Calcium phosphates (CaPs) are biocompatible and biodegradable materials showing a great promise in bone regeneration as good alternative to the use of auto- and allografts to guide and support tissue regeneration in critically-sized bone defects. This can be certainly attributed to their similarity to the mineral phase of natural bone. Among CaPs, hydroxyapatite (HA) deserves a special attention as it, actually is the main inorganic component of bone tissue. This review offers a comprehensive overview of past and current trends in the use of HA as grafting material, with a focus on manufacturing strategies and their effect on the mechanical properties of the final products. Recent advances in materials processing allowed the production of HA-based grafts in different forms, thus meeting the requirements for a range of clinical applications and achieving enthusiastic results both in vitro and in vivo. Furthermore, the growing interest in the optimization of three-dimensional (3D) porous grafts, mimicking the trabecular architecture of human bone, has opened up new challenges in the development of bone-like scaffolds showing suitable mechanical performances for potential use in load bearing anatomical sites.

Bone tissue is able to self-regenerate, but, in the presence of large defects due to trauma, tumor removal or congenital diseases, surgical insertion of a bone graft is needed to promote a faster and effective tissue healing. It was estimated that more than 2 million people worldwide annually undergo bone surgery to repair critical osseous defects. 1 At present, both biological (i.e. transplant materials) and synthetic grafts are used. The latter option is usually preferred in modern bone

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