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 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.

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

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.

Effects of preoperative obesity and psychiatric comorbidities on minimum clinically important differences for lumbar fusion in grade 1 degenerative spondylolisthesis: analysis from the prospective Quality Outcomes Database registry

2020 ◽  
Vol 33 (5) ◽  
pp. 635-642
Author(s):  
Joseph Laratta ◽  
Leah Y. Carreon ◽  
Avery L. Buchholz ◽  
Andrew Y. Yew ◽  
Erica F. Bisson ◽  
...  
Keyword(s):  
Spinal Fusion ◽  
Preoperative Diagnosis ◽  
Rating Scale ◽  
Lumbar Fusion ◽  
Degenerative Spondylolisthesis ◽  
Leg Pain ◽  
Quality Outcomes ◽  
Medical Comorbidities ◽  
Fusion Procedure ◽  
Patient Reported

OBJECTIVEMedical comorbidities, particularly preoperatively diagnosed anxiety, depression, and obesity, may influence how patients perceive and measure clinical benefit after a surgical intervention. The current study was performed to define and compare the minimum clinically important difference (MCID) thresholds in patients with and without preoperative diagnoses of anxiety or depression and obesity who underwent spinal fusion for grade 1 degenerative spondylolisthesis.METHODSThe Quality Outcomes Database (QOD) was queried for patients who underwent lumbar fusion for grade 1 degenerative spondylolisthesis during the period from January 2014 to August 2017. Collected patient-reported outcomes (PROs) included the Oswestry Disability Index (ODI), health status (EQ-5D), and numeric rating scale (NRS) scores for back pain (NRS-BP) and leg pain (NRS-LP). Both anchor-based and distribution-based methods for MCID calculation were employed.RESULTSOf 462 patients included in the prospective registry who underwent a decompression and fusion procedure, 356 patients (77.1%) had complete baseline and 12-month PRO data and were included in the study. The MCID values for ODI scores did not significantly differ in patients with and those without a preoperative diagnosis of obesity (20.58 and 20.69, respectively). In addition, the MCID values for ODI scores did not differ in patients with and without a preoperative diagnosis of anxiety or depression (24.72 and 22.56, respectively). Similarly, the threshold MCID values for NRS-BP, NRS-LP, and EQ-5D scores were not statistically different between all groups. Based on both anchor-based and distribution-based methods for determination of MCID thresholds, there were no statistically significant differences between all cohorts.CONCLUSIONSMCID thresholds were similar for ODI, EQ-5D, NRS-BP, and NRS-LP in patients with and without preoperative diagnoses of anxiety or depression and obesity undergoing spinal fusion for grade 1 degenerative spondylolisthesis. Preoperative clinical and shared decision-making may be improved by understanding that preoperative medical comorbidities may not affect the way patients experience and assess important clinical changes postoperatively.

scholarly journals Design of Customize Interbody Fusion Cages of Ti64ELI with Gradient Porosity by Selective Laser Melting Process

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 307
Author(s):  
Cheng-Tang Pan ◽  
Che-Hsin Lin ◽  
Ya-Kang Huang ◽  
Jason S. C. Jang ◽  
Hsuan-Kai Lin ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Selective Laser Melting ◽  
Stress Shielding ◽  
Simulation Software ◽  
Surrounding Tissue ◽  
Shielding Effect ◽  
Stress And Strain ◽  
Laser Melting ◽  
Flexion Extension ◽  
Intervertebral Cage

Intervertebral fusion surgery for spinal trauma, degeneration, and deformity correction is a major vertebral reconstruction operation. For most cages, the stiffness of the cage is high enough to cause stress concentration, leading to a stress shielding effect between the vertebral bones and the cages. The stress shielding effect affects the outcome after the reconstruction surgery, easily causing damage and leading to a higher risk of reoperation. A porous structure for the spinal fusion cage can effectively reduce the stiffness to obtain more comparative strength for the surrounding tissue. In this study, an intervertebral cage with a porous gradation structure was designed for Ti64ELI alloy powders bonded by the selective laser melting (SLM) process. The medical imaging software InVesalius and 3D surface reconstruction software Geomagic Studio 12 (Raindrop Geomagic Inc., Morrisville, NC, USA) were utilized to establish the vertebra model, and ANSYS Workbench 16 (Ansys Inc, Canonsburg, PA, USA) simulation software was used to simulate the stress and strain of the motions including vertical body-weighted compression, flexion, extension, lateral bending, and rotation. The intervertebral cage with a hollow cylinder had porosity values of 80–70–60–70–80% (from center to both top side and bottom side) and had porosity values of 60–70–80 (from outside to inside). In addition, according to the contact areas between the vertebras and cages, the shape of the cages can be custom-designed. The cages underwent fatigue tests by following ASTM F2077-17. Then, mechanical property simulations of the cages were conducted for a comparison with the commercially available cages from three companies: Zimmer (Zimmer Biomet Holdings, Inc., Warsaw, IN, USA), Ulrich (Germany), and B. Braun (Germany). The results show that the stress and strain distribution of the cages are consistent with the ones of human bone, and show a uniform stress distribution, which can reduce stress concentration.

