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Dawn M Elliott - One of the best experts on this subject based on the ideXlab platform.
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human disc Nucleotomy alters annulus fibrosus mechanics at both reference and compressed loads
Journal of Biomechanical Engineering-transactions of The Asme, 2019Co-Authors: Amy A Claeson, Edward J Vresilovic, Brent L Showalter, Alexander C Wright, Neil R Malhotra, Dawn M ElliottAbstract:: Nucleotomy is a common surgical procedure and is also performed in ex vivo mechanical testing to model decreased nucleus pulposus (NP) pressurization that occurs with degeneration. Here, we utilize magnetic resonance imaging (MRI) to study internal 3D annulus fibrosus (AF) deformations after partial Nucleotomy and during axial compression by evaluating changes in internal AF deformation at reference loads (50N) and physiological compressive loads (~10% strain). Intact grade II L3-L4 discs before and after Nucleotomy were subjected to identical mechanical testing and imaging protocols. Internal disc deformation fields were calculated by registering MR images captured in each loading state (reference and compressed) and each condition (intact and Nucleotomy). Comparisons were drawn between the resulting three deformation states (intact at compressed load, Nucleotomy at reference load, Nucleotomy at compressed load) with regards to the magnitude of internal strain and direction of internal displacements. Under compressed load, internal AF axial strains averaged -18.5% when intact and -22.5% after Nucleotomy. Deformations of intact discs under compressed load oriented in-plane, whereas deformations after Nucleotomy oriented axially. For intact discs, in-plane components of displacements under compression loads were oriented radially outward and circumferentially. After Nucleotomy, in-plane displacements oriented radially inward under reference load and were not significantly different from the intact state at compressed loads. Re-establishment of outward displacements after Nucleotomy indicates increased axial loading restores the characteristics of internal pressurization. Results may have implications for the recurrence of pain, design of novel therapeutics, or progression of disc degeneration.
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Nucleotomy reduces the effects of cyclic compressive loading with unloaded recovery on human intervertebral discs
Journal of Biomechanics, 2014Co-Authors: Brent L Showalter, Edward J Vresilovic, Neil R Malhotra, Dawn M ElliottAbstract:Abstract The first objective of this study was to determine the effects of physiological cyclic loading followed by unloaded recovery on the mechanical response of human intervertebral discs. The second objective was to examine how Nucleotomy alters the disc׳s mechanical response to cyclic loading. To complete these objectives, 15 human L5-S1 discs were tested while intact and subsequent to Nucleotomy. The testing consisted of 10,000 cycles of physiological compressive loads followed by unloaded hydrated recovery. Cyclic loading increased compression modulus (3%) and strain (33%), decreased neutral zone modulus (52%), and increased neutral zone strain (31%). Degeneration was not correlated with the effect of cyclic loading in intact discs, but was correlated with cyclic loading effects after Nucleotomy, with more degenerate samples experiencing greater increases in both compressive and neutral zone strain following cyclic loading. Partial removal of the nucleus pulposus decreased the compression and neutral zone modulus while increasing strain. These changes correspond to hypermobility, which will alter overall spinal mechanics and may impact low back pain via altered motion throughout the spinal column. Nucleotomy also reduced the effects of cyclic loading on mechanical properties, likely due to altered fluid flow, which may impact cellular mechanotransduction and transport of disc nutrients and waste. Degeneration was not correlated with the acute changes of Nucleotomy. Results of this study provide an ideal protocol and control data for evaluating the effectiveness of a mechanically-based disc degeneration treatment, such as a nucleus replacement.
