Recent advances in biomaterials and structural design of 3D printed multiphasic scaffolds for osteochondral regeneration

Osteochondral defects (OCD) involve simultaneous damage to articular cartilage (AC), calcified cartilage (CC) and subchondral bone (SB). The hierarchical organization of these tissues, together with their distinct mechanical and biological functions, creates major challenges for clinical repair. Osteochondral tissue engineering (OTE) has emerged as a promising strategy, particularly through the development of multiphasic scaffolds designed to mimic the compositional and structural heterogeneity of the native osteochondral unit. This review first examines key additive manufacturing (AM) techniques currently used for osteochondral scaffold fabrication, including material extrusion (ME), vat photopolymerization (VP), and powder bed fusion (PBF), highlighting their working principles, material compatibility, fabrication capability, and recent applications in osteochondral scaffold design. Then, biomaterials used for osteochondral scaffolds were systematically reviewed, including polymers, bioceramics, biodegradable metals, and advanced composites, with particular emphasis on the biomechanical characteristics of monomaterial systems and the functional synergy enabled by composite strategies. Furthermore, structural design approaches for multiphasic scaffolds are discussed in depth, with a comprehensive analysis of recent advances in multilayer and gradient scaffold architectures for region-specific mechanical support, transport regulation, and interfacial integration. Finally, future perspectives are outlined, including the development of novel biomaterials, AI-assisted and image-based design strategies, and the clinical, manufacturing, and regulatory pathways required for translation. By integrating progress in AM, biomaterials, structural design, and bioengineering, this review provides a framework for the rational design of next-generation osteochondral scaffolds for effective and clinically relevant tissue regeneration.