scholarly journals Analysis of Mechanical Properties and Permeability of Trabecular-Like Porous Scaffold by Additive Manufacturing

2021 ◽  
Vol 9 ◽  
Author(s):  
Long Chao ◽  
Chen Jiao ◽  
Huixin Liang ◽  
Deqiao Xie ◽  
Lida Shen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bone Repair ◽  
Bone Cells ◽  
Porous Scaffold ◽  
Bone Ingrowth ◽  
Voronoi Tessellation ◽  
Stress Shielding ◽  
Porous Scaffolds ◽  
Porous Structures ◽  
Element Analysis

Human bone cells live in a complex environment, and the biomimetic design of porous structures attached to implants is in high demand. Porous structures based on Voronoi tessellation with biomimetic potential are gradually used in bone repair scaffolds. In this study, the mechanical properties and permeability of trabecular-like porous scaffolds with different porosity levels and average apertures were analyzed. The mechanical properties of bone-implant scaffolds were evaluated using finite element analysis and a mechanical compression experiment, and the permeability was studied by computational fluid dynamics. Finally, the attachment of cells was observed by confocal fluorescence microscope. The results show that the performance of porous structures can be controlled by the initial design of the microstructure and tissue morphology. A good structural design can accurately match the performance of the natural bone. The study of mechanical properties and permeability of the porous structure can help address several problems, including stress shielding and bone ingrowth in existing biomimetic bone structures, and will also promotes cell adhesion, migration, and eventual new bone attachment.

scholarly journals Characterization and in vitro assessment of three-dimensional extrusion Mg-Sr codoped SiO2-complexed porous microhydroxyapatite whisker scaffolds for biomedical engineering

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Chengyong Li ◽  
Tingting Yan ◽  
Zhenkai Lou ◽  
Zhimin Jiang ◽  
Zhi Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Proliferation ◽  
Pore Size ◽  
Osteogenic Differentiation ◽  
Bone Repair ◽  
Porous Scaffold ◽  
Porous Scaffolds ◽  
Sprague Dawley ◽  
Active Elements

Abstract Background Large bone defects have always been a great challenge for orthopedic surgeons. The use of a good bone substitute obtained by bone tissue engineering (BTE) may be an effective treatment method. Artificial hydroxyapatite, a commonly used bone defect filler, is the main inorganic component of bones. Because of its high brittleness, fragility, and lack of osteogenic active elements, its application is limited. Therefore, its fragility should be reduced, its osteogenic activity should be improved, and a more suitable scaffold should be constructed. Methods In this study, a microhydroxyapatite whisker (mHAw) was developed, which was doped with the essential trace active elements Mg2+ and Sr2+ through a low-temperature sintering technique. After being formulated into a slurry, a bionic porous scaffold was manufactured by extrusion molding and freeze drying, and then SiO2 was used to improve the mechanical properties of the scaffold. The hydrophilicity, pore size, surface morphology, surface roughness, mechanical properties, and release rate of the osteogenic elements of the prepared scaffold were detected and analyzed. In in vitro experiments, Sprague–Dawley (SD) rat bone marrow mesenchymal stem cells (rBMSCs) were cultured on the scaffold to evaluate cytotoxicity, cell proliferation, spreading, and osteogenic differentiation. Results Four types of scaffolds were obtained: mHAw-SiO2 (SHA), Mg-doped mHAw-SiO2 (SMHA), Sr-doped mHAw-SiO2 (SSHA), and Mg-Sr codoped mHAw-SiO2 (SMSHA). SHA was the most hydrophilic (WCA 5°), while SMHA was the least (WCA 8°); SMHA had the smallest pore size (247.40 ± 23.66 μm), while SSHA had the largest (286.20 ± 19.04 μm); SHA had the smallest Young's modulus (122.43 ± 28.79 MPa), while SSHA had the largest (188.44 ± 47.89 MPa); and SHA had the smallest compressive strength (1.72 ± 0.29 MPa), while SMHA had the largest (2.47 ± 0.25 MPa). The osteogenic active elements Si, Mg, and Sr were evenly distributed and could be sustainably released from the scaffolds. None of the scaffolds had cytotoxicity. SMSHA had the highest supporting cell proliferation and spreading rate, and its ability to promote osteogenic differentiation of rBMSCs was also the strongest. Conclusions These composite porous scaffolds not only have acceptable physical and chemical properties suitable for BTE but also have higher osteogenic bioactivity and can possibly serve as potential bone repair materials.

