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Elizabeth A. Friis - One of the best experts on this subject based on the ideXlab platform.
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Effect of follower load on motion and stiffness of the human thoracic spine with intact rib cage.
Journal of Biomechanics, 2016Co-Authors: Hadley L. Sis, Erin M. Mannen, Dennis E. Anderson, Benjamin M. Wong, Eileen S. Cadel, Mary L. Bouxsein, Elizabeth A. FriisAbstract:Abstract Researchers have reported on the importance of the rib cage in maintaining mechanical stability in the thoracic spine and on the validity of a compressive follower preload. However, dynamic mechanical testing using both the rib cage and follower load has never been studied. An in vitro biomechanical study of human cadaveric thoracic specimens with rib cage intact in lateral bending, flexion/extension, and axial rotation under varying compressive follower preloads was performed. The objective was to characterize the motion and stiffness of the thoracic spine with intact rib cage and follower preload. The hypotheses tested for all modes of bending were (i) range of motion, Elastic Zone, and neutral Zone will be reduced with a follower load, and (ii) neutral and Elastic Zone stiffness will be increased with a follower load. Eight human cadaveric thoracic spine specimen (T1–T12) with intact rib cage were subjected to 5 Nm pure moments in lateral bending, flexion/extension, and axial rotation under follower loads of 0–400 N. Range of motion, Elastic and neutral Zones, and Elastic and neutral Zone stiffness values were calculated for functional spinal units and segments within the entire thoracic section. Combined segmental range of motion decreased by an average of 34% with follower load for every mode. Application of a follower load with intact rib cage impacts the motion and stiffness of the human cadaveric thoracic spine. Researchers should consider including both aspects to better represent the physiologic implications of human motion and improve clinically relevant biomechanical thoracic spine testing.
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mechanical analysis of the human cadaveric thoracic spine with intact rib cage
Journal of Biomechanics, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:The goal of this study was to characterize the overall in-plane and basic coupled motion of a cadaveric human thoracic spine with intact true ribs. Researchers are becoming increasingly interested in the thoracic spine due to both the high prevalence of injury and pain in the region and also innovative surgical techniques that utilize the rib cage. Computational models can be useful tools to predict loading patterns and understand effects of surgical procedures or medical devices, but they are often limited by insufficient cadaveric input data. In this study, pure moments to ±5 Nm were applied in flexion-extension, lateral bending, and axial rotation to seven human cadaveric thoracic spine specimens (T1-T12) with intact true ribs to determine symmetry of in-plane motion, differences in neutral and Elastic Zone motion and stiffness, and significance of out-of-plane rotations and translations. Results showed that lateral bending and axial rotation exhibited symmetric motion, neutral and Elastic Zone motion and stiffness values were significantly different for all modes of bending (p<0.05), and out-of-plane rotations and translations were greater than zero for most rotations and translations. Overall in-plane rotations were 7.7±3.4° in flexion, 9.6±3.7° in extension, 23.3±8.4° in lateral bending, and 26.3±12.2° in axial rotation. Results of this study could provide inputs or validation comparisons for computational models. Future studies should characterize coupled motion patterns and local and regional level biomechanics of cadaveric human thoracic spines with intact true ribs.
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Mechanical Contribution of the Rib Cage in the Human Cadaveric Thoracic Spine.
Spine, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:STUDY DESIGN An in vitro biomechanical human cadaveric study of T1-T12 thoracic specimens was performed with 4 conditions (with and without rib cage, instrumented and uninstrumented) in flexion-extension, lateral bending, and axial rotation. OBJECTIVE The objective was to understand the influence of the rib cage on motion and stiffness parameters of the human cadaveric thoracic spine. Hypotheses tested for overall motion in all modes of bending for both uninstrumented and instrumented specimens were (i) in-plane range of motion and neutral and Elastic Zones will be greater without the rib cage, (ii) neutral and Elastic Zone stiffness values will be different for specimens without the rib cage, and (iii) out-of-plane rotations will be different for specimens without the rib cage. SUMMARY OF BACKGROUND DATA The rib cage is presumed to provide significant stability to the thoracic spine, but no studies have been conducted to determine the influence of the rib cage in both uninstrumented and instrumented conditions in the full thoracic human cadaveric specimens. METHODS Seven human cadaveric spine specimens (T1-T12) with 4 conditions (with and without rib cage, instrumented and uninstrumented) were subjected to 5 N·m pure moments in flexion-extension, lateral bending, and axial rotation. Range of motion, neutral and Elastic Zones, neutral and Elastic Zone stiffness values, and out-of-plane rotations were calculated for the overall specimen. RESULTS In-plane range of motion was significantly higher without a rib cage for most modes of bending. Out-of-plane motions were also influenced by the rib cage. Neutral Zone stiffness was significantly higher with a rib cage present. CONCLUSION Testing without a rib cage yields different motion and stiffness measures, directly impacting the translation of research results to clinical interpretation. Researchers should consider these differences when evaluating the mechanical impact of surgical procedures or instrumentation in cadaveric or computational models. LEVEL OF EVIDENCE 5.
