Applications of X‐ray computed tomography for the evaluation of biomaterial‐mediated bone regeneration in critical‐sized defects

Abstract

Bone as such displays an intrinsic regenerative potential following fracture; however, this capacity is limited with large bone defects that cannot heal spontaneously. The management of critical‐sized bone defects remains a major clinical and socioeconomic need with osteoregenerative biomaterials constantly under development aiming at promoting and enhancing bone healing. X‐ray computed tomography (XCT) has become a standard and essential tool for quantifying structure–function relationships in bone and biomaterials, facilitating the development of novel bone tissue engineering strategies. This paper presents recent advancements in XCT analysis of biomaterial‐mediated bone regeneration. As a noninvasive and nondestructive technique, XCT allows for qualitative and quantitative evaluation of three‐dimensional (3D) scaffolds and biomaterial microarchitecture, bone growth into the scaffold as well as the 3D characterisation of biomaterial degradation and bone regeneration in vitro and in vivo. Furthermore, in combination with in situ mechanical testing and digital volume correlation (DVC), XCT demonstrated its potential to better understand the bone–biomaterial interactions and local mechanics of bone regeneration during the healing process in relation to the regeneration achieved in vivo, which will likely provide valuable knowledge for the development and optimisation of novel osteoregenerative biomaterials. Lay Description Bone, being a dynamically adaptable material, displays excellent regenerative properties following fracture. However, the self‐healing capacity of bone becomes more difficult with large bone defects. Those defects are common and occur in many clinical situations; hence, biomaterials are mostly used to restore both bone structure and function in the defect site. X‐ray computed tomography (XCT) is a powerful tool to evaluate bone regeneration in critical‐sized defects after the implantation of biomaterials, allowing to an improved understanding of the regeneration process following different bone tissue engineering approaches. This paper focuses on recent advancements in XCT analysis to characterise biomaterial‐mediated bone regeneration in critical‐sized defects. XCT supports three‐dimensional (3D) analysis of biomaterials, scaffolds and regenerated bone microarchitecture, as well as bone ingrowth into the scaffold. As a nondestructive technique, XCT allows for a 3D characterisation of biomaterial degradation and bone regeneration over time. In addition, XCT combined with in situ mechanical experiments and digital volume correlation (DVC) provides a 3D evaluation and quantification of bone–biomaterial interactions and deformation mechanisms during the regeneration process. This remains essential for the development and enhancement of novel biomaterials able to produce bone that is comparable with the native tissue they aim to replace.

Fiber-Templated 3D Calcium-Phosphate Scaffolds for Biomedical Applications: The Role of the Thermal Treatment Ambient on Physico-Chemical Properties

“…The three-dimensional (3D) nano-CT reconstructions of the PP samples sintered in air or nitrogen ambient at each Gr amount are presented in Figure 7 . This non-destructive imaging technique allows for the visualization of complex surfaces and internal architectures in terms of spatial heterogeneity of pores and channels throughout the entire product, as compared to the surface-limitation of the frequently used complementary SEM method [ 71 , 72 , 73 ]. In this regard, the pore distribution, size, and geometry and, most importantly, the interconnectivity and tortuosity degree, frame the usefulness of this processing approach for various materials (ceramics included) [ 74 ].…”

“…Therefore, the practicality of Lu fiber use as porogen template is restricted by the concomitant addition of the Gr agent (as mechanical reinforcement agent) up to maximum 0.50 wt.% when the sintering program is conducted in nitrogen ambient. Other than that, the proposed 3D geometries comply with the tortuosity and interconnectivity degree, the pore and channel sizes (around 100–500 μm) [ 5 , 8 , 71 ], and can stand as precursor arrays for future osteogenesis when implemented in various bone healing applications. Since the mechanical features are also of great importance for favorable in vivo performance of the scaffolds, a compromise can be attained with respect to the porosity degree [ 32 ], by modulating the amounts of Lu fibers and/or Gr agents.…”

3D microstructure and critical current properties of ultra-fine-grain Ba(Fe,Co)2As2 bulk superconductors

“…Three-dimensional microstructures are important in many bio-, structural, and functional materials as well. Three-dimensional microstructure observation is carried out by several methods [28][29][30], among which, we have chosen and used the serial sectioning method, which involves the use of scanning electron microscope (SEM) equipped with a focus ion beam (FIB) mill and has a high spatial resolution to extract materials from the micrometer scale to 10-100 nm [28]. We adopted image processing with OpenCV to remove the artifacts that arise because of the complex contrasts in the background, as well as those originating from the material, during the analysis.…”

Exploratory Full-Field Strain Analysis of Regenerated Bone Tissue from Osteoinductive Biomaterials

“…High-resolution X-ray imaging (i.e., micro-computed tomography: microCT) has been extensively used to investigate, in a three-dimensional (3D) manner, the ex vivo implantation site in a non-destructive way [28]. MicroCT imaging allows for a morphological analysis of the regenerated bone tissue [29], as well as the distribution and degree of tissue mineralization, when appropriate densiometric calibration is carried out [30].…”