scholarly journals Porous Biodegradable Lumbar Interbody Fusion Cage Design and Fabrication Using Integrated Global-Local Topology Optimization With Laser Sintering

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Heesuk Kang ◽  
Scott J. Hollister ◽  
Frank La Marca ◽  
Paul Park ◽  
Chia-Ying Lin
Keyword(s):  
Topology Optimization ◽  
Lumbar Spine ◽  
Interbody Fusion ◽  
Optimization Technique ◽  
Stress Shielding ◽  
Interconnected Porosity ◽  
Human Lumbar Spine ◽  
Fusion Cage ◽  
Material Layout ◽  
Interbody Fusion Cage

Biodegradable cages have received increasing attention for their use in spinal procedures involving interbody fusion to resolve complications associated with the use of nondegradable cages, such as stress shielding and long-term foreign body reaction. However, the relatively weak initial material strength compared to permanent materials and subsequent reduction due to degradation may be problematic. To design a porous biodegradable interbody fusion cage for a preclinical large animal study that can withstand physiological loads while possessing sufficient interconnected porosity for bony bridging and fusion, we developed a multiscale topology optimization technique. Topology optimization at the macroscopic scale provides optimal structural layout that ensures mechanical strength, while optimally designed microstructures, which replace the macroscopic material layout, ensure maximum permeability. Optimally designed cages were fabricated using solid, freeform fabrication of poly(ε-caprolactone) mixed with hydroxyapatite. Compression tests revealed that the yield strength of optimized fusion cages was two times that of typical human lumbar spine loads. Computational analysis further confirmed the mechanical integrity within the human lumbar spine, although the pore structure locally underwent higher stress than yield stress. This optimization technique may be utilized to balance the complex requirements of load-bearing, stress shielding, and interconnected porosity when using biodegradable materials for fusion cages.

Evaluation of Lumbar Spine Stabilization Using Anterior Interbody Fusion Cage

2002 ◽  
Author(s):  
Robert X. Gao ◽  
Mathew E. Mitchell ◽  
R. Scott Cowan
Keyword(s):  
Lumbar Spine ◽  
Interbody Fusion ◽  
Lumbar Fusion ◽  
Healing Process ◽  
Spine Stabilization ◽  
Anterior Interbody Fusion ◽  
Wide Range ◽  
Flexion Extension ◽  
Fusion Cage ◽  
Interbody Fusion Cage

Spinal surgery uses a wide range of instrumentation devices to provide comfort to the patient, stabilize the spine, and enhance the bony healing process after surgery. In order to improve upon the effectiveness of these devices, the interaction between the spine and the implant devices needs to be studied from both medical and engineering perspectives. This paper investigates the effect of an anterior interbody fusion cage on lumbar spine stabilization, by means of numerical analysis using the finite element technique and experimental testing. Specifically, the relative displacement within an intact L4-L5 motion segment has been simulated and measured, under a range of compression, flexion, extension, torsion, and lateral bending loads. Subsequently, the effect of a single anterior lumbar fusion cage implanted into the segment was simulated and experimentally validated, under similar loading conditions. Comparison between the intact and cage-implanted segments indicated varying stabilizing ability of the fusion cage, which is highly dependent upon the cage position and the type of loading.

scholarly journals A lattice topology optimization of cervical interbody fusion cage and finite element comparison with ZK60 and Ti-6Al-4V cages

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Jun Sun ◽  
Qiuan Wang ◽  
Dazhao Cai ◽  
Wenxiang Gu ◽  
Yiming Ma ◽  
...  
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Topology Optimization ◽  
Bone Graft ◽  
Interbody Fusion ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Cervical Disc ◽  
Significant Difference ◽  
Fusion Cage

