POROUS BONE SCREW
A bone screw includes a core and an outer portion. The core is constructed at least substantially of a porous material. The outer portion is proximate an outer surface of the core and defines a thread portion. The thread portion helically surrounds the core to define a plurality of helical windings such that the core is intermittently exposed axially between adjacent helical windings at least substantially along the length of the thread portion.
1 . A bone screw comprising:
a core constructed of a first material and including a bore; and
an outer portion proximate an outer surface of the core, the outer portion formed from a second material to include a thread portion, a head, and a tip, the head having a first aperture in communication with the bore and the tip having a second aperture in communication with the bore,
wherein the thread portion helically surrounds the core to define a plurality of helical windings such that the core is intermittently exposed axially between adjacent helical windings along the length of the thread portion.
2 . The bone screw of claim 1 , wherein the outer portion is monolithically formed from the second material.
3 . The bone screw of claim 2 , wherein the second material includes a solid material.
4 . The bone screw of claim 1 , wherein the first material includes a porous material.
5 . The bone screw of claim 4 , wherein the porous material includes a porous metallic material.
6 . The bone screw of claim 5 , wherein the second material includes a solid metallic material.
7 . The bone screw of claim 1 , wherein the first material includes a solid material.
8 . The bone screw of claim 1 , wherein the bore includes a driving feature.
9 . The bone screw of claim 1 , wherein the core includes a proximal end aligned with the head, and a distal end aligned with the tip.
10 . The bone screw of claim 9 , wherein the bore extends from the proximal end to the distal end.
11 . The bone screw of claim 1 , wherein the second material is different than the first material.
12 . The bone screw of claim 1 , further comprising a shell coaxially disposed between the core and the outer portion.
13 . The bone screw of claim 12 , wherein the shell is constructed of a third material different than the first and second materials.
14 . The bone screw of claim 13 , wherein the second and third materials include a substantially porous material, and the first material includes a substantially solid material.
15 . A method of manufacturing a bone screw, the method comprising:
forming a porous shaft portion by a first manufacturing process;
forming a solid outer portion on the shaft portion by a second manufacturing process; and
removing a portion of the solid outer portion to form a head, a helical thread portion, and a tip.
16 . The method of claim 15 , wherein removing a portion of the solid outer portion includes machining a portion of the solid outer portion.
17 . The method of claim 15 , wherein at least one of the first and second manufacturing processes includes an additive manufacturing process.
18 . The method of claim 17 , wherein the additive manufacturing process includes one of an electron beam melting process and a laser sintering process.
19 . The method of claim 15 , further comprising:
forming a driving feature in the head portion;
forming an aperture in the tip; and
forming a bore in the shaft portion that is in communication with at least one of the driving feature and the aperture.
20 . A method of manufacturing a bone screw, the method comprising:
forming a porous shaft portion by a first additive manufacturing process;
forming a solid outer portion by a second additive manufacturing process; and
coupling the outer portion to the shaft portion.
21 . The method of claim 20 , removing a portion of the outer portion to form a head, a helical thread portion, and a tip.