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 bore 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. A method for stabilizing a spine comprising: providing a coupling element having upper and lower ends, a rod receiving opening adapted to receive an elongated stabilizing rod, a bore extending through the lower end and a conical-shaped seat surrounding said bore adjacent the lower end; providing and a fastener having upper and lower ends, a head having a radial surface, and at least one anchoring element between the lower end of said fastener and the head; assembling, wherein said fastener is assembled with said coupling element so that the lower end of said fastener passes through the bore of said coupling element and the radial surface of said head engages the conical-shaped seat;
 anchoring said fastener to bone; 
 moving said coupling element relative to said fastener for capturing said elongated stabilizing rod in the rod receiving opening; 
 urging said captured stabilizing rod toward the head of said fastener so that said rod contacts said head and forces the radial surface of said head against the conical-shaped seat of said coupling element for locking said coupling element from further movement relative to said fastener. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the urging step comprises:
 providing a locking element associated with said coupling element; 
 using said locking element in cooperation with said coupling element to apply a force upon said stabilizing rod positioned in said rod receiving opening. 
 
     
     
       3. The method as claimed in  claim 2 , wherein said coupling element has threads extending from the upper end thereof toward the lower end thereof and said locking element has threads adapted for mating with the threads of said coupling element during the urging step. 
     
     
       4. The method, as claimed in  claim 3 , wherein said coupling element has internal threads formed on an interior surface thereof and said locking element has external threads. 
     
     
       5. The method as claimed in  claim 3 , wherein said coupling element has external threads formed on an external surface thereof and said locking element has internal threads. 
     
     
       6. The method as claimed in  claim 1 , wherein said coupling element and said fastener are made from a material selected from the group consisting of titanium and stainless steel. 
     
     
       7. The method as claimed in  claim 1 , wherein said fastener is a screw fastener and the at least one anchoring element comprises screw threads extending between the upper and lower ends thereof. 
     
     
       8. The method as claimed in  claim 1 , wherein the at least one anchoring element comprises a hook at the lower end of said fastener. 
     
     
       9. A method of stabilizing a spinal column comprising:
 providing a fastener including a bone anchoring element and a head having a first radial surface with a first radius at an underside thereof and a second radial surface with a second radius at a top side thereof, wherein the first radius at the underside is greater than the second radius at the top side; providing and a coupling element having upper and lower ends, a rod receiving opening adapted to receive an elongated rod, a bore extending through the lower end of said coupling element, and a conical-shaped seat; assembling said fastener with said coupling element so that, wherein said fastener passes is sized to pass through said bore with the first radial surface at the underside of said head opposing the conical-shaped seat; 
 anchoring said fastener to bone; 
 after the anchoring step, moving said coupling element for capturing said elongated rod in the rod receiving opening; 
 urging said elongated rod against said head of said fastener for forcing the first radial surface of said head against the conical-shaped seat of said coupling element for locking said coupling element from further movement relative to said fastener. 
 
     
     
       10. The method as claimed in  claim 9 , wherein said coupling element includes an exterior surface having one or more notches formed therein, and wherein the moving step includes engaging said notches with a gripping tool. 
     
     
       11. The method as claimed in  claim 9 , wherein the urging step includes using a locking element in association with said coupling element for forcing said stabilizing rod against the second radial surface of said head which in turn forces the first radial surface of said head against, the conical-shaped seat of said coupling element for preventing said coupling element and said fastener from pivoting and rotating relative to one another. 
     
     
       12. The method as claimed in  claim 9 , wherein said fastener includes screw threads extending between upper and lower ends thereof. 
     
     
       13. The method as claimed in  claim 9 , wherein said fastener includes a hook. 
     
     
       14. A method of stabilizing a vertebral column comprising:
 providing a coupling element having upper and lower ends, a rod receiving opening adapted for receiving an elongated stabilizing rod, an exterior surface, an interior surface defining a central bore extending through the lower end thereof, and a conical-shaped seat adjacent the lower end; providing, and a fastener having upper and lower ends, at least one anchoring element between the upper and lower ends, and a head at the upper end having a radial surface and assembling said fastener with said coupling element so that the radial surface of said head engages the conical-shaped seat and the to engage to conical-shaped seat and the lower end of said fastener passes is sized to pass through said central bore; 
 anchoring the lower end of said fastener to vertebral bone; 
 after the anchoring step, moving said coupling element to capture said stabilizing rod in the rod receiving opening; 
 utilizing a locking element in association with said coupling element to urge said stabilizing rod into direct engagement with the head of said fastener for forcing the radial surface of said head against the conical-shaped seat of said coupling element for preventing further movement of said coupling element and said fastener relative to one another. 
 
     
     
       15. The method as claimed in  claim 14 , wherein said fastener is a screw fastener and said anchoring element comprises screw threads. 
     
     
       16. The method as claimed in  claim 14 , wherein said coupling element and said fastener are made of materials selected from the group consisting of titanium and stainless steel. 
     
     
       17. The method as claimed in  claim 15 , wherein said coupling element has threads extending from the upper end toward the lower end thereof and said locking element has threads adapted for meshing with the threads of said coupling element. 
     
     
       18. The method as claimed in  claim 14 , wherein the head of said fastener includes at least one groove extending from the top surface toward the underside thereof, said at least one groove being adapted for receiving a driver for inserting said fastener into bone. 
     