Abstract Background In current clinical practice, the most commonly used fusion cage materials are titanium (Ti) alloys. However, titanium alloys are non-degradable and may cause stress shielding. ZK60 is a bio-absorbable implant that can effectively avoid long-term complications, such as stress shielding effects, implant displacement, and foreign body reactions. In this study, we aimed at investigating the biomechanical behavior of the cervical spine after implanting different interbody fusion cages. Methods The finite element (FE) models of anterior cervical disc removal and bone graft fusion (ACDF) with a ZK60 cage and a Ti cage were constructed, respectively. Simulations were performed to evaluate their properties of flexion, extension, lateral bending, and axial rotation of the cervical spine. Moreover, a side-by-side comparison was conducted on the range of motion (ROM), the deformation of cages, the stress in the cages, bone grafts, and cage-end plate interface. Simultaneously, according to the biomechanical analysis results, the microporous structure of the ZK60 cage was improved by the lattice topology optimization technology and validation using static structure. Results The ROMs in the current study were comparable with the results reported in the literature. There was no significant difference in the deformation of the two cages under various conditions. Moreover, the maximum stress occurred at the rear of the cage in all cases. The cage’s and endplate-cage interface’s stress of the ZK60 group was reduced compared with the Ti cage, while the bone graft stress in the ZK60 fusion cage was significantly greater than that in the Ti fusion cage (average 27.70%). We further optimized the cage by filling it with lattice structures, the volume was decreased by 40%, and validation showed more significant biomechanical properties than ZK60 and Ti cages. Conclusion The application of the ZK60 cage can significantly increase the stress stimulation to the bone graft by reducing the stress shielding effect between the two instrumented bodies. We also observed that the stress of the endplate-cage interface decreased as the reduction of the cage’s stiffness, indicating that subsidence is less likely to occur in the cage with lower stiffness. Moreover, we successfully designed a porous cage based on the biomechanical load by lattice optimization.

Interbody Fusion Cage Design Using Integrated Global Layout and Local Microstructure Topology Optimization

Spine ◽  
2004 ◽  
Vol 29 (16) ◽  
pp. 1747-1754 ◽  
Author(s):  
Chia-Ying Lin ◽  
Chun-Ching Hsiao ◽  
Po-Quan Chen ◽  
Scott J. Hollister
Keyword(s):  
Topology Optimization ◽  
Interbody Fusion ◽  
Fusion Cage ◽  
Interbody Fusion Cage

scholarly journals Imaging anatomy and clinical significance of percutaneous endoscopic transforaminal oblique fixation from posterior corner in lumbar spine

2020 ◽  
Author(s):  
Feifei Chen ◽  
Xiaoyang Liu ◽  
Jianmin Sun ◽  
Jun Xin ◽  
Cheng Su ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Interbody Fusion ◽  
Axial Plane ◽  
Minor Trauma ◽  
Lumbar Interbody Fusion ◽  
Significant Difference ◽  
One Stop ◽  
Anatomic Basis ◽  
Fusion Cage ◽  
Interbody Fusion Cage

Abstract BackgroundPercutaneous endoscopic transforaminal lumbar interbody fusion (PE-TLIF) has been widely discussed due to its advantages of less trauma, less bleeding, quick recovery, high safety, and relatively fewer complications, as well as other adverse factors such as incomplete decompression, steep learning curve, low fusion rate, and high radiation risk. It can keep the posterior structure of spine intact to the greatest extent, ensure the stability of spine after surgery, and achieve decompression with minor trauma. However, posterior percutaneous pedicle screws are often needed for fusion and fixation after decompression, and additional posterior trauma, postural changes and anesthesia methods are often required. Interbody fixation and fusion are often independent and not one-stop completion. The authors consider whether the percutaneous spinal endoscopy can be used to achieve complete decompression and fusion under a single minimally invasive channel, while achieving one-stop endoscopic decompression, fusion and fixation. The purpose of this paper is to provide the anatomic feasibility for oblique fixation by measuring the imaging anatomic parameters, especially to provide the anatomic basis for the design of new endoscopic lumbar interbody fusion cage.Methods Sixty volunteers (22 men and 38 women) who underwent lumbar CT scans were collected and sent to the GEAW4.4 workstation. The distances from posterior corner in the lumbar spine to the corresponding targets of the contralateral anterior corner and the included angles between each path line in sagittal and axial plane were measured and analyzed statistically.Results In the medium group, PC path was the shortest, PA path and PB path had little difference (P=0.123), with no statistical significance. In the full-length group, PF path was the shortest, and there was no significant difference between PD path and PE path (P =0.177). PE was the optimal path. The included angles a1, a2, a3, b1, b2, and b3 in sagittal plane and c1, c2 and c3 in axial plane were significantly different (P=0.000), namely, a1 >a2>a3, b1>b2>b3, and c1<c2<c3. Conclusions This study provides anatomic feasibility for percutaneous endoscopic transforaminal oblique fixation from posterior corner in lumbar spine and particularly provides anatomic basis for the design of new endoscopic lumbar interbody fusion cage.

