysis was conducted and reported using cost-effectiveness acceptability curves. RESULTS: The Circumferential group demonstrated clinical superiority over the posterolateral fusion group in functional outcome (P < 0.01), fusion rate (P < 0.04), and number of reoperations (P < 0.01) among others. Cost-utility analysis demonstrated Circumferential fusion dominant over posterolateral fusion, that is, for each QALY gained performing Circumferential fusion, the incremental saving was estimated at U.S. $49,306 (95% confidence interval, $27,183-$2,735,712). Results proved to be strong to various sensitivity analyses; only a differentiated underestimation of patients' need for postoperative household help against the Circumferential approach could alter the dominance; however, still the probability of cost-effectiveness was >0.85 given a threshold for willingness to pay of U.S. $50,000 per QALY. CONCLUSION: Circumferential fusion is dominant over instrumented posterolateral fusion, that is, both being significantly cheaper and significantly better in a long-term, societal perspective.
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Circumferential fusion improves outcome in comparison with instrumented posterolateral fusion long term results of a randomized clinical trial
Spine, 2006Co-Authors: Tina S Videbaek, Rikke Soegaard, Finn B Christensen, Ebbe Stender Hansen, Peter Helmig, Bent Niedermann, Soren P Eiskjœr, Cody E. BüngerAbstract:STUDY DESIGN: Prospective randomized clinical study with a 5- to 9-year follow-up period. OBJECTIVE: The aim of the present study was to analyze the long-term outcome with respect to functional disability, pain, and general health of patients treated by means of Circumferential lumbar fusion in comparison with those treated by means of instrumented posterolateral lumbar fusion. SUMMARY OF BACKGROUND DATA: Circumferential fusion has become a common procedure in lumbar spinal fusion both as a primary and salvage procedure. However, the claimed advantages of Circumferential fusion over conventional posterolateral fusion lack scientific documentation. (The primary report with a 2-year follow-up has been published in Spine in 2002.) METHODS: From April 1996 to November 1999, a total of 148 patients (mean age, 45 years) with severe chronic low back pain were randomly selected for either posterolateral lumbar fusion (titanium Cotrel-Dubousset) or Circumferential lumbar fusion (instrumented posterolateral fusion with anterior intervertebral support by a Brantigan cage). The primary outcome measure was the Dallas Pain Questionnaire (DPQ). The secondary outcome measures were the Oswestry Disability Index, the SF-36 instrument, and the Low Back Pain Rating Scale. All measures assessed the endpoint outcomes at 5 to 9 years after surgery. RESULTS: The available response rate was 93%. The Circumferential group showed a significantly better improvement (P < 0.05) in comparison with the posterolateral group with respect to all four DPQ categories: daily activities, work/leisure, anxiety/depression, and social interest. The Oswestry Disability Index supported these results (P < 0.01). General health, as assessed by means of the SF-36, also showed significantly better physical health (P < 0.01) in the Circumferential group, whereas no significant difference was found with respect to mental health compared with the posterolateral group. The Circumferential group experienced significantly less back pain (P < 0.05) in comparison with the posterolateral group. In regard to leg pain, no significant difference was found. CONCLUSION: Circumferential lumbar fusion demands more extensive operative resources compared with posterolateral lumbar fusion. However, 5 to 9 years after surgery, the Circumferentially fused patients had a significantly improved outcome compared with those treated by means of posterolateral fusion. These new results not only emphasize the superiority of Circumferential fusion in the complex pathology of the lumbar spine but are also strongly supported in all of the validated questionnaires used in the study.
