scholarly journals Preclinical Evaluation of a Novel 3D-Printed Movable Lumbar Vertebral Complex for Replacement: In Vivo and Biomechanical Evaluation of Goat Model

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Feng Zhang ◽  
Jiantao Liu ◽  
Xijing He ◽  
Rui Wang ◽  
Teng Lu ◽  
...  
Keyword(s):  
Ct Scan ◽  
Statistical Significance ◽  
Lumbar Vertebrae ◽  
Lateral Bending ◽  
Intervertebral Space ◽  
Intact Group ◽  
Lumbar Vertebral Body ◽  
Imaging Results ◽  
Flexion Extension

Purpose. This was an in vivo study to develop a novel movable lumbar artificial vertebral complex (MLVC) in a goat model. The purpose of this study was to evaluate clinical and biomechanical characteristics of MLVC and to provide preclinical data for a clinical trial in the future. Methods. According to the preoperative X-ray and CT scan data of the lumbar vertebrae, 3D printing of a MLVC was designed and implanted in goats. The animals were randomly divided into three groups: intact, fusion, and nonfusion. In the intact group, only the lumbar vertebrae and intervertebral discs were exposed during surgery. Both the fusion and nonfusion groups underwent resection of the lumbar vertebral body and the adjacent intervertebral disc. Titanium cages and lateral plates were implanted in the fusion group. MLVC was implanted in the nonfusion group. All groups were evaluated by CT scan and micro-CT to observe the spinal fusion and tested using the mechanical tester at 6 months after operation. Results. The imaging results showed that with the centrum, the artificial endplates of the titanium cage and MLVC formed compact bone trabeculae. In the in vitro biomechanical test, the average ROM of L3-4 and L4-5 for the nonfusion group was found to be similar to that of the intact group and significantly higher in comparison to that of the fusion group ( P < 0.05 ). The average ROM of flexion, extension, lateral bending, and rotation in the L2-3 intervertebral space significantly increased in the fusion group compared with the intact group and the nonfusion group ( P < 0.001 ). There were no significant differences in flexion, extension, lateral bending, and rotation between the nonfusion and intact groups ( P > 0.05 ). The average ROM of flexion, extension, lateral bending, and rotation in the L2-5 intervertebral space was not significantly different between the intact group, the fusion group, and the nonfusion group, and there was no statistical significance ( P > 0.05 ). HE staining results did not find any metal and polyethylene debris caused by abrasion. Conclusion. In vivo MLVC can not only reconstruct the height and stability of the centrum of the operative segment but also retain the movement of the corresponding segment.

Adjacent-segment effects of lumbar cortical screw–rod fixation versus pedicle screw–rod fixation with and without interbody support

2021 ◽  
pp. 1-7
Author(s):  
Piyanat Wangsawatwong ◽  
Anna G. U. Sawa ◽  
Bernardo de Andrada Pereira ◽  
Jennifer N. Lehrman ◽  
Luke K. O’Neill ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Interbody Fusion ◽  
Lumbar Fusion ◽  
Statistical Significance ◽  
Adjacent Segment ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Single Level ◽  
Cortical Screw ◽  
Flexion Extension

