Early osteointegration evaluation of porous Ti6Al4V scaffolds designed based on triply periodic minimal surface models

Abstract

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.

Porous polylactic acid scaffolds for bone regeneration: A study of additively manufactured triply periodic minimal surfaces and their osteogenic potential

“…In a recent in vivo study, Schwarz-based porous graded titanium alloy scaffolds produced by SLM demonstrated good osteointegration in tibial defects in mini pigs, highlighting the promising features of this particular TPMS structure. 63 Overall, these results suggest that multimodal pore size distributions may have a higher interference in cell fate when interconnectivity is guaranteed.…”

3D printed Ti6Al4V bone scaffolds with different pore structure effects on bone ingrowth

“…The matching degree of titanium implants with the host bone is also higher, and the incidence of bone resorption and implant loosening is also reduced [ 3 ]. Porous structures are considered to be an effective method to eliminate elastic modulus mismatches [ 4 – 6 ]. Porous titanium scaffolds with a low elastic modulus can further reduce the stress masking effect, fit well with the host bone, reduce bone absorption, and promote rapid bone formation and integration at the bone-implant interface [ 7 ].…”

High performance hydroxyapatite ceramics and a triply periodic minimum surface structure fabricated by digital light processing 3D printing

“…Recently, Ali et al [13] designed eight different bone scaffolds based on TPMS and proved these architectures have a significant impact on permeability. Li et al [14] successfully prepared the Ti6Al4V scaffold with TPMS of p-cell. With the least surface area, better fluid permeability [14][15][16][17] and improved early osteogenesis, osteointegration resulted from the decreased stress shielding effect [14] were achieved with the p-cell TPMS structure.…”

“…Li et al [14] successfully prepared the Ti6Al4V scaffold with TPMS of p-cell. With the least surface area, better fluid permeability [14][15][16][17] and improved early osteogenesis, osteointegration resulted from the decreased stress shielding effect [14] were achieved with the p-cell TPMS structure. However, there is still no HA bioceramics with such a bio-inspired TPMS structure being studied.…”