Abstract:Background Conventional core decompression (CD) is a well-known procedure for treatment of avascular necrosis of the femoral head. Weight bearing is usually restricted in the early postoperative weeks to avoid the risk of fracture. Theoretically, a properly positioned implantation of the new tantalum rod after reaming of the necrotic area has the advantages of decompression, supports the remaining bone to avoid collapse, lowers the risk of subtrochanteric fracture, and allows for early weight bearing. The obje… Show more
“…More importantly, the gradually changed pore size can contain the optimal size and porosity for bone ingrowth. For some early implantation failure in dental and orthopaedic applications, the implants with poor stability and lack of complete bone ingrowth are high-risk factors [7], [8]. The space in the scaffolds has a momentous role in osteogenesis and vascularisation, which can lead to biological fixation at an early stage of bone healing [43].Figure 9The internal stress transmission of (A) D1, (B) D2, (C) D3 and (D) a homogeneous porous scaffold.…”
Section: Discussionmentioning
confidence: 99%
“…As a result, the bone tissues can become atrophic and gradually lose the load-bearing capability, which may cause osteoporosis and fracture around the implants [6]. In addition, the bone resorption around the implants can lead to an unstable interface between bone and implants, which can be regarded as the high risk for early implantation failure [7], [8]. To address these issues and to construct a long-lasting implant, the porous design is introduced to mimic the elasticity modulus and yield the strength of the nature bone [9].…”
BackgroundThe graded porous structures were designed using triply periodic minimal surfaces models to mimic the biomechanical properties of bone. The mechanical properties and bone formation ability were evaluated to explore the feasibility of the design method in bone tissue engineering.MethodsThe scaffolds were designed using a P-surface with different pore sizes. All materials were fabricated using 3D printing technology and the mechanical properties were tested by an electronic universal testing device. The biomechanical properties were then analyzed by finite element method, while the ontogenesis of the material in vivo was examined by implanting the scaffolds for five weeks in pigs.ResultsAccording to the obtained results, the pore size ranged between 100 μm to about 700 μm and porosity were around 49.54%. The graded porous architectures can decrease the stiffness of implants and reduce the stress shielding effect. In addition, these porous structures can stimulate bone ingrowth and achieve a stable interface between implants and surrounding bone tissues after 5 weeks' implantation. The micro-CT results also demonstrated the obviously bone formation around all the porous structures.ConclusionTo sum up, the triply periodic minimal surfaces based graded porous structure is effective in decreasing the stress shielding effect, promoting early osteogenesis and osteointegration. This is the first research to explore the effect of this kind of porous structures on bone formation in vivo where the obtained results supported the previous theoretical research on the application potential in bone tissue engineering.The translational potential of this articlePorous architecture designed using triply periodic minimal surface models can achieve gradually changed pore size and appropriate porosity for bone regeneration. This kind of structure can mimic the Young’s modulus of natural bone tissue, improve the stress transmission capability and dismiss the stress shielding effect. It also can stimulate the early bone integration in vivo and enhance the binding force between bone and implants, which may bring a new design method for orthopaedic implants and their surface structure.
“…More importantly, the gradually changed pore size can contain the optimal size and porosity for bone ingrowth. For some early implantation failure in dental and orthopaedic applications, the implants with poor stability and lack of complete bone ingrowth are high-risk factors [7], [8]. The space in the scaffolds has a momentous role in osteogenesis and vascularisation, which can lead to biological fixation at an early stage of bone healing [43].Figure 9The internal stress transmission of (A) D1, (B) D2, (C) D3 and (D) a homogeneous porous scaffold.…”
Section: Discussionmentioning
confidence: 99%
“…As a result, the bone tissues can become atrophic and gradually lose the load-bearing capability, which may cause osteoporosis and fracture around the implants [6]. In addition, the bone resorption around the implants can lead to an unstable interface between bone and implants, which can be regarded as the high risk for early implantation failure [7], [8]. To address these issues and to construct a long-lasting implant, the porous design is introduced to mimic the elasticity modulus and yield the strength of the nature bone [9].…”
BackgroundThe graded porous structures were designed using triply periodic minimal surfaces models to mimic the biomechanical properties of bone. The mechanical properties and bone formation ability were evaluated to explore the feasibility of the design method in bone tissue engineering.MethodsThe scaffolds were designed using a P-surface with different pore sizes. All materials were fabricated using 3D printing technology and the mechanical properties were tested by an electronic universal testing device. The biomechanical properties were then analyzed by finite element method, while the ontogenesis of the material in vivo was examined by implanting the scaffolds for five weeks in pigs.ResultsAccording to the obtained results, the pore size ranged between 100 μm to about 700 μm and porosity were around 49.54%. The graded porous architectures can decrease the stiffness of implants and reduce the stress shielding effect. In addition, these porous structures can stimulate bone ingrowth and achieve a stable interface between implants and surrounding bone tissues after 5 weeks' implantation. The micro-CT results also demonstrated the obviously bone formation around all the porous structures.ConclusionTo sum up, the triply periodic minimal surfaces based graded porous structure is effective in decreasing the stress shielding effect, promoting early osteogenesis and osteointegration. This is the first research to explore the effect of this kind of porous structures on bone formation in vivo where the obtained results supported the previous theoretical research on the application potential in bone tissue engineering.The translational potential of this articlePorous architecture designed using triply periodic minimal surface models can achieve gradually changed pore size and appropriate porosity for bone regeneration. This kind of structure can mimic the Young’s modulus of natural bone tissue, improve the stress transmission capability and dismiss the stress shielding effect. It also can stimulate the early bone integration in vivo and enhance the binding force between bone and implants, which may bring a new design method for orthopaedic implants and their surface structure.