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Nucleotomy alters mechanical function following cyclic loading and unloaded recovery of human discs
ASME 2012 Summer Bioengineering Conference Parts A and B, 2012Co-Authors: Brent L Showalter, Dawn M Elliott, Ian S Maclean, Neil R MalhotraAbstract:The intervertebral disc plays a critical role in supporting loads, permitting spinal motion, and dissipating energy. Unfortunately, it is also commonly degenerated, resulting in altered spinal mechanics and low back pain. Nucleotomy is a common treatment for herniated discs and is also used experimentally to simulate degeneration.[1] The procedure, which involves a posterior annular incision and removal of a portion of the nucleus pulposus (NP), has also been shown to alter disc mechanics. These changes include acute changes of decreased NP pressure, decreased disc height, and increased neutral zones.[2, 3] Cyclic studies have shown that trans-endplate Nucleotomy permanently alters creep mechanical properties of sheep discs.[4] However, the effects of annular Nucleotomy on the cyclic properties of human discs have not yet been studied. This work studied the mechanical effect of annular Nucleotomy on human discs subjected to physiological axial cyclic loading.Copyright © 2012 by ASME
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the effect of Nucleotomy and the dependence of degeneration of human intervertebral disc strain in axial compression
Spine, 2011Co-Authors: Grace D Oconnell, Edward J Vresilovic, Neil R Malhotra, Dawn M ElliottAbstract:Study Design. Biomechanics of human intervertebral discs before and after Nucleotomy. Objective. To noninvasively quantify the effect of Nucleotomy on internal strains under axial compression inexion, neutral, and extension positions, and to determine whether the change in strains depended on degeneration. Summary of Background Data. Herniation and Nucleotomy may accelerate the progression of disc degeneration. Removal of nucleus pulposus (NP) tissue has resulted in altered disc mechanics in vitro , including a decrease in internal pressure and an increase in the deformations at physiologically relevant strains. We recently presented a technique to quantify internal disc strains using magnetic resonance imaging (MRI). Methods. Degeneration was quantitatively assessed by the T 1 ρ relaxation time in the NP. Samples were prepared from human levels L3-L4 and/or L4-L5. A 1000-N compressive load was applied while in the magnetic resonance scanner. Nucleotomy was performed by removing 2 g of NP through the posterior-lateral annulusbrosus (AF). The discs were rehydrated, reimaged, and retested. The analyzed parameters include axial deformation, AF radial bulge, and strains. Results. The axial deformation was more compressive after Nucleotomy. In the neutral position, the axial deformation after Nucleotomy correlated with degeneration (as quantied by T 1 ρ in the NP), with minimal alteration in nondegenerated discs. Nucleotomy altered the radial displacements and strains in the neutral position, such that the inner AF radial bulge decreased and the radial strains were more tensile in the lateral AF and less tensile in the posterior AF. In the bending loading positions the radial strains were not affected by Nucleotomy. Conclusion. Nucleotomy alters the internal radial and axial AF strains in the neutral position, which may leave the AF vulnerable to damage and microfractures. In bending, the effects of Nucleotomy were minimal, likely due to more of the applied load being directed over the AF. Some of the Nucleotomy effects are modulated by degeneration, where the mechanical effect of Nucleotomy was magnied in degenerated discs and may further induce mechanical
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Optimization of image registration and application to human disc mechanics with Nucleotomy
2011 IEEE 37th Annual Northeast Bioengineering Conference (NEBEC), 2011Co-Authors: K.m. Gerasimowicz, Edward J Vresilovic, Alexander C Wright, Neil R Malhotra, J.h. Yoder, N.j. Tustison, G. Song, G.d. O'connell, Dawn M ElliottAbstract:Introduction: Advanced Normalization Tools (ANTs) is an image registration program that has been validated for analysis of several tissues, but not previously applied to the disc. The objectives of this study were to optimize ANTs for disc image registration and to validate ANTs strain measurements by comparison with Vic2D, a commercially available software previously applied to quantify disc strain, before and after Nucleotomy. Methods: Human lumbar motion segments (n = 5) underwent 1000 N compression before and after Nucleotomy and MR images were acquired in a reference and deformed state. Image overlap statistics were used to select mapping parameters, and strain analysis was used to select the optimal number of splines. Once the optimal registration method was selected (elastic mapping, 0.01 outlier, 6×6 splines), axial and radial strains were measured in the AAF, PAF, and IVD. Results: Excellent overlap statistics were achieved. No significant differences were found for strains calculated with ANTs and Vic2D (p ≥ 0.35). With Nucleotomy, the axial compressive strain increased in the PAF (p = 0.04) and there was a trend towards decrease in radial strain (p = 0.07). Discussion: ANTs is an accurate and powerful tool to calculate disc strains from MR images.
Hansjoachim Wilke - One of the best experts on this subject based on the ideXlab platform.
