Recent Strategies in Osteochondral Substitutes Design: Towards the Mimicking of a Multifaceted Anatomical Unit from the Nano to the Macro Level

Abstract

Nowadays regenerative medicine takes advantages not only of traditional implants, but also of engineered biocompatible parts, including degradable porous scaffolds integrated with cells or molecules. These approaches, positioned at the interdisciplinary area between biomedical materials science and medicine, will become more achievable when combined with biomimicry, which not only optimizes biomaterial interaction with biological tissues but also mimics biogenic materials in their structure and functionalities. Such methodologies are particularly attractive for bone and osteochondral related materials: in other words, cartilage and mineralized tissues are ideal example to learn-from in setting up biomaterial science researches. These tissues are highly integrated systems, having found a compromise between different properties and functions, above all thanks to their hierarchical structure. Hard tissues display order on multiple lengths scale, from the nano to the macro level, whereas osteochondral tissue in particular exhibits an inherent gradient structure. Bearing this in mind, bone and osteochondral scaffold design must enable hierarchical composites porous structures to attain desired mechanical function and mass transport, for example, permeability and diffusion, and to produce these structures within arbitrary and complex three-dimensional (3D) anatomical shapes. In this context, this review will supply a hint of the strategies for biomimetic orthopaedic substitutes, actualizing the role of biomimicry, materials chemistry and process engineering in projecting and fabricating custom-made scaffolds.