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.

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 Transforaminal Lumbar Interbody Fusion With 1 or 2 Cages by Finite-Element Analysis

2013 ◽  
Vol 73 (2) ◽  
pp. ons198-ons205 ◽  
Author(s):  
Hao Xu ◽  
Wen Ju ◽  
Neng Xu ◽  
Xiaojian Zhang ◽  
Xiaodong Zhu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bone Graft ◽  
Interbody Fusion ◽  
Transforaminal Lumbar Interbody Fusion ◽  
Lumbar Interbody Fusion ◽  
Element Analysis ◽  
Single Cage ◽  
Significant Difference ◽  
Flexion Extension

Abstract BACKGROUND: Anterior lumbar interbody fusion and posterior lumbar interbody fusion with 1 cage have been shown to have similar biomechanics compared with the use of 2 cages. However, there have been no reports on the biomechanical differences between using 1 or 2 cages in transforaminal lumbar interbody fusion (TLIF) surgery. OBJECTIVE: To determine the biomechanical differences between the use of 1 or 2 cages in TLIF by finite-element analysis. METHODS: Three validated finite-element models of the L3-L5 lumbar segment were created (intact model and single- and paired-cage TLIF models). To study the biomechanics, a compressive preload of 400 N over 7.5 N-m was applied to the superior surfaces of the L3 vertebral body to simulate flexion, extension, rotation, and lateral bending. RESULTS: There was no significant difference in the range of motion between single-cage and paired-cage TLIF models, < 1° for all loading cases. Cage stress was high in the single-cage TLIF model under all loading conditions. Bone graft stress was high in the single-cage TLIF model. Pedicle screw stress was higher in the single-cage compared with the paired-cage TLIF. CONCLUSION: Single-cage TLIF approximates biomechanical stability and increases the stress of the bone graft. The use of a single cage may simplify the standard TLIF procedure, shorten operative times, decrease cost, and provide satisfactory clinical outcomes. Thus, single-cage TLIF is a useful alternative to traditional 2-cage TLIF.

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.

Biomechanical analysis of combination Ti/PEEK fusion cage designed with topology optimization

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1245-1252
Author(s):  
Hongwei Wang ◽  
Yi Wan ◽  
Xinyu Liu ◽  
Zhanqiang Liu ◽  
Xiao Zhang ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Lumbar Fusion ◽  
Stress Shielding ◽  
Peak Stress ◽  
Biomechanical Analysis ◽  
Shielding Effect ◽  
Peek Cage ◽  
Fusion Procedure ◽  
Cage Subsidence ◽  
Fusion Cage

Fusion cage has been used in lumbar fusion procedure to treat degenerative disc disorders for decades. To address the drawback of Titanium (Ti) and polyetheretherketone (PEEK) cage, a combination Ti/PEEK cage was proposed in present study. Topology optimization was performed to tailor the topological structure of Ti/PEEK cage. The biomechanical performance was comprehensively assessed using finite element method under simulated physiological load conditions. The volume of optimized cage was reduced by 9.7%. The increased volume for bone graft might improve the fusion performance. The lower peak stress was observed on superior and inferior bone endplates of Ti/PEEK cage model, which reduced the risk of cage subsidence. Meanwhile, Ti/PEEK cage effectively reduced the stress shielding effect associated with over-stiffness of Ti cage. In conclusion, the combination Ti/PEEK cage might be a better choice for fusion surgery in relation to Ti or PEEK cage.

scholarly journals Topology Optimization to Reduce the Stress Shielding Effect for Orthopedic Applications

Procedia CIRP ◽  
2017 ◽  
Vol 65 ◽  
pp. 202-206 ◽  
Author(s):  
Abdulsalam A. Al-Tamimi ◽  
Chris Peach ◽  
Paulo Rui Fernandes ◽  
Akos Cseke ◽  
Paulo J.D.S. Bartolo
Keyword(s):  
Topology Optimization ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Orthopedic Applications

Impact of Cervical Artificial Disc Implantation on the Biomechanical Function of Adjacent Segments

2013 ◽  
Vol 748 ◽  
pp. 358-364
Author(s):  
Wen Zhi Zhao ◽  
Bin Li ◽  
Bing Zhi Chen ◽  
Sheng Wei He ◽  
Jin Su ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Intervertebral Disc ◽  
Interbody Fusion ◽  
Element Model ◽  
Cervical Disc ◽  
Adjacent Segment ◽  
Artificial Disc ◽  
Range Of Movement ◽  
Fusion Surgery ◽  
Adjacent Segments

The range of movement(ROM) of adjacent segments and the change of intervertebral disc stress after implanting artificial cervical disc are investigated. The contact problem for bio-modeling is introduced. A normal cervical spine finite element model is proposed. The bone graft and fusion between C5 and C6 and C5/6 artificial disc implantation were simulated. The range of movement on adjacent segment and the change of intervertebral disc’s stress in such two cases are analyzed. Computational results show that the model includes the ligaments, joint capsule and other soft tissue structures, which is real, fine and high accuracy. When the adjacent intervertebral ROM was increased after interbody fusion surgery, the stress of corresponding intervertebral disc was increased obviously and the stress of upper segment of nucleus pulposus and annulus fibrosus were also increased about 70% ,besides the next-bit segments was increased about 40%. There were no differences among cervical spine ROM except extension (p> 0.05) after the implantation of artificial disc, and the stress on adjacent segments was increased less than 10%. The implantation of artificial cervical disc can release the stress on adjacent segments in a certain extent, and resume cervical activities at the same time.

