Posterior prosthetic intervertebral disc

Abstract

A prosthetic intervertebral disc is formed of first and second end plates sized and shaped to fit within an intervertebral space and to be implanted from the back of the patient, thereby decreasing the invasiveness of the procedure. The posterior approach provides for a smaller posterior surgical incision and avoids important blood vessels located anterior to the spine particularly for lumbar disc replacements. The first and second plates are each formed of first, second and third parts are arranged in a first configuration in which the parts are axially aligned to form a low profile device appropriate for insertion through the small opening available in the TLIF or PLIF approaches described above. The three parts of both of the plates rotate and translate with respect to one another in situ to a second configuration or a deployed configuration in which the parts are axially unaligned with each other to provide a maximum coverage of the vertebral end plates for a minimum of insertion profile. Upon deployment of the disc, a height of the disc is increased.

What is claimed is: 
     
         1 . A method of deploying an implant in a spine of a patient, the method comprising:
 providing an implant having first and second elongated articulating portions each of the first and second elongated articulating portions having a length, a width, a height and an axis extending along the length, wherein the length is longer than the width and the height;   arranging the first and second elongated articulating portions with their axes substantially aligned in an insertion configuration;   inserting the implant into a disc space between two vertebrae in the insertion configuration;   deploying the implant in situ from the aligned insertion configuration to an unaligned deployed configuration in which the axes of the first and second elongated articulating portions are axially unaligned with each other; and   increasing a distance between the two vertebra by increasing a height of the implant from an initial height to a deployed height.   
     
     
         2 . The method of  claim 1 , wherein the first and second elongated articulating portions each comprise a pivot at one end thereof for deploying the implant. 
     
     
         3 . The method of  claim 2 , wherein the second elongated articulating portion comprises a coupling for connecting to a deployment instrument at an end opposite the pivot. 
     
     
         4 . The method of  claim 1 , wherein the step of inserting is performed by a PLIF approach in a lumbar portion of the spine. 
     
     
         5 . The method of  claim 1 , wherein the step of inserting is performed by a TLIF approach in a lumbar portion of the spine. 
     
     
         6 . The method of  claim 1 , wherein outer vertebral contacting surfaces of the first and second elongated articulating portions comprise teeth, grooves or ridges. 
     
     
         7 . the method of  claim 6 , wherein the teeth, grooves or ridges are angled to ease insertion and prevent migration. 
     
     
         8 . The method of  claim 1 , wherein the implant is inserted by a deployment instrument fixed to an end of the disc in the axially aligned insertion configuration. 
     
     
         9 . The method of  claim 3 , further comprising attaching the deployment instrument to the coupling and inserting the implant with the deployment instrument. 
     
     
         10 . The method of  claim 1 , wherein the step of deploying the implant from the aligned insertion configuration to the unaligned deployed configuration is caused by contact of a leading end of the disc with an annulus of the natural disc. 
     
     
         11 . The method of  claim 1 , wherein the step of deploying the implant includes pivoting of the first and second elongated articulating portions of the implant with respect to one another. 
     
     
         12 . The method of  claim 1 , wherein the step of increasing the height of the implant is performed during the deploying step. 
     
     
         13 . The method of  claim 1 , wherein the step of increasing the height of the implant is performed after the deploying step. 
     
     
         14 . The method of  claim 1 , wherein the step of increasing the height of the implant includes sliding an implant part along a ramp inside the second elongated articulating portion. 
     
     
         15 . The method of  claim 14 , wherein the part slides in the direction of the axis of the second elongated articulating portion. 
     
     
         16 . The method of  claim 1 , wherein the insertion and deployment of the disc is performed through a single posterior opening into the disc space. 
     
     
         17 . The method of  claim 1 , wherein the insertion and deployment of the disc is performed through two posterior openings into the disc space. 
     
     
         18 . The method of  claim 1 , wherein the deployed height is at least 1.5 times the height in the insertion configuration. 
     
     
         19 . A method of deploying an implant in a spine of a patient, the method comprising:
 providing an implant having first and second elongated articulating portions each of the first and second elongated articulating portions having a length, a width, a height and an axis extending along the length, wherein the length is longer than the width and the height and wherein the first and second elongated articulating portions are interconnected and pivotable;   arranging the first and second elongated articulating portions with their axes substantially aligned in an insertion configuration;   connecting an end of the second elongated articulating portion to a deployment instrument;   inserting the implant into a disc space between two vertebrae in the insertion configuration; and   contacting a leading end of the first elongated articulating portion with an annulus of the natural disc to cause the implant to articulate in situ from the aligned insertion configuration to an unaligned deployed configuration in which the axes of the first and second elongated articulating portions are axially unaligned with each other;   expanding the implant in the height direction; and   disconnecting the deployment instrument from the second elongated articulating portion.   
     
     
         20 . The method of  claim 19 , wherein the first and second elongated articulating portions each comprise a pivot at one end thereof for deploying the implant. 
     
     
         21 . The method of  claim 20 , wherein the second elongated articulating portion comprises a coupling for connecting to the deployment instrument at an end opposite the pivot. 
     
     
         22 . The method of  claim 19 , wherein the step of inserting is performed by a PLIF approach. 
     
     
         23 . The method of  claim 19 , wherein the leading end of the first elongated articulating portion which contacts the annulus of the natural disc to cause the implant to articulate in situ is curved. 
     
     
         24 . The method of  claim 19 , wherein outer vertebral contacting surfaces of the first and second elongated articulating portions comprise teeth, grooves or ridges. 
     
     
         25 . The method of  claim 24 , wherein the teeth, grooves or ridges are angled to ease insertion and prevent migration. 
     
     
         26 . The method of  claim 19 , wherein the step of expanding the implant in the height direction is performed during the deploying step. 
     
     
         27 . The method of  claim 19 , wherein the step of expanding the implant in the height direction is performed after the deploying step. 
     
     
         28 . The method of  claim 19 , wherein the step of expanding the implant in the height direction includes sliding an implant part inside the second elongated articulating portion. 
     
     
         29 . The method of  claim 28 , wherein the part slides in the direction of the axis of the second elongated articulating portion toward the pivot. 
     
     
         30 . The method of  claim 19 , wherein a deployed height of the implant is at least 1.5 times a height of the implant in the insertion configuration.