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Nucleus replacement could get a new chance with annulus closure
European Spine Journal, 2020Co-Authors: Laura Zengerle, Anne Köhler, Elisabeth Debout, Carsten Hackenbroch, Hansjoachim WilkeAbstract:Purpose Disc herniations are usually treated by decompression of the spinal nerves via a partial Nucleotomy. As a consequence of reduced disc height (DH), reduced intradiscal pressure (IDP) and increased range of motion (ROM), accelerated degeneration may occur. Nucleus replacement implants are intended to restore those values, but are associated with the risk of extrusion. Methods In six fresh frozen lumbar spinal segments (L2-3/L3-4/L4-5/L5-S1, age median 64.5 years (57–72), Pfirrmann grade 2–3), a prolapse was provoked through a box defect (6 × 10 mm) in the annulus. The herniated nucleus material was removed and replaced by a novel collagen-based nucleus implant. An annulus closure device sealed the defect. ROM, neutral zone (NZ) and IDP were measured in the (1) intact and (2) defect state, (3) postoperatively and (4) after cyclic loading (n = 100,000 cycles) applying pure moments (± 7.5 Nm) in flexion–extension, lateral bending and axial rotation. Additionally, the change in DH was determined. Extrusion of implants or nucleus material was evaluated macroscopically. Results In all specimens, a prolapse could be provoked which decreased DH. Subsequent Nucleotomy changed ROM/NZ and IDP considerably. Initial values could be restored by the implantation. Macroscopically, none of the implants nor nucleus material did migrate after cyclic loading. Conclusions In this study, a prolapse followed by a Nucleotomy resulted in a biomechanical destabilisation. Implantation of the nucleus replacement combined with an annulus closure restored the intact condition without showing signs of extrusion nor migration after cyclic loading. Hence, nucleus replacements could have a new chance in combination with annulus closure devices.
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increase or decrease in stability after Nucleotomy conflicting in vitro and in vivo results in the sheep model
Journal of the Royal Society Interface, 2014Co-Authors: Sandra Reitmaier, Hansjoachim Wilke, David Volkheimer, Nikolaus Bergerroscher, Anita IgnatiusAbstract:Nucleotomy is a common surgical procedure to treat disc herniations. The potential occurrence of segmental instability after surgery, however, is suspected to necessitate re-operation and fusion. Although in vitro studies support the theory of destabilization after Nucleotomy, a prior, in-house animal study contrarily revealed an increase in stability after surgery. To identify which structural compartment of the motion segment is decisive for increased stability after Nucleotomy in vivo, the flexibilities of ovine motion segments were measured after different stepwise reductions at the anterior and posterior spinal column. Different test groups were used in which Nucleotomy had been performed during surgery in vivo and under isolated in vitro conditions, respectively. In accordance with expectations, in vitro Nucleotomy on ovine motion segments significantly increased flexibility. By contrast, Nucleotomy significantly decreased flexibility 12 weeks after surgery. After removal of the posterior structures, however, the differences in flexibility diminished. The present results thus suggest that it might not exclusively be the trauma to the intervertebral disc during surgery which is decisive for post-operative stability, but rather adaptive mechanisms in the posterior structures. Therefore, care should be taken to minimize the damage to the posterior structures in the course of the surgical approach, which more likely compromises stability.
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a new porcine in vivo animal model of disc degeneration response of anulus fibrosus cells chondrocyte like nucleus pulposus cells and notochordal nucleus pulposus cells to partial Nucleotomy
Spine, 2009Co-Authors: Georg W Omlor, Hansjoachim Wilke, Andreas G Nerlich, Michael Pfeiffer, Helga Lorenz, Markus Schaafkeim, Helge Bertram, Wiltrud Richter, C Carstens, Thorsten GuehringAbstract:STUDY DESIGN: In vivo animal study. OBJECTIVES: To describe a new porcine disc degeneration model, and to analyze disc remodeling and degeneration after Nucleotomy with special view to the different nucleus pulposus (NP) cell types. SUMMARY OF BACKGROUND DATA: Thus far, predominantly smaller animals were used for disc degeneration models; however, such small discs were inappropriate to investigate cell implementation therapies. Though notochordal cells (NCs) are important for disc formation and maintenance, differences in the amount of NCs between human and animal discs have often been neglected. METHODS: Twenty-four Goettingen minipigs underwent partial Nucleotomy with a 16G biopsy cannula, to remove approximately 10% of total NP volume. Animals were followed up for 3, or 24 weeks and analyzed by radiographs, MRIs, (immuno)histology, gene expression analysis, and biomechanical testing. RESULTS: Three weeks after Nucleotomy disc height was reduced by 26%, and magnetic resonance imaging signal intensity by 40%. At 24 weeks disc height was decreased by 32%. Increased degenerative changes were found in a histodegeneration score 3 and 24 weeks after Nucleotomy, as well as considerable NP scarification after 3 weeks. In controls, cytokeratin-8 immunohistochemistry identified NCs in proximity to chondrocyte-like NP cells at approximately equal ratio. After Nucleotomy, NCs were considerably reduced to <10% of total NP cells. Matrix genes were upregulated, except for aggrecan that decreased to 35% of initial values 3 weeks after Nucleotomy. Matrix degrading factors (matrix metalloproteinases 13 and 3) were continuously upregulated, whereas transcripts of their inhibitors (tissue inhibitors of matrix metalloproteinase 2 and 3) were downregulated. No significant changes in segmental spinal flexibility or bone density were found after Nucleotomy. CONCLUSION: We introduced a new disc degeneration model with relatively large discs that could be used for cell therapeutic approaches. The study gives further information about disc remodeling after Nucleotomy and indicates the relevance of an altered cellular composition for the development of disc degeneration.
