Bone Ingrowth to Ti Fibre Knit Block with High Deformability

OBJECTIVES: The objective of this study is to develop a Ti fibre knit block without sintering, and to evaluate its deformability and new bone formation in vivo.

MATERIAL AND METHODS: A Ti fibre with a diameter of 150 μm was knitted to fabricate a Ti mesh tube. The mesh tube was compressed in a metal mould to fabricate porous Ti fibre knit blocks with three different porosities of 88%, 69%, and 50%. The elastic modulus and deformability were evaluated using a compression test. The knit block was implanted into bone defects of a rabbit's hind limb, and new bone formation was evaluated using micro computed tomography (micro-CT) analysis and histological analysis.

RESULTS: The knit blocks with 88% porosity showed excellent deformability, indicating potential appropriateness for bone defect filling. Although the porosities of the knit block were different, they indicated similar elastic modulus smaller than 1 GPa. The elastic modulus after deformation increased linearly as the applied compression stress increased. The micro-CT analysis indicated that in the block with 50% porosity new bone filled nearly all of the pore volume four weeks after implantation. In contrast, in the block with 88% porosity, new bone filled less than half of the pore volume even 12 weeks after implantation. The histological analysis also indicated new bone formation in the block.

CONCLUSIONS: The titanium fibre knit block with high porosity is potentially appropriate for bone defect filling, indicating good bone ingrowth after porosity reduction with applied compression.