Anwendung eines Bandscheibenersatzimplantats aus einer neuartigen porösen TiO2/Glas-Keramik – Teil 1: Einsatz in der Schafs-Halswirbelsäule und radiologische Verlaufsuntersuchungen / Application of a Stand-Alone Interbody Fusion Cage Based on a Novel Porous TiO2/glass Composite – Part 1: Implantation in the Sheep Cervical Spine and Radiological Evaluation

2004 ◽  
Vol 49 (12) ◽  
Author(s):  
M. C Korinth ◽  
T Hero ◽  
A. H Mahnken ◽  
C Ragoß ◽  
K Scherer
Keyword(s):  
Cervical Spine ◽  
Interbody Fusion ◽  
Porous Ceramic ◽  
In Vivo Models ◽  
Bone Replacement ◽  
Radiological Changes ◽  
Fusion Cage ◽  
Interbody Fusion Cage

AbstractZur Beurteilung des radiologischen, biomechanischen und histologischen Einwachsverhaltens neuer Materialien, Implantate und Cages für die zervikale interkorporelle Fusion, bieten sich Tiermodelle und hier insbesondere das Schafs-Halswirbelsäulenmodell an.In biomechanischen In-vitro-Versuchen an humanen Kadaver-Halswirbelsäulen wurden erste Erfahrungen hinsichtlich Primärstabilität eines Cage aus einer neuartigen, porösen TiOZur entsprechenden In-vivo-Beurteilung fusionierten wir 10 Schafs-Halswirbelsäulen in den Höhen C2/3 und C4/5 jeweils mit PMMA und einem Ecopore-Keramik-Cage und führten nativradiologische, sowie computertomographische Verlaufsuntersuchungen direkt post-operativ und alle 4 Wochen in den folgenden 2 bzw. 4 Monaten durch. Neben der Etablierung des Tiermodells, wurden die radiologischen Veränderungen im Verlauf und die Fusion der operierten Segmente analysiert. Darüberhinaus wurden Messungen der entsprechenden Bandscheibenfachhöhen (DSH) und Intervertebralwinkel (IVA) durchgeführt und verglichen.Nach Einbringen der Implantate in die Bandscheibenfächer nahm zunächst in beiden Gruppen die mittlere Bandscheibenfachhöhe und der Intervertebralwinkel zu (34,8%; 53,9%). In den folgenden Monaten verringerte sich die Bandscheibenfachhöhe nicht signifikant, deutlicher nach Ecopore-Fusion als nach PMMA-Interposition bis auf Werte unterhalb der Ausgangswerte. Ebenso nahm der Intervertebralwinkel im postoperativen Verlauf, deutlicher in der Ecopore-Gruppe als in der PMMA-Gruppe, ab (p < 0,05). Diese Veränderungen im Sinne einer Einsinterung der Implantate, konnte in den radiologischen Verlaufskontrollen morphologisch bestätigt werden. Die radiologisch beurteilbare Fusion, d.h. solide knöcherne Überbauung des operierten Segments, war nach Implantation eines Ecopore-Cage ausgeprägter (83%) als nach PMMA-Interposition (50%) (nicht statistisch signifikant).In diesem ersten Teil unserer In-vivo-Untersuchungen zu dem Einsatz des neuartigen Cage-Materials wurde die Anwendung im Spondylodesemodell der Schafs-Halswirbelsäule aufgezeigt. Es zeigten sich radiologische Unterschiede, in Bezug auf die ausgeprägtere Einsinterung des Ecopore-Cage und die deutlichere, nachweisbare Fusion des mit dem neuen Material operierten Segments. In dem ersten Teil dieser Studie wurden die radiologischen Veränderungen der fusionierten Segmente über mehrere Monate dargestellt und morphologisch analysiert, bevor die biomechanischen Analysen und Vergleiche in einem weiteren Teil präsentiert werden sollen. Animals are becoming more and more common as in vitro and in vivo models for the human spine. Especially the sheep cervical spine is stated to be of good comparability and usefulness in the evaluation of in vivo radiological, biomechanical and histological behaviour of new bone replacement materials, implants and cages for cervical spine interbody fusion.In preceding biomechanical in vitro examination human cervical spine specimens were tested after fusion with either a cubical stand-alone interbody fusion cage manufactured from a new porous TiOImmediately after placement of both implants in the disc spaces the mean DSH and IVA increased (34.8% and 53.9%, respectively). During the following months DSH decreased to a greater extent in the Ecopore-segments than in the PMMA-segments, even to a value below the initial value (p > 0,05). Similarly, the IVA decreased in both groups in the postoperative time lapse, but more distinct in the Ecopore-segments (p < 0,05). These changes in terms of a subsidence of the implants, were confirmed morphologically in the radiological examination in the course. The radiologically evaluated fusion, i.e. bony bridging of the operated segments, was more pronounced after implantation of an Ecopore-cage (83%), than after PMMA interposition (50%), but did not gain statistical significance.In this first in vivo examination of our new porous ceramic bone replacement material we showed its application in the spondylodesis model of the sheep cervical spine. Distinct radiological changes regarding evident subsidence and detectable fusion of the segments, operated on with the new biomaterial, were seen. We demonstrated the radiological changes of the fused segments during several months and analysed them morphologically, before the biomechanical evaluation will be presented in a subsequent publication.

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