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A new porcine in vivo animal model of disc degeneration: response of anulus fibrosus cells, chondrocyte-like nucleus pulposus cells, and notochordal nucleus pulposus cells to partial Nucleotomy.
Spine, 2009Co-Authors: Georg W Omlor, Hansjoachim Wilke, Andreas G Nerlich, Michael Pfeiffer, Helga Lorenz, Helge Bertram, Wiltrud Richter, C Carstens, Markus Schaaf-keim, Thorsten GuehringAbstract:STUDY DESIGN: In vivo animal study. OBJECTIVES: To describe a new porcine disc degeneration model, and to analyze disc remodeling and degeneration after Nucleotomy with special view to the different nucleus pulposus (NP) cell types. SUMMARY OF BACKGROUND DATA: Thus far, predominantly smaller animals were used for disc degeneration models; however, such small discs were inappropriate to investigate cell implementation therapies. Though notochordal cells (NCs) are important for disc formation and maintenance, differences in the amount of NCs between human and animal discs have often been neglected. METHODS: Twenty-four Goettingen minipigs underwent partial Nucleotomy with a 16G biopsy cannula, to remove approximately 10% of total NP volume. Animals were followed up for 3, or 24 weeks and analyzed by radiographs, MRIs, (immuno)histology, gene expression analysis, and biomechanical testing. RESULTS: Three weeks after Nucleotomy disc height was reduced by 26%, and magnetic resonance imaging signal intensity by 40%. At 24 weeks disc height was decreased by 32%. Increased degenerative changes were found in a histodegeneration score 3 and 24 weeks after Nucleotomy, as well as considerable NP scarification after 3 weeks. In controls, cytokeratin-8 immunohistochemistry identified NCs in proximity to chondrocyte-like NP cells at approximately equal ratio. After Nucleotomy, NCs were considerably reduced to
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a new laser scanning technique for imaging intervertebral disc displacement and its application to modeling Nucleotomy
Clinical Biomechanics, 2008Co-Authors: Frank Heuer, Hendrik Schmidt, L Claes, Hansjoachim WilkeAbstract:BACKGROUND: Nucleotomy is a standard procedure for treating disc prolapse. It can reduce intervertebral disc height, flattening and displacing the disc, which could lead to a painful narrowing of the foramina due to nerve root compression. The purpose of this study was to investigate the disc displacement of a complete spinal segment with and without Nucleotomy. We hypothesized that a Nucleotomy under a certain load combination might amplify disc displacement. METHODS: A laser scanner was developed for recording three-dimensional disc displacement of six loaded L4-5 specimens for three conditions: intact, disc with vertebral bodies and subsequent Nucleotomy. Specimens were exposed to pure moments of 7.5 N m in the three principal anatomical directions. Disc displacement was obtained at maximal deflection. A finite element model was validated and subsequently utilized to determine disc displacement. The task of the finite element model was to provide supplemental data for the posterolateral region, which could not be measured from intact specimens. FINDINGS: Disc displacement measurements of intact specimens were limited to the anterior part of discs, whereas the finite element model was able to provide the missing data of the dorsal disc region. The simulation of load combinations showed that the highest disc displacement was 1.9 mm at the lateral or posterolateral region. The Nucleotomy increased the disc displacement up to 2.1mm, whereas the displacement zenith migrated posterolaterally. INTERPRETATION: These results could be a possible explanation for disadvantages of Nucleotomy as a treatment. With the methodology presented here, we would be able to assess the performance of nucleus implants by determining the disc displacement map. This could also give us appropriate information of the annular deformation, which is needed for the development of motion preserving implants.
Thorsten Guehring - One of the best experts on this subject based on the ideXlab platform.
