Composite porous interbodies and methods of manufacture
A method of forming a composite titanium body for use in forming spinal implant interbodies includes selecting a metal alloy body, carving out a top portion and a bottom portion from the metal alloy body, and bonding a porous material to the carved-out top and bottom portions. Multiple pieces may be cut from the composite titanium body, each having a front face formed of the metal alloy, top and bottom portions formed of the porous material, and with a medial portion of the metal alloy extending from the front face to the back. Methods and devices for spinal interbodies having locking mechanisms to prevent bone screw back-out are also described.
1. A composite interbody system comprising:
a body having an anterior face and an opposing posterior face, a top portion and a bottom portion, with a medial portion extending through the body from the anterior face to the opposing posterior face, the medial portion separating the top portion and the bottom portion, the anterior face anterior to the top portion and the bottom portion;
a first locking mechanism and a second locking mechanism;
the anterior face formed of a solid metal alloy, the top portion and bottom portion formed of a porous metal, and the medial portion formed of a solid metal alloy;
the anterior face comprising a first bore for receiving a first bone screw, and a first inwardly extending channel proximal to the first bore, the first inwardly extending channel for receiving the first locking mechanism;
the anterior face comprising a second bore for receiving a second bone screw, and a second inwardly extending channel proximal to the second bore, the second inwardly extending channel for receiving the second locking mechanism;
the first locking mechanism comprising a first cylinder receivable into the first inwardly extending channel, the first cylinder having an inward end and an outward end, and a first tab projecting outwardly from the outward end of the cylinder, the first tab projecting at least partially into the first bore; and
the second locking mechanism comprising a second cylinder receivable in the second inwardly extending channel, the second cylinder having an inward end and an outward end and a second tab projecting outwardly from the cylinder, the second tab projecting at least partially into the second bore,
wherein the first tab and second tab comprise an angled face and are biased to project at least partially into the first bore and second bore, respectively, and
wherein the outward ends of the first and second cylinders each comprise a cut-away to allow, respectively, the first tab of the first locking mechanism to be forced out of the first bore by pressure of an inwardly moving first bone anchor and the second tab of the second locking mechanism to be forced out of the second bore by pressure of an inwardly moving second bone anchor.
2. The composite interbody system of claim 1 , wherein the anterior face and the medial portion are formed of a single piece of titanium alloy.
3. The composite interbody system of claim 2 , wherein the porous metal comprises sheets of porous titanium diffusion bonded together to form the porous titanium.
4. The composite interbody system of claim 3 , wherein the top portion is diffusion bonded to a top surface of the medial portion and the bottom portion is diffusion bonded to a bottom surface of the medial portion.
5. The composite interbody system of claim 1 , wherein the body is cut from a composite titanium block formed by a method comprising:
selecting a solid titanium body having a top side and a bottom side;
carving out a portion of the top side of the solid titanium body to form a top portion void;
carving out a portion of the bottom side of the solid titanium body to form a bottom portion void;
diffusion bonding porous titanium to the top portion void;
diffusion bonding porous titanium to the bottom portion void, the steps of diffusion bonding porous titanium to the top portion void and bottom portion void forming a composite titanium block; and
cutting out a composite interbody from the composite titanium block.
6. The composite interbody system of claim 1 , wherein the first or the second bore is at least partially threaded.
7. The composite interbody system of claim 6 , wherein the threads are configured to engage with corresponding threads on the first or second bone screw, respectively.
8. The composite interbody system of claim 1 , wherein the first or second bone screw has a head portion that is at least partially threaded.