Tissue protector and method of use

Abstract

A tissue protector has a body structure having a longitudinal extending thin web. The body structure has an unconstrained first shape configured to form a nerve shield and is configured to shrink about a longitudinal axis to a smaller constrained second shape sized to fit into a lumen of a cannula. Preferably, the second constrained shape is oval or round having a maximum diameter equal or less than an inside diameter of the lumen. The body structure is configured to return to the first shape when the cannula is withdrawn or returned to this shape as the implant advances.

What is claimed is: 
     
         1 . A tissue protector comprises:
 a body structure having a longitudinal extending thin web, the body structure having an unconstrained first shape configured to form a tissue protector and is configured to shrink about a longitudinal axis to a smaller constrained second shape sized to fit into a lumen of a cannula.   
     
     
         2 . The body structure of  claim 1  wherein the second constrained shape is oval or round having a maximum diameter equal or less than an inside diameter of the lumen. 
     
     
         3 . The tissue protector of  claim 1  wherein the body structure is configured to return to the first shape when the cannula is withdrawn from between two adjacent vertebral bodies and the body structure is held in position. 
     
     
         4 . The tissue protector of  claim 3  wherein the web is configured to shield a nerve root. 
     
     
         5 . The tissue protector of  claim 4  wherein the unconstrained first shape of the web is sized to receive a spinal implant for insertion between the two vertebral bodies. 
     
     
         6 . The tissue protector of  claim 5  wherein the web forms a guide and a shield for the spinal implant. 
     
     
         7 . The tissue protector of  claim 6  wherein the web has a thin oval or circular cross section in the unconstrained first shape. 
     
     
         8 . The tissue protector of  claim 6  wherein the web has a channel or “U” cross section in the unconstrained first shape. 
     
     
         9 . The body structure of  claim 1  further comprises:
 a pair of rails on each lateral end or side of the web, the web being interposed between said rails. 
 
     
     
         10 . The body structure of  claim 9  wherein the body structure is configured to return to the first shape when the cannula is withdrawn from between two adjacent vertebral bodies and the body structure is held in position. 
     
     
         11 . The tissue protector of  claim 5  wherein the rails when unconstrained have at least one rail shielding a nerve root. 
     
     
         12 . The tissue protector of  claim 6  wherein the rails are spaced by the web when the body structure is in the unconstrained first shape a lateral distance to receive a spinal implant. 
     
     
         13 . The tissue protector of  claim 7  wherein the pair of rails are configured to guide a spinal implant during insertion while at least one of said rails shields the nerve root. 
     
     
         14 . The body structure of  claim 9  wherein the rails are enlarged longitudinally extending projections. 
     
     
         15 . The body structure of  claim 14  wherein the rails have a round or at least partially round cross section. 
     
     
         16 . The tissue protector of  claim 12  wherein the rails have a round or at least partially round cross section. 
     
     
         17 . The tissue protector of  claim 12  wherein the web has a thin rectangular cross section in the unconstrained first shape. 
     
     
         18 . A method of shielding a nerve root during a spinal surgical procedure comprises the steps of:
 making an incision;   inserting a cannula between or just above two adjacent vertebral bodies, wherein the cannula has a tissue protector constrained inside the lumen of the cannula;   positioning the distal end of the cannula past or beside a nerve root;   withdrawing the cannula while holding the tissue protector in position past or beside the nerve root; and   freeing the tissue protector allowing movement from a constrained shape to an unconstrained shape to protect and shield the nerve root.   
     
     
         19 . The method of  claim 18  further comprising:
 inserting a spinal implant using the unconstrained tissue protector as a guide to position the implant between two vertebral bodies.