β-type TiNbSn Alloy Plates With Low Young Modulus Accelerates Osteosynthesis in Rabbit Tibiae

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Materials Engineering

Background:

• Ti6Al4V alloy, common in biomedical implants, has a Young's modulus (110 GPa) significantly higher than human bone (11-20 GPa), potentially causing stress shielding.
• A novel beta-type TiNbSn alloy exhibits a lower Young's modulus (40-49 GPa), offering potential for improved load sharing and bone healing.
• The efficacy of TiNbSn alloy in fracture healing compared to Ti6Al4V has not been previously assessed.

Purpose of the Study:

• To evaluate the impact of TiNbSn alloy plates versus Ti6Al4V alloy plates on fracture healing.
• Assessments included bony bridging, callus volume, new bone formation, cartilage tissue, osteoblast activity, and mechanical properties.
• Utilize a small-animal model for initial assessment of the new titanium alloy's benefits.

Main Methods:

• Fracture plates made of TiNbSn (49 GPa) and Ti6Al4V (110 GPa) alloys were compared in a rabbit tibia osteotomy model.
• Bone healing was quantitatively assessed using micro-CT, histomorphometry, immunohistochemistry, and mechanical testing at 4 and 8 weeks post-surgery.
• Standardized tibial transverse osteotomy with a 1-mm gap was created, and plates were fixed with screws.

Main Results:

• At 4 weeks, TiNbSn plates showed significantly larger bone volumes and more bridging structures compared to Ti6Al4V plates.
• Histological analysis revealed greater new bone formation and a higher number of osteocalcin-positive cells in the TiNbSn group.
• The TiNbSn group exhibited superior bone strength and stiffness at 4 weeks, though no differences were observed at 8 weeks.

Conclusions:

• TiNbSn alloy plates enhanced early bone formation and callus stiffness compared to Ti6Al4V plates.
• The lower Young's modulus of TiNbSn appears beneficial for the initial stages of fracture healing.
• TiNbSn alloy shows promise as a biomaterial for fracture treatment devices, warranting further investigation into its long-term mechanical integrity.