Method of manufacturing a core and shell coupling of a composite material bone implant and composite material bone implant produced thereby
A method of manufacturing fiber-reinforced polymer matrix composite material bone screws having threads surfaced with a metallic outer layer is described. In some embodiments, the method includes preparing a metallic outer layer by 3-D printing, inserting a composite material into the metallic outer layer, and attaching the metallic outer layer onto the composite material.
1 . A method of manufacturing a screw comprising:
preparing a metallic outer layer of the screw by 3-D printing, said metallic outer layer being hollow and including screw threads and formed by the 3-D printing with an inner roughness;
inserting a composite material into the metallic outer layer, wherein the inner roughness is configured for gripping the composite material; and
attaching the metallic layer onto the composite material.
2 . The method according to claim 1 , wherein said attaching includes performing compression molding on the metallic outer layer with the composite material inserted thereinto.
3 . The method according to claim 2 , wherein said compression molding is performed in a mold having an internal cavity which is sized and shaped to accommodate the metallic outer layer.
4 . The method according to claim 2 , wherein said compression molding includes a combination of heating and applying pressure.
5 . The method according to claim 4 , wherein said heating includes applying enough heat to melt a polymer portion of the composite material.
6 . The method according to claim 5 , wherein said compression molding includes heating the composite material to about 400° C.
7 . The method according to claim 2 , wherein said compression molding includes causing composite material matrix to flow into prepared spaces of the metallic outer layer.
8 . The method according to claim 1 further including, after said preparing a metallic outer layer by 3-D printing, electro-polishing the metallic outer layer.
9 . The method according to claim 8 , wherein said electro-polishing reduces a thickness of the metallic outer layer, at least at some portions of the metallic outer layer.
10 . The method according to claim 1 , wherein the composite material comprises a fiber-reinforced polymer matrix.
11 . The method according to claim 1 , wherein said metallic layer resists a shearing force applied to the metallic layer when the screw is rotated within the bone.
12 . The method according to claim 1 , wherein the metallic layer comprises at least one of titanium and a titanium alloy.
13 . The method according to claim 12 , wherein the at least one of titanium and a titanium alloy is anodized.
14 . The method according to claim 1 , wherein the metallic layer has a thickness in a range of from 1-200 microns.
15 . The method according to claim 1 , wherein the screw is cannulated.
16 . The method according to claim 1 , wherein said metallic layer further covers a non-threaded region of said screw.
17 . A bone screw having screw threads for rotating insertion to a bone, the bone screw comprising:
a body formed from a composite material; and
a metallic layer surfacing the body, said metallic layer formed by 3-D printing, wherein said metallic layer is formed by the 3-D printing with an inner roughness for gripping said composite material;
wherein said metallic layer resists a shearing force applied to the metallic layer when the screw is rotated within the bone.
18 . The bone screw according to claim 17 , wherein said metallic layer includes a drilling tip at a distal end of the metallic layer.
19 . The bone screw according to claim 17 , wherein the composite material comprises a fiber-reinforced polymer matrix.
20 . The bone screw according to claim 17 , wherein the metallic layer comprises at least one of titanium and a titanium alloy.
21 . The bone screw according to claim 20 , wherein the titanium or titanium alloy is anodized.
22 . The bone screw according to claim 17 , wherein the metallic layer has a thickness in the range of from 1-200 microns.
23 . The bone screw according to claim 17 , wherein the screw is cannulated.
24 . The bone screw according to claim 17 , wherein said metallic layer further covers a non-threaded region of said screw.
25 . The bone screw according to claim 17 , wherein said screw comprises said body and a single said metallic layer formed by the 3-D printing.
26 . The bone screw according to claim 17 , wherein said metallic layer is an outermost layer of said bone screw.