Devices and Methods for Tissue Engineering
A silicon nitride porous tissue engineering scaffold is fabricated from a silicon-based fiber that is converted to silicon nitride through a reaction at elevated temperatures in a nitrogen environment. Porosity in the form of interconnected pore space is provided by the pore space between the fiber material in a porous matrix. The silicon nitride porous tissue engineering scaffold can be formed from raw materials that are a precursor to silicon nitride. The silicon nitride porous tissue engineering scaffold supports tissue in-growth to provide osteoconductivity as a biocompatible tissue scaffold used as an implantable medical device for the repair of damaged and/or diseased bone tissue.
1 . A method of fabricating a porous synthetic bone prosthesis comprising:
mixing a silicon-based fiber with a bonding agent, a pore former, a binder, and a liquid to provide a plastically formable batch, the silicon-based fiber having an intertangled and overlapping relationship;
forming the plastically formable batch into a shaped object;
drying the shaped object by removing substantially all the liquid;
removing the binder and the pore former wherein the intertangled and overlapping relationship is substantially maintained; and
heating the shaped object in a nitrogen environment to react the silicon-based fiber with the nitrogen to form a silicon nitride composition having a porosity to support tissue ingrowth.
2 . The method according to claim 1 wherein the silicon-based fiber comprises silica.
3 . The method according to claim 2 wherein the mixing step includes carbon and wherein the step of heating the shaped object in a nitrogen environment comprises a carbothermal reduction of the silica using the carbon.
4 . The method according to claim 2 wherein the pore former comprises carbon particles wherein the step of heating the shaped object in a nitrogen environment comprises a carbothermal reduction of the silica using the pore former.
5 . The method according to claim 1 wherein the bonding agent includes silicon nitride particles.
6 . The method according to claim 1 wherein the bonding agent includes yttrium oxide.
7 . The method according to claim 1 wherein the bonding agent is in the form of a coating on the silicon-based fiber.
8 . The method according to claim 3 wherein the silicon-based fiber is a silica quartz glass.
9 . A synthetic bone prosthesis comprising:
intertangled and overlapping fibers bonded into a rigid three-dimensional matrix, the rigid three-dimensional matrix having a silicon nitride composition;
a bulk porosity in the range of about 40% to about 70%; and
a pore size distribution in the rigid three-dimensional matrix with a mode in the range of about 200-600 μm.
10 . The synthetic bone prosthesis according to claim 9 wherein the pore size distribution in the rigid three-dimensional matrix has a mode in the range of about 50 μm.
11 . The synthetic bone prosthesis according to claim 9 adapted for use as a intervertebral device.
12 . The synthetic bone prosthesis according to claim 9 adapted for use as an osteotomy wedge.
13 . The synthetic bone prosthesis according to claim 9 adapted for use as a bone graft.
14 . The synthetic bone prosthesis according to claim 9 adapted for use as a bone defect filler.
15 . The synthetic bone prosthesis according to claim 9 adapted for use as a subtalar implant.