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D. C. Barton - One of the best experts on this subject based on the ideXlab platform.
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spinal cord fragment interactions following Burst Fracture an in vitro model
Journal of Neurosurgery, 2006Co-Authors: R. M. Hall, Ruth K Wilcox, R J Oakland, D. C. BartonAbstract:Object The purpose of the study was to develop an in vitro model of the bone fragment and spinal cord interactions that occur during a Burst Fracture and further the understanding of how the velocity of the bone fragment and the status of the posterior longitudinal ligament (PLL) affect the deformation of the cord. Methods An in vitro model was developed such that high-speed video and pressure measurements recorded the impact of a simulated bone fragment on sections of explanted bovine spinal cord. The model simulated the PLL and the posterior elements. The status of the PLL had a significant effect on both the maximum occlusion of the spinal cord and the time for occlusion to occur. Raising the fragment velocity led to an overall increase in the spinal cord deformation. Interestingly the dura mater appeared to have little or no effect on the extent of occlusion. Conclusions These findings may indicate the importance of the dura’s interaction with the cerebrospinal fluid in protecting the cord during this...
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A dynamic investigation of the Burst Fracture process using a combined experimental and finite element approach
European Spine Journal, 2004Co-Authors: R. K. Wilcox, D. J. Allen, R. M. Hall, D. Limb, D. C. Barton, R. A. DicksonAbstract:Spinal Burst Fractures account for about 15% of spinal injuries and, because of their predominance in the younger population, there are large associated social and healthcare costs. Although several experimental studies have investigated the Burst Fracture process, little work has been undertaken using computational methods. The aim of this study was to develop a finite element model of the Fracture process and, in combination with experimental data, gain a better understanding of the Fracture event and mechanism of injury. Experimental tests were undertaken to simulate the Burst Fracture process in a bovine spine model. After impact, each specimen was dissected and the severity of Fracture assessed. Two of the specimens tested at the highest impact rate were also dynamically filmed during the impact. A finite element model, based on CT data of an experimental specimen, was constructed and appropriate high strain rate material properties assigned to each component. Dynamic validation was undertaken by comparison with high-speed video data of an experimental impact. The model was used to determine the mechanism of Fracture and the postFracture impact of the bony fragment onto the spinal cord. The dissection of the experimental specimens showed Burst Fractures of increasing severity with increasing impact energy. The finite element model demonstrated that a high tensile strain region was generated in the posterior of the vertebral body due to the interaction of the articular processes. The region of highest strain corresponded well with the experimental specimens. A second simulation was used to analyse the fragment projection into the spinal canal following Fracture. The results showed that the posterior longitudinal ligament became stretched and at higher energies the spinal cord and the dura mater were compressed by the fragment. These structures deformed to a maximum level before forcing the fragment back towards the vertebral body. The final position of the fragment did not therefore represent the maximum dynamic canal occlusion.
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measurement of canal occlusion during the thoracolumbar Burst Fracture process
Journal of Biomechanics, 2002Co-Authors: Ruth K Wilcox, R. M. Hall, D. Limb, D. C. Barton, T O Boerger, R. A. DicksonAbstract:Post-injury CT scans are often used following Burst Fracture trauma as an indication for decompressive surgery. Literature suggests, however, that there is little correlation between the observed fragment position and the level of neurological injury or recovery. Several studies have aimed to establish the processes that occur during the Fracture using indirect methods such as pressure measurements and pre/post impact CT scans. The purpose of this study was to develop a direct method of measuring spinal canal occlusion during a simulated Burst Fracture by using a high-speed video technique. The Fractures were produced by dropping a mass from a measured height onto three-vertebra bovine specimens in a custom-built rig. The specimens were constrained to deform only in the impact direction such that pure compression Fractures were generated. The spinal cord was removed prior to testing and the video system set up to film the inside of the spinal canal during the impact. A second camera was used to film the outside of the specimen to observe possible buckling during impact. The video images were analysed to determine how the cross-sectional area of the spinal canal changed during the event. The images clearly showed a fragment of bone being projected from the vertebral body into the spinal canal and recoiling to the final resting position. To validate the results, CT scans were taken pre- and post-impact and the percentage canal occlusion was calculated. There was good agreement between the final canal occlusion measured from the video images and the CT scans.
