Wave Spring for a Spinal Implant
A spinal implant includes a coiled wave spring configured to surround a nucleus. The wave spring is formed with at least one wire having a sinusoidal shape and made of a shape memory material. The shape memory material is tailored to achieve a stress-induced martensitic transformation when a critical stress is exceeded. The implant may further include an artificial nucleus configured to simulate a disc nucleus. Methods of forming and implanting the spinal implant are also disclosed.
1 . A spinal implant comprising:
a coiled wave spring configured to surround a nucleus, wherein the wave spring is formed with at least one wire having a sinusoidal shape and made of a shape memory material, and the shape memory material is tailored to achieve a stress-induced martensitic transformation when a critical stress is exceeded.
2 . The spinal implant according to claim 1 , wherein the shape memory material is further trained to expand to a preset shape when the wave spring temperature exceeds its transition temperature.
3 . The spinal implant according to claim 1 , wherein the wave spring is wedge shaped.
4 . The spinal implant according to claim 1 , wherein the shape memory material is selected from the group consisting of Nitinol, a Titanium-Niobium alloy, and combinations thereof.
5 . The spinal implant according to claim 1 , wherein the wave spring is formed with one or more flat wires.
6 . The spinal implant according to claim 1 , wherein the wave spring is formed with one or more rectangular wires.
7 . The spinal implant according to claim 1 , further comprising:
an artificial nucleus configured to simulate a disc nucleus, wherein the wave spring surrounds the artificial nucleus.
8 . The spinal implant according to claim 7 , wherein the artificial nucleus is made from a polymer material or a hydro-gel material.
9 . The spinal implant according to claim 7 , wherein the artificial nucleus is a wave spring.
10 . A method of forming a spinal implant, the method comprising:
forming a coiled wave spring, the wave spring having at least one wire with a sinusoidal shape and made of a shape memory material, and the shape memory material is tailored to achieve a stress-induced martensitic transformation when a critical stress is exceeded; and
configuring the wave spring to surrounding a nucleus.
11 . The method according to claim 10 , wherein the wave spring is wedge shaped.
12 . The method according to claim 10 , wherein the shape memory material is selected from the group consisting of Nitinol, a Titanium-Niobium alloy, and combinations thereof.
13 . The method according to claim 10 , wherein the wave spring is formed with one or more flat wires or rectangular wires.
14 . The method according to claim 10 , further comprising forming an artificial nucleus configured to simulate a disc nucleus, wherein the wave spring surrounds the artificial nucleus.
15 . The method according to claim 14 , wherein the artificial nucleus is formed from a polymer material or a hydro-gel material.
16 . The method according to claim 14 , wherein the artificial nucleus is formed from a wave spring.
17 . The method according to claim 10 , wherein forming the coiled wave spring further comprises:
providing the shape memory material with about 30-40% cold work;
coiling the wave spring; and
subsequently age heat treating the shape memory material after coiling the wave spring.
18 . The method according to claim 10 , wherein the shape memory material is further trained to expand to a preset shape when the wave spring temperature exceeds its transition temperature.
19 . A method of implanting a spinal implant, the method comprising:
inserting a coiled wave spring into an intervertebral space, wherein the wave spring is formed with at least one wire having a sinusoidal shape and made of a shape memory material, and the shape memory material is tailored to achieve a stress-induced martensitic transformation when a critical stress is exceeded; and
introducing a nucleus material into an interior area of the wave spring, the nucleus material configured to simulate a disc nucleus.
20 . The method according to claim 19 , wherein the shape memory material is further trained to expand to a preset shape when the wave spring temperature exceeds its transition temperature.