scholarly journals Biomechanical analysis of reduction technique for lumbar spondylolisthesis: anterior lever versus posterior lever reduction method

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yu-Tsung Lin ◽  
Kuo-Chih Su ◽  
Kun-Hui Chen ◽  
Chien-Chou Pan ◽  
Cheng-Min Shih ◽  
...  
Keyword(s):  
Axial Force ◽  
Reduction Method ◽  
Fusion Rate ◽  
Angular Motion ◽  
Biomechanical Analysis ◽  
Contributing Factors ◽  
Biomechanical Behavior ◽  
Adjacent Disc ◽  
Vertebral Bodies ◽  
Lumbar Spondylolisthesis

Abstract Background Reduction of lumbar spondylolisthesis during spinal fusion surgery is important for improving the fusion rate and restoring the sagittal alignment. Despite the variety of reduction methods, the fundamental mechanics of lumbar spondylolisthesis reduction remain unclear. This study aimed to investigate the biomechanical behavior while performing spondylolisthesis reduction with the anterior and posterior lever reduction method. Methods We developed an L4–L5 spondylolisthesis model using sawbones. Two spine surgeons performed the simulated reduction with a customized Cobb elevator. The following data were collected: the torque and angular motion of Cobb, displacement of vertebral bodies, change of lordotic angle between L4 and L5, total axial force and torque applied on the model, and force received by adjacent disc. Results Less torque value (116 N-cm vs. 155 N-cm) and greater angular motion (53o vs. 38o) of Cobb elevator were observed in anterior lever reduction. Moreover, the total axial force received by the entire model was greater in the posterior lever method than that in the anterior lever method (40.8 N vs. 16.38 N). Besides, the displacement of both vertebral bodies was greater in the anterior lever method. Conclusions The anterior lever reduction is a more effort-saving method than the posterior lever reduction method. The existing evidence supports the biomechanical advantage of the anterior reduction method, which might be one of the contributing factors to successfully treating high-grade lumbar spondylolisthesis with short-segment instrumentation.

scholarly journals Comparison between selective caudal fixed screw construct and all variable screw construct in anterior cervical discectomy and fusion

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jae Jun Yang ◽  
Sehan Park ◽  
Seongyun Park
Keyword(s):  
Fusion Rate ◽  
Anterior Cervical Discectomy ◽  
Disc Space ◽  
Cervical Discectomy ◽  
Locking Mechanism ◽  
Adjacent Disc ◽  
One Year ◽  
The Stability ◽  
Retrospective Comparative Study ◽  
Caudal Level

AbstractThis retrospective comparative study aimed to compare the efficacy of selective caudal fixed screw constructs with all variable screw constructs in anterior cervical discectomy and fusion (ACDF). Thirty-five patients who underwent surgery using selective caudal fixed screw construct (SF group) were compared with 44 patients who underwent surgery using all variable constructs (AV group). The fusion rate, subsidence, adjacent level ossification development (ALOD), adjacent segmental disease (ASD), and plate-adjacent disc space distance were assessed. The one-year fusion rates assessed by computed tomography bone bridging and interspinous motion as well as the significant subsidence rate did not differ significantly between the AV and SF groups. The ALOD and ASD rates and plate-adjacent disc space distances did not significantly differ between the two groups at both the cranial and caudal adjacent levels. The number of operated levels was significantly associated with pseudarthrosis in the logistic regression analysis. The stability provided by the locking mechanism of the fixed screw did not lead to an increased fusion rate at the caudal level. Therefore, the screw type should be selected based on individual patient’s anatomy and surgeon’s experience without concern for increased complications caused by screw type.

scholarly journals In vivo intervertebral disc deformation: intratissue strain patterns within adjacent discs during flexion–extension

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Robert L. Wilson ◽  
Leah Bowen ◽  
Woong Kim ◽  
Luyao Cai ◽  
Stephanie Ellyse Schneider ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Biomechanical Analysis ◽  
Resonance Imaging ◽  
Tissue Architecture ◽  
Mechanical Responses ◽  
Flexion Extension ◽  
Adjacent Disc ◽  
Shear Strains ◽  
Magnetic Resonance Imaging Mri