Cari M. Whyne - One of the best experts on this subject based on the ideXlab platform.
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a biomechanical assessment of kyphoplasty as a stand alone treatment in a human cadaveric Burst Fracture model
Spine, 2015Co-Authors: Edwin King Yat Wong, Cari M. Whyne, Devin Anand Singh, Michael FordAbstract:Study Design. In vitro biomechanics study. Objective. To determine whether kyphoplasty is an adequate stand-alone treatment for restoring biomechanical stability in the spine after experiencing high-energy vertebral Burst Fractures. Summary of Background Data. Kyphoplasty in the treatment of high-energy vertebral Burst Fractures has been shown by previous studies to significantly improve stiffness when used in conjunction with pedicle screw instrumentation. However, it is not known whether kyphoplasty as a stand-alone treatment may be an acceptable method for restoring biomechanical stability of a spinal motion segment post–Burst Fracture while allowing flexibility of the motion segment through the intervertebral discs. Methods. Young cadaveric spines (15–50 yr old; 3 males and 1 female; bone mineral density 0.27–0.31 gHA/cm3) were divided into motion segments consisting of 3 intact vertebrae separated by 2 intervertebral discs (T11–L1 and L2–L4). Mechanical testing in axial, flexion/extension, lateral bending, and torsion was performed on each specimen in an intact state, after an experimentally simulated Burst Fracture and postkyphoplasty. Computed tomography was used to confirm the Burst Fractures and quantify cement placement. Results. Between the intact and Burst-Fractured states significant decreases in stiffness were seen in all loading modes (63%–69%). Burst Fracture increased the average angulation of the vertebral endplates 147% and decreased vertebral body height by an average of 40%. Postkyphoplasty, only small recoveries in stiffness were seen in axial, flexion/extension, and lateral bending (4%–12%), with no improvement in torsional stiffness. Large angular deformations (85%) and height loss (31%) remained postkyphoplasty as compared with the intact state. Conclusion. Lack of overall improvement in biomechanical stiffness indicates failure of kyphoplasty to sufficiently restore stability as a stand-alone treatment after high-energy Burst Fracture. The lack of stability can be explained by an inability to biomechanically repair the compromised intervertebral discs. Conclusion. Level of Evidence: 3
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Metastatic Burst Fracture Risk Assessment Based on Complex Loading of the Thoracic Spine
Annals of Biomedical Engineering, 2006Co-Authors: Craig E. Tschirhart, Joel A. Finkelstein, Cari M. WhyneAbstract:The mechanical integrity of vertebral bone is compromised when metastatic cancer cells migrate to the spine, rendering it susceptible to Burst Fracture under physiologic loading. Risk of Burst Fracture has been shown to be dependent on the magnitude of the applied load, however limited work has been conducted to determine the effect of load type on the stability of the metastatic spine. The objective of this study was to use biphasic finite element modeling to evaluate the effect of multiple loading conditions on a metastatically-involved thoracic spinal motion segment. Fifteen loading scenarios were analyzed, including axial compression, flexion, extension, lateral bending, torsion, and combined loads. Additional analyses were conducted to assess the impact of the ribcage on the stability of the thoracic spine. Results demonstrate that axial loading is the predominant load type leading to increased risk of Burst Fracture initiation, while rotational loading led to only moderate increases in risk. Inclusion of the ribcage was found to reduce the potential for Burst Fracture by 27%. These findings are important in developing a more comprehensive understanding of Burst Fracture mechanics and in directing future modeling efforts. The results in this study may also be useful in advising less harmful activities for patients affected by lytic spinal metastases.