“…The results of the in vivo study have confirmed this point of view. For some early implantation failure in dental and orthopedics, the implants with poor stability and lack of complete bone ingrowth are high risk factors (58,59). The histological evaluations demonstrated that new bone tissues were evenly distributed inside and around the scaffolds, and the PDA coating titanium scaffolds can acquire superior bone ingrowth in a short time-period.…”
Background: Titanium implants are widely used in orthopedic and dental for more than 30 years. Its stable physicochemical properties and mechanical strength are indeed appropriate for implantation. However, the Bioinertia oxidized layer and higher elastic modulus often lead to the early implantation failure. Methods: In this study, we proposed a simple design of porous structure to minimize the disparity between scaffold and natural bone tissue, and introduced a one-step reaction to form a polydopamine (PDA) layer on the surface of titanium for the purpose of improving osteogenesis as well. The porous scaffolds with pore size of 400 μm and porosity of 44.66% were made by additive manufacturing. The cell behavior was tested by seeding MC3T3-E1 cells on Ti6Al4V films for 15 days. The biomechanical properties were then analyzed by finite element (FE) method and the in vivo osteogenesis effect was accordingly evaluated by implanting the scaffolds for 5 weeks in rabbits. Results: According to the achieved results, it was revealed that the immersion for 40 min with dopamine could significantly improve the cell adhesion. The proposed method for design of porous structure can avoid the stress shielding effect and bone growth inside the PDA coating scaffolds, which were observed at the early stage of bone healing process. Conclusions: It can be concluded that the proposed PDA coating method is effective in promoting early osteogenesis, as well as being easy to operate, and can be helpful in the future clinical application of titanium implants.
“…Во избежание резорбции окружающей костной ткани имплантат должен иметь пористую структуру [5,6], способствующую миграции и пролиферации остеобластов и мезенхимальных стволовых клеток, транспортировке питательных веществ и кислорода, необходимых для васкуляризации во время роста костной ткани [7,8]. По данным литературы, размер пор и структура также влияют и на остеокондукцию [9,10].…”
Introduction. Additive technologies make it possible to create implants to replace bone defects. Determining the optimal parameters of a porous structure remains an urgent issue. The experimental research aimed to study the biocompatibility of implants made of titanium alloy with different pore diameters. Materials and methods. The study was carried out in two stages. The first stage included an in vitro study carried out on test cultures of diploid human fibroblasts to assess the cytotoxicity of the titanium alloy, from which samples were made for the second stage in vivo. The in vivo study was performed on three groups of rabbits (n=18), which received samples of the developed implants. The average age of subjects was 7±1 months, the weight being 4.675±258 g. All samples were 4 mm in diameter and 6 mm high. In group 1, the pore size was 100 μm; in group 2 – 200 μm; and in group 3 – 400 μm; the porosity was 55%, 62%, and 70%, respectively. The animals were sacrificed on day 90 after placement of the samples. Histological, morphological, and electron microscopic studies were performed to assess the osseointegrative properties of the implants. Results. In the in vitro study, we detected no toxic effects of the material on the test culture. In the in vivo study, the histological analysis did not reveal inflammation in peri-implant tissues in any of the groups. The morphological study showed a newly formed tissue in the area of the formed defect which consisted of young bone trabeculae with osteoblasts located on their surface. In group 3, we found the greatest prevalence of mature bone trabeculae. The samples with a 400-μm pore diameter revealed the largest area of filling the implant with newly formed bone tissue. Conclusion. Samples with a pore diameter of 400 μm have the highest osteointegrative properties. Keywords: osteointegration, biocompatibility, titanium implants, additive technologies, 3D-printing
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