Composite scaffolds for bone and osteochondral defects

The fast replacement of native functionality (i.e., biological, chemical, mechanical) of damaged skeletal tissues currently represents an important challenge of clinical surgery. Through an accurate study of natural tissues and biomimesis, advanced biomaterials can be designed in the form of porous scaffolds to create hierarchical porous structures with the desired mechanical performances and mass transport properties (permeability and diffusion) while reproducing the complex 3D anatomical shapes. Recently, bioinspired composite scaffolds have been successfully used for the regeneration of bone and osteochondral tissue due to their unique ability to accurately mimic tissue functions and organization at different size scale levels. As a function of the filler/matrix coupling, they may ensure biochemical affinity with the host tissue through a judicious mix of specific morphological and chemical cues, also mimicking the response under load exhibited by natural tissue through a complex organization of material phases. This chapter provides an overview of recently developed composite porous and nonporous platforms used for repair/regeneration of bone and osteochondral tissue. In particular, we have classified composite scaffolds by distinguishing between those with biodegradable and bioresorbable matrices. Moreover, we describe different strategies to functionalize them with organic or inorganic phases by remarking, case by case, their passive or active reinforcement role as a function of intrinsic properties (i.e., degradation, magnetism) and different shapes (i.e., long or short fibers, particles with different shape ratios). Different manufacturing protocols are described, emphasizing their main advantages and disadvantages, and can be adopted to realize functionally and mechanically performed tissue substitutes.