Innovative prospects in 3D printed bio-scaffolds for osteochondral tissue engineering: A systematic review

Table 1 Summary of innovations in 3D printed osteochondral bio-scaffolds based on material type, printing strategy, model used, and translational readiness

Material type	Bioprinting strategy	Application model	Reported innovation	Translational readiness
GelMA + nHA hydrogel	Extrusion-based	In vitro, animal	Improved ECM mimicry, layered zonal design	Preclinical feasibility, limited long-term data
PCL/PLGA composites	Melt electrospinning, extrusion	Large animal, cadaveric	Enhanced mechanical strength, zonal stiffness gradients	Reproducible structure; lacks dynamic in vivo data
Bioactive glass ink	Inkjet, laser-assisted	In vitro	Osteoconductive matrix, micron-scale resolution	Technologically promising; scale-up challenges
Chitosan–collagen blends	Extrusion-based	In vitro	Biocompatibility, crosslinkable for customized geometry	Biologically safe; lacks osteoinductive strength
4D smart polymers	Photo-crosslinkable/thermal cues	Preclinical concept models	Stimuli-responsive shape adaptation and integration signaling	Early stage; requires safety and degradation data

ECM: Extracellular matrix; PCL/PLGA: Polycaprolactone/poly (lacto-co-glycolic acid); GelMA: Gelatin methacrylate; nHA: Nano-hydroxyapatite.