AbstractThe biomechanical function of the intervertebral disc (IVD) is a critical indicator of tissue health and pathology. The mechanical responses (displacements, strain) of the IVD to physiologic movement can be spatially complex and depend on tissue architecture, consisting of distinct compositional regions and integrity; however, IVD biomechanics are predominately uncharacterized in vivo. Here, we measured voxel-level displacement and strain patterns in adjacent IVDs in vivo by coupling magnetic resonance imaging (MRI) with cyclic motion of the cervical spine. Across adjacent disc segments, cervical flexion–extension of 10° resulted in first principal and maximum shear strains approaching 10%. Intratissue spatial analysis of the cervical IVDs, not possible with conventional techniques, revealed elevated maximum shear strains located in the posterior disc (nucleus pulposus) regions. IVD structure, based on relaxometric patterns of T2 and T1ρ images, did not correlate spatially with functional metrics of strain. Our approach enables a comprehensive IVD biomechanical analysis of voxel-level, intratissue strain patterns in adjacent discs in vivo, which are largely independent of MRI relaxometry. The spatial mapping of IVD biomechanics in vivo provides a functional assessment of adjacent IVDs in subjects, and provides foundational biomarkers for elastography, differentiation of disease state, and evaluation of treatment efficacy.

scholarly journals Comparison Between Selective Caudal Fixed Screw Construct and All Variable Screw Construct in Anterior Cervical Discectomy and Fusion

2020 ◽  
Author(s):  
Jae Jun Yang ◽  
Sehan Park ◽  
Seongyun Park
Keyword(s):  
Fusion Rate ◽  
Anterior Cervical Discectomy ◽  
Disc Space ◽  
Cervical Discectomy ◽  
Locking Mechanism ◽  
Adjacent Disc ◽  
One Year ◽  
The Stability ◽  
Retrospective Comparative Study ◽  
Caudal Level

Abstract Objectives: This retrospective comparative study aimed to compare the efficacy of selective caudal fixed screw constructs with all variable screw constructs in anterior cervical discectomy and fusion (ACDF). Methods: Thirty-five patients who underwent surgery using selective caudal fixed screw construct (SF group) were compared with 44 patients who underwent surgery using all variable constructs (AV group). The fusion rate, subsidence, adjacent level ossification development (ALOD), adjacent segmental disease (ASD), and plate-adjacent disc space distance were assessed.Results: The one-year fusion rates assessed by computed tomography bone bridging and interspinous motion as well as the significant subsidence rate did not differ significantly between the AV and SF groups. The ALOD and ASD rates and plate-adjacent disc space distances did not significantly differ between the two groups at both the cranial and caudal adjacent levels. The number of operated levels was significantly associated with pseudarthrosis in the logistic regression analysis.Conclusion: The stability provided by the locking mechanism of the fixed screw did not lead to an increased fusion rate at the caudal level. Therefore, the screw type should be selected based on individual patient’s anatomy and surgeon’s experience without concern for increased complications caused by screw type.

scholarly journals Biomechanical Analysis of Angular Motion in Association with Bilateral Semicircular Canal Function

2019 ◽  
Author(s):  
Shuang Shen ◽  
Fei Zhao ◽  
Zhaoyue Chen ◽  
Qingyin Zheng ◽  
Shen Yu ◽  
...  
Keyword(s):  
Theoretical Approach ◽  
Semicircular Canal ◽  
Amplitude Ratio ◽  
Semicircular Canals ◽  
Vestibular Dysfunction ◽  
Angular Motion ◽  
Biomechanical Analysis ◽  
Fe Model ◽  
Healthy Human ◽  
Horizontal Semicircular Canal

AbstractThe aim of this study was to develop a finite element (FE) model of bilateral human semicircular canals (SCCs) in order to simulate and analyze the complex fluid-structural interaction between the endolymph and cupulae by calculating the degree of cupular expansion and the cupular deflection. The results showed that cupular deflection responses were consistent with Ewald’s II law, whereas each pair of bilateral cupulae simultaneously expanded or compressed to the same degree. In addition, both the degree of cupular expansion and cupular deflection can be expressed as the solution of forced oscillation during head sinusoidal rotation, and the amplitude of cupular expansion was approximately two times greater than that of cupular deflection. Regarding the amplitude-frequency and phase-frequency characteristics, the amplitude ratios among the horizontal semicircular canal (HC) cupular expansion, the anterior semicircular canal (AC) cupular expansion, and the posterior semicircular canal (PC) cupular expansion was constant at 1:0.82:1.62, and the phase differences among them were constant at 0 or 180 degrees at the frequencies of 0.5 to 6 Hz. However, both the amplitude ratio and the phase differencies of the cupular deflection incresed nonlinearly with the increase of frequency and tended to be constant at the frequency band between 2 and 6 Hz. The results indicate that the responses of cupular expansion might only be related to the mass and rigidity of three cupulae and the endolymph, but the responses of cupular deflection are related to the mass, rigidity, or damping of them, and these physical properties would be affected by vestibular dysfunction. Therefore, both the degree of cupular expansion and cupular deflection should be considered important mechanical variables for induced neural signals. Such a numerical model can be further built to provide a useful theoretical approach for exploring the biomechanical nature underlying vestibular dysfunction.Statement of significanceBy taking the advantage of the torsional pendulum model and the FE model, a healthy human vestibular SCCs was developed to investigate the angular motion in association with SCC function. As a result, the responses of cupular expansion and deflection during head horizontal sinusoidal rotation were analyzed for the first time, showing quantitative correlation to the eye movement due to the vestibular ocular reflex (VOR) pathway. These responses play important roles in the cupular mechano-electrical transduction process. The significant outcome derived from this study provides a useful theoretical approach for further exploring the biomechanical nature underlying vestibular dysfunction.