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effects of tumor location shape and surface serration on Burst Fracture risk in the metastatic spine
Journal of Biomechanics, 2004Co-Authors: Craig E. Tschirhart, Amik Nagpurkar, Cari M. WhyneAbstract:Spinal metastatic disease occurs in up to one-third of all cancer patients. Advanced spread can lead to vertebral Burst Fracture, which may result in neurologic compromise. Developing a better understanding of factors affecting Burst Fracture risk has significant clinical importance, as early intervention can prevent vertebral Fracture in high-risk patients. The primary objective of this study was to quantify the effects of tumor location and shape on vertebral body stability and Burst Fracture risk in the metastatic spine using poroelastic parametric finite element modeling. This study also compared two distinct surface modeling techniques in the representation of lytic defects. A total of 16 ellipsoidal tumor scenarios were analyzed. Single tumors were situated in central, anterior, posterior, superior, inferior, and lateral locations, with smooth and serrated tumor surfaces. Two central shapes and two serrated surface multi-tumor scenarios were also analyzed. Outcome parameters of maximum vertebral bulge and axial displacement were assessed as representative of Burst Fracture risk. Posterior movement of the tumor caused the greatest increase in vertebral bulge. Tumor shape also affected Burst Fracture risk. The multi-tumor scenarios yielded the greatest reductions in both vertebral bulge and axial displacement. Serrated tumor scenarios abided by similar trends as smooth tumor scenarios, although tumor serration caused a slight increase in Fracture risk. Tumor shape and volume are best controlled by smooth surface modeling. Improved understanding of factors contributing to metastatic Burst Fracture risk will aid in directing future modeling efforts and in the development of accurate risk assessment criteria.
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metastatic Burst Fracture risk prediction using biomechanically based equations
Clinical Orthopaedics and Related Research, 2004Co-Authors: Sandra E Roth, Payam Mousavi, Edward Chow, Joel S Finkelstein, Hans J Kreder, Cari M. WhyneAbstract:Clinical guidelines are a useful adjunct to select patients with spinal metastases for prophylactic intervention. The objective of this study is to determine the ability of biomechanically based models to accurately predict metastatic Burst Fracture risk. Ninety-two vertebrae with osteolytic spinal metastases were examined retrospectively. Vertebrae were categorized as Burst Fractured, wedge Fractured, or intact and analyzed using three predictive models: vertebral bulge (maximum radial displacement under load), vertebral axial displacement (maximum axial displacement under load), and a volumetric estimate of tumor size. The load-bearing capacity parameter (tumor volume, bone mineral density, disc quality, pedicle involvement) was determined from computed tomography while the load-bearing requirement parameter (pressure load, loading rate) was determined using computed tomography and patient records (retrieved for 37 patients [52%]). Fracture prediction was optimized using the vertebral bulge model considering only load-bearing capacity with a specificity, sensitivity, and confidence interval of 1 to yield a clear threshold for Burst Fracture risk. Fracture prediction in the other two models, vertebral axial displacement considering only load-bearing capacity and tumor size, also was strong with receiver-operator curve values of 0.992 and 0.988, respectively. The predictive power of these models can provide useful clinical information for prophylactic decision-making.
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Burst Fracture in the metastatically involved spine development validation and parametric analysis of a three dimensional poroelastic finite element model
Spine, 2003Co-Authors: Cari M. Whyne, Jeffery C. LotzAbstract:Study Design. A finite-element study and in vitro experimental validation was performed for a parametric investigation of features that contribute to Burst Fracture risk in the metastatically involved spine. Objectives. To develop and validate a three-dimensional poroelastic model of a metastatically compromised vertebral segment, to evaluate the effect of lytic lesions on vertebral strains and pressures, and to determine the influence of loading and motion segment status (bone density, pedicle involvement, disc degeneration, and tumor size) on the relative risk of Burst Fracture initiation. Summary of Background Data. Finite-element analysis has been used successfully to predict failure loads and Fracture patterns for bone. Although models for vertebra affected with tumors have been presented, these have not been thoroughly validated experimentally. Consequently, their predictive capabilities remain uncertain. Methods. A three-dimensional poroelastic finite-element model of the first lumbar vertebra and adjacent intervertebral discs, including a tumor of variable size, was developed. To validate the model, 12 cadaver spinal motion segments were tested in axial compression, in intact condition, and with simulated osteolytic defects. Features of the validated model were parametrically varied to investigate the effects of tumor size, trabecular bone density, pedicle involvement, applied loads, loading rates, and disc degeneration using outcome variables of vertebral bulge and vertebral axial deformation. Results. Consistent trends between the experimental data and model predictions were observed. Overall, the model results suggest that tumor size contributes most toward the risk of initiating Burst Fracture, followed by the applied load magnitude and bone density. Conclusions. The parametric analysis suggests that the principal factors affecting the initiation of Burst Fracture in metastatically affected vertebrae are tumor size, magnitude of spinal loading, and bone density. Consequently, patient-specific measures of these factors should be factored into decisions regarding clinical prophylaxis. Pedicle involvement or disc degeneration was less important according to the outcome measures in this study.