Erin M. Mannen - One of the best experts on this subject based on the ideXlab platform.
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Effect of follower load on motion and stiffness of the human thoracic spine with intact rib cage.
Journal of Biomechanics, 2016Co-Authors: Hadley L. Sis, Erin M. Mannen, Dennis E. Anderson, Benjamin M. Wong, Eileen S. Cadel, Mary L. Bouxsein, Elizabeth A. FriisAbstract:Abstract Researchers have reported on the importance of the rib cage in maintaining mechanical stability in the thoracic spine and on the validity of a compressive follower preload. However, dynamic mechanical testing using both the rib cage and follower load has never been studied. An in vitro biomechanical study of human cadaveric thoracic specimens with rib cage intact in lateral bending, flexion/extension, and axial rotation under varying compressive follower preloads was performed. The objective was to characterize the motion and stiffness of the thoracic spine with intact rib cage and follower preload. The hypotheses tested for all modes of bending were (i) range of motion, Elastic Zone, and neutral Zone will be reduced with a follower load, and (ii) neutral and Elastic Zone stiffness will be increased with a follower load. Eight human cadaveric thoracic spine specimen (T1–T12) with intact rib cage were subjected to 5 Nm pure moments in lateral bending, flexion/extension, and axial rotation under follower loads of 0–400 N. Range of motion, Elastic and neutral Zones, and Elastic and neutral Zone stiffness values were calculated for functional spinal units and segments within the entire thoracic section. Combined segmental range of motion decreased by an average of 34% with follower load for every mode. Application of a follower load with intact rib cage impacts the motion and stiffness of the human cadaveric thoracic spine. Researchers should consider including both aspects to better represent the physiologic implications of human motion and improve clinically relevant biomechanical thoracic spine testing.
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mechanical analysis of the human cadaveric thoracic spine with intact rib cage
Journal of Biomechanics, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:The goal of this study was to characterize the overall in-plane and basic coupled motion of a cadaveric human thoracic spine with intact true ribs. Researchers are becoming increasingly interested in the thoracic spine due to both the high prevalence of injury and pain in the region and also innovative surgical techniques that utilize the rib cage. Computational models can be useful tools to predict loading patterns and understand effects of surgical procedures or medical devices, but they are often limited by insufficient cadaveric input data. In this study, pure moments to ±5 Nm were applied in flexion-extension, lateral bending, and axial rotation to seven human cadaveric thoracic spine specimens (T1-T12) with intact true ribs to determine symmetry of in-plane motion, differences in neutral and Elastic Zone motion and stiffness, and significance of out-of-plane rotations and translations. Results showed that lateral bending and axial rotation exhibited symmetric motion, neutral and Elastic Zone motion and stiffness values were significantly different for all modes of bending (p<0.05), and out-of-plane rotations and translations were greater than zero for most rotations and translations. Overall in-plane rotations were 7.7±3.4° in flexion, 9.6±3.7° in extension, 23.3±8.4° in lateral bending, and 26.3±12.2° in axial rotation. Results of this study could provide inputs or validation comparisons for computational models. Future studies should characterize coupled motion patterns and local and regional level biomechanics of cadaveric human thoracic spines with intact true ribs.
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Mechanical Contribution of the Rib Cage in the Human Cadaveric Thoracic Spine.
