3D-bioprinting for joint regeneration.

Joint injuries represent a significant clinical challenge with limited regenerative options. Three-dimensional (3D) bioprinting has emerged as a transformative technology, enabling the precise fabrication of patient-specific, anatomically matched, multilayered scaffolds that replicate the complex structure and gradient of natural joint tissues. This review comprehensively summarizes advances in bioprinting techniques, cell sources, and biomaterial formulations, emphasizing cell-laden bioinks composed of biomaterials and viable cells to create functional, bioactive constructs. Beyond basic fabrication, we evaluate the functional performance of bioprinted cartilage, bone, and ligaments, and we discuss strategies for engineering osteochondral interfaces and ligament-bone interfaces to support biomimetic mechanical properties and tissue integration. We further compare major printing modalities, including extrusion-based printing, inkjet, and laser-assisted bioprinting, and we discuss how modality-specific trade-offs in resolution, viscosity window, and cell stress influence construct fidelity and repair outcomes. In addition, we examine biofunctionalization strategies that incorporate growth factors, stem cells, and exosomes to enhance regenerative signaling and matrix remodeling. Notably, 3D bioprinting for joint regeneration is transitioning from bench to bedside, and we detail the current landscape of clinical translation, including commercialized products like Nanochon and active clinical trials for knee and hip repair. However, challenges such as insufficient vascularization and the mechanical performance of the printed constructions remain significant hurdles for clinical translation. Overall, this work underscores the potential of personalized 3D bioprinted scaffolds to advance joint tissue engineering and clarifies key directions for integrating these technologies into clinical practice.