Effects of External and Internal Porous Structure Design on Mechanical Properties of Porous Scaffold: A Finite Element Analysis

2020 ◽  
Vol 861 ◽  
pp. 534-539
Author(s):  
Jin Yang Zhang ◽  
Xiao Zhang ◽  
Wei Feng ◽  
Xianshuai Chen
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Performance ◽  
Porous Scaffold ◽  
Peak Stress ◽  
Structure Design ◽  
Porous Scaffolds ◽  
Optimized Design ◽  
Element Analysis

In this paper, bionic designs and 3D modeling of external and internal porous scaffold with different pore sizes and porosities were precisely fabricated using CAD software. The mechanical performance and stress distribution pattern of two porous scaffolds were studied using finite element analysis. The results indicated that the static mechanical performance of external porous scaffold deteriorated with increasing pore size, and large peak stress and total deformation were observed. However, the calculated peak stress of internal porous scaffold was reduced by almost 58.3% to 69.4%, and the elastic modulus remains almost unchanged. The mechanical properties of porous scaffold can be optimized and greatly improved by adding a solid layer with a suitable thickness. The novel optimized design of porous scaffold is conducive to bone tissue repair and reconstruction.

Evaluation of mechanical properties of Ti-25Nb BCC porous cell structure and their association with structure porosity: A combined finite element analysis and analytical approach for orthopedic application

2021 ◽  
pp. 095441192110113
Author(s):  
Soham Chowdhury ◽  
Amit Anand ◽  
Adhish Singh ◽  
Bidyut Pal
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Performance ◽  
Bone Ingrowth ◽  
Structural Parameters ◽  
Cell Structure ◽  
Porous Structures ◽  
Element Analysis ◽  
Functional Relationships

Ti-based alloys have been commonly employed in manufacturing implants for orthopedic applications. Binary Titanium-Niobium (Ti-25Nb) alloy is a promising material for potential applications in orthopedics because of their lower elastic moduli and superior biocompatibility than the conventional Ti-based alloys. Implants with porous structures encourage bone ingrowth and reduce the effect of stress-shielding further. This study is aimed at establishing the relationship between the mechanical performance and structural parameters of porous body-centered-cubic (BCC) structures made up of Ti-25Nb (25% by wt.). Solid models of BCC porous structures were constructed (unit cell size: 2 mm; overall size: 8 × 8 × 8 mm3). Finite element analysis (FEA) of the BCC structures with porosity ranging from 29% to 79% (seven porosities) was conducted under tension, bending, and torsional loads. The Gibson-Ashby model and Exponential regression model were also employed to determine the stiffness of the above porous structures. The functional relationships between effective Young’s modulus, effective yield strength, and porosity generated from both the models were found to match the FEA results well. Results indicated that porosity in the range of 50%−70% can be used to design graded porous stems to mimic the mechanical properties of cortical bone.

scholarly journals Influence of HIP Treatment on Mechanical Properties of Ti6Al4V Scaffolds Prepared by L-PBF Process

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1267 ◽  
Author(s):  
Lili Liu ◽  
Huade Zheng ◽  
Chunlin Deng
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Oxide Layer ◽  
Critical Stress ◽  
Porous Scaffold ◽  
Optical Microscope ◽  
Post Treatment ◽  
Material Surface ◽  
Porous Scaffolds ◽  
Pressure Test

To improve biocompatibility and mechanical compatibility, post-treatment is necessary for porous scaffolds of bone tissue engineering. Hot isostatic pressing (HIP) is introduced into post-treatment of metal implants to enhance their mechanical properties by eliminating residual stress and pores. Additionally, oxide film formed on the material surface can be contributed to improve its biocompatibility. Ti6Al4V porous scaffolds fabricated by laser-powder bed fusion (L-PBF) process is studied in this paper, their mechanical properties are measured by pressure test, and the macroscopic surface morphology and microstructure are observed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). After HIP treatment, an oxide layer of 0.8 μm thickness forms on the surface of Ti6Al4V porous scaffolds and the microstructure of Ti6Al4V transforms from α’ phase to α + β dual-phase, as expected. However, the pressure test results of Ti6Al4V porous scaffolds show a definitely different variation trend of mechanical properties from solid parts, unexpectedly. Concerning Ti6Al4V porous scaffolds, the compression stiffness and critical stress improves clearly using HIP treatment, and the fracture morphology shows obvious brittle fracture. Both the strengthening and brittleness transition of Ti6Al4V porous scaffolds result from the formation of an oxide layer and an oxygen atom diffusion layer. The critical stress of Ti6Al4V porous scaffolds can be calculated by fully considering these two strengthening layers. To obtain a porous scaffold with specific mechanical properties, the effect of post-treatment should be considered during structural design.