Spine, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:STUDY DESIGN An in vitro biomechanical human cadaveric study of T1-T12 thoracic specimens was performed with 4 conditions (with and without rib cage, instrumented and uninstrumented) in flexion-extension, lateral bending, and axial rotation. OBJECTIVE The objective was to understand the influence of the rib cage on motion and stiffness parameters of the human cadaveric thoracic spine. Hypotheses tested for overall motion in all modes of bending for both uninstrumented and instrumented specimens were (i) in-plane range of motion and neutral and Elastic Zones will be greater without the rib cage, (ii) neutral and Elastic Zone stiffness values will be different for specimens without the rib cage, and (iii) out-of-plane rotations will be different for specimens without the rib cage. SUMMARY OF BACKGROUND DATA The rib cage is presumed to provide significant stability to the thoracic spine, but no studies have been conducted to determine the influence of the rib cage in both uninstrumented and instrumented conditions in the full thoracic human cadaveric specimens. METHODS Seven human cadaveric spine specimens (T1-T12) with 4 conditions (with and without rib cage, instrumented and uninstrumented) were subjected to 5 N·m pure moments in flexion-extension, lateral bending, and axial rotation. Range of motion, neutral and Elastic Zones, neutral and Elastic Zone stiffness values, and out-of-plane rotations were calculated for the overall specimen. RESULTS In-plane range of motion was significantly higher without a rib cage for most modes of bending. Out-of-plane motions were also influenced by the rib cage. Neutral Zone stiffness was significantly higher with a rib cage present. CONCLUSION Testing without a rib cage yields different motion and stiffness measures, directly impacting the translation of research results to clinical interpretation. Researchers should consider these differences when evaluating the mechanical impact of surgical procedures or instrumentation in cadaveric or computational models. LEVEL OF EVIDENCE 5.
F Kandziora - One of the best experts on this subject based on the ideXlab platform.
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biomechanical testing of the lumbar facet interference screw
Spine, 2005Co-Authors: F Kandziora, Philip Schleicher, Matti Scholz, Robert Pflugmacher, Tanja Eindorf, N P Haas, P W PavlovAbstract:Study Design. An in vitro study was conducted to determine the biomechanical properties of a new simple, percutaneous, posterior fixation technique for the lumbar spine involving a new implant, the so-called Lumbar Facet Interference Screw. Objectives. The purpose of this study was to compare the biomechanical properties of this new fixation device with translaminar and pedicle screw fixation. Summary of Background Data. Several techniques were described to perform a minimal invasive posterior stabilization of the lumbar spine after an anterior lumbar interbody fusion procedure. Yet, due to the high complexity of these minimally invasive surgical procedures, currently, hardly any of these percutaneous posterior fixation techniques is carried out routinely. Methods. Ten human lumbar spines were tested in flexion, extension, axial rotation, and lateral bending using a nonconstrained testing method. First, all motion segments were evaluated intact (group 1). After complete discectomy of L4-L5, the following stabilization techniques were tested sequentially (n=10/group): group 2: "stand-alone" cage; group 3: cage plus translaminar screws; group 4: cage plus Lumbar Facet Interference Screw; and group 5: cage plus pedicle screws. Stiffness, ranges of motion, and neutral and Elastic Zones were determined. Results. In comparison to the intact motion segment, the "stand-alone" cage showed a significantly higher (P<0.05) range of motion, neutral Zone, and Elastic Zone and a significantly lower (P<0.05) stiffness in extension and rotation. Generally, all fixation techniques using cages plus posterior stabilization decreased range of motion, neutral Zone, and Elastic Zone and increased stiffness in comparison to the "stand-alone" cage group. There was no significant difference between the cage plus interference screw and the cage plus translaminar screw group in all test modes. In comparison to the 2 facet joint stabilization techniques, pedicle screw stabilization decreased (P<0.01) range of motion, neutral Zone, and Elastic Zone and increased (P<0.01) stiffness significantly in flexion and rotation. Conclusions. Results of this study indicate that the new Lumbar Facet Interference Screw fixation yields initial biomechanical stability similar to translaminar screw fixation, yet inferior biomechanical stability compared to pedicle screw fixation. Although these results are encouraging, additional biomechanical studies including cyclic loading tests have to evaluate the mid- and long-term stabilization capacity of this new minimally invasive fixation technique before human application.