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short term follow up of disc cell therapy in a porcine Nucleotomy model with an albumin hyaluronan hydrogel in vivo and in vitro results of metabolic disc cell activity and implant distribution
European Spine Journal, 2014Co-Authors: G. W. Omlor, J Holschbach, J Fischer, K Kleinschmitt, Karin Benz, K Brohm, Martina Anton, Thorsten GuehringAbstract:Purpose Cell therapy would be favorably performed immediately after Nucleotomy, to restore intervertebral disc functionality and to slow down disc degeneration. Promising results were reported from small animal models but remaining problems, especially in larger animals, include loss of vital cells due to annular damage at the injection site and detrimental intradiscal conditions. The aim of the present study was to optimize cell-based disc therapy using a new albumin–hyaluronan hydrogel together with bone marrow-derived mesenchymal stem cells in a large porcine disc model.
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a new porcine in vivo animal model of disc degeneration response of anulus fibrosus cells chondrocyte like nucleus pulposus cells and notochordal nucleus pulposus cells to partial Nucleotomy
Spine, 2009Co-Authors: Georg W Omlor, Hansjoachim Wilke, Andreas G Nerlich, Michael Pfeiffer, Helga Lorenz, Markus Schaafkeim, Helge Bertram, Wiltrud Richter, C Carstens, Thorsten GuehringAbstract:STUDY DESIGN: In vivo animal study. OBJECTIVES: To describe a new porcine disc degeneration model, and to analyze disc remodeling and degeneration after Nucleotomy with special view to the different nucleus pulposus (NP) cell types. SUMMARY OF BACKGROUND DATA: Thus far, predominantly smaller animals were used for disc degeneration models; however, such small discs were inappropriate to investigate cell implementation therapies. Though notochordal cells (NCs) are important for disc formation and maintenance, differences in the amount of NCs between human and animal discs have often been neglected. METHODS: Twenty-four Goettingen minipigs underwent partial Nucleotomy with a 16G biopsy cannula, to remove approximately 10% of total NP volume. Animals were followed up for 3, or 24 weeks and analyzed by radiographs, MRIs, (immuno)histology, gene expression analysis, and biomechanical testing. RESULTS: Three weeks after Nucleotomy disc height was reduced by 26%, and magnetic resonance imaging signal intensity by 40%. At 24 weeks disc height was decreased by 32%. Increased degenerative changes were found in a histodegeneration score 3 and 24 weeks after Nucleotomy, as well as considerable NP scarification after 3 weeks. In controls, cytokeratin-8 immunohistochemistry identified NCs in proximity to chondrocyte-like NP cells at approximately equal ratio. After Nucleotomy, NCs were considerably reduced to <10% of total NP cells. Matrix genes were upregulated, except for aggrecan that decreased to 35% of initial values 3 weeks after Nucleotomy. Matrix degrading factors (matrix metalloproteinases 13 and 3) were continuously upregulated, whereas transcripts of their inhibitors (tissue inhibitors of matrix metalloproteinase 2 and 3) were downregulated. No significant changes in segmental spinal flexibility or bone density were found after Nucleotomy. CONCLUSION: We introduced a new disc degeneration model with relatively large discs that could be used for cell therapeutic approaches. The study gives further information about disc remodeling after Nucleotomy and indicates the relevance of an altered cellular composition for the development of disc degeneration.
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A new porcine in vivo animal model of disc degeneration: response of anulus fibrosus cells, chondrocyte-like nucleus pulposus cells, and notochordal nucleus pulposus cells to partial Nucleotomy.
Spine, 2009Co-Authors: Georg W Omlor, Hansjoachim Wilke, Andreas G Nerlich, Michael Pfeiffer, Helga Lorenz, Helge Bertram, Wiltrud Richter, C Carstens, Markus Schaaf-keim, Thorsten GuehringAbstract:STUDY DESIGN: In vivo animal study. OBJECTIVES: To describe a new porcine disc degeneration model, and to analyze disc remodeling and degeneration after Nucleotomy with special view to the different nucleus pulposus (NP) cell types. SUMMARY OF BACKGROUND DATA: Thus far, predominantly smaller animals were used for disc degeneration models; however, such small discs were inappropriate to investigate cell implementation therapies. Though notochordal cells (NCs) are important for disc formation and maintenance, differences in the amount of NCs between human and animal discs have often been neglected. METHODS: Twenty-four Goettingen minipigs underwent partial Nucleotomy with a 16G biopsy cannula, to remove approximately 10% of total NP volume. Animals were followed up for 3, or 24 weeks and analyzed by radiographs, MRIs, (immuno)histology, gene expression analysis, and biomechanical testing. RESULTS: Three weeks after Nucleotomy disc height was reduced by 26%, and magnetic resonance imaging signal intensity by 40%. At 24 weeks disc height was decreased by 32%. Increased degenerative changes were found in a histodegeneration score 3 and 24 weeks after Nucleotomy, as well as considerable NP scarification after 3 weeks. In controls, cytokeratin-8 immunohistochemistry identified NCs in proximity to chondrocyte-like NP cells at approximately equal ratio. After Nucleotomy, NCs were considerably reduced to
Edward J Vresilovic - One of the best experts on this subject based on the ideXlab platform.
