title: Novel multilayer Ti foam with cortical bone strength and cytocompatibility.
abstract: The major functions required for load-bearing orthopaedic implants are load-bearing and mechanical or biological fixation with the surrounding bone. Porous materials with appropriate mechanical properties and adequate pore structure for fixation are promising candidates for load-bearing implant material. In previous work, the authors developed a novel titanium (Ti) foam sheet 1-2mm thick by an original slurry foaming method. In the present work, novel Ti foam is developed with mechanical properties compatible with cortical bone and biological fixation capabilities by layer-by-layer stacking of different foam sheets with volumetric porosities of 80% and 17%. The resulting multilayer Ti foam exhibited a Young's modulus of 11-12GPa and yield strength of 150-240MPa in compression tests. In vitro cell culture on the sample revealed good cell penetration in the higher-porosity foam (80% volumetric porosity), which reached 1.2mm for 21 days of incubation. Cell penetration into the high-porosity layers of a multilayer sample was good and not influenced by the lower-porosity layers. Calcification was also observed in the high-porosity foam, suggesting that this Ti foam does not inhibit bone formation. Contradictory requirements for high volumetric porosity and high strength were attained by role-sharing between the foam sheets of different porosities. The unique characteristics of the present multilayer Ti foam make them attractive for application in the field of orthopaedics.
authors.affiliation: Mitsubishi Material Corp., 1-297 Kitabukuro-cho, Omiya-ku, Saitama 330-8508, Japan. kkato@mmc.co.jp
authors.forename: K
authors.initials: K
authors.lastname: Kato
authors.forename: S
authors.initials: S
authors.lastname: Ochiai
authors.forename: A
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Daigo
authors.forename: K
authors.initials: K
authors.lastname: Honma
authors.forename: S
authors.initials: S
authors.lastname: Matano
authors.forename: K
authors.initials: K
authors.lastname: Omori
mesh_terms: D001842:Bone and Bones / Q000187:drug effects* / Q000502:physiology*; D002113:Calcification, Physiologic / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D019245:Compressive Strength / Q000187:drug effects; D006801:Humans; D008856:Microscopy, Fluorescence; D016062:Porosity / Q000187:drug effects; D011208:Powders; D013718:Tensile Strength / Q000187:drug effects; D014025:Titanium / Q000494:pharmacology*
chemical_list: D011208:Powders; D014025:Titanium