Composite material bone implant
A composite bone implant. In some embodiments, one or more features are provided, such as markers for passageways, axial engagement of bone screws, sliding support of bone screws and/or a cannulated channel for a guide wire.
1. A bone fixation screw comprising: a composite core formed of a threaded, polymer body containing longitudinally extending reinforcing fibers; and a metal exterior surface on the core to provide additional hardness to the screw; wherein said metal exterior surface is thin enough so that it does not cause artifacts in CT or MRI images that would significantly interfere with visualization, having a thickness ranging between 0.02 and 0.1 mm; and wherein said metal exterior surface is smooth.
2. A bone fixation screw according to claim 1 , wherein the metal surface is titanium or a titanium alloy.
3. A bone fixation screw according to claim 1 , wherein the metal surface is threaded with screw threads.
4. A bone fixation screw according to claim 3 , wherein a portion of the composite core penetrates an inner surface of the metal threads.
5. A bone fixation screw according, to claim 3 , wherein an interface between the composite core and the metal surface includes complementary projections and recesses.
6. A bone fixation screw according to claim 3 , wherein the screw threads are oversized or mismatched in pitch relative to screw holes in a bone implant configured to receive the screws.
7. A bone fixation screw according to claim 1 , wherein the material comprising the metal surface is crimped around proximal and/or distal ends of the composite core of the screw.
8. A bone fixation screw according to claim 1 , wherein the metal surface adds strength to said screw.
9. A bone fixation screw according to claim 1 , wherein said bone screw has a self-tapping tip.
10. A. bone fixation screw according to claim 9 , wherein said self tapping tip is covered by said layer.
11. A bone fixation screw according to claim 1 , wherein said screw is cannulated.
12. A bone fixation screw according to claim 1 , comprising an implant which adds hardness to the screw.
13. A bone fixation screw according to claim 12 , wherein said implant is embedded in the screw.
14. A bone fixation screw according to claim 1 , wherein said body includes a material layer between said body and said metal layer.
15. A bone fixation screw according to claim 14 , wherein said layer comprises a composite material with helically wound fibers at an angle of +−45 degrees.
16. A bone fixation screw according to claim 1 , wherein said metal layer is crimped on said screw.