Custom-made macroporous bioceramic implants based on triply-periodic minimal surfaces for bone defects in load-bearing sites

Abstract

The architectural features of synthetic bone grafts are key parameters for regulating cell functions and tissue formation for the successful repair of bone defects. In this regard, macroporous structures based on triplyperiodic minimal surfaces (TPMS) are considered to have untapped potential. In the present study, custom-made implants based on a gyroid structure, with (GPRC) and without (GP) a cortical-like reinforcement, were specifically designed to fit an intended bone defect in rat femurs. Sintered hydroxyapatite implants were produced using a dedicated additive manufacturing technology and their morphological, physico-chemical and mechanical features were characterized. The implants' integrity and ability to support bone ingrowth were assessed after 4, 6 and 8 weeks of implantation in a 3-mm-long, femoral defect in Lewis rats. GP and GPRC implants were manufactured with comparable macro-to nano-architectures. Cortical-like reinforcement significantly improved implant effective stiffness and resistance to fracture after implantation. This cortical-like reinforcement also concentrated new bone formation in the core of the GPRC implants, without affecting newly formed bone quantity or maturity. This study showed, for the first time, that custom-made TPMS-based bioceramic implants could be produced and successfully implanted in load-bearing sites. Adding a cortical-like reinforcement (GPRC implants) was a relevant solution to improve implant mechanical resistance, and changed osteogenic mechanism compared to the GP implants.

Fractal Design Boosts Extrusion-Based 3D Printing of Bone-Mimicking Radial-Gradient Scaffolds

“…The novel bone-mimicking radial-gradient scaffold models with different geometrical dimensions and radial gradient porosity can be obtained by adjusting the geometric parameters (D Inner , D Outer , and H Scaffold ) and the fractal parameters (D Filament , NCA, and α) (Figure 3(a)). As reported in the previous research, a cortical-like outer shell scaffold has been proven to promote bone regeneration in the central area and prevent fibroblasts from growing into the scaffold [36]. In this work, the inner and outer shell of the 3-iteration fractal-like scaffolds are somewhat similar to cancellous bone and cortical bone, respectively.…”

Copper-Doped Biphasic Calcium Phosphate Powders: Dopant Release, Cytotoxicity and Antibacterial Properties

“…After synthesis, Cu-doped BCP powders were pre-treated by incubation in distilled water for 48 h at a concentration of 250 mg/L in order to remove CaO traces, which were responsible for deleterious pH increases as reported before [ 7 ]. Before biological evaluations, Cu-doped BCP samples were sterilized with dry heat in an oven at 180 °C for 2 h [ 17 , 18 ].…”

Bioactive Ceramic Scaffolds for Bone Tissue Engineering by Powder Bed Selective Laser Processing: A Review

“…Usually, porous bioactive ceramic scaffolds are considered as a potential replacement for the trabecular or cancellous region of the bone. Only a few works have been reported on the fabrication of single-phase bioactive ceramic scaffolds for long bone or load-bearing defects, which simultaneously promote bone regeneration [ 73 , 74 , 75 , 76 , 77 ].…”

“…Metal porous TPMSs can be easily fabricated and are well known for BTE [173][174][175][176][177][178][179]. However, on the other hand, there is very limited progress and development of TPMS bioactive ceramic surfaces, although there are some recent studies in the literature [76,180,181]. More and more efforts are currently dedicated to topology optimization and fundamental material design.…”