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human disc Nucleotomy alters annulus fibrosus mechanics at both reference and compressed loads
Journal of Biomechanical Engineering-transactions of The Asme, 2019Co-Authors: Amy A Claeson, Edward J Vresilovic, Brent L Showalter, Alexander C Wright, Neil R Malhotra, Dawn M ElliottAbstract:: Nucleotomy is a common surgical procedure and is also performed in ex vivo mechanical testing to model decreased nucleus pulposus (NP) pressurization that occurs with degeneration. Here, we utilize magnetic resonance imaging (MRI) to study internal 3D annulus fibrosus (AF) deformations after partial Nucleotomy and during axial compression by evaluating changes in internal AF deformation at reference loads (50N) and physiological compressive loads (~10% strain). Intact grade II L3-L4 discs before and after Nucleotomy were subjected to identical mechanical testing and imaging protocols. Internal disc deformation fields were calculated by registering MR images captured in each loading state (reference and compressed) and each condition (intact and Nucleotomy). Comparisons were drawn between the resulting three deformation states (intact at compressed load, Nucleotomy at reference load, Nucleotomy at compressed load) with regards to the magnitude of internal strain and direction of internal displacements. Under compressed load, internal AF axial strains averaged -18.5% when intact and -22.5% after Nucleotomy. Deformations of intact discs under compressed load oriented in-plane, whereas deformations after Nucleotomy oriented axially. For intact discs, in-plane components of displacements under compression loads were oriented radially outward and circumferentially. After Nucleotomy, in-plane displacements oriented radially inward under reference load and were not significantly different from the intact state at compressed loads. Re-establishment of outward displacements after Nucleotomy indicates increased axial loading restores the characteristics of internal pressurization. Results may have implications for the recurrence of pain, design of novel therapeutics, or progression of disc degeneration.
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Nucleotomy reduces the effects of cyclic compressive loading with unloaded recovery on human intervertebral discs
Journal of Biomechanics, 2014Co-Authors: Brent L Showalter, Edward J Vresilovic, Neil R Malhotra, Dawn M ElliottAbstract:Abstract The first objective of this study was to determine the effects of physiological cyclic loading followed by unloaded recovery on the mechanical response of human intervertebral discs. The second objective was to examine how Nucleotomy alters the disc׳s mechanical response to cyclic loading. To complete these objectives, 15 human L5-S1 discs were tested while intact and subsequent to Nucleotomy. The testing consisted of 10,000 cycles of physiological compressive loads followed by unloaded hydrated recovery. Cyclic loading increased compression modulus (3%) and strain (33%), decreased neutral zone modulus (52%), and increased neutral zone strain (31%). Degeneration was not correlated with the effect of cyclic loading in intact discs, but was correlated with cyclic loading effects after Nucleotomy, with more degenerate samples experiencing greater increases in both compressive and neutral zone strain following cyclic loading. Partial removal of the nucleus pulposus decreased the compression and neutral zone modulus while increasing strain. These changes correspond to hypermobility, which will alter overall spinal mechanics and may impact low back pain via altered motion throughout the spinal column. Nucleotomy also reduced the effects of cyclic loading on mechanical properties, likely due to altered fluid flow, which may impact cellular mechanotransduction and transport of disc nutrients and waste. Degeneration was not correlated with the acute changes of Nucleotomy. Results of this study provide an ideal protocol and control data for evaluating the effectiveness of a mechanically-based disc degeneration treatment, such as a nucleus replacement.