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biomechanical comparison of expandable cages for vertebral body replacement in the thoracolumbar spine
Spine, 2004Co-Authors: Robert Pflugmacher, Matti Scholz, N P Haas, Philipp Schleicher, Jan Schaefer, Kathrin Ludwig, C Khodadadyanklostermann, F KandzioraAbstract:STUDY DESIGN An in vitro biomechanical study of expandable cages for vertebral body replacement in the human thoracolumbar spine. OBJECTIVES The purpose of this study was to compare the in vitro biomechanical properties of 3 different expandable cages with a nonexpandable cage. SUMMARY AND BACKGROUND DATA Recently, there has been a rapid increase in the use and the commercial availability of expandable cages for vertebral body replacement in the thoracolumbar spine. Although all 3 expandable cages, evaluated in this study, are approved for clinical use in Europe, little information is available concerning the biomechanical properties of these implants. MATERIAL AND METHODS Thirty-two human thoracolumbar spines (T11 to L3) were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive loading technique using an unconstrained testing apparatus. Three-dimensional displacement was measured using an optical measurement system. First, all motion segments were tested intact. After complete corporectomy of L1, cages were implanted according to producer's information. The following implants (n = 8/group) were tested: 1) meshed titanium cage (nonexpandable cage, DePuy AcroMed); 2) X-tenz (expandable cage, DePuy AcroMed); 3) Synex (expandable Cage; Synthes); and 4) VBR (expandable cage, Ulrich). Finally, posterior stabilization using the Universal Spine System (Synthes), posterior-anterior stabilization using the Universal Spine System (Synthes), and anterior plating (Locking Compression Plate, Synthes) was applied to each test specimen. The mean apparent stiffness values, range of motion, and neutral and Elastic Zone were calculated from the corresponding load-displacement curves. RESULTS No significant differences could be determined between the in vitro biomechanical properties of expandable and nonexpandable cages. In comparison to the intact motion segment, isolated anterior stabilization using cages and anterior plating significantly decreased stiffness and increased range of motion in all directions. In contrast, additional posterior stabilization significantly increased stiffness and decreased range of motion in all directions compared to the intact motion segment. The combined anterior-posterior stabilization demonstrated greatest stiffness results. CONCLUSION Biomechanical results indicate that design variations of expandable cages for vertebral body replacement are of little importance. Additionally, no significant difference could be determined between the biomechanical properties of expandable and nonexpandable cages. After corporectomy, isolated implantation of expandable cages plus anterior plating was not able to restore normal stability of the motion segment. Therefore, isolated anterior stabilization using cages plus Locking Compression Plate should not be used for vertebral body replacement in the thoracolumbar spine.
John T. Anderson - One of the best experts on this subject based on the ideXlab platform.
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mechanical analysis of the human cadaveric thoracic spine with intact rib cage
Journal of Biomechanics, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:The goal of this study was to characterize the overall in-plane and basic coupled motion of a cadaveric human thoracic spine with intact true ribs. Researchers are becoming increasingly interested in the thoracic spine due to both the high prevalence of injury and pain in the region and also innovative surgical techniques that utilize the rib cage. Computational models can be useful tools to predict loading patterns and understand effects of surgical procedures or medical devices, but they are often limited by insufficient cadaveric input data. In this study, pure moments to ±5 Nm were applied in flexion-extension, lateral bending, and axial rotation to seven human cadaveric thoracic spine specimens (T1-T12) with intact true ribs to determine symmetry of in-plane motion, differences in neutral and Elastic Zone motion and stiffness, and significance of out-of-plane rotations and translations. Results showed that lateral bending and axial rotation exhibited symmetric motion, neutral and Elastic Zone motion and stiffness values were significantly different for all modes of bending (p<0.05), and out-of-plane rotations and translations were greater than zero for most rotations and translations. Overall in-plane rotations were 7.7±3.4° in flexion, 9.6±3.7° in extension, 23.3±8.4° in lateral bending, and 26.3±12.2° in axial rotation. Results of this study could provide inputs or validation comparisons for computational models. Future studies should characterize coupled motion patterns and local and regional level biomechanics of cadaveric human thoracic spines with intact true ribs.
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Mechanical Contribution of the Rib Cage in the Human Cadaveric Thoracic Spine.