Stress Shielding in Box and Cylinder Cervical Interbody Fusion Cage Designs

Spine ◽  
2005 ◽  
Vol 30 (8) ◽  
pp. 908-914 ◽  
Author(s):  
Devakara R. Epari ◽  
Frank Kandziora ◽  
Georg N. Duda
Keyword(s):  
Interbody Fusion ◽  
Stress Shielding ◽  
Fusion Cage ◽  
Interbody Fusion Cage

scholarly journals Biomechanical comparison of cervical interbody fusion cages with ZK60 and Ti-6Al-4V materials: A finite element analysis and lattice topology optimization

2020 ◽  
Author(s):  
Jun Sun ◽  
Qiuan Wang ◽  
Dazhao Cai ◽  
Wenxiang Gu ◽  
Yiming Ma ◽  
...  
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Topology Optimization ◽  
Bone Graft ◽  
Interbody Fusion ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Cervical Disc ◽  
Significant Difference ◽  
Fusion Cage

Abstract Background In current clinical practice, the most commonly used fusion cage materials are titanium (Ti) alloys. However, titanium alloys are non-degradable and may cause stress shielding. ZK60 is a bio-absorbable implant that can effectively avoid long-term complications, such as stress shielding effects, implant displacement, and foreign body reactions. In this study, we aimed at investigating the biomechanical behavior of the cervical spine after implanting different interbody fusion cages.Methods The finite element (FE) models of anterior cervical disc removal and bone graft fusion (ACDF) with a ZK60 cage and a Ti cage were constructed, respectively. Simulations were performed to evaluate their properties of flexion, extension, lateral bending, and axial rotation of the cervical spine. Moreover, a side-by-side comparison was conducted on the range of motion (ROM), the deformation of cages, the stress in the cages, bone grafts, and cage-end plate interface. Simultaneously, according to the results of biomechanical analysis, the microporous structure of the ZK60 cage was improved by the lattice topology optimization technology and validation using static structure.Results The ROMs in the current study were comparable with the results reported in the literature. There was no significant difference in the deformation of the two cages under various conditions. Moreover, the maximum stress occurred at the rear of the cage in all cases. The cage's and endplate-cage interface's stress of the ZK60 group was reduced compared with the Ti cage, while the bone graft stress in the ZK60 fusion cage was significantly greater than that in the Ti fusion cage (average 27.70%). We further optimized the cage by filling with lattice structures, the volume was decreased by 40%, and validation showed more significant biomechanical properties than ZK60 and Ti cages.Conclusion The application of the ZK60 cage can significantly increase the stress stimulation to the bone graft by reducing the stress shielding effect between the two instrumented bodies. We also observed that the stress of the endplate-cage interface decreased as the reduction of the cage's stiffness, indicating that subsidence is less likely to occur in the cage with lower stiffness. Moreover, we successfully designed a porous cage on the basis of the biomechanical load by lattice optimization.