Fang Huang - One of the best experts on this subject based on the ideXlab platform.
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The relationship between static spinal canal encroachment in thoracolumbar Burst Fracture and spinal cord injury
Modern Medicine Health, 2004Co-Authors: Fang HuangAbstract:Objective:To study the relationship between static spinal canal encroachment in thoracolumbar Burst Fracture and spinal cord injury(SCT).Methods:Fifty-six patients with thoracolumbar Burst Fracture were included.Computed tomographic scans were used to measure the sagittal diameters and the surface area of the spinal canal.The percentage of spinal canal stenosis and spinal canal impingement at the level of injury were calculated to reflect the static spinal canal encroachment of the spinal canal.The neurological status was evaluated with ASIA impair-ment scale and the motor index score.Then the static spinal canal encroachments of the spinal canals with different neurological statuses were compared.Results:No difference was found at the level of injury in the percentage of spinal canal stenosis and spinal canal impingement between the patients with and without SCI(P0.05).However,the percentage of spinal canal stenosis and spinal canal impingement was significantly higher in the SCI patients with lower motor scores(25points)than that with higher motor scores(≥25points)(P0.05).The percentages of spinal canal stenosis and spinal canal impingement showed a negative correlation with both ASIA impairment and motor index score(rs=-0.46～-0.52,P≤0.01).Conclusion:The static canal encroachment in thoracolumbar Burst Fracture affects SCI,the percentage of spinal canal stenosis and spinal canal impingement can reflect the degree of SCI in a certain extent.
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Relation between thoracolumbar Burst Fracture and spinal cord injury
Journal of Traumatic Surgery, 2004Co-Authors: Fang HuangAbstract:Thoracoiumbar Burst Fracture is a serious trauma and may lead to severe aftermath or spinal cord injury. In the past 10 years, the research on the mechanism of spinal cord injury caused by the thoracolumbar Burst Fracture and its relationship has obtained much progress. This review gave a summary of progress of the experimental and clinical research about the relation between thoracolumbar Burst Fracture and spinal cord injury.
R. M. Hall - One of the best experts on this subject based on the ideXlab platform.
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spinal cord fragment interactions following Burst Fracture an in vitro model
Journal of Neurosurgery, 2006Co-Authors: R. M. Hall, Ruth K Wilcox, R J Oakland, D. C. BartonAbstract:Object The purpose of the study was to develop an in vitro model of the bone fragment and spinal cord interactions that occur during a Burst Fracture and further the understanding of how the velocity of the bone fragment and the status of the posterior longitudinal ligament (PLL) affect the deformation of the cord. Methods An in vitro model was developed such that high-speed video and pressure measurements recorded the impact of a simulated bone fragment on sections of explanted bovine spinal cord. The model simulated the PLL and the posterior elements. The status of the PLL had a significant effect on both the maximum occlusion of the spinal cord and the time for occlusion to occur. Raising the fragment velocity led to an overall increase in the spinal cord deformation. Interestingly the dura mater appeared to have little or no effect on the extent of occlusion. Conclusions These findings may indicate the importance of the dura’s interaction with the cerebrospinal fluid in protecting the cord during this...