Biomechanical behavior of MRI-signal-inducing bone cements after vertebroplasty in osteoporotic vertebral bodies: An experimental cadaver study

2014 ◽  
Vol 29 (5) ◽  
pp. 571-576 ◽  
Author(s):  
Florian Wichlas ◽  
Heidi Trzenschik ◽  
Serafim Tsitsilonis ◽  
Antonius Rohlmann ◽  
Hermann-Josef Bail
Keyword(s):  
Cadaver Study ◽  
Bone Cements ◽  
Biomechanical Behavior ◽  
Vertebral Bodies

The protective role of dynamic stabilization on the adjacent disc to a rigid instrumented level. An in vitro biomechanical analysis

2013 ◽  
Vol 133 (4) ◽  
pp. 443-448 ◽  
Author(s):  
J. Cabello ◽  
J. M. Cavanilles-Walker ◽  
M. Iborra ◽  
M. T. Ubierna ◽  
A. Covaro ◽  
...  
Keyword(s):  
Protective Role ◽  
Dynamic Stabilization ◽  
Biomechanical Analysis ◽  
Adjacent Disc

Clinical Results of Instrumentation Reduction and Posterolateral Fusion After Decompression of Symptomatic Lumbar Spondylolisthesis

1998 ◽  
Vol 02 (02) ◽  
pp. 109-122
Author(s):  
Kam Kong Chan
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Clinical Results ◽  
Fusion Rate ◽  
Radicular Pain ◽  
Posterolateral Fusion ◽  
Low Back ◽  
Loss Of Reduction ◽  
Grade Ii ◽  
Lumbar Spondylolisthesis

From July 1990 to June 1993, 35 patients suffering lumbar spondylolisthesis (21 degenerative; 14 isthmic) were operated on and reviewed. They all had single-level involvement either L4-5 or L5-S1 and only this level was confined for operation. The operative procedures included decompression, posterolateral fusion and pedicle screw instrumentation for fixation and reduction of the vertebral slip. The age ranged from 42 to 65 years old, with an average of 55 years. There were 21 patients with grade 1 slip; 13 with grade II; and 1 with grade III. The follow-up periods ranged from 30 to 55 months with an average of 42 months. The clinical results were evaluated according to the improvement of low back pain, radicular pain, claudication and the incidence of fusion. Twenty-four patients (74%) were rated good to excellent and the fusion rate was 88%. However, there were 16 patients who still suffered from significant low back pain and who had reportd that such pain adversely affected the rating of clinical result. Loss of reduction were found in 16 patients, but there was no difference in clinical outcome between patients with or without reduction loss after the operation. The purpose of this paper is to report the clinical outcomes of the treatment of symptomatic spondylolisthesis with decompression, posterolateral fusion and instrumental reduction of the slip. The incidence of reduction loss and the prevalence of remaining low back pain are two important factors to consider in doing such reduction procedure. We inferred that slip reduction may not be a worthwile procedure in the treatment of adult spondylolisthesis if ordinary posterolateral fusion with short segment instrumentation is contemplated.

Biomechanical analysis of spinal implants with different rod diameters under static and fatigue loads: an experimental study

2019 ◽  
Vol 64 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Halim Kovacı ◽  
Ali Fatih Yetim ◽  
Ayhan Çelik
Keyword(s):  
Dynamic Compression ◽  
Fatigue Behavior ◽  
Pedicle Screws ◽  
Fatigue Tests ◽  
Biomechanical Analysis ◽  
Static Tension ◽  
Test Results ◽  
Spinal Implants ◽  
Biomechanical Behavior ◽  
Load Carrying

