Repairing large bone defects caused by mandibular tumor resection or severe trauma poses challenges. The traditional method of “autologous bone grafting + metal plate fixation” has issues such as donor site damage, stress shielding, and imaging interference, while absorbable scaffolds struggle to achieve synchronized osteogenesis and degradation.Recently, a team led by Professor Jeremy M. Crook from the University of Wollongong, in collaboration with Professor David R. McKenzie from the University of Sydney, proposed a novel paradigm for bone regeneration. They constructed a permanent, patient-matched, mechanically optimized, and specially surface-treated 3D-printed polyether ketone (PEK) artificial bone scaffold.
This scaffold is filled with absorbable ceramic lattices and hydrogels loaded with stem cells, which together promote bone regeneration. The research team successfully applied this novel artificial bone to repair a 6 cm long segmental defect model in sheep mandibles. The results showed that this artificial bone achieved lasting clinical functionality, proving
its feasibility as an alternative to traditional metal plate fixation bone grafting methods. The related findings were published in the journal Nature Communications under the title “Mechanobiologically-optimized non-resorbable artificial bone for patient-matched scaffold-guided bone regeneration.”
Highlights | Innovations and Breakthroughs
1. Permanent PEK scaffold replaces traditional degradable scaffoldsThe study innovatively proposes using PEK as the main material, replacing easily degradable biological scaffolds. This material possesses excellent mechanical stability and radiolucency, maintaining structural integrity under long-term load conditions and avoiding mechanical failure issues caused by mismatched degradation rates and bone regeneration rates.
2. Goodbye to metal fixation platesThe research achieved sufficient structural strength and stability of the PEK scaffold through precise patient-matched design, advanced manufacturing processes (laser sintering LS-PEK), and mechanical optimization (finite element analysis FEA), eliminating the need for additional metal plates for fixation.
3. Surface functionalization enhances bone integration capabilityThrough nitrogen plasma immersion ion implantation (PIII) surface modification, the hydrophilicity and bioactivity of the PEK surface were significantly improved. The treated material surface effectively promotes osteoblast adhesion and differentiation, achieving stable integration with host bone.
4. Composite bone induction core promotes new bone formationInside the permanent PEK framework, absorbable β-tricalcium phosphate (βTCP) ceramic lattices are embedded, filled with adipose-derived stem cells (ADSCs) loaded GelMA hydrogel, collectively constructing a composite microenvironment with calcium sources and bone induction signals, effectively promoting osteogenesis and vascularization.
Why: Research Background and Significance
Repairing “critical size” bone defects caused by tumor resection or trauma, especially segmental defects in the mandible, has always been a clinical challenge. Traditional autologous bone grafting requires sacrificing donor site tissue and relies on metal fixation plates, which have issues with morphological mismatch, mechanical imbalance, and complication risks. The high elastic modulus of metal plates can easily cause stress shielding and bone resorption, and radiological artifacts affect postoperative monitoring and radiotherapy dose distribution.
In recent years, scaffold-guided bone regeneration (SGBR) technology has gained attention, but mainstream biodegradable materials (such as PCL, βTCP) still face issues of degradation and bone generation rate mismatch, and there are currently no successful cases of segmental bone defect repair without metal assistance in clinical practice.
This study proposes a patient-customized 3D-printed polyether ketone (PEK) artificial bone system based on permanence, mechanical optimization, and surface modification. This strategy aims to achieve long-term stable support, excellent bone integration, and radiolucency, providing a new solution for complex bone defect reconstruction.
What: Research ContentThe research team constructed a composite artificial bone system consisting of three core components:
1. Main load-bearing framework (PIII-LS-PEK): A high-performance polymer PEK, precisely formed through laser sintering, serves as a permanent structure. This framework is personalized based on individual animal CBCT data, designed through VSP, and mechanically optimized using finite element models to ensure sufficient inherent strength to bear physiological loads, thus eliminating the need for metal plate reinforcement. After manufacturing, the framework undergoes thermal toughening (annealing) and nitrogen plasma immersion ion implantation (PIII) surface treatment, which significantly enhances its hydrophilicity and bioactivity, crucial for stable bone integration. Its internal design features a single Gyroid triply periodic minimal surface (TPMS) porous structure to balance mechanical performance, manufacturability, and bone ingrowth potential.
2. Bone induction functional core (β-TCP/ADSC-GelMA): Composed of a light-cured 3D-printed β-TCP lattice, infused with GelMA hydrogel loaded with autologous adipose-derived stem cells (ADSCs). Before implantation, this composite structure undergoes in vitro osteogenic induction culture to activate its bone induction capability. During surgery, this core is placed in a reserved cavity of the PEK framework and fixed with a small LS-PEK crossbar. This design provides a lasting supply of calcium ions and releases osteogenic factor signals, synergistically promoting new bone formation and vascularization.
3. Precision fixation system: To achieve precise implantation, the research employs a 3D-printed nylon-12 surgical guide designed by VSP to guide osteotomy and screw hole positioning. Finite element analysis (FEA) optimizes the stress path and morphological design of the scaffold, ensuring its structural stability and reasonable stress transmission in high-strength chewing environments.
How: Research Methods
Material bone integration performance evaluation: The study implanted PIII-treated laser-sintered PEK and clinically standard 3D-printed titanium alloy in sheep mandibles for comparison. Histological analysis showed that months later, the bone contact area and new bone formation amount were comparable for both, providing the first evidence that PIII-LS-PEK possesses excellent bone integration capability equivalent to metal, laying the foundation for its use as a load-bearing entity.
Scaffold structural performance optimization: Laser-sintered PEK scaffolds outperformed fused deposition PEEK in terms of bone ingrowth and interface bonding strength, thanks to their superior surface properties and intact structure. Finite element analysis optimized the internal structure to a Gyroid porous configuration, achieving an ideal balance between mechanical performance and osteogenic space. Bone induction core construction: The research designed an innovative “in vivo bioreactor” to test various material combinations. The combination of β-TCP ceramic and GelMA hydrogel loaded with stem cells exhibited the strongest osteogenic potential, initiating an efficient endochondral ossification process. Large animal model functional validation: After implanting the customized artificial bone in a 6 cm sheep mandibular defect model, imaging and histological results analyzed the successful ingrowth of new bone into the scaffold, firmly integrating with the host bone, and restoring nearly normal mechanical strength. The computer model simulated bone growth closely matched actual conditions, validating its stress-driven bone regeneration design concept.
Summary and Outlook
This study successfully achieved segmental bone defect repair without metal plates or autologous bone grafting, marking the first verification of the feasibility and stability of permanent non-degradable PEK artificial bone scaffolds in mechanical support and biological integration in a large animal model. The success of this system stems from the synergistic effects of multiple factors: the micro-rough interface brought by LS technology, the enhanced bone integration capability from PIII surface modification, the stress transmission ensured by individualized mechanical optimization, and the local bone induction promoted by the βTCP–ADSCs composite core.
Although there are individual differences in the osteogenic efficiency of the βTCP core, the stable PEK–host bone integration can support long-term functional loading. The research indicates that for permanent scaffolds, “stable integration” is more critical than “complete replacement.” Future work will further evaluate the performance stability of this material in radiotherapy environments, optimize the osteogenic efficiency and degradation controllability of the bone induction core, and explore the impact of scaffold surface topology on soft tissue integration. Overall, this research provides a new example of transitioning from “degradable alternatives” to “permanent integration” for scaffold-guided bone regeneration, bringing new hope for clinical translation in maxillofacial and load-bearing bone repair.
Keywords: Personalized Bone Regeneration, 3D Printing, Artificial Bone, Bone Integration, Osteogenesis