Low profile pedicle screw and rod assembly

• US 20060276792A1
• Filed: 05/25/2006
• Published: 12/07/2006
• Est. Priority Date: 05/25/2005
• Status: Active Grant

• Current Assignee: K2M, Inc (Stryker Corporation)
• Original Assignee: K2M, Inc (Stryker Corporation)
• Inventors: Hawkes, David T., Ensign, Michael D.
• Granted Patent: US 8,100,947 B2
• Time in Patent Office: Days
• US Class Current: 606/264
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped

Abstract

A pedicle screw and rod assembly is provided which has a low profile in the final assembled position. The pedicle screw includes a screw having a threaded portion and a head portion. A tulip is positioned on the head portion of the screw. A fastener assembly is coupled to the tulip and positioned to retain the tulip on the head portion. A rod retainer member is positioned inside the tulip and grips the rod, to hold it in position relative to the tulip assembly and pedicle screw. The top of rod retaining member is approximately equal in height to, or lower than the rod itself. This provides a low profile pedicle screw and rod assembly since the rod itself will normally be the uppermost member of the completed assembly.

Claims

1. A pedicle screw and rod assembly comprising:

a screw having a threaded portion and a head portion;

a tulip positioned on the head portion of the screw;

a fastener assembly coupled to the tulip and positionable to retain the tulip on the head portion;

a rod retaining member coupled to the tulip, the rod retaining member having a gripping region; and

a rod coupled to the gripping region of the rod retaining member;

wherein the gripping region of the rod retaining member is configured to dispose the uppermost portion of the rod further from the head portion of the screw than an upper portion of the rod retaining member when the rod retaining member is engaged.

2. The pedicle screw assembly of claim 1 wherein the fastener assembly comprises a compression ring configured to be coupled to at least a part of the head portion of the screw.

3. The pedicle screw assembly of claim 2 wherein the compression ring comprises a split in the ring that permits the diameter of the ring to vary from a first, larger diameter to a second, smaller diameter.

4. The pedicle screw assembly of claim 1 further comprising an engaging tab on the fastener assembly that engages the rod retaining member, the tab being moveable from an engaging position to a non-engaging position to couple the rod retaining member to the pedicle screw.

5. The pedicle screw assembly of claim 1 wherein the tulip includes an internal wall region with a recess, the recess being shaped to receive the fastener assembly and the rod retaining member.

6. The pedicle screw of claim 5 wherein the recess extends from a top region of the tulip to a lower region of the tulip and is sized to permit a substantial portion of the fastener assembly and the rod retaining member to fit within the internal walls of the tulip when the rod is attached to the rod retaining member.

7. The pedicle screw assembly according to claim 1 wherein the rod retaining assembly is moveable from a first extended position in which a substantial part of the rod retaining assembly is outside the tulip to a second depressed position in which a substantial portion of the rod retaining assembly is positioned within the tulip.

8. A pedicle screw and rod assembly for securing a rod, comprising:

a screw having a threaded portion and a head portion;

a tulip positioned on the head portion of the screw, the tulip being configured to couple the rod, the tulip including at least one side orifice providing access to an inner cavity of the tulip;

a fastener assembly associated with the tulip, the fastener assembly being positioned adjacent the head portion of the screw to retain the tulip assembly on the screw; and

a rod retaining member coupled to the tulip, the rod retaining member having a gripping region for holding the rod in a fixed position relative to the tulip, the gripping region being positioned such that a top most portion of the rod retainer assembly being approximately equal to or less than the height of the top most portion of the rod when coupled in the gripping region.

9. The pedicle screw and rod assembly of claim 8 further comprising:

an engaging tab on the fastener that couples the fastener to the rod retaining member to couple the rod retaining member to the tulip;

the engaging tab engaging the side orifice when unengaged.

10. The pedicle screw and rod assembly of claim 9, further comprising:

an engagement tool including an outer housing configured to engage an outer wall of the tulip; and

at least one protrusion extending from an inner wall of the outer housing, the at least one protrusion being sized to enter the side orifice and release the engagement tab from interfering with the side orifice.

11. A pedicle screw system comprising:

a screw having threads and a head;

a tulip coupled to the screw;

a fastener internal to the tulip and positioned to couple the tulip to the screw;

a rod retaining assembly having a substantial portion of the rod retaining assembly internal to the tulip.

12. The pedicle screw system according to claim 11, wherein the top most portion of the rod retaining assembly is approximately at the same height at the top most portion of the tulip assembly.

13. The pedicle screw system according to claim 11, wherein the rod retaining assembly includes at least one split that permits the diameter of the rod retainer assembly to vary from a first, large diameter to a second, small diameter.

14. The pedicle screw system according to claim 11, wherein the fastener includes at least one split that permits the diameter of the fastener to vary from a first, large diameter to a second, small diameter.

15. The pedicle screw system according to claim 11, further including a coupling tab member between the fastener and the rod retainer assembly to couple the fastener and the rod retainer assembly to each other within the tulip.

16. A method of connecting a rod to a pedicle screw assembly comprising:

threading a screw having a head into bone of a patient;

attaching a tulip assembly to the head of the screw;

moving a fastener from a first position within the tulip to a second position within the tulip to connect the tulip to the screw;

placing a rod into a gripping portion of a rod retaining member that is coupled to the tulip;

depressing the rod retaining member with the rod connected to it into the tulip until the top of the rod retaining member is equal to or slightly above the top of the tulip, thereby locking the rod in the tulip assembly.

17. The method according to claim 16 wherein the step of depressing the rod retaining member into the tulip causes the rod retaining member to apply a gripping pressure on the rod, to retain the rod in a fixed position.

18. The method according to claim 16 further comprising the step of depressing a tab on the fastener to release the rod retaining member from the fastener to permit the rod retaining member to be pressed into the tulip.

19. The method according to claim 18, further comprising:

inserting a locking tool into an aperture of the tulip to depress the tab and release the rod assembly from the retaining member.

20. The method according to claim 16, further comprising:

applying a pulling force on the tulip assembly after it is coupled to the pedicle screw to perform a spondy reduction on the patient prior to coupling the rod to the tulip assembly.

21. The method according to claim 16, wherein pressing the rod retainer member into the tulip moves the rod retainer along an internal wall of the tulip with a portion of the rod retaining member being pressed to a smaller diameter by the internal wall of the tulip to increase a gripping pressure on the rod.