Finite Element Analysis of Stability of Internal Fixation Reconstruction Methods for Lumbar Total Vertebral Resection

Abstract Objective To compare the effect of different fixation methods on spinal stability after total en bloc spondylectomy(TES) of lumbar spine.Method The finite element models were established based on the CT scan of a healthy volunteer. After the validity of the models was confirmed, the models with different posterior fixation methods of the lumbar spine were established with and without the artificial vertebral body, respectively. The motions of flexion, extension, lateral bending and rotation under supine and standing conditions were simulated. The angular displacement of T11-L3 and stress of internal fixations were compared and analyzed.Results The finite element models of spinal reconstruction after TES were obtained. When the anterior support existed, the movement of the spine after TES was not affected by the gravity of the upper body. The movements in the opposite direction on the same plane were similar. All three methods provided enough stability to the spine. The improved short-segment fixation shared stress of the artificial vertebral body with no obvious negative effect. The long-segment fixation had stronger fixation effect with the huge loss of the range of motion of lumbar spine. When the anterior support failed, obvious rotation showed in lateral bending in all models. The short-segment fixation and the long-segment fixation failed to maintain the spinal stability with fixations breakage or functional loss. The improved short-segment fixations showed strong ability in maintaining the spinal stability. The vertebral body screws can prevent the failure of anterior fixation by sharing great stress of the whole internal fixation system. The improved short-segment had huge advantages over the others.Conclusion After TES, the improved short-segment fixation can provide more stability to the spine. The vertebral body screws can prevent the failure of the internal fixation by reducing the stress of the anterior support. This fixation method should be promoted in clinical practice while the effect requires more observation.

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Biomechanical finite element analysis of vertebral column resection and posterior unilateral vertebral resection and reconstruction osteotomy

Journal of Orthopaedic Surgery and Research ◽

10.1186/s13018-021-02237-4 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Ye Han ◽

Xiaodong Wang ◽

Jincheng Wu ◽

Hanpeng Xu ◽

Zepei Zhang ◽

...

Keyword(s):

Internal Fixation ◽

Vertebral Body ◽

Vertebral Column ◽

Vertebral Compression Fractures ◽

Lateral Bending ◽

Short Segment ◽

Vertebral Column Resection ◽

Compression Fractures ◽

Short Segment Fixation ◽

Vertebral Resection

Abstract Background Regarding the repair of vertebral compression fractures, there is a lack of adequate biomechanical verification as to whether only half of the vertebral body and the upper and lower intervertebral discs affect spinal biomechanics; there also remains debate as to the appropriate length of fixation. Methods A model of old vertebral compression fractures with kyphosis was established based on CT data. Vertebral column resection (VCR) and posterior unilateral vertebral resection and reconstruction (PUVCR) were performed at T12; long- and short-segment fixation methods were applied, and we analyzed biomechanical changes after surgery. Results Range of motion (ROM) decreased in all fixed models, with lumbar VCR decreasing the most and short posterior unilateral vertebral resection and reconstruction (SPUVCR) decreasing the least; in the long posterior unilateral vertebral resection and reconstruction (LPUVCR) model, the internal fixation system produced the maximum VMS stress of 213.25 mPa in a lateral bending motion and minimum stress of 40.22 mPa in a lateral bending motion in the SVCR. Conclusion There was little difference in thoracolumbar ROM between PUVCR and VCR models, while thoracolumbar ROM was smaller in long-segment fixation than in short-segment fixation. In all models, the VMS was most significant at the screw-rod junction and greatest at the ribcage–vertebral body interface, partly explaining the high probability of internal fixation failure and prosthesis migration in these two positions.

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Treatment of Old Vertebral Compression Fracture With Kyphosis by Different Reconstruction Methods: a Finite Element Analysis

10.21203/rs.3.rs-129832/v1 ◽

2020 ◽

Author(s):

Han Ye ◽

Wang Xiaodong ◽

Wu Jincheng ◽

Xu Hanpeng ◽

Zhang Zepei ◽

...