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the effect of Nucleotomy and the dependence of degeneration of human intervertebral disc strain in axial compression
Spine, 2011Co-Authors: Grace D Oconnell, Edward J Vresilovic, Neil R Malhotra, Dawn M ElliottAbstract:Study Design. Biomechanics of human intervertebral discs before and after Nucleotomy. Objective. To noninvasively quantify the effect of Nucleotomy on internal strains under axial compression inexion, neutral, and extension positions, and to determine whether the change in strains depended on degeneration. Summary of Background Data. Herniation and Nucleotomy may accelerate the progression of disc degeneration. Removal of nucleus pulposus (NP) tissue has resulted in altered disc mechanics in vitro , including a decrease in internal pressure and an increase in the deformations at physiologically relevant strains. We recently presented a technique to quantify internal disc strains using magnetic resonance imaging (MRI). Methods. Degeneration was quantitatively assessed by the T 1 ρ relaxation time in the NP. Samples were prepared from human levels L3-L4 and/or L4-L5. A 1000-N compressive load was applied while in the magnetic resonance scanner. Nucleotomy was performed by removing 2 g of NP through the posterior-lateral annulusbrosus (AF). The discs were rehydrated, reimaged, and retested. The analyzed parameters include axial deformation, AF radial bulge, and strains. Results. The axial deformation was more compressive after Nucleotomy. In the neutral position, the axial deformation after Nucleotomy correlated with degeneration (as quantied by T 1 ρ in the NP), with minimal alteration in nondegenerated discs. Nucleotomy altered the radial displacements and strains in the neutral position, such that the inner AF radial bulge decreased and the radial strains were more tensile in the lateral AF and less tensile in the posterior AF. In the bending loading positions the radial strains were not affected by Nucleotomy. Conclusion. Nucleotomy alters the internal radial and axial AF strains in the neutral position, which may leave the AF vulnerable to damage and microfractures. In bending, the effects of Nucleotomy were minimal, likely due to more of the applied load being directed over the AF. Some of the Nucleotomy effects are modulated by degeneration, where the mechanical effect of Nucleotomy was magnied in degenerated discs and may further induce mechanical
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Optimization of image registration and application to human disc mechanics with Nucleotomy
2011 IEEE 37th Annual Northeast Bioengineering Conference (NEBEC), 2011Co-Authors: K.m. Gerasimowicz, Edward J Vresilovic, Alexander C Wright, Neil R Malhotra, J.h. Yoder, N.j. Tustison, G. Song, G.d. O'connell, Dawn M ElliottAbstract:Introduction: Advanced Normalization Tools (ANTs) is an image registration program that has been validated for analysis of several tissues, but not previously applied to the disc. The objectives of this study were to optimize ANTs for disc image registration and to validate ANTs strain measurements by comparison with Vic2D, a commercially available software previously applied to quantify disc strain, before and after Nucleotomy. Methods: Human lumbar motion segments (n = 5) underwent 1000 N compression before and after Nucleotomy and MR images were acquired in a reference and deformed state. Image overlap statistics were used to select mapping parameters, and strain analysis was used to select the optimal number of splines. Once the optimal registration method was selected (elastic mapping, 0.01 outlier, 6×6 splines), axial and radial strains were measured in the AAF, PAF, and IVD. Results: Excellent overlap statistics were achieved. No significant differences were found for strains calculated with ANTs and Vic2D (p ≥ 0.35). With Nucleotomy, the axial compressive strain increased in the PAF (p = 0.04) and there was a trend towards decrease in radial strain (p = 0.07). Discussion: ANTs is an accurate and powerful tool to calculate disc strains from MR images.
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disc mechanics with trans endplate partial Nucleotomy are not fully restored following cyclic compressive loading and unloaded recovery
Journal of Biomechanical Engineering-transactions of The Asme, 2006Co-Authors: Edward J Vresilovic, Wade Johannessen, Dawn M ElliottAbstract:Mechanical function of the intervertebral disc is maintained through the interaction between the hydrated nucleus pulposus, the surrounding annulus fibrosus, and the superior and inferior endplates. In disc degeneration the normal transfer of load between disc substructures is compromised. The objective of this study was to explore the mechanical role of the nucleus pulposus in support of axial compressive loads over time. This was achieved by measuring the elastic slow ramp and viscoelastic stress-relaxation mechanical behaviors of cadaveric sheep motion segments before and after partial Nucleotomy through the endplate (keeping the annulus fibrosus intact). Mechanics were evaluated at five conditions: Intact, intact after 10,000 cycles of compression, acutely after Nucleotomy, following Nucleotomy and 10,000 cycles of compression, and following unloaded recovery. Radiographs and magnetic resonance images were obtained to examine structure. Only the short time constant of the stress relaxation was altered due to Nucleotomy. In contrast, cyclic loading resulted in significant and large changes to both the stiffness and stress relaxation behaviors. Moreover, the Nucleotomy had little to no effect on the disc mechanics after cyclic loading, as there were no significant differences comparing mechanics after cyclic loading with or without the Nucleotomy. Following unloaded recovery the mechanical changes that had occurred as a consequence of cyclic loading were restored, leaving only a sustained change in the short time constant due to the trans-endplate Nucleotomy. Thus the swelling and redistribution of the remaining nucleus pulposus was not able to fully restore mechanical behaviors. This study reveals insights into the role of the nucleus pulposus in disc function, and provides new information toward the potential role of altered nucleus pulpous function in the degenerative cascade.
