Wave Spring for a Spinal Implant

Abstract

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.

What is claimed is: 
     
         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.