Force limiting persuader-reducer

• US 20080221626A1
• Filed: 09/25/2007
• Published: 09/11/2008
• Est. Priority Date: 09/25/2006
• Status: Active Grant

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Stryker Spine
• Inventors: Butters, Joshua A., Fallin, T. Wade, Hays, Greta Jo, Pierce, Nathan, Esplin, Carson
• Granted Patent: US 8,979,848 B2
• Time in Patent Office: Days
• US Class Current: 606/86A
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7086 Rod reducers, i.e. devices providing a mechanical advantage to allow a user to force a rod into or onto an anchor head other than by means of a rod-to-bone anchor locking element; rod removers
• CPC Class Codes: A61B 2090/0811 for the position of a particular part of an instrument with respect to the rest of the instrument, e.g. position of the anvil of a stapling instrument
• CPC Class Codes: A61B 90/03 Automatic limiting or abutting means, e.g. for safety

Abstract

An apparatus and method for advancement of a spinal rod in a spinal implant, wherein the apparatus includes a body and a handle attached to the body. A shaft is slidably attached to the body, the shaft is coupled to the handle and has a first end adapted to engage the spinal rod. At least one retractor blade is attached to the body and the spinal implant. The operation of the handle results in the shaft persuading the spinal rod in the spinal implant. The force exerted by the shaft on the spinal rod is limited to a pre-selected force. The apparatus can also be operated in a non-limiting mode when a reduction retractor blade is used.

Claims

1. An apparatus for advancement of a spinal rod in a spinal implant, the apparatus comprising:

a body;

a handle attached to the body;

a shaft slidably attached to the body, the shaft being coupled to the handle and having a first end adapted engage the spinal rod; and

at least one retractor blade, the retractor blade having a third end adapted to attach to the body and a fourth end adapted to be attached to the spinal implant,

wherein the operation of the handle results in the shaft persuading the spinal rod in the spinal implant and wherein the force exerted by the shaft on the spinal rod is limited to a pre-selected force.

2. The apparatus of claim 1, further comprising:

a biasing member attached to the body; and

a movable carriage attached to the biasing member,

wherein the biasing member exerts the pre-selected force on the movable carriage.

3. The apparatus of claim 2, wherein the pre-selected force is less than 375 N.

4. The apparatus of claim 2, further comprising:

a bottom rocker plate, the bottom rocker plate adapted to lock the shaft such that the shaft is stopped from retracting from engagement with the spinal rod.

5. The apparatus of claim 4, further comprising:

indications formed on the shaft, the indications capable of indicating to the user that the spinal rod is fully seated in the spinal implant.

6. The apparatus of claim 4, further comprising:

a carriage lock, the carriage lock capable of unlocking the movable carriage to allow the force exerted by the shaft on the spinal rod to be limited to a pre-selected force.

7. A persuasion and reduction apparatus for advancement of spinal rod in a spinal implant, the apparatus comprising:

a body;

a handle attached to the body;

a shaft slidably attached to the body, the shaft being coupled to the handle and having a first end adapted engage the spinal rod; and

at least one reduction retractor blade or persuasion retractor blade, each retractor blade having a third end adapted to attach to the body and a fourth end adapted to be attached to the spinal implant,

wherein the apparatus limits the force exerted by the shaft on the spinal rod to a pre-selected force when the persuasion retractor blade is used and the apparatus allows the shaft to exert unlimited application of force on the spinal rod when the reduction retractor blade is used.

8. The apparatus of claim 7, further comprising:

a biasing member attached to the body; and

a movable carriage attached to the biasing member,

wherein the biasing member exerts the pre-selected force on the movable carriage.

9. The apparatus of claim 8, wherein the pre-selected force is less than 375 N.

10. The apparatus of claim 8, further comprising:

a bottom rocker plate, the bottom rocker plate adapted to lock the shaft such that the shaft is stopped from retracting from engagement with the spinal rod.

11. The apparatus of claim 10, further comprising:

indications formed on the shaft, the indications capable of indicating to the user that the spinal rod is fully seated in the spinal implant.

12. The apparatus of claim 10, further comprising:

a carriage lock, the carriage lock capable of locking the movable carriage to allow all the force applied to the handle to be transmitted to the spinal rod via the shaft.

13. A method of advancing a spinal rod in a spinal implant, the method comprising the steps of:

implanting a first spinal implant in a first vertebra;

implanting a second spinal implant in a second vertebra;

placing a rod in the first and the second implant;

attaching at least one persuasion retractor blade to the first vertebra;

attaching a persuading and reducing apparatus to the persuasion retractor blade; and

operating the handle on the persuading and reducing apparatus to advance a shaft and thereby persuade the rod in the first spinal implant, the shaft applying a force on the rod that is less than a pre-selected force.

14. The method of claim 13, further comprising the steps of:

attaching at least one reduction retractor blade to the second vertebra;

attaching the persuading and reducing apparatus to the reduction retractor blade; and

operating the handle on the persuading and reducing apparatus to advance a shaft and thereby advance the rod in the second spinal implant thereby reducing the second vertebra.

15. The method of claim 14, further comprising the steps of:

locking the shaft in the advanced position to hold the rod in the implant; and

inserting a screw in the first and the second spinal implant to hold the rod in place.

16. The method of claim 14, wherein the reduction retractor blade has a first end adapted to be coupled to the persuading and reducing apparatus and coupling of the first end of the retractor blade to the persuading and reducing apparatus automatically disables a force limiting function of the persuading and reducing apparatus.

17. An apparatus for advancement of a spinal rod in a spinal implant, the apparatus comprising:

a body having a handle and a shaft slidably attached to the body, wherein the operation of the handle results in the shaft persuading the spinal rod in the spinal implant; and

at least one first retractor blade, the first retractor blade having a first end adapted to attach to the body and a second end adapted to attach to the spinal implant,

wherein the first end operates to activate a force limiting mechanism such that a force exerted by the shaft on the spinal rod is limited to a pre-selected force.

18. The apparatus of claim 17, further comprising:

at least one second retractor blade, the second retractor blade having a third end adapted to attach to the body and a fourth end adapted to attach to the spinal implant,

wherein the second retractor blade, when used in place of the first retractor blade de-activates a force limiting mechanism such that all of a force exerted on the shaft is transmitted to the spinal rod.

19. The apparatus of claim 18, wherein the first retractor blade is made from aluminum and the second retractor blade is made from steel.

20. An apparatus for advancement of a spinal rod in a spinal implant, the apparatus comprising:

a body having a handle and a shaft slidably attached to the body, wherein the operation of the handle results in the shaft persuading the spinal rod in the spinal implant, the body being adapted to receive a first retractor blade that operates to activate a force limiting mechanism such that a force exerted by the shaft on the spinal rod cannot exceed a pre-selected force.

21. The apparatus of claim 20, wherein the body is adapted to receive a second retractor blade in place of the first retractor blade, the second retractor blade operates to de-activate a force limiting mechanism such that all of a force exerted on the shaft is transmitted to the spinal rod.

22. The apparatus of claim 20, wherein the first retractor blade is made from aluminum and the second retractor blade is made from steel.