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

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

Bone scaffolds are widely employed for treating various bone disorders, including defects, fractures, and accidents. Gradient bone scaffolds present a promising approach by incorporating gradients in shape, porosity, density, and other properties, mimicking the natural human body structure. This design offers several advantages over traditional scaffolds. A key advantage is the enhanced matching of human tissue properties, facilitating cell adhesion and migration. Furthermore, the gradient structure fosters a smooth transition between scaffold and surrounding tissue, minimizing the risk of inflammation or rejection. Mechanical stability is also improved, providing better support for bone regeneration. Additionally, gradient bone scaffolds can integrate drug delivery systems, enabling controlled release of drugs or growth factors to promote specific cellular activities during the healing process. This comprehensive review examines the design aspects of gradient bone scaffolds, encompassing structure and drug delivery capabilities. By optimizing the scaffold's inherent advantages through gradient design, bone regeneration outcomes can be improved. The insights presented in this article contribute to the academic understanding of gradient bone scaffolds and their applications in bone tissue engineering.

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

This study proposed a composite tibia defect scaffold with radial gradient porosity, utilizing finite element analysis to assess stress in the tibial region with significant critical-sized defects. Simulations for scaffolds with different porosities were conducted, designing an optimal tibia defect scaffold with radial gradient porosity for repairing and replacing critical bone defects. Radial gradient porosity scaffolds resulted in a more uniform stress distribution, reducing titanium alloy stiffness and alleviating stress shielding effects. The scaffold was manufactured using selective laser melting (SLM) technology with stress relief annealing to simplify porous structure fabrication. The study used New Zealand white rabbits' tibia defect sites as simulation parameters, reconstructing the 3D model and implanting the composite scaffold. Finite element analysis in ANSYS-Workbench simulated forces under high-activity conditions, analyzing stress distribution and strain. In the simulation, the titanium alloy scaffold bore a maximum stress of 122.8626 MPa, while the centrally encapsulated HAp material delivered 27.92 MPa. The design demonstrated superior structural strength, thereby reducing stress concentration. The scaffold was manufactured using SLM, and the uniform design method was used to determine a collection of optimum annealing parameters. Nanoindentation and compression tests were used to determine the influence of annealing on the elastic modulus, hardness, and strain energy of the scaffold.

"Metal-bone" scaffold for accelerated peri-implant endosseous healing

Restoring bone defects caused by conditions such as tumors, trauma, or inflammation is a significant clinical challenge. Currently, there is a need for the development of bone tissue engineering scaffolds that meet clinical standards to promote bone regeneration in these defects. In this study, we combined the porous Ti6Al4V scaffold in bone tissue engineering with advanced bone grafting techniques to create a novel "metal-bone" scaffold for enhanced bone regeneration. Utilizing 3D printing technology, we fabricated a porous Ti6Al4V scaffold with an average pore size of 789 ± 22.69 μm. The characterization and biocompatibility of the scaffold were validated through in vitro experiments. Subsequently, the scaffold was implanted into the distal femurs of experimental animals, removed after 3 months, and transformed into a "metal-bone" scaffold. When this "metal-bone" scaffold was re-implanted into bone defects in the animals, the results demonstrated that, in comparison to a plain porous Ti6Al4V scaffold, the scaffold containing bone tissue achieved accelerated early-stage bone regeneration. The experimental group exhibited more bone tissue generation in the early stages at the defect site, resulting in superior bone integration. In conclusion, the "metal-bone" scaffold, containing bone tissue, proves to be an effective bone-promoting scaffold with promising clinical applications.