Additive manufacturing of biomorphic scaffolds for bone tissue engineering

Fabrizia Caiazzo,Vittorio Alfieri,Brahim David Bujazha

doi:10.1007/s00170-021-06773-5

Fabrizia Caiazzo, Vittorio Alfieri + Show 1 more

Open Access

https://doi.org/10.1007/s00170-021-06773-5

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Abstract

Bone tissue engineering has evolved owing to new opportunities of deep customisation offered by additive manufacturing technologies. Gyroid structures, which have been widely used for energy absorption or chemical catalysis, are now being employed as biomorphic structures as well to provide customer-oriented scaffolds for missing or injured bones. Unfortunately, limited data in terms of manufacturability and mechanical properties are available in the literature to support a wide application scope, because the bone to match is strongly dependent on the individual. Therefore, the study aimed at addressing this lack of knowledge, assessing the manufacturability of metal gyroids and further developing the correlation of the structural response with the designed geometry, so to allow the designer to provide the proper biomorphic structure on a case-by-case basis. Biocompatible steel was used to manufacture samples via laser powder-bed fusion; their elastic moduli and yield strengths were evaluated as a function of the orientation of the elementary cells, the symmetry and the wall thickness based on compression testing. Grounds have been given to support potential applications for tibias and vertebras.

Highlights

Many techniques have been reported in the literature for replacing missing or injured bones; these include surgery, drug therapy and artificial prostheses
Bone tissue engineering (BTE) has been recently developed as a multidisciplinary field aiming at inducing bone regeneration using biomaterials, cells and factor therapy [5]
Graded pieces can be even manufactured by proper design of the architecture and the void distribution along the scaffold [24]; namely, the size distribution of the pores is given a direction, so to benefit from a specific variation of properties [25]. This is crucial in reproducing the actual structure of a natural bone, wherein the outer part has a higher mechanical strength and modulus in comparison with those of the inner part [9]

Summary

Introduction

Many techniques have been reported in the literature for replacing missing or injured bones; these include surgery, drug therapy and artificial prostheses. Graded pieces can be even manufactured by proper design of the architecture and the void distribution along the scaffold [24]; namely, the size distribution of the pores is given a direction, so to benefit from a specific variation of properties [25] This is crucial in reproducing the actual structure of a natural bone, wherein the outer part (i.e. the cortical bone) has a higher mechanical strength and modulus in comparison with those of the inner part (i.e. the cancellous or trabecular bone, resembling sponge or foam materials with lower strength) [9]. The accuracy has been checked; the elastic modulus and the yield strength, which are among the main features to match when designing a biomorphic scaffold, have been measured With this approach, the authors aim at assessing the manufacturability of metal gyroids via AM and determining a correlation to design custom-oriented TPMSs properly

Design of gyroids

Manufacturing

Testing

Accuracy of the manufacturing process

Mechanical properties