OBJECTIVE Cortical screw–rod (CSR) fixation has emerged as an alternative to the traditional pedicle screw–rod (PSR) fixation for posterior lumbar fixation. Previous studies have concluded that CSR provides the same stability in cadaveric specimens as PSR and is comparable in clinical outcomes. However, recent clinical studies reported a lower incidence of radiographic and symptomatic adjacent-segment degeneration with CSR. No biomechanical study to date has focused on how the adjacent-segment mobility of these two constructs compares. This study aimed to investigate adjacent-segment mobility of CSR and PSR fixation, with and without interbody support (lateral lumbar interbody fusion [LLIF] or transforaminal lumbar interbody fusion [TLIF]). METHODS A retroactive analysis was done using normalized range of motion (ROM) data at levels adjacent to single-level (L3–4) bilateral screw–rod fixation using pedicle or cortical screws, with and without LLIF or TLIF. Intact and instrumented specimens (n = 28, all L2–5) were tested using pure moment loads (7.5 Nm) in flexion, extension, lateral bending, and axial rotation. Adjacent-segment ROM data were normalized to intact ROM data. Statistical comparisons of adjacent-segment normalized ROM between two of the groups (PSR followed by PSR+TLIF [n = 7] and CSR followed by CSR+TLIF [n = 7]) were performed using 2-way ANOVA with replication. Statistical comparisons among four of the groups (PSR+TLIF [n = 7], PSR+LLIF [n = 7], CSR+TLIF [n = 7], and CSR+LLIF [n = 7]) were made using 2-way ANOVA without replication. Statistical significance was set at p < 0.05. RESULTS Proximal adjacent-segment normalized ROM was significantly larger with PSR than CSR during flexion-extension regardless of TLIF (p = 0.02), or with either TLIF or LLIF (p = 0.04). During lateral bending with TLIF, the distal adjacent-segment normalized ROM was significantly larger with PSR than CSR (p < 0.001). Moreover, regardless of the types of screw-rod fixations (CSR or PSR), TLIF had a significantly larger normalized ROM than LLIF in all directions at both proximal and distal adjacent segments (p ≤ 0.04). CONCLUSIONS The use of PSR versus CSR during single-level lumbar fusion can significantly affect mobility at the adjacent segment, regardless of the presence of TLIF or with either TLIF or LLIF. Moreover, the type of interbody support also had a significant effect on adjacent-segment mobility.

scholarly journals Experimental evaluation of precision and accuracy of RSA in the lumbar spine

2020 ◽  
Author(s):  
Marie Christina Keller ◽  
Christof Hurschler ◽  
Michael Schwarze
Keyword(s):  
Lumbar Spine ◽  
Focal Spot ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Hip And Knee Arthroplasty ◽  
Spinal Region ◽  
Precision And Accuracy ◽  
Bone Structures

Abstract Purpose Roentgen stereophotogrammetric analysis is a technique to make accurate assessments of the relative position and orientation of bone structures and implants in vivo. While the precision and accuracy of stereophotogrammetry for hip and knee arthroplasty is well documented, there is insufficient knowledge of the technique’s precision and, especially accuracy when applied to rotational movements in the spinal region. Methods The motion of one cadaver lumbar spine segment (L3/L4) was analyzed in flexion–extension, lateral bending and internal rotation. The specific aim of this study was to examine the precision and accuracy of stereophotogrammetry in a controlled in vitro setting, taking the surrounding soft tissue into account. The second objective of this study was to investigate the effect of different focal spot values of X-ray tubes. Results Overall, the precision of flexion–extension measurements was found to be better when using a 0.6 mm focal spot value rather than 1.2 mm (± 0.056° and ± 0.153°; respectively), and accuracy was also slightly better for the 0.6 mm focal spot value compared to 1.2 mm (− 0.137° and − 0.170°; respectively). The best values for precision and accuracy were obtained in lateral bending for both 0.6 mm and 1.2 mm focal spot values (precision: ± 0.019° and ± 0.015°, respectively; accuracy: − 0.041° and − 0.035°). Conclusion In summary, the results suggest stereophotogrammetry to be a highly precise method to analyze motion of the lumbar spine. Since precision and accuracy are better than 0.2° for both focal spot values, the choice between these is of minor clinical relevance.

