Clinical translation of 3D-bioprinted orthopedic grafts: Design specifications, evaluation domains, and regulatory considerations for bone, cartilage, and osteochondral repair
Three-dimensional (3D) bioprinting has advanced rapidly, but clinical translation of orthopedic grafts remains constrained by a mismatch between printable constructs and indication-specific failure modes. Bone, cartilage, and osteochondral defects impose distinct requirements: vascularized remodeling and load sharing for bone, phenotypic stability and low-friction durability for cartilage, and mechanically integrated compartmental organization for osteochondral repair. This narrative review synthesizes recent evidence on 3D bioprinted orthopedic grafts with a translational focus on design specifications, validation endpoints, manufacturing control, and regulatory readiness. Rather than treating bioinks, printing platforms, and cell sources as isolated technologies, the review organizes them according to clinical function: structural support, biological instruction, process control, maturation, immune compatibility, and product qualification. Current evidence indicates that many constructs remain validated mainly by early biological markers, representative imaging, or short-term animal outcomes, whereas clinically relevant tests of fatigue, wear, degradation-coupled mechanics, host-graft integration, vascular perfusion, immune response, sterility, dimensional tolerance, and release criteria are less consistently reported. Near-term translation appears most plausible for acellular or minimally cellular reinforced constructs, patient-specific but quality-testable bone scaffolds, and selected intraoperative applications with clear surgical utility. More complex living grafts that combine vascular, immune-instructive, and multi-tissue functions will require stronger preclinical models, standardized reporting, and product-specific regulatory strategies. Translation in orthopedic bioprinting should begin with the clinical failure mode and proceed toward measurable release specifications, not with printability alone.