Spine, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:STUDY DESIGN An in vitro biomechanical human cadaveric study of T1-T12 thoracic specimens was performed with 4 conditions (with and without rib cage, instrumented and uninstrumented) in flexion-extension, lateral bending, and axial rotation. OBJECTIVE The objective was to understand the influence of the rib cage on motion and stiffness parameters of the human cadaveric thoracic spine. Hypotheses tested for overall motion in all modes of bending for both uninstrumented and instrumented specimens were (i) in-plane range of motion and neutral and Elastic Zones will be greater without the rib cage, (ii) neutral and Elastic Zone stiffness values will be different for specimens without the rib cage, and (iii) out-of-plane rotations will be different for specimens without the rib cage. SUMMARY OF BACKGROUND DATA The rib cage is presumed to provide significant stability to the thoracic spine, but no studies have been conducted to determine the influence of the rib cage in both uninstrumented and instrumented conditions in the full thoracic human cadaveric specimens. METHODS Seven human cadaveric spine specimens (T1-T12) with 4 conditions (with and without rib cage, instrumented and uninstrumented) were subjected to 5 N·m pure moments in flexion-extension, lateral bending, and axial rotation. Range of motion, neutral and Elastic Zones, neutral and Elastic Zone stiffness values, and out-of-plane rotations were calculated for the overall specimen. RESULTS In-plane range of motion was significantly higher without a rib cage for most modes of bending. Out-of-plane motions were also influenced by the rib cage. Neutral Zone stiffness was significantly higher with a rib cage present. CONCLUSION Testing without a rib cage yields different motion and stiffness measures, directly impacting the translation of research results to clinical interpretation. Researchers should consider these differences when evaluating the mechanical impact of surgical procedures or instrumentation in cadaveric or computational models. LEVEL OF EVIDENCE 5.
Paul M. Arnold - One of the best experts on this subject based on the ideXlab platform.
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mechanical analysis of the human cadaveric thoracic spine with intact rib cage
Journal of Biomechanics, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:The goal of this study was to characterize the overall in-plane and basic coupled motion of a cadaveric human thoracic spine with intact true ribs. Researchers are becoming increasingly interested in the thoracic spine due to both the high prevalence of injury and pain in the region and also innovative surgical techniques that utilize the rib cage. Computational models can be useful tools to predict loading patterns and understand effects of surgical procedures or medical devices, but they are often limited by insufficient cadaveric input data. In this study, pure moments to ±5 Nm were applied in flexion-extension, lateral bending, and axial rotation to seven human cadaveric thoracic spine specimens (T1-T12) with intact true ribs to determine symmetry of in-plane motion, differences in neutral and Elastic Zone motion and stiffness, and significance of out-of-plane rotations and translations. Results showed that lateral bending and axial rotation exhibited symmetric motion, neutral and Elastic Zone motion and stiffness values were significantly different for all modes of bending (p<0.05), and out-of-plane rotations and translations were greater than zero for most rotations and translations. Overall in-plane rotations were 7.7±3.4° in flexion, 9.6±3.7° in extension, 23.3±8.4° in lateral bending, and 26.3±12.2° in axial rotation. Results of this study could provide inputs or validation comparisons for computational models. Future studies should characterize coupled motion patterns and local and regional level biomechanics of cadaveric human thoracic spines with intact true ribs.
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Mechanical Contribution of the Rib Cage in the Human Cadaveric Thoracic Spine.
Spine, 2015Co-Authors: Erin M. Mannen, John T. Anderson, Paul M. Arnold, Elizabeth A. FriisAbstract:STUDY DESIGN An in vitro biomechanical human cadaveric study of T1-T12 thoracic specimens was performed with 4 conditions (with and without rib cage, instrumented and uninstrumented) in flexion-extension, lateral bending, and axial rotation. OBJECTIVE The objective was to understand the influence of the rib cage on motion and stiffness parameters of the human cadaveric thoracic spine. Hypotheses tested for overall motion in all modes of bending for both uninstrumented and instrumented specimens were (i) in-plane range of motion and neutral and Elastic Zones will be greater without the rib cage, (ii) neutral and Elastic Zone stiffness values will be different for specimens without the rib cage, and (iii) out-of-plane rotations will be different for specimens without the rib cage. SUMMARY OF BACKGROUND DATA The rib cage is presumed to provide significant stability to the thoracic spine, but no studies have been conducted to determine the influence of the rib cage in both uninstrumented and instrumented conditions in the full thoracic human cadaveric specimens. METHODS Seven human cadaveric spine specimens (T1-T12) with 4 conditions (with and without rib cage, instrumented and uninstrumented) were subjected to 5 N·m pure moments in flexion-extension, lateral bending, and axial rotation. Range of motion, neutral and Elastic Zones, neutral and Elastic Zone stiffness values, and out-of-plane rotations were calculated for the overall specimen. RESULTS In-plane range of motion was significantly higher without a rib cage for most modes of bending. Out-of-plane motions were also influenced by the rib cage. Neutral Zone stiffness was significantly higher with a rib cage present. CONCLUSION Testing without a rib cage yields different motion and stiffness measures, directly impacting the translation of research results to clinical interpretation. Researchers should consider these differences when evaluating the mechanical impact of surgical procedures or instrumentation in cadaveric or computational models. LEVEL OF EVIDENCE 5.