Effects of γ-Ray Irradiation on the Properties of Nano-Hydroxyapatite/Polyurethane Composite Porous Scaffolds

2016 ◽  
Vol 852 ◽  
pp. 422-427 ◽  
Author(s):  
Jia Xing Jiang ◽  
Li Mei Li ◽  
Li Li Lin ◽  
Yi Zuo ◽  
Yu Bao Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Irradiation Dose ◽  
Porous Scaffold ◽  
Porous Scaffolds ◽  
Mechanical And Thermal Properties ◽  
Structure And Properties ◽  
Composite Scaffolds ◽  
Remarkable Effect ◽  
Polyurethane Composite ◽  
Γ Ray

To well understand the influence of the sterilization on the properties of biomaterials prior to application is pivotal. The effect of γ-ray irradiation on the mechanical and thermal properties of nanohydroxyapatite/polyurethane (n-HA/PU) porous scaffold for bone tissue engineering was studied in this paper. The mechanical testing, fourier transform infrared spectroscopy and thermal analysis were employed to determine the structure and properties change of these composite scaffolds after γ-ray irradiation with different doses.The results show that thermal stability, and mechanical properties of the composite scaffolds increase after γ-ray irradiation with doses of15 kGy to 25 kGy, especially the irradiation dose of 15kGy which imposed a remarkable effect on these properties. However, a reverse trend is found when the 50kGy irradiation dose was applied.In general, it can be concluded that sterilization using γ-ray irradiation with proper dose has no adverse effect on the properties of n-HA/PU composite scaffolds.

scholarly journals Finite Element Analysis of Porous Ti-6Al-4V Alloy Structures for Biomedical Applications

2021 ◽  
Vol 2070 (1) ◽  
pp. 012224
Author(s):  
N Ganesh ◽  
S Rambabu
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Cortical Bone ◽  
Bone Ingrowth ◽  
Stress Shielding ◽  
Shielding Effect ◽  
Element Analysis ◽  
Human Cortical Bone ◽  
Porous Ti ◽  
Manufacturing Technologies

Abstract In this article, design and finite element simulation of porous Ti-6Al-4V alloy structures was presented. Typically, titanium and titanium alloy implants can be manufactured with required pore size and porosity volume by using powder bed fusion techniques due to advancement in additive manufacturing technologies. However, the mismatch of elastic modulus between human cortical bone and the dense Ti-6Al-4V alloy implant resulted in stress shielding which accelerate the implant failure. The porous implant structures help in reduce the mismatch of elastic modulus between the cortical bone and implant structure and also improve the bone ingrowth. Hence, the present work focuses on design of Ti-6Al-4V alloy porous structures with various porosities ranging from 10% to 70% and simulated to determine the elastic modulus suitable for human cortical bone. The sample with 45% porosity is found to be best suited for replacement of cortical bone with elastic modulus of 74Gpa, preventing stress shielding effect and enhanced chances of bone ingrowth.

scholarly journals Enhanced Crystallinity and Antibacterial of PHBV Scaffolds Incorporated with Zinc Oxide

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Cijun Shuai ◽  
Chen Wang ◽  
Fangwei Qi ◽  
Shuping Peng ◽  
Wenjing Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Zno Nanoparticles ◽  
Bone Repair ◽  
Porous Scaffold ◽  
Selective Laser Sintering ◽  
Polymer Chains ◽  
Relative Crystallinity ◽  
Cell Behaviors ◽  
Positive Results

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has a great potential in bone repair, but unfortunately, the poor mechanical properties limit its further application. In this work, zinc oxide (ZnO) nanoparticles were incorporated into PHBV porous scaffold fabricated by selective laser sintering technique. It was because ZnO nanoparticles could provide nucleating sites for the orderly stacking of polymer chains, thereby enhancing the crystallinity of PHBV. It was well known that the mechanical properties of PHBV scaffold could be enhanced with the increase of crystallinity. More significantly, the released Zn2+ would combine negatively charged cell membranes of bacterial through electrostatic interaction and consequently destructed the protein structure and resulted in the death of bacterial, which was highly desired in reducing the risk of implant infection. Results indicated that the relative crystallinity of scaffold with 3 wt.% ZnO increased remarkably from 38% to 64% compared to pure PHBV scaffold, which effectively enhanced the compression strength and modulus by 56% and 51.5%, respectively. Moreover, the scaffold had a favorable antibacterial activity. Cell culture experiments proved that the scaffold could promote the cell behaviors. The positive results demonstrated the scaffold may serve as a potential replacement in bone repair.

scholarly journals Next Generation Orthopaedic Implants by Additive Manufacturing Using Electron Beam Melting