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Circumferential lumbar spinal fusion with brantigan cage versus posterolateral fusion with titanium cotrel dubousset instrumentation a prospective randomized clinical study of 146 patients
Spine, 2002Co-Authors: Finn B Christensen, Ebbe Stender Hansen, Soren Peter Eiskjaer, Peter Helmig, Pavel Neumann, Bent Niedermann, Cody E. BüngerAbstract:STUDY DESIGN: A prospective randomized clinical study with a 2-year follow-up period was conducted. OBJECTIVE: To analyze the effects of Circumferential fusion using ALIF radiolucent carbon fiber cages and titanium posterior instrumentation on functional outcome, fusion rate, complications, and lumbar lordosis. SUMMARY OF BACKGROUND DATA: Circumferential fusion has become a common procedure in lumbar spine fusion, both as a primary and salvage procedure. However, the claimed advantages of ALIF plus PLF over conventional PLF lack scientific documentation. METHODS: From April 1996 through November 1999, a total of 148 patients with severe chronic low back pain were randomly selected for either posterolateral lumbar fusion with titanium CD-Horizon (posterolateral group) or Circumferential fusion with a ALIF Brantigan cage plus posterior instrumentation. The Dallas Pain Questionnaire (DPQ), the Low Back Pain Rating Scale (LBPR), and a questionnaire concerning work status assessed their outcomes. RESULTS: Both groups showed highly significant improvement in all four categories of life quality (DPQ) as well as in the back pain and leg pain index (LBPR), as compared with preoperative status. There was a clear tendency toward better overall functional outcome for patients with the Circumferential procedure ( < 0.08), and this patient group also showed significantly less leg pain at the 1-year follow-up evaluation ( < 0.03) and less peak back pain at 2 years ( < 0.04). Sagittal lordosis was restored and maintained in the Circumferential group ( < 0.01). The Circumferential fusion patients showed a higher posterolateral fusion rate (92%) than the posterolateral group (80%)( < 0.04). The repeat operation rate including implant removal was significantly lower in the Circumferential group (7%) ( < 0.009) than in the posterolateral group (22%). CONCLUSIONS: Circumferential lumbar fusion restored lordosis, provided a higher union rate with significantly fewer repeat operations, showed a tendency toward better functional outcome, and resulted in less peak back pain and leg pain than instrumented posterolateral fusion. The clinical perspective of the current study implies a recommendation to favor Circumferential fusion as a definitive surgical procedure in complex lumbar pathology involving major instability, flatback, and previous disc surgery in younger patients, as compared with posterolateral fusion with pedicle screws alone.
Matilda Larsson - One of the best experts on this subject based on the ideXlab platform.
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Circumferential strain by velocity vector imaging and speckle tracking echocardiography validation against sonomicrometry in an aortic phantom
Clinical Physiology and Functional Imaging, 2018Co-Authors: Johan Petrini, Maria J Eriksson, Kenneth Caidahl, Matilda LarssonAbstract:Evaluation of arterial deformation and mechanics using strain analysis on ultrasound greyscale images has gained increasing scientific interest. The aim of this study was to validate in vitro measurements of Circumferential strain by velocity vector imaging (VVI) and speckle-tracking echocardiography (STE) against sonomicrometry as a reference method.Two polyvinyl alcohol phantoms sized to mimic the descending aorta were constructed and connected to a pulsatile flow pump to obtain high-resistance flow profiles. The ultrasound images of the phantom used for strain analyses were acquired with a transesophageal probe. Global and regional Circumferential strains were estimated using VVI and STE and were compared with the strain acquired by sonomicrometry.Global Circumferential peak strain estimated by VVI and STE correlated well to sonomicrometry (r = 0·90, P≤0·001; and r = 0·97, P≤0·01) with a systematic bias of -0·78% and +0·63%, respectively. The reference strain levels were 1·07-2·54%. Circumferential strain values obtained by VVI were significantly lower than those obtained by STE (bias -1·41%, P≤0·001).Global Circumferential strain measured by VVI and STE correlates well with sonomicrometry. However, strain values obtained by VVI and STE differ significantly, which should be taken into consideration when comparing results from studies using different software for aortic strain measurements.
J Ryhanen - One of the best experts on this subject based on the ideXlab platform.
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nickel titanium wire in Circumferential suture of a flexor tendon repair a comparison to polypropylene
Journal of Hand Surgery (European Volume), 2010Co-Authors: T Karjalainen, Mingguang He, Alphonsus K S Chong, J RyhanenAbstract:Purpose Nickel-titanium (NiTi) has been proposed as an alternative material for flexor tendon core suture. To our knowledge, its suitability as a Circumferential suture of flexor tendon repair has not been investigated before. The purpose of this ex vivo study was to investigate the biomechanical properties of NiTi Circumferential repairs and to compare them with commonly used polypropylene. Methods Forty porcine flexor tendons were cut and repaired by simple running or interlocking mattress technique using 100 μm NiTi wire or 6-0 polypropylene. Results The NiTi Circumferential repairs showed superior stiffness, gap resistance, and load to failure when compared to polypropylene repairs with both techniques. Conclusions Nickel-titanium wire seems to be a potential material for Circumferential repair of flexor tendons.