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A dynamic investigation of the Burst Fracture process using a combined experimental and finite element approach
European Spine Journal, 2004Co-Authors: R. K. Wilcox, D. J. Allen, R. M. Hall, D. Limb, D. C. Barton, R. A. DicksonAbstract:Spinal Burst Fractures account for about 15% of spinal injuries and, because of their predominance in the younger population, there are large associated social and healthcare costs. Although several experimental studies have investigated the Burst Fracture process, little work has been undertaken using computational methods. The aim of this study was to develop a finite element model of the Fracture process and, in combination with experimental data, gain a better understanding of the Fracture event and mechanism of injury. Experimental tests were undertaken to simulate the Burst Fracture process in a bovine spine model. After impact, each specimen was dissected and the severity of Fracture assessed. Two of the specimens tested at the highest impact rate were also dynamically filmed during the impact. A finite element model, based on CT data of an experimental specimen, was constructed and appropriate high strain rate material properties assigned to each component. Dynamic validation was undertaken by comparison with high-speed video data of an experimental impact. The model was used to determine the mechanism of Fracture and the postFracture impact of the bony fragment onto the spinal cord. The dissection of the experimental specimens showed Burst Fractures of increasing severity with increasing impact energy. The finite element model demonstrated that a high tensile strain region was generated in the posterior of the vertebral body due to the interaction of the articular processes. The region of highest strain corresponded well with the experimental specimens. A second simulation was used to analyse the fragment projection into the spinal canal following Fracture. The results showed that the posterior longitudinal ligament became stretched and at higher energies the spinal cord and the dura mater were compressed by the fragment. These structures deformed to a maximum level before forcing the fragment back towards the vertebral body. The final position of the fragment did not therefore represent the maximum dynamic canal occlusion.
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measurement of canal occlusion during the thoracolumbar Burst Fracture process
Journal of Biomechanics, 2002Co-Authors: Ruth K Wilcox, R. M. Hall, D. Limb, D. C. Barton, T O Boerger, R. A. DicksonAbstract:Post-injury CT scans are often used following Burst Fracture trauma as an indication for decompressive surgery. Literature suggests, however, that there is little correlation between the observed fragment position and the level of neurological injury or recovery. Several studies have aimed to establish the processes that occur during the Fracture using indirect methods such as pressure measurements and pre/post impact CT scans. The purpose of this study was to develop a direct method of measuring spinal canal occlusion during a simulated Burst Fracture by using a high-speed video technique. The Fractures were produced by dropping a mass from a measured height onto three-vertebra bovine specimens in a custom-built rig. The specimens were constrained to deform only in the impact direction such that pure compression Fractures were generated. The spinal cord was removed prior to testing and the video system set up to film the inside of the spinal canal during the impact. A second camera was used to film the outside of the specimen to observe possible buckling during impact. The video images were analysed to determine how the cross-sectional area of the spinal canal changed during the event. The images clearly showed a fragment of bone being projected from the vertebral body into the spinal canal and recoiling to the final resting position. To validate the results, CT scans were taken pre- and post-impact and the percentage canal occlusion was calculated. There was good agreement between the final canal occlusion measured from the video images and the CT scans.
Liu Zhi-yuan - One of the best experts on this subject based on the ideXlab platform.
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Titanium Mesh Cage and Z-Plate for the Treatment of Thoracolumbar Vertebral Burst Fracture
Journal of Elinical Research, 2005Co-Authors: Liu Zhi-yuanAbstract:To evaluate the efficacy of Titanium mesh cage with anterior z-plate fixation system and interbody fusion for the treatment of thoracolumbar vetebral Burst Fracture.Thirty-six cases with thoracolumbar vertebral Burst Fracture were treated by anterior vertebral body sub-total cut,Titanium mesh filled with bone fragments interbody fusion and internal fixation with Z-plate system.The ASIA impairment scale of preoperation and postoperation and X-ray were observed.Follow up were 3~21months .The neurological deficits ameliorated in different grades. The bone in Titanium mesh was tightly united with upper and lower vertebral body.[Conclusion]Anterior decompression and application of titanium mesh combined with anterior fixtion system are a valuable method for restoring of spinal stability and improving of neurological function.