Prediction of in vivo lower cervical spinal loading using musculoskeletal multi-body dynamics model during the head flexion/extension, lateral bending and axial rotation

2018 ◽  
Vol 232 (11) ◽  
pp. 1071-1082 ◽  
Author(s):  
Hao Diao ◽  
Hua Xin ◽  
Zhongmin Jin
Keyword(s):  
Cervical Spine ◽  
Axial Rotation ◽  
Intervertebral Disk ◽  
Lateral Bending ◽  
Spinal Loading ◽  
Flexion Extension ◽  
Body Dynamics ◽  
Head Flexion ◽  
Multi Body

Cervical spine diseases lead to a heavy economic burden to the individuals and societies. Moreover, frequent post-operative complications mean a higher risk of neck pain and revision. At present, controversy still exists for the etiology of spinal diseases and their associated complications. Knowledge of in vivo cervical spinal loading pattern is proposed to be the key to answer these questions. However, direct acquisition of in vivo cervical spinal loading remains challenging. In this study, a previously developed cervical spine musculoskeletal multi-body dynamics model was utilized for spinal loading prediction. The in vivo dynamic segmental contributions to head motion and the out-of-plane coupled motion were both taken into account. First, model validation and sensitivity analysis of different segmental contributions to head motion were performed. For model validation, the predicted intervertebral disk compressive forces were converted into the intradiskal pressures and compared with the published experimental measurements. Significant correlations were found between the predicted values and the experimental results. Thus, the reliability and capability of the cervical spine model was ensured. Meanwhile, the sensitivity analysis indicated that cervical spinal loading is sensitive to different segmental contributions to head motion. Second, the compressive, shear and facet joint forces at C3–C6 disk levels were predicted, during the head flexion/extension, lateral bending and axial rotation. Under the head flexion/extension movement, asymmetric loading patterns of the intervertebral disk were obtained. In comparison, symmetrical typed loading patterns were found for the head lateral bending and axial rotation movements. However, the shear forces were dramatically increased during the head excessive extension and lateral bending. Besides, a nonlinear correlation was seen between the facet joint force and the angular displacement. In conclusion, dynamic cervical spinal loading was both intervertebral disk angle-dependent and level-dependent. Cervical spine musculoskeletal multi-body dynamics model provides an attempt to comprehend the in vivo biomechanical surrounding of the human head-neck system.

scholarly journals The effect of multiplanar loading on the intradiscal pressure of the whole human spine: systematic review and meta-analysis

2021 ◽  
Vol 41 ◽  
pp. 388-400
Author(s):  
C Liebsch ◽  
◽  
HJ Wilke
Keyword(s):  
Meta Analysis ◽  
Statistical Significance ◽  
Intradiscal Pressure ◽  
External Loading ◽  
Upper Cervical Spine ◽  
Loading Conditions ◽  
Lateral Bending ◽  
Validation Data ◽  
Human Spine ◽  
Flexion Extension

For spinal load and muscle force estimation as well as for numerical model and experimental setup validation, data on human intradiscal pressure are essential. Therefore, the aim of the present meta-analysis was to summarise all in vitro measurements of human intradiscal pressure performed under defined boundary conditions, i.e. without external loading (intrinsic pressure), under axial loading (compression, traction, shear) and under single-planar bending loading (flexion, extension, lateral bending, axial rotation). Data were evaluated based on segmental level and normalised to force and moment. Regression analysis was performed to investigate coefficients of determination and statistical significance of relationships between intradiscal pressure and segmental level for the single loading conditions. 35 studies fulfilled the inclusion criteria, from which a total of 451 data points were collected for the meta-analysis. High coefficients of determination were found in axial compression (r2 = 0.875) and flexion (r2 = 0.781), while being low for intrinsic pressure (r2 = 0.266) and lateral bending (r2 = 0.385), all showing significant regression fitting (p < 0.01). Intradiscal pressure decreases from the upper cervical spine to the sacrum in all loading conditions, considering the same amount of loading for all segmental levels, while the intrinsic pressure exhibits a minimum of the regression curve in the mid-thoracic spine. Apart from its potential for numerical and experimental model validation, this dataset may help to understand the load distribution along the human spine.

scholarly journals A Dynamic Radiographic Imaging Study of Lumbar Intervertebral Disc Morphometry and Deformation In Vivo

