A New Design of Porosity Gradient Ti-6Al-4V Encapsulated Hydroxyapatite Dual Materials Composite Scaffold for Bone Defects

Abstract

The tibia of New Zealand White rabbits was used as a model of critical bone defects to investigate a new design of composite scaffold for bone defects composed of dual materials. The all-in-one design of a titanium alloy (Ti-6Al-4V) scaffold comprised the structure of a bone plate and gradient porosity cage. Hydroxyapatite (HAp), a biodegradable material, was encapsulated in the center of the scaffold. The gradient pore structure was designed with 70%-65%-60%-55%-50% porosity, since the stresses could be distributed more uniformly when the all-in-one scaffold was placed on the bone contact surface. By covering the center of the scaffold with a low strength of HAp to contact the relatively low strength of bone marrow tissues, the excessive stiffness of the Ti-6Al-4V can be effectively reduced and further diminish the incidence of the stress shielding effect. The simulation results show that the optimized composite scaffold for the 3D model of tibia had a maximum stress value of 27.862 MPa and a maximum strain of 0.065%. The scaffold prepared by selective laser melting was annealed and found that the Young’s coefficient increased from 126.44 GPa to 131.46 GPa, the hardness increased from 3.9 GPa to 4.12 GPa, and the strain decreased from 2.27% to 1.13%. The result demonstrates that the removal of residual stress can lead to a more stable structural strength, which can be used as a reference for the design of future clinical tibial defect repair scaffolds.

“Metal-bone” scaffold for accelerated peri-implant endosseous healing

“…This finding aligns with previous research, which also demonstrated that Ti6Al4V porous scaffolds exhibit excellent bone integration effects, especially with pore sizes in the range of 600–900 μm and a porosity of 70% ( Taniguchi et al, 2016 ). The appropriate pore size facilitates the ingrowth of new bone tissue and nutrient supply, while a 70% porosity rate closely resembles the porosity rate of physiological bone trabeculae, making it a biomimetic physiological condition that achieves optimal bone integration effects ( Pan et al, 2021 ).…”

Advancements in gradient bone scaffolds: enhancing bone regeneration in the treatment of various bone disorders

“…This study can be said to provide theoretical support and reference for femoral bone repair in terms of structure. On the other hand, Pan et al [51] using the New Zealand white rabbit tibia as a critical bone defect model, studied the design of a novel composite scaffold composed of two materials. The integrated design of the titanium alloy (Ti-6Al-4V) scaffold includes the structure of the bone plate and the gradient pore cage.…”

Design, Manufacture, and Characterization of a Critical-Sized Gradient Porosity Dual-Material Tibial Defect Scaffold

“…This mitigates the risk of post-operative migration and significantly reduces the likelihood of complications. Our team has conducted previous studies on bone defects [32,33].…”