     
       19. The method as claimed in  claim 18 , wherein said at least one groove includes a plurality of grooves spaced apart from one another. 
     
     
       20. The method as claimed in  claim 19 , wherein the anchoring step comprises:
 providing a driver having a shaft with a lower end and a plurality of prongs extending from the lower end; 
 inserting the prongs into the grooves of said head; 
 rotating said driver for driving said fastener into the vertebral bone. 
 
     
     
       21. A stabilizing assembly comprising:
 a fastener having an upper end and a lower end, a head at the upper end, and at least one anchoring element between the upper and lower ends thereof;   said head including a center, an underside including a first radial surface and a top side including a second radial surface, wherein said first radial surface defines a first radius from the center of said head and said second radial surface defines a second radius from the center of said head; and   a coupling element having an upper end and a lower end, said coupling element including a rod receiving opening adapted to receive a stabilizing rod, a bore extending through the lower end of said coupling element for receiving said fastener, a seat adjacent the lower end of said coupling element, and an annular lip having a diameter less than twice the first radius of said head between the upper end and the seat of said coupling element, wherein the annular lip prevents the fastener from passing into the upper end, and wherein the stabilizing rod contacts the top side of said head so that the stabilizing rod forces the underside of said head against the seat of said coupling element.   
     
     
       22. The stabilizing assembly as claimed in claim 21, wherein the first radius of the first radial surface of said head is greater than the second radius of the second radial surface. 
     
     
       23. The stabilizing assembly as claimed in claim 21, wherein the seat of said coupling element includes inwardly tapering conical-shaped sidewalls. 
     
     
       24. The stabilizing assembly as claimed in claim 21, wherein said coupling element includes one or more cuts between the rod-receiving opening and the exterior surface thereof. 
     
     
       25. The stabilizing assembly as claimed in claim 24, wherein one or more notches are formed on the exterior surface of said coupling element. 
     
     
       26. The stabilizing assembly as claimed in claim 25, wherein the anchoring element of said fastener comprises screw threads and said fastener includes a neck having a reduced diameter between the head and the screw threads. 
     
     
       27. A stabilizing assembly comprising:
 a fastener having an upper end and a lower end, a head at the upper end, and at least one anchoring element between the upper and lower ends thereof, said head including a center and an underside defining a first radius from the center of said head;   a coupling element having an upper end and a lower end, said coupling element including a rod receiving opening adapted to receive a stabilizing rod, a bore extending through the lower end of said coupling element for receiving said fastener, a seat adjacent the lower end of said coupling element, and an annular lip located between the upper end of said coupling element and the seat of said coupling element, said annular lip having a diameter less than twice the first radius of said head, wherein the annular lip prevents the fastener from passing into the upper end, and wherein said coupling element includes one or more cuts between the rod-receiving opening and the exterior surface thereof for minimizing the width of said coupling element.   
     
     
       28. The stabilizing assembly as claimed in claim 27, wherein the underside of said head includes a first radial surface and a top side of said head includes a second radial surface, wherein said first radial surface defines the first radius from the center of said head and the second radial surface defines a second radius from the center of said head. 
     
     
       29. The stabilizing assembly as claimed in claim 28, wherein the first radius of the first radial surface of said head is greater than the second radius of the second radial surface of said head. 
     
     
       30. The stabilizing assembly as claimed in claim 27, wherein the stabilizing rod contacts a top side of said head so that the stabilizing rod forces an underside of said head against the seat of said coupling element. 
     
     
       31. A stabilizing assembly comprising:
 a fastener having an upper end and a lower end, a head at the upper end, and at least one anchoring element between the upper and lower ends thereof;   said head including a center, an underside including a first radial surface, wherein said first radial surface defines a first radius from the center of said head; and   a coupling element having an upper end and a lower end, said coupling element including a rod receiving opening adapted to receive a stabilizing rod, a bore extending through the lower end of said coupling element for receiving said fastener, a conical-shaped seat adjacent the lower end of said coupling element, and one or more cuts between the rod-receiving opening and the exterior surface thereof for minimizing the width of said coupling element, and wherein the stabilizing rod contacts the top side of said head so that the stabilizing rod forces the underside of said head against the seat of said coupling element.   
     
     
       32. A method for stabilizing a spine comprising: providing a coupling element having upper and lower ends, a rod receiving opening adapted to receive an elongated stabilizing rod, a bore extending through the lower end and a conical-shaped seat surrounding said bore adjacent the lower end, and an annular lip, and a fastener having upper and lower ends, a head having a radial surface, and at least one anchoring element between the lower end of said fastener and the head, the lower end of said fastener is sized to pass through the bore of said coupling element and the radial surface of said head engages the conical-shaped seat, wherein said annular lip having a diameter less than twice the first radius of said head between the upper end and the seat of said coupling element, wherein the annular lip prevents the fastener from passing into the upper end;
 anchoring said fastener to bone;   moving said coupling element relative to said fastener for capturing said elongated stabilizing rod in the rod receiving opening;   urging said captured stabilizing rod toward the head of said fastener so that said rod contacts said head and forces the radial surface of said head against the conical-shaped seat of said coupling element for locking said coupling element from further movement relative to said fastener.