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ryan M. Byrne ◽  
Ameet K. Aiyangar ◽  
Xudong Zhang
Keyword(s):  
Structural Integrity ◽  
Intervertebral Discs ◽  
Body Motion ◽  
Lumbar Region ◽  
Low Back ◽  
Radiographic Imaging ◽  
Lumbar Vertebral Body ◽  
Flexion Extension ◽  
Dynamic Radiographic Imaging

Abstract Intervertebral discs are important structural components of the spine but also are significant sources of morbidity, especially for the “low back” lumbar region. Mechanical damage to, or degeneration of, the lumbar discs can diminish their structural integrity and elicit debilitating low back pain. Advancement of reparative or regenerative means to treat damaged or degenerated discs is hindered by a lack of basic understanding of the disc load-deformation characteristics in vivo. The current study presents an in vivo analysis of the morphometry and deformation of lumbar (L2-S1) intervertebral discs in 10 healthy participants while performing a common lifting act, using novel dynamic radiographic imaging of the lumbar vertebral body motion. Data analyses show uniquely different (p < 0.05) characteristics in morphometry, normal and shear strain patterns of the L5S1 discs, while the rest of lumbar discs exhibit great similarity. In particular shear strains in L2-L5 discs exhibited stronger linear correlations (R2 ≥ 0.80) between strain changes and amount of lumbar flexion-extension motion compared to L5S1 (R2 ≤ 0.5). The study therefore advances the state of knowledge on in vivo mechanical responses of the lumbar intervertebral discs during functional tasks.

A Cable-Actuated Robotic Lumbar Spine for Palpatory Training of Medical Students

2010 ◽  
Author(s):  
Ernur Karadogan ◽  
Robert L. Williams
Keyword(s):  
Lumbar Spine ◽  
Medical Students ◽  
Lumbar Vertebrae ◽  
Lumbar Vertebra ◽  
Professional Lives ◽  
Human Lumbar Spine ◽  
Flexion Extension ◽  
Hands On ◽  
Spine Robot

This paper presents the kinematic and pseudostatic analyses of a fully cable-actuated robotic lumbar spine (RLS) which can mimic in vivo human lumbar spine movements to provide better hands-on training for medical students. The design incorporates five active lumbar vertebrae between the first lumbar vertebra and the sacrum, with dimensions of an average adult human spine. Medical schools can benefit from a tool, system, or method that will help instructors train students and assess their tactile proficiency throughout their education. The robotic lumbar spine has the potential to satisfy these needs in palpatory diagnosis. Medical students will be given the opportunity to examine their own patient that can be programmed with many dysfunctions related to the lumbar spine before they start their professional lives as doctors. The robotic lumbar spine can be used to teach and test medical students in their capacity to be able to recognize normal and abnormal movement patterns of the human lumbar spine under flexion-extension and lateral bending. This project focus is on palpation, but the spine robot could also benefit surgery training/planning and other related biomedical applications.

scholarly journals Biomechanical effects of a novel posteriorly placed sacroiliac joint fusion device integrated with traditional lumbopelvic long-construct instrumentation

2021 ◽  
pp. 1-10
Author(s):  
Bernardo de Andrada Pereira ◽  
Jennifer N. Lehrman ◽  
Anna G. U. Sawa ◽  
Derek P. Lindsey ◽  
Scott A. Yerby ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Axial Rotation ◽  
High Rate ◽  
Joint Motion ◽  
Bending Moments ◽  
Lateral Bending ◽  
Fusion Device ◽  
Joint Fusion ◽  
Flexion Extension ◽  
Si Joint