Joji Mochida - One of the best experts on this subject based on the ideXlab platform.
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the risks and benefits of percutaneous Nucleotomy for lumbar disc herniation a ten year longitudinal study
Journal of Bone and Joint Surgery-british Volume, 2001Co-Authors: Joji Mochida, T Nomura, K NishimuraAbstract:Percutaneous Nucleotomy is a relatively new technique for treating lumbar disc herniation. There is no agreement as to the volume of disc material to be removed. A long-term study of clinical and radiological data from patients treated by percutaneous Nucleotomy was designed to identify the factors associated with favourable and unfavourable outcomes. We studied 42 patients for at least ten years; the mean follow-up was 10.9 years. They were divided into two subgroups to assess the value of preserving the nucleus pulposus in the central area of the disc. The overall success rate for both subgroups was 50%. A decrease in disc height on plain radiography and a decrease in signal intensity on MRI were observed more infrequently in patients in whom the nucleus pulposus in the central area of the disc had been preserved, than in those in whom it had been extensively removed. These adverse radiological findings correlated closely with increased low back pain during the first one to two years after operation and a poorer overall outcome. We conclude that percutaneous Nucleotomy is most likely to be successful when the central area of the disc is preserved.
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the risks and benefits of percutaneous Nucleotomy for lumbar disc herniation
Journal of Bone and Joint Surgery-british Volume, 2001Co-Authors: Joji Mochida, T Nomura, K NishimuraAbstract:Percutaneous Nucleotomy is a relatively new technique for treating lumbar disc herniation. There is no agreement as to the volume of disc material to be removed. A long-term study of clinical and radiological data from patients treated by percutaneous Nucleotomy was designed to identify the factors associated with favourable and unfavourable outcomes. We studied 42 patients for at least ten years; the mean follow-up was 10.9 years. They were divided into two subgroups to assess the value of preserving the nucleus pulposus in the central area of the disc. The overall success rate for both subgroups was 50%. A decrease in disc height on plain radiography and a decrease in signal intensity on MRI were observed more infrequently in patients in whom the nucleus pulposus in the central area of the disc had been preserved, than in those in whom it had been extensively removed. These adverse radiological findings correlated closely with increased low back pain during the first one to two years after operation and a poorer overall outcome. We conclude that percutaneous Nucleotomy is most likely to be successful when the central area of the disc is preserved.
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Percutaneous Nucleotomy in Elite Athletes
Journal of Spinal Disorders, 2001Co-Authors: Joji Mochida, Kazuhiro Nishimura, Masahiko Okuma, Takeshi NomuraAbstract:Summary: Percutaneous Nucleotomy in elite athletes is considered a minimally invasive treatment of lumbar disc herniation. However, long-term effectiveness has not been established by careful follow-up studies. This article evaluates the outcome of percutaneous Nucleotomy in elite athletes who have undergone the procedure. Thirty elite athletes with lumbar disc herniation who underwent percutaneous Nucleotomy and had been followed for at least 2 years were compared with a matched group of 42 nonathletes. The outcome in athletes was worse than in nonathletes. Early return to vigorous sports activity in less than 3 months correlated with increased symptoms. Similarly, more extensive resection of disc material was associated with an unexpected rapid worsening of the outcome and the lower rate of return to preoperative sports. Patient selection and postoperative management of athletes and nonathletes undergoing percutaneous Nucleotomy should be the same, and the procedure in athletes is probably not worthwhile if they do not obey postoperative management such as the timing of return to sports activity.
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percutaneous Nucleotomy in lumbar disc herniation patient selection and role in various treatments
Spine, 1993Co-Authors: Joji Mochida, Kazuhiro Nishimura, Takeshi Nomura, Toru ArimaAbstract:Patients in percutaneous Nucleotomy who meet our new criteria for patient selection in 1992 showed 73% successful results. The success rate was not satisfactory in comparison with that (88%) in the open surgery through posterior approach (herniotomy), however. The purpose of this report is to re-evaluate 70 patients with follow-up more than 2 years based on imaging and clinical findings before percutaneous Nucleotomy