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Lawrence E. Murr ◽  
Sara M. Gaytan ◽  
Edwin Martinez ◽  
Frank Medina ◽  
Ryan B. Wicker
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Additive Manufacturing ◽  
Electron Beam Melting ◽  
Stress Shielding ◽  
Bone Cell ◽  
Cellular Structures ◽  
Patient Specific ◽  
Porous Structures ◽  
Orthopaedic Implants

This paper presents some examples of knee and hip implant components containing porous structures and fabricated in monolithic forms utilizing electron beam melting (EBM). In addition, utilizing stiffness or relative stiffness versus relative density design plots for open-cellular structures (mesh and foam components) of Ti-6Al-4V and Co-29Cr-6Mo alloy fabricated by EBM, it is demonstrated that stiffness-compatible implants can be fabricated for optimal stress shielding for bone regimes as well as bone cell ingrowth. Implications for the fabrication of patient-specific, monolithic, multifunctional orthopaedic implants using EBM are described along with microstructures and mechanical properties characteristic of both Ti-6Al-4V and Co-29Cr-6Mo alloy prototypes, including both solid and open-cellular prototypes manufactured by additive manufacturing (AM) using EBM.

scholarly journals Investigation of Mechanical and Biological Properties of FDM 3D-Printed PLA Scaffolds With Radial Gradient Porosity for Tissue Engineering

2021 ◽  
Author(s):  
Meltem Eryildiz
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Fused Deposition Modeling ◽  
Bone Ingrowth ◽  
Biological Properties ◽  
Porous Scaffolds ◽  
Radial Gradient ◽  
Fused Deposition ◽  
Novel Approach

Abstract Scaffolds with gradient porosity have become very promising candidates for tissue engineering and bone implants because of the combination of better mechanical and biological requirements. In this paper, a novel approach is proposed to design bone scaffolds with gradient porosity similar to the structure of cortical and spongy (cancellous) bones. The radial gradient PLA scaffolds were designed to consist of three different regions with the gyroid infill and, fabricated by Fused deposition modeling (FDM). The biological and mechanical properties of the scaffolds were investigated in vitro. Dense scaffold (G100) had improved mechanical properties but showed decreased bone ingrowth properties. In addition, porous scaffolds provided enhanced biological properties but decreased in mechanical strength (G40-G20). The scaffolds with radial gradient porosity (G100-40-20) gave highest cell proliferation. Because, mean pore size is an important aspect of scaffolds for mimicking bone.

scholarly journals 3D Printing of Macro Porous Sol-Gel Derived Bioactive Glass Scaffolds and Assessment of Biological Response

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5946
Author(s):  
Ricardo Bento ◽  
Anuraag Gaddam ◽  
Párástu Oskoei ◽  
Helena Oliveira ◽  
José M. F. Ferreira
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Bioactive Glass ◽  
Bone Ingrowth ◽  
Sol Gel ◽  
Biological Response ◽  
Treatment Temperature ◽  
Bone Tissue Regeneration ◽  
Porous Scaffolds ◽  
Potential Game

3D printing emerged as a potential game-changer in the field of biomedical engineering. Robocasting in particular has shown excellent capability to produce custom-sized porous scaffolds from pastes with suitable viscoelastic properties. The materials and respective processing methods developed so far still need further improvements in order to obtain completely satisfactory scaffolds capable of providing both the biological and mechanical properties required for successful and comprehensive bone tissue regeneration. This work reports on the sol-gel synthesis of an alkali-free bioactive glass and on its characterization and processing ability towards the fabrication of porous scaffolds by robocasting. A two-fold increase in milling efficiency was achieved by suitably adjusting the milling procedures. The heat treatment temperature exerted a profound effect on the surface area of mesoporous powders. Robocasting inks containing 35 vol.% solids were prepared, and their flow properties were characterized by rheological tests. A script capable of preparing customizable CAD scaffold geometries was developed. The printing process was adjusted to increase the technique’s resolution. The mechanical properties of the scaffolds were assessed through compressive strength tests. The biomineralization ability and the biological performance were assessed by immersing the samples in simulated body fluid (SBF) and through MTT assays, respectively. The overall results demonstrated that scaffolds with macro porous features suitable for bone ingrowth (pore sizes of ~340 mm after sintering, and a porosity fraction of ~70%) in non-load-bearing applications could be successfully fabricated by 3D printing from the bioactive glass inks. Moreover, the scaffolds exhibited good biomineralization activity and good biocompatibility with human keratinocytes, suggesting they are safe and thus suited for the intended biomedical applications.

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