Keyword(s):

Internal Fixation ◽

Vertebral Body ◽

Compression Fracture ◽

Vertebral Compression Fractures ◽

Lateral Bending ◽

Short Segment ◽

Compression Fractures ◽

Reconstruction Methods ◽

Short Segment Fixation ◽

Vertebral Resection

Abstract Background: In repair of vertebral compression fractures, there is a lack of effective biomechanical verification as to whether only half of the vertebral body and the upper and lower intervertebral discs has any effect on spinal biomechanics; there also remains debate as to the appropriate length of fixation.Methods: A model of old vertebral compression fractures with kyphosis was established based on CT data. Vertebral column resection (VCR) and posterior unilateral vertebral resection and reconstruction (PUVCR) were performed at T12; long- and short-segment fixation methods were applied, and we analyzed biomechanical changes after surgery.Results: Range of motion (ROM) decreased in all fixed models, with lumbar VCR decreasing the most and short posterior unilateral vertebral resection and reconstruction (SPUVCR) decreasing the least; in the long posterior unilateral vertebral resection and reconstruction (LPUVCR) model, the internal fixation system produced the maximum VMS stress of 213.25 MPa in a lateral bending motion, and a minimum stress of 40.22 MPa in a lateral bending motion in the SVCR.Conclusion: There was little difference in thoracolumbar ROM between PUVCR and VCR models, while thoracolumbar ROM was smaller in long-segment fixation than in short-segment fixation. In all models, the VMS was greatest at the screw-rod junction and greatest at the ribcage–vertebral body interface, which partly explains the high probability of internal fixation failure and prosthesis migration in these two positions.

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Biomechanical Comparison of Different Pedicle Screw Fixations for Thoracolumbar Burst Fractures Using Finite Element Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.117-119.699 ◽

2011 ◽

Vol 117-119 ◽

pp. 699-702 ◽

Cited By ~ 2

Author(s):

Dong Mei Wang ◽

Du Fang Shi ◽

Xi Lei Li ◽

Jian Dong ◽

Chun Hui Wang ◽

...

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Pedicle Screw ◽

Pedicle Screws ◽

Loading Conditions ◽

Lateral Bending ◽

Short Segment ◽

Thoracolumbar Burst Fractures ◽

Burst Fractures ◽

Short Segment Fixation

This study was designed to compare the biomechanical effects of three posterior fixations for thoracolumbar burst fractures using the finite element (FE) method. Five T11-L1 FE models, including the intact, the fractured at T12, the monosegment fixated at the level of the fracture, the short-segment fixated with four pedicle screws and the short-segment fixated with five pedicle screws, were created. And four loading conditions (flexion, extension, lateral bending and torsion) were imposed on these models and deformations in these models under different loading conditions were calculated by finite element method. The biomechanical effects of the three different pedicle screw fixations for thoracolumbar burst fractures were compared and analyzed. The results showed that the displacement level in monosegment fixation model was close to that in the intact one. The extension motion was more limited in short-segment fixation models than that in monosegment fixation model. Under the lateral bending condition, the level of the displacements in these models were similar and the peak rotation angles in the three fixation models were close to that in the intact one. The displacements in fractured T12 were increased in monosegment fixation model under all loading conditions. These indicated that the monosegment fixation couldn’t provide desirable stability for the fractured T11-L1 and the short-segment fixation with five pedicle screws was the best selection because of ideal stability and movability.

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A Finite Element Study on the Treatment of Thoracolumbar Fracture with a New Spinal Fixation System

BioMed Research International ◽

10.1155/2021/8872514 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Hui Guo ◽

Jiantao Li ◽

Yuan Gao ◽

Shaobo Nie ◽

Chenliang Quan ◽

...

Keyword(s):

Finite Element ◽

Internal Fixation ◽

Vertebral Body ◽

Spinal Fixation ◽

Short Segment ◽

Element Analysis ◽

The Finite Element Analysis ◽

Model C ◽

Internal Fixation System ◽

Fixation System

Objective. In this study, the mechanical properties of the new spinal fixation system (NSFS) in the treatment of thoracolumbar fractures were evaluated by the finite element analysis method, so as to provide a mechanical theoretical basis for the later biomechanical experiments and clinical experiments. Methods. T12-L2 bone model was constructed to simulate L1 vertebral fracture, and three models of internal fixation systems were established on the basis of universal spinal system (USS): Model A: posterior short-segment fixation including the fractured vertebra (PSFFV); Model B: short-segment pedicle screw fixation (SSPF); Model C: new spinal fixation system (NSFS). After assembling the internal fixation system and fracture model, the finite element analysis was carried out in the ANSYS Workbench 18.0 software, and the stress of nail rod system, fracture vertebral body stress, vertebral body mobility, and vertebral body displacement were recorded in the three models. Results. The peak values of internal fixation stress, vertebral body stress, vertebral body maximum displacement, and vertebral body maximum activity in Model C were slightly smaller than those in Model B. Conclusions. Compared with the traditional internal fixation system, the new spinal internal fixation system may have the mechanical advantage and can provide sufficient mechanical stability for thoracolumbar fractures.