Biomechanical comparison of transdiscal fixation and posterior fixation with and without transforaminal lumbar interbody fusion in the treatment of L5–S1 lumbosacral joint

2018 ◽  
Vol 232 (4) ◽  
pp. 371-377 ◽  
Author(s):  
Hakan Özalp ◽  
Mustafa Özkaya ◽  
Onur Yaman ◽  
Teyfik Demir
Keyword(s):  
Pedicle Screw ◽  
Axial Compression ◽  
Interbody Fusion ◽  
Screw Fixation ◽  
Transforaminal Lumbar Interbody Fusion ◽  
Pedicle Screw Fixation ◽  
Posterior Fixation ◽  
Lumbar Interbody Fusion ◽  
Fusion Cage ◽  
Interbody Fusion Cage

Transdiscal screw fixation is generally performed in the treatment of high-grade L5–S1 spondylolisthesis. The main thought of the study is that the biomechanical performances of the transdiscal pedicle screw fixation can be identical to standard posterior pedicle screw fixations with or without transforaminal lumbar interbody fusion cage insertion. Lumbosacral portions and pelvises of 45 healthy lambs’ vertebrae were dissected. Animal cadavers were randomly and equally divided into three groups for instrumentation. Three fixation systems, L5–S1 posterior pedicle screw fixation, L5–S1 posterior pedicle screw fixation with transforaminal lumbar interbody fusion cage insertion, and L5–S1 transdiscal pedicle screw fixation, were generated. Axial compression, flexion, and torsion tests were conducted on test samples of each system. In axial compression, L5–S1 transdiscal fixation was less stiff than L5–S1 posterior pedicle screw fixation with transforaminal lumbar interbody fusion cage insertion. There were no significant differences between groups in flexion. Furthermore, L5–S1 posterior fixation was stiffest under torsional loads. When axial compression and flexion loads are taken into consideration, transdiscal fixation can be alternatively used instead of posterior pedicle screw fixation in the treatment of L5–S1 spondylolisthesis because it satisfies enough stability. However, in torsion, posterior fixation is shown as a better option due to its higher stiffness.

Design and Research of Interspinous Lumbar Non-Fusion Device

2010 ◽  
Author(s):  
Lei Li ◽  
Zhaohua Chang ◽  
Xuelian Gu ◽  
Chengli Song
Keyword(s):  
Stress Concentration ◽  
Vertebral Body ◽  
Interbody Fusion ◽  
Lumbar Fusion ◽  
Pedicle Screws ◽  
Adjacent Level ◽  
Flexion Extension ◽  
Fusion Cage ◽  
Adjacent Level Degeneration ◽  
Interbody Fusion Cage

Objective: Long term clinical data showed that lumbar fusion for Lumbar spinal stenosis (LSS) and lumbar disc degeneration (LDD) therapy could change the loads of disc and articular facet and increase the motion of adjacent segments which lead to facet arthropathy and adjacent level degeneration. This study is to design and analyze an interspinous process device (IPD) that could prevent adjacent level degeneration in the LSS and LDD therapy. Method: The IPD was designed based on anatomical parameters measured from 3D CT images directly. The IPD was inserted at the validated finite element model of the mono-segmental L3/L4. The biomechanical performance of a pair of interbody fusion cages and a paired pedicel screws were studied to compare with the IPD. The model was loaded with the upper body weight and muscle forces to simulate five loading cases including standing, compression, flexion, extension, lateral bending and axial rotation. Results: The interbody fusion cage induced serious stress concentration on the surface of vertebral body, has the worst biomechanical performance among the three systems. Pedicle screws and interbody fusion cage could induce stress concentration within vertebral body which leads to vertebral compression fracture or screw loosening. Regarding to disc protection, the IPD had higher percentage to share the load of posterior lumbar structure than the pedicel screws and interbody fusion cage. Conclusion: IPD has the same loads as pedicle screw-rod which suggests it has a good function in the posterior stability. While the IPD had much less influence on vertebral body. Furthermore, IPD could share the load of intervertebral discs and facet joints to maintain the stability of lumbar spine.

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