3D Biomimetic Porous Titanium (Ti6Al4V ELI) Scaffolds for Large Bone Critical Defect Reconstruction: An Experimental Study in Sheep

Abstract

The main goal in the treatment of large bone defects is to guarantee a rapid loading of the affected limb. In this paper, the authors proposed a new reconstructive technique that proved to be suitable to reach this purpose through the use of a custom-made biomimetic porous titanium scaffold. An in vivo study was undertaken where a complete critical defect was experimentally created in the diaphysis of the right tibia of twelve sheep and replaced with a five-centimeter porous scaffold of electron beam melting (EBM)-sintered titanium alloy (EBM group n = 6) or a porous hydroxyapatite scaffold (CONTROL group, n = 6). After surgery, the sheep were allowed to move freely in the barns. The outcome was monitored for up to 12 months by periodical X-ray and clinical examination. All animals in the CONTROL group were euthanized for humane reasons within the first month after surgery due to the onset of plate bending due to mechanical overload. Nine months after surgery, X-ray imaging showed the complete integration of the titanium implant in the tibia diaphysis and remodeling of the periosteal callus, with a well-defined cortical bone. At 12 months, sheep were euthanized, and the tibia were harvested and subjected to histological analysis. This showed bone tissue formations with bone trabeculae bridging titanium trabeculae, evidencing an optimal tissue-metal interaction. Our results show that EBM-sintered titanium devices, if used to repair critical bone defects in a large animal model, can guarantee immediate body weight-bearing, a rapid functional recovery, and a good osseointegration. The porous hydroxyapatite scaffolds proved to be not suitable in this model of large bone defect due to their known poor mechanical properties.

Convergence of scaffold-guided bone regeneration and RIA bone grafting for the treatment of a critical-sized bone defect of the femoral shaft

“…In the past decades, scaffold-guided bone tissue engineering has emerged as a promising strategy to overcome the shortcomings associated with established techniques [ 17 – 19 ]. The ability of 3D-printing allows the design and manufacture of osteoconductive scaffolds which are optimized for clinical translation in terms of pore size, layering, and degradation [ 20 ].…”

Convergence of Scaffold Guided Bone Regeneration and RIA Bone Grafting for the Treatment of a Critical-Sized Bone Defect of the Femoral Shaft

“…In the past decades, scaffold guided bone tissue engineering has emerged as a promising strategy to overcome the shortcomings associated with established techniques [17][18][19]. The ability of 3D-printing allows the design and manufacture of osteoconductive scaffolds which are optimized for clinical translation in terms of pore size, layering, and degradation [20].…”

Tissue Integration and Biological Cellular Response of SLM-Manufactured Titanium Scaffolds

“…The duration of the follow-up period of the in vivo studies varies from 8 weeks to 1 year (Figure 3), while the in vitro studies vary from 5 to 52 days (Figure 4). From 29 studies, 15 had an in vitro design [17,18,22,30,32,[84][85][86][87][88][89][90][91][92][93][94], 9 in vivo [95][96][97][98][99][100][101][102], and 5 studied both in vitro and in vivo methods [32,[103][104][105][106] (Figure 2). The duration of the follow-up period of the in vivo studies varies from 8 weeks to 1 year (Figure 3), while the in vitro studies vary from 5 to 52 days (Figure 4).…”

“…Besides hip reconstruction, SLM Ti scaffolds find their utility in vertebral reconstruction; Wang et al produced a Tantalum (Ta)-coated porous T 6 Al 4 V scaffold, which proved to be superior to other coating materials, due to its high strength, corrosion resistance in acidic environment and does not change in weight or surface roughness, and heat resistance [29]. Crovace et al conducted an animal study, in which a 5-cm bone fragment on tibial diaphysis of ovines (N = 12) was replaced by an Electron Beam Melting or porous HA Ti scaffold, with a mean pore dimension of 1.5 mm length × 2.4 mm width [30]. The healing of the tibial bone (after 12 months) resulted in new cortical bone that bridged the defect and continued with lamellar bone in apposition to the titanium pores of the scaffolds.…”

“…Cont. Cont.From 29 studies, 15 had an in vitro design[17,18,22,30,32,[84][85][86][87][88][89][90][91][92][93][94], 9 in vivo…”