Outcomes of contemporary use of rectangular titanium stand-alone cages in anterior cervical discectomy and fusion: Cage subsidence and cervical alignment

2012 ◽  
Vol 19 (12) ◽  
pp. 1673-1678 ◽  
Author(s):  
Toru Yamagata ◽  
Toshihiro Takami ◽  
Takehiro Uda ◽  
Hidetoshi Ikeda ◽  
Takashi Nagata ◽  
...  
Keyword(s):  
Anterior Cervical Discectomy ◽  
Cervical Discectomy ◽  
Cervical Alignment ◽  
Cage Subsidence ◽  
Fusion Cage

scholarly journals Bioactivity of PEEK GRF30 and Ti6Al4V SLM in Simulated Body Fluid and Hank’s Balanced Salt Solution

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2059
Author(s):  
Piotr Prochor ◽  
Żaneta Anna Mierzejewska
Keyword(s):  
Simulated Body Fluid ◽  
Salt Solution ◽  
Body Fluid ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Orthopedic Implant ◽  
New Materials ◽  
Optical Analysis ◽  
Calcium Phosphate Layer ◽  
Cylindrical Samples

In recent years, scientists have defined two main paths for orthopedic implant fabrication: searching for new materials with properties closest to natural bone in order to reduce the stress-shielding effect or creating individually adapted geometry of the implant with the use and Rapid Prototyping methods. Therefore, materials such as PEEK GRF30 and Ti6Al4V selective laser melting (SLM) are of interest. They are defined as materials suitable for implants, however, the knowledge of their bioactivity, a feature which is one of the most desirable properties of biomaterials, is still insufficient. Using Simulated Body Fluid and Hank’s Balanced Salt Solution, the bioactivity of PEEK GRF30 and Ti6Al4V SLM was assessed, as well as commercial Ti6Al4V as a reference material. Ten cylindrical samples of each material were prepared and immersed in solutions per period from 2 to 28 days at 37 °C. Optical analysis of the changes on the examined surfaces suggested that right after 2-day crystals with different morphologies were formed on each material. Further analysis of the chemical composition of the altered surfaces confirmed the formation of a calcium phosphate layer on them, however, the Ca/P ratio was slightly different from 1.67. On the basis of the obtained results, it can be concluded that both PEEK GRF30 and Ti6Al4V SLM are characterized by appropriate—comparable to Ti6Al4V—bioactivity.

The Effects of Bone Microstructure on Subsidence Risk for ALIF, LLIF, PLIF, and TLIF Spine Cages

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Vivek Palepu ◽  
Melvin D. Helgeson ◽  
Michael Molyneaux-Francis ◽  
Srinidhi Nagaraja
Keyword(s):  
Trabecular Bone ◽  
Bone Quality ◽  
Volume Fraction ◽  
Lumbar Fusion ◽  
Lumbar Vertebrae ◽  
Micro Ct ◽  
Cage Subsidence ◽  
Maximum Subsidence ◽  
Trabecular Bone Quality ◽  
The Impact

Several approaches (anterior, posterior, lateral, and transforaminal) are used in lumbar fusion surgery. However, it is unclear whether one of these approaches has the greatest subsidence risk as published clinical rates of cage subsidence vary widely (7–70%). Specifically, there is limited data on how a patient's endplate morphometry and trabecular bone quality influences cage subsidence risk. Therefore, this study compared subsidence (stiffness, maximum force, and work) between anterior (ALIF), lateral (LLIF), posterior (PLIF), and transforaminal (TLIF) lumbar interbody fusion cage designs to understand the impact of endplate and trabecular bone quality on subsidence. Forty-eight lumbar vertebrae were imaged with micro-ct to assess trabecular microarchitecture. micro-ct images of each vertebra were then imported into image processing software to measure endplate thickness (ET) and maximum endplate concavity depth (ECD). Generic ALIF, LLIF, PLIF, and TLIF cages made of polyether ether ketone were implanted on the superior endplates of all vertebrae and subsidence testing was performed. The results indicated that TLIF cages had significantly lower (p < 0.01) subsidence stiffness and maximum subsidence force compared to ALIF and LLIF cages. For all cage groups, trabecular bone volume fraction was better correlated with maximum subsidence force compared to ET and concavity depth. These findings highlight the importance of cage design (e.g., surface area), placement on the endplate, and trabecular bone quality on subsidence. These results may help surgeons during cage selection for lumbar fusion procedures to mitigate adverse events such as cage subsidence.

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