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

Scientific Reports ◽

10.1038/s41598-021-82086-7 ◽

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.

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Design and development of a novel expanding flexible rod device (FRD) for stability in the lumbar spine: A finite-element study

The International Journal of Artificial Organs ◽

10.1177/0391398820917390 ◽

2020 ◽

Vol 43 (12) ◽

pp. 803-810 ◽

Cited By ~ 2

Author(s):

Masud Rana ◽

Sandipan Roy ◽

Palash Biswas ◽

Shishir Kumar Biswas ◽

Jayanta Kumar Biswas

Keyword(s):

Finite Element ◽

Lumbar Spine ◽

Range Of Motion ◽

Pedicle Screw ◽

Axial Rotation ◽

Von Mises Stress ◽

Lateral Bending ◽

Intact Bone ◽

Flexion Extension ◽

Von Mises

The aim of this study is to design a novel expanding flexible rod device, for pedicle screw fixation to provide dynamic stability, based on strength and flexibility. Three-dimensional finite-element models of lumbar spine (L1-S) with flexible rod device on L3-L4-L5 levels are developed. The implant material is taken to be Ti-6Al-4V. The models are simulated under different boundary conditions, and the results are compared with intact model. In natural model, total range of motion under 10 Nm moment were found 66.7°, 24.3° and 13.59°, respectively during flexion–extension, lateral bending and axial rotation. The von Mises stress at intact bone was 4 ± 2 MPa and at bone, adjacent to the screw in the implanted bone, was 6 ± 3 MPa. The von Mises stress of disc of intact bone varied from 0.36 to 2.13 MPa while that of the disc between the fixed vertebra of the fixation model reduced by approximately 10% for flexion and 25% for extension compared to intact model. The von Mises stresses of pedicle screw were 120, 135, 110 and 90 MPa during flexion, extension, lateral bending, and axial rotation, respectively. All the stress values were within the safe limit of the material. Using the flexible rod device, flexibility was significantly increased in flexion/extension but not in axial rotation and lateral bending. The results suggest that dynamic stabilization system with respect to fusion is more effective for homogenizing the range of motion of the spine.

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Biomechanical Study of Cortical Bone Trajectory Screws in Intervertebral Fixation of Lumbar Tuberculosis

10.21203/rs.3.rs-680733/v1 ◽

2021 ◽

Author(s):

Chen-Wei Zhang ◽

Shi-Yuan Shi ◽

De-Xin Hu ◽

Shen-Ping Hu ◽

Jin-Ping Hu ◽

...

Keyword(s):