OBJECTIVE S2-alar-iliac (S2AI) screw fixation effectively ensures stability and enhances fusion in long-segment constructs. Nevertheless, pelvic fixation is associated with a high rate of mechanical failure. Because of the transarticular nature of the S2AI screw, adding a second point of fixation may provide additional stability and attenuate strains. The objective of the study was to evaluate changes in stability and strain with the integration of a sacroiliac (SI) joint fusion device, implanted through a novel posterior SI approach, supplemental to posterior long-segment fusion. METHODS L1-pelvis human cadaveric specimens underwent pure moment (7.5 Nm) and compression (400 N) tests in the following conditions: 1) intact, 2) L2–S1 pedicle screw and rod fixation with L5–S1 interbody fusion, 3) added S2AI screws, and 4) added bilateral SI joint fixation (SIJF). The range of motion (ROM), rod strain, and screw bending moments (S1 and S2AI) were analyzed. RESULTS S2AI fixation decreased L2–S1 ROM in flexion-extension (p ≤ 0.04), L5–S1 ROM in flexion-extension and compression (p ≤ 0.004), and SI joint ROM during flexion-extension and lateral bending (p ≤ 0.03) compared with S1 fixation. SI joint ROM was significantly less with SIJF in place than with the intact joint, S1, and S2AI fixation in flexion-extension and lateral bending (p ≤ 0.01). The S1 screw bending moment decreased following S2AI fixation by as much as 78% in extension, but with statistical significance only in right axial rotation (p = 0.03). Extending fixation to S2AI significantly increased the rod strain at L5–S1 during flexion, axial rotation, and compression (p ≤ 0.048). SIJF was associated with a slight increase in rod strain versus S2AI fixation alone at L5–S1 during left lateral bending (p = 0.048). Compared with the S1 condition, fixation to S2AI increased the mean rod strain at L5–S1 during compression (p = 0.048). The rod strain at L5–S1 was not statistically different with SIJF compared with S2AI fixation (p ≥ 0.12). CONCLUSIONS Constructs ending with an S2AI screw versus an S1 screw tended to be more stable, with reduced SI joint motion. S2AI fixation decreased the S1 screw bending moments compared with fixation ending at S1. These benefits were paired with increased rod strain at L5–S1. Supplementation of S2AI fixation with SIJF implants provided further reductions (approximately 30%) in the sagittal plane and lateral bending SI joint motion compared with fixation ending at the S2AI position. This stability was not paired with significant changes in rod or screw strains.

scholarly journals Biomechanical properties of a novel nonfusion artificial vertebral body for anterior lumbar vertebra resection and internal fixation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiantao Liu ◽  
Xijing He ◽  
Binbin Niu ◽  
Yin Yang ◽  
Yanzheng Gao ◽  
...  
Keyword(s):  
Finite Element ◽  
Vertebral Body ◽  
Lumbar Vertebra ◽  
Biomechanical Properties ◽  
Finite Element Models ◽  
Facet Joints ◽  
Lateral Bending ◽  
Intact Group ◽  
Flexion Extension ◽  
Artificial Vertebral Body

AbstractThe aim of the study was to evaluate the biomechanical properties of a novel nonfused artificial vertebral body in treating lumbar diseases and to compare with those of the fusion artificial vertebral body. An intact finite element model of the L1–L5 lumbar spine was constructed and validated. Then, the finite element models of the fusion group and nonfusion group were constructed by replacing the L3 vertebral body and adjacent intervertebral discs with prostheses. For all finite element models, an axial preload of 500 N and another 10 N m imposed on the superior surface of L1. The range of motion and stress peaks in the adjacent discs, endplates, and facet joints were compared among the three groups. The ranges of motion of the L1–2 and L4–5 discs in flexion, extension, left lateral bending, right lateral bending, left rotation and right rotation were greater in the fusion group than those in the intact group and nonfusion group. The fusion group induced the greatest stress peaks in the adjacent discs and adjacent facet joints compared to the intact group and nonfusion group. The nonfused artificial vertebral body could better retain mobility of the surgical site after implantation (3.6°–8.7°), avoid increased mobility and stress of the adjacent discs and facet joints.

scholarly journals The Robotic Lumbar Spine: Dynamics and Feedback Linearization Control

