3D-printed porous Ti6Al4V scaffolds for long bone repair in animal models: a systematic review

Abstract

Background Titanium and its alloys have been widely employed for bone tissue repair and implant manufacturing. The rapid development of three-dimensional (3D) printing technology has allowed fabrication of porous titanium scaffolds with controllable microstructures, which is considered to be an effective method for promoting rapid bone formation and decreasing bone absorption. The purpose of this systematic review was to evaluate the osteogenic potential of 3D-printed porous Ti6Al4V (Ti64) scaffold for repairing long bone defects in animal models and to investigate the influential factors that might affect its osteogenic capacity. Methods Electronic literature search was conducted in the following databases: PubMed, Web of Science, and Embase up to September 2021. The SYRCLE's tool and the modified CAMARADES list were used to assess the risk of bias and methodological quality, respectively. Due to heterogeneity of the selected studies in relation to protocol and outcomes evaluated, a meta-analysis could not be performed. Results The initial search revealed 5858 studies. Only 46 animal studies were found to be eligible based on the inclusion criteria. Rabbit was the most commonly utilized animal model. A pore size of around 500–600 µm and porosity of 60–70% were found to be the most ideal parameters for designing the Ti64 scaffold, where both dodecahedron and diamond pores optimally promoted osteogenesis. Histological analysis of the scaffold in a rabbit model revealed that the maximum bone area fraction reached 59.3 ± 8.1% at weeks 8–10. Based on micro-CT assessment, the maximum bone volume fraction was found to be 34.0 ± 6.0% at weeks 12. Conclusions Ti64 scaffold might act as a promising medium for providing sufficient mechanical support and a stable environment for new bone formation in long bone defects. Trail registration The study protocol was registered in the PROSPERO database under the number CRD42020194100.

Influence of different fixation modes on biomechanical conduction of 3D printed prostheses for treating critical diaphyseal defects of lower limbs: A finite element study

“…The main requirements to be met for the application of 3D printed titanium alloy prosthesis to repair diaphyseal defects include: (1) the contour and shape of a prosthesis should match the bone defect, which can be achieved by the mirror symmetry effect as shown in Figure 1 ; (2) the mechanical strength of a prosthesis can meet the requirements of bone biological stress transmission, which can be adjusted by changing the pore size and porosity of the prosthesis ( 24 , 25 ); (3) appropriate fixation mode, which should guarantee initial and long-term stability, does not affect new bone regeneration, and does not produce stress shielding; and (4) the stress shared by the internal fixation implants should not cause itself to loosen and break, ensuring the safety of lower extremity weight-bearing and functional exercise.…”

Continuously released Zn2+ in 3D-printed PLGA/β-TCP/Zn scaffolds for bone defect repair by improving osteoinductive and anti-inflammatory properties

“…According to previous studies, pore size of 500–600 μm and porosity of 60–70% in 3D printed Ti6Al4V scaffolds are optimal design parameters for promoting osteogenesis [ 32 ]. Therefore, to ensure that the mechanical properties of the scaffold were sufficient, the scaffold structure was designed according to the following structural parameters: pore size = 500 μm, porosity = 60%.…”

Evolution from Bioinert to Bioresorbable: In Vivo Comparative Study of Additively Manufactured Metal Bone Scaffolds

“…Consequently, research has delved into the potential of additively manufactured Ti scaffolds for bone regeneration applications. [12][13][14][15] The porous structure obtained through additive manufacturing techniques lowers the elastic moduli of Ti-based materials, and numerous clinical trials have showcased the successful use of these scaffolds in calvaria and tibia defects. [16][17][18][19] Despite these promising preclinical findings, Ti-based scaffolds possess non-biodegradable and bio-inert properties, causing their material, structure, and biomechanics to remain largely unaltered long after implantation.…”