Pedicle screw assembly and methods therefor

Abstract

A method for stabilizing a spine includes providing a coupling element having upper and lower ends, a rod receiving opening adapted to receive an elongated stabilizing rod, a bone extending through the lower end and a conical-shaped seat surrounding the bore adjacent the lower end; providing a fastener having upper and lower ends, a head having a radial surface, and at least one anchoring element between the lower end of the fastener and the head; assembling the fastener with the coupling element so that the lower end of the fastener passes through the bore of the coupling element and the radial surface of the head engages the conical-shaped seat. The method also includes anchoring the fastener to bone; moving the coupling element relative to the fastener for capturing the elongated stabilizing rod in the rod receiving opening; and urging the captured stabilizing rod toward the head of the fastener so that the rod contacts the head and forces the radial surface of the head against the conical-shaped seat of the coupling element for locking the coupling element from further movement relative to the fastener.

1 . (canceled) 
     
     
         2 . A stabilizing assembly comprising:
 a stabilizing rod,   a fastener having
 an upper end and a lower end, 
 a head at the upper end, said head including a center and at least a portion of said head having a radius of curvature from the center of the head, 
 a body with a diameter and a plurality of threads, wherein the diameter tapers from the upper end to the lower end and the plurality of threads have a first depth at the upper end and a second depth at the lower end such that the diameter of the fastener remains constant from the upper end to the lower end; and 
   a coupling element having
 an outer surface, an interior wall having a diameter, an upper end and a lower end, 
 a rod receiving opening adapted to receive the stabilizing rod, 
 a bore extending through the lower end for receiving said fastener, 
 a cavity adjacent to said lower end, and 
 a seat. 
   
     
     
         3 . The stabilizing assembly of  claim 2 , wherein the portion of said head of the fastener having the radius of curvature includes an underside of said head, the radius of curvature defining a first radius. 
     
     
         4 . The stabilizing assembly of  claim 3 , wherein said head further comprises a top side, the top side having a second radius of curvature from the center defining a second radius. 
     
     
         5 . The stabilizing rod of  claim 4 , wherein the first radius is larger than the second radius. 
     
     
         6 . The stabilizing assembly of  claim 2 , wherein the seat of said coupling element includes inwardly tapering conical-shaped sidewalls. 
     
     
         7 . The stabilizing assembly of  claim 2 , wherein said coupling element includes one or more cuts between the rod-receiving opening and the outer surface. 
     
     
         8 . The stabilizing assembly of  claim 2 , further comprising an annular lip located between the upper end of said coupling element and the seat of said coupling element, said annular lip having a radius less than the radius of curvature of said portion of said head, wherein the annular lip prevents the fastener from passing into the upper end. 
     
     
         9 . The stabilizing assembly of  claim 2 , further comprising a locking element associated with said coupling element to apply a force upon a stabilizing rod positioned in said rod receiving opening, wherein said stabilizing rod is in direct contact with and applies a force upon the head for forcing the head against the seat for preventing further pivotal and rotational movement of said fastener and said coupling element relative to one another. 
     
     
         10 . A method for stabilizing a bone structure comprising:
 providing a fastener, a coupling element, and a stabilizing rod;   said fastener having   an upper end and a lower end,   a head at the upper end, said head including a center and at least a portion of said head having a first radius of curvature from the center of the head, and   at least one anchoring element between the upper and lower ends thereof; and   said coupling element having   an outer surface, an interior wall having a diameter, an upper end and a lower end,   a rod receiving opening adapted to receive said stabilizing rod,   a bore extending through the lower end for receiving said fastener,   a cavity adjacent to said lower end,   a seat, and   an annular lip located between the upper end of said coupling element and the seat of said coupling element wherein said annular lip has a diameter less than the diameter of said interior wall and a diameter of an adjacent portion of said cavity,   anchoring said fastener to bone;   moving said coupling element to capture said stabilizing rod in said rod receiving opening;   urging said stabilizing rod against said head to force the portion of the head having the radius of curvature against the seat of said coupling element.   
     
     
         11 . The method of  claim 10 , wherein the head is between the annular lip and the seat prior to the urging step. 
     
     
         12 . The method of  claim 10 , wherein the moving the coupling element step comprises engaging at least two parallel grooves formed on the outer surface of the coupling element with a tool. 
     
     
         13 . The method of  claim 10 , wherein the fastener has a neck having a reduced diameter between the head of said fastener and the lower end,
 wherein the neck is within the bore prior to the urging step.   
     
     
         14 . The method of  claim 13 , wherein during the moving step, the neck allows greater mobility of the coupling element with respect to the fastener. 
     
     
         15 . The method of  claim 10 , further comprising providing a locking element associated with said coupling element,
 applying a force upon said stabilizing rod positioned in said rod receiving opening with said locking element,   wherein said stabilizing rod applies a force upon the head for forcing the head against the seat for preventing further pivotal and rotational movement of said fastener and said coupling element relative to one another.   
     
     
         16 . A method of stabilizing a bone structure comprising:
 providing a fastener, a coupling element, a stabilizing rod, and a driver;   wherein the fastener has an upper end and a lower end,   a head at the upper end, the head including a center and at least a portion of the head having a radius of curvature from the center of the head;   wherein the coupling element has an outer surface, an upper end and a lower end,   a rod receiving opening adapted to receive a stabilizing rod,   a bore extending through the lower end for receiving the fastener,   internal threads, and   a seat;   wherein the driver has external shaft threads and is configured to couple to the fastener to insert the fastener into bone;   coupling the driver to the fastener and coupling the internal threads of the coupling element to the external threads of the driver;   anchoring the fastener to bone;   decoupling the driver from the coupling element;   moving the coupling element to capture the stabilizing rod in the rod receiving opening; and   urging the stabilizing rod against the head of the fastener to force the portion of the head having a radius of curvature against the seat of said coupling element.   
     
     
         17 . The method of  claim 16 , wherein the driver has prongs extending from a first end and the fastener has grooves formed on an exterior surface of the head, and
 wherein the coupling the driver to the fastener step includes inserting the prongs into the grooves.   
     
     
         18 . The method of  claim 16 , wherein the fastener has a neck having a reduced diameter between the head of said fastener and the lower end,
 wherein prior to the moving step the neck is within the bore, and   wherein the neck allows greater mobility of the coupling element with respect to the fastener.   
     
     
         19 . The method of  claim 16 , wherein the moving the coupling element step comprises engaging at least two parallel grooves formed on the outer surface of the coupling element with a tool. 
     
     
         20 . The method of  claim 16 , further comprising providing a locking element associated with said coupling element,
 applying a force upon said stabilizing rod positioned in said rod receiving opening with said locking element,   wherein said stabilizing rod applies a force upon the head for forcing the head against the seat for preventing further pivotal and rotational movement of said fastener and said coupling element relative to one another.   
     
     
         21 . The method of  claim 20 , wherein the coupling element has external threads configured to mate with the internal threads of the coupling element and the applying a force upon said stabilizing rod step comprises
 coupling the external threads of the locking element to the internal threads of the coupling element, and   rotating the locking element to advance the locking element toward the seat.