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Ernur Karadogan ◽  
Robert L. Williams
Keyword(s):  
Lumbar Spine ◽  
Medical Students ◽  
Feedback Linearization ◽  
Lumbar Vertebrae ◽  
Professional Lives ◽  
Human Lumbar Spine ◽  
Flexion Extension ◽  
Hands On ◽  
Feedback Linearization Control

The robotic lumbar spine (RLS) is a 15 degree-of-freedom, fully cable-actuated robotic lumbar spine which can mimicin vivohuman lumbar spine movements to provide better hands-on training for medical students. The design incorporates five active lumbar vertebrae and the sacrum, with dimensions of an average adult human spine. It is actuated by 20 cables connected to electric motors. Every vertebra is connected to the neighboring vertebrae by spherical joints. Medical schools can benefit from a tool, system, or method that will help instructors train students and assess their tactile proficiency throughout their education. The robotic lumbar spine has the potential to satisfy these needs in palpatory diagnosis. Medical students will be given the opportunity to examine their own patient that can be programmed with many dysfunctions related to the lumbar spine before they start their professional lives as doctors. The robotic lumbar spine can be used to teach and test medical students in their capacity to be able to recognize normal and abnormal movement patterns of the human lumbar spine under flexion-extension, lateral bending, and axial torsion. This paper presents the dynamics and nonlinear control of the RLS. A new approach to solve for positive and nonzero cable tensions that are also continuous in time is introduced.

New Posterior Atlantoaxial Restricted Non-Fusion Fixation for Atlantoaxial Instability

Neurosurgery ◽  
2015 ◽  
Vol 78 (5) ◽  
pp. 735-741 ◽  
Author(s):  
Jinshui Chen ◽  
Fengjin Zhou ◽  
Bin Ni ◽  
Qunfeng Guo ◽  
Huapeng Guan ◽  
...  
Keyword(s):  
Axial Rotation ◽  
Odontoid Fracture ◽  
Fracture Model ◽  
Atlantoaxial Instability ◽  
Atlantoaxial Joint ◽  
Type Ii ◽  
Long Term Effects ◽  
Lateral Bending ◽  
Intact Group ◽  
Flexion Extension

Abstract BACKGROUND: Loss of axial rotation and lateral bending after atlantoaxial fusion reduces a patient's quality of life. Therefore, effective, nonfusion fixation alternatives are needed for atlantoaxial instability. OBJECTIVE: To evaluate the initial stability and function of posterior atlantoaxial restricted nonfusion fixation (PAARNF), a new protocol, using cadaveric cervical spines compared with the intact state, destabilization, and posterior C1-C2 rod fixation. METHODS: Cervical areas C0 through C3 were used from 6 cadaveric spines to test flexion-extension, lateral bending, and axial rotation range of motion (ROM). With the use of a machine, 1.5-Nm torque at a rate of 0.1 Nm/s was used and held for 10 seconds. The specimens were loaded 3 times, and data were collected in the third cycle and tested in the following sequence: (1) intact, (2) destabilization (using a type II odontoid fracture model), (3) destabilization with PAARNF (PAARNF group), and (4) rod implantation (rod group). The order of tests for the PAARNF and rod groups was randomly assigned. RESULTS: The average flexion-extension ROM in the PAARNF group was 7.44 ± 2.05°, which was significantly less than in the intact (P = .00) and destabilization (P = .00) groups but not significantly different from that of the rod group (P = .07). The average lateral bending ROM (10.59 ± 2.33°; P = .00) and axial rotation ROM (38.79 ± 13.41°; P = .00) of the PAARNF group were significantly greater than in the rod group. However, the values of the PAARNF group showed no significant differences compared with those of the intact group. CONCLUSION: PAARNF restricted atlantoaxial flexion-extension but preserved axial rotation and lateral bending at the atlantoaxial joint in a type II odontoid fracture model. However, it should not be used clinically until further studies have been performed to test the long-term effects of this procedure.

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