Abstract Spinal implants are commonly used in the treatment of spinal disorders or injuries. However, the biomechanical analyses of them are rarely investigated in terms of both biomechanical and clinical perspectives. Therefore, the main purpose of this study is to investigate the effects of rod diameter on the biomechanical behavior of spinal implants and to make a comparison among them. For this purpose, three spinal implants composed of pedicle screws, setscrews and rods, which were manufactured from Ti6Al4V, with diameters of 5.5 mm, 6 mm and 6.35 mm were used and a bilateral vertebrectomy model was applied to spinal systems. Then, the obtained spinal systems were tested under static tension-compression and fatigue (dynamic compression) conditions. Also, failure analyses were performed to investigate the fatigue behavior of spinal implants. After static tension-compression and fatigue tests, it was found that the yield loads, stiffness values, load carrying capacities and fatigue performances of spinal implants enhanced with increasing spinal rod diameter. In comparison to spinal implants with 5.5 mm rods, the fatigue limits of implants showed 13% and 33% improvements in spinal implants having 6 mm and 6.35 mm rods, respectively. The highest static and fatigue test results were obtained from spinal implants having 6.35 mm rods among the tested implants. Also, it was observed that the increasing yield load and stiffness values caused an increase in the fatigue limits of spinal implants.

scholarly journals T1-weighted MR imaging of bone marrow pattern in children with adolescent idiopathic scoliosis: a preliminary study

2018 ◽  
Vol 12 (2) ◽  
pp. 181-186 ◽  
Author(s):  
S. I. Shiran ◽  
L. Shabtai ◽  
L. Ben-Sira ◽  
D. Ovadia ◽  
S. Wientroub
Keyword(s):  
Bone Marrow ◽  
Adolescent Idiopathic Scoliosis ◽  
Idiopathic Scoliosis ◽  
Diagnostic Study ◽  
Level Of Evidence ◽  
Lenke Classification ◽  
Adjacent Disc ◽  
Vertebral Bodies ◽  
Preliminary Study ◽  
Mri Study

Purpose Distinct normal physiological patterns of fat conversion in vertebrae were described both for children and adults. Our aim was to evaluate the T1-weighted bone marrow pattern of the vertebral bodies in various sites along the scoliotic spine of children with adolescent idiopathic scoliosis (AIS). Methods We retrospectively evaluated spine MRI studies of children with AIS. Scoliosis radiographs were assessed for type of curvature according to the Lenke classification. A paediatric neuroradiologist assessed the T1-weighted signal of vertebral bodies in comparison with the adjacent disc and distinct patterns of fatty conversion within the apical and stable vertebral bodies. Statistical assessment was performed. Results MRI study of the spines of 75 children with AIS were assessed, 59 (79%) of whom were female, with an age range of nine to 19 years. The relative overall T1-weighted signal intensity of the vertebral body bone marrow relative to the intervertebral disc was hyperintense in 76% and isointense in 24%. Fatty conversion grade of the stable vertebra was higher than the apex vertebra (p = 0.0001). A significant tendency to have more advanced fat conversion patterns in the apex vertebra up to age 13.5 years old compared with adolescents above that (p = 0.015) was seen. Conclusion This preliminary study suggests a different pattern of bone marrow conversion in AIS from the normal physiologic pattern described in the literature. Whether these changes are secondary to the biomechanics of the curved spine or may suggest that bone marrow maturation rate and content have a role in the pathogenesis of AIS remains to be further researched. Level of Evidence Level III (Diagnostic Study)

The Patient-Specific Brace Design and Biomechanical Analysis of Adolescent Idiopathic Scoliosis

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Wen-Zhong Nie ◽  
Ming Ye ◽  
Zu-De Liu ◽  
Cheng-Tao Wang
Keyword(s):  
Finite Element ◽  
Measurement System ◽  
Element Model ◽  
Biomechanical Study ◽  
Biomechanical Analysis ◽  
Patient Specific ◽  
Sacral Slope ◽  
Element Analysis ◽  
Biomechanical Behavior ◽  
Idiopathic Adolescent Scoliosis

Brace application has been reported to be an effective approach in treating mild to moderate idiopathic adolescent scoliosis. However, little attention is focused on the biomechanical study of patient-specific brace treatment. The purpose of this study was to propose a design method of personalized brace and to analyze its biomechanical behavior and to compare the brace forces with the I-Scan measurement system. Based on a three-dimensional patient-specific finite element model of the spine, rib cage, pelvis, and abdomen, a parametric patient-specific model of a thoracolumbosacral orthosis was built. The interaction between the torso and the brace was modeled by surface-to-surface contact interface. Three standard strap tensions (20 N, 40 N, and 60 N) were loaded on the back of the brace to simulate the strap tension. The I-Scan distribution pressure measurement system was used to measure the different region pressures, and the equivalent forces in these regions were calculated. The spinal curve changes and the forces acted on the brace generated by the strap tension were evaluated and compared with the measurement. The reduction in the coronal curvature was about 60% for a strap tension of 60 N. The sacral slope and the lordosis were partially reduced in this case, but the kyphosis had no obvious change. The brace slightly modified the axial rotation at the apex of the scoliotic curve. The forces generated in finite element analysis were approximately in good agreement with the measurement. The design and biomechanical analysis methods of patient-specific brace should be useful in the design of more effective braces.

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