Lumbar Spine ◽

Internal Fixation ◽

Bone Graft ◽

Lateral Bending ◽

Flexion Extension ◽

Group A ◽

Group B ◽

Group D ◽

State 1 ◽

Screw Group

Abstract BackgroundWe aimed to explore the biomechanical stability and advantages of cortical bone trajectory (CBT) screws in the treatment of lumbar spine tuberculosis and provide biomechanical basis for the choice of clinical fixation methods. Methods16 pig spine specimens (T12-L5) were selected to simulate the lumbar spine(L2-L3) tuberculosis bone destruction model in vitro. The 16 specimens were randomly divided into 4 groups, and short segments (pedicle screws of the diseased vertebrae) were assigned respectively. Fixation (group A), short-segment fixation (group B), fixation with pedicle screw (group C), fixation with CBT screw (group D), 4 specimens in each group , Each specimen in each group was subjected to biomechanical testing in the state of complete specimen (state 1) and L2-3 spinal tuberculosis model bone graft fusion and internal fixation (state 2). Load each specimen on the spine 3D exercise machine, respectively apply moments of 2N·m, 2.5N·m, 1N·m, 3N·m, meanwhile record the movement of the specimens in the four directions of flexion，extension，lateral bending and torsion ROM, compare Simultaneously analyze each group of ROM. ResultsThe ROMs of flexion, extension, lateral bending, and torsion in group A in state 1 and state 3 modes were （8.47±1.76）°、（7.01±1.10）°、（5.03±0.92）°、（4.48±0.41）°and （4.78±0.07）°、（2.91±0.16）°、（2.66±0.09）°、（2.23±0.05）°; the ROMs of flexion, extension, lateral bending and torsion in group B in state 1 and state 3 modes were （7.32±0.75）°、（5.35±0.69）°、（3.44±0.51）°、（3.36±1.02）°and（3.51±0.29）°、（1.74±0.04）°、（1.53±0.31）°、（1.23±0.08）°; The ROMs of flexion, extension, lateral bending, and torsion in group C in state 1 and state 3 modes were （10.01±0.39）°、（9.05±0.25）°、（7.42±1.06）°、（6.92±1.15）°and （7.21±0.17）°、（5.07±0.02）°、（5.12±0.74）°、（4.58±0.01）°; The ROMs of flexion, extension, lateral bending, and torsion in group D in state 1 and state 3 modes were （9.20±1.37）°、（7.38±0.88）°、（6.89±1.22）°、（6.00±0.52）°and （6.06±0.16）°、（3.99±0.02）°、（3.85±0.08）°、（3.47±0.10）°. The ROM value of each fixed mode group under the state of bone graft fusion and internal fixation was lower than that of the intact state, and the difference was statistically significant (P<0.05)，The t values are 4.531, 5.346, 6.008, 4.149; 9.481, 16.181, 11.814, 4.769; 4.349, 8.002, 4.473, 4.800; 5.041, 4.146, 12.232, 10.58. ConclusionCBT screw disease intervertebral fixation can not only provide sufficient mechanical stability, but also provide stronger stability when using the same fixed segment, and The fixed segments are minimized.

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Effect of the Short-Segment Internal Fixation with Intermediate Inclined-Angle polyaxial Screw at the Fractured Vertebra on the Treatment of Denis type B Thoracolumbar Fracture

10.21203/rs.2.22037/v3 ◽

2020 ◽

Author(s):

chengjie xiong ◽

Biwang Huang ◽

Tanjun Wei ◽

Hui Kang ◽

Feng Xu

Keyword(s):

Internal Fixation ◽

Vertebral Body ◽

Body Height ◽

Type B ◽

Short Segment ◽

Average Value ◽

Significant Difference ◽

Surgical Options ◽

Inclined Angle ◽

Duration Of Operation

Abstract Background: Short-segment internal fixation with intermediate straight-forward monoaxial screws (SSIF-SFM) and long-segment internal fixation (LSIF) are the tow major surgical options for thoracolumbar (TL) fracture. However, SS IF-SFM might not provide adequate support to the spine and LSIF is un necessarily extensive. SSIF with intermediate inclined-angle polyxial screw (SSIF-IAP) might offer an alternative solution for the treatment of TL fracture. Methods: A retrospective study was conducted. 69 patients (47 males and 22 females; average 34.5 years) with Denis type B TL fracture who met the criteria for inclusion were enrolled. Sagittal Cobb’s angle (SCA), anterior vertebral body height (AVBH), vertebral body index (VBI) and spinal canal encroachment (SCE) were measured and assessed. Visual analogue scale (VAS) and oswestry disability index (ODI) were also evaluated. Results: The average value of incision length, blood loss, duration of operation and hospital stay in the SSIF–IAP group and SSIF-SFM group were significantly decreased compared with those in the LSIF group. The AVBH and VBI in the SSIF-IAP group and LSIF group were significantly improved than those in the SSIF–SFM group at 6-month and the latest follow-ups (p < 0.05). The correction losses of AVBH and VBI (calculated by the reduction of AVBH and VBI) in the SSIF-IAP group and LSIF group were also significantly decreased compared with those in the SSIF–SFM group at 6-month and the latest follow-ups (P < 0.05). There was no significant difference of SCE among the three groups postoperatively. The VAS and ODI in the SSIF-IAP group and SSIF-SFM group were significantly decreased compared with those in the LSIF group at 6-month and the latest follow-ups (P < 0.05). Conclusion: Both SSIF- IAP and LSIF can improve the biomechanical stability as compared with SSIF -SFM . Moreover, SSIF-IAP was an effective and reliable operative technique for patients with Denis type B TL fracture.

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Effect of the Short-Segment Internal Fixation with Intermediate Inclined-Angle polyaxial Screw at the Fractured Vertebrae on the Treatment of Denis type B Thoracolumbar Fracture

10.21203/rs.2.22037/v2 ◽

2020 ◽

Author(s):

Chengjie Xiong ◽

Biwang Huang ◽

Tanjun Wei ◽

Hui Kang ◽

Feng Xu

Keyword(s):

Internal Fixation ◽

Vertebral Body ◽

Body Height ◽

Type B ◽

Short Segment ◽

Significant Difference ◽

Surgical Options ◽

Cobb’S Angle ◽

Inclined Angle ◽

Duration Of Operation

Abstract Backgroud Short-segment internal fixation with straight-forward monoaxial screw (SSIF-SFM) and long-segment internal fixation (LSIF) are two major surgical options for thoracolumbar (TL) fracture, however, limitations of both surgical options l are obvious. SSIF with inclined-angle polyxial screw (SSIF-IAP) have been developed to take advantage of their benefits and minimize their adverse effects . Methods 69 consecutive patients (47 males and 22 females; average 34.5 years ) who met the criteria for inclusion were enrolled in this study . Sagittal Cobb’s angle (SCA), anterior vertebral body height (AVBH), vertebral body index (VBI) and spinal canal encroachment (SCE) were measured and assessed . Functional recovery Visual Analogue Scale (VAS) and Oswestry disability index (ODI) were also evaluated. Results The value of incision length, mean blood loss, duration of operation and hospital stay in the SSIF–IAP group and SSIF-SFM group were significantly lower than those in the LSIF group. The AVBH and VBI in the SSIF–IA P group and LSIF group were significantly more improved than those in the SSIF–SFM group at 6 months and the latest follow-ups (p < 0.05). The correction losses of AVBH and VBI ( calculated by the reduction of AVBH and VBI) in the SSIF-IAP group and LSIF group were also significantly lower than those in the SSIF–SFM group at 6 months and the latest follow-ups (P<0.05). There was no significant difference of SCE among three groups. The VAS and ODI in the SSIF–IAP group and SSIF-SFM group were significantly lower than those in the LSIF group at 6 months and the latest follow-ups (P<0.05). Conclusion SSIF-IAP can achieve comparable treatment outcomes compared with LSIF, but it was less invasive compared with LSIF . The SSIF–IA was an effective and reliable operative technique for patients with Denis type B TL fracture.

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Inclusion of the fractured level into the construct of short segment fixation in patients with thoracolumbar fractures: clinical and radiological outcome

Egyptian Journal of Neurosurgery ◽

10.1186/s41984-021-00137-7 ◽

2021 ◽

Vol 36 (1) ◽

Author(s):

Ali R. Hamdan ◽

Radwan Nouby Mahmoud ◽

Ahmed G. Tammam ◽

Eslam El-Sayed El-Khateeb

Keyword(s):

Cobb Angle ◽

Vertebral Body ◽

Compression Ratio ◽

Body Height ◽

Surgical Approaches ◽

Thoracolumbar Fractures ◽

Vertebral Body Height ◽

Short Segment ◽

The Mean ◽

Short Segment Fixation

Abstract Background Thoracolumbar fractures represent a widespread injuries that can cause significant disability and strain the healthcare system. Different surgical approaches are described in the literature. This study was conducted to evaluate the fractured level inclusion in short-segment fixation of thoracolumbar junction spine fractures. Results Preoperative neurological deficit was reported in seven patients ranging from ASIA grade C to D. All of these patients improved to grade E by the end of the follow-up period, except for one patient who improved from grade C to D. The mean Oswestry Disability Index was 19.87%. The mean postoperative Cobb angle was 11.77° which significantly improved compared to a preoperative value of 19.37°. There was a significant improvement in the postoperative anterior and posterior vertebral body height compared to the preoperative values. The vertebral body compression ratio significantly improved during the postoperative period to a mean of 84% compared to 76% preoperative. Conclusions There was significant improvement of the postoperative values of the mean Cobb angle, the anterior and the posterior vertebral body height as well as the vertebral body compression ratio compared to the preoperative values.

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