Guide wire mounting collar for spinal fixation using minimally invasive surgical techniques

Abstract

An improved guide wire having a collar member for affixation to a pedicle screw, the guide wire assembly used in a system, set of instrumentation and method comprising the combination and use of plural pedicle screws, a rod for connecting pedicle screws in a relatively rigid manner, and instrumentation means to optimize insertion of the rod into the pedicle screws, such means comprising a guide wire and instrumentation to position the guide wire in the pedicle screws, whereby the guide wire is mounted to a pedicle screw, all the screws are implanted into the vertebrae, and the rod subsequently guided into the pedicle screws along the guide wire, all using minimally invasive surgical incisions.

Description

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/005,323, filed Dec. 4, 2007.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of systems, instrumentation and methodology for the fixation or fusing of vertebrae relative to each other, and more particularly relates to such systems, instrumentation and methodology that utilize pedicle screws affixed to vertebral pedicles and one or more rods that rigidly connect the pedicle screws of plural vertebrae. Even more particularly, the invention relates to such systems, instrumentation and methodology that utilize a guide wire inserted through the pedicle screws as a means to guide and locate a fixation or stabilization rod through the pedicle screws.

Traditional surgical techniques for affixing rods to vertebrae entail relatively long incisions to provide access to the vertebrae. Large bands of back muscles are stripped and pulled free from the spine (i.e., retracted) to provide access to the vertebrae. Newer techniques utilize single or multiple short or stab percutaneous incisions at chosen locations rather than a single long incision, with tubular cannulas being inserted to provide access pathways to the vertebrae. Such techniques are often referred to as minimally invasive surgery (MIS). The MIS techniques are preferable with regard to recovery time, since muscle retraction, muscle stripping and the like are minimized or obviated.

This MIS technique involves the insertion of pedicle screws into the vertebral pedicles. A pedicle is the strong, cylindrical, anatomic bridge between the dorsal spine elements and the vertebral body, and consists of a strong shell of cortical bone and a core of cancellous bone. Each vertebra has two pedicles and these provide a sturdy base to securely receive the threaded shaft of a pedicle screw. The pedicle screw may be a rigid member but most preferably comprises a slotted, rod-receiving head mounted in a swiveling or rotating manner to a threaded shaft, such as for example by the use of a ball and socket-type connection. Such screw structures are known in the art. Spinal fixation or fusion is accomplished by inserting pedicle screws into multiple vertebrae and connecting the screws to each other with a rigid rod secured to the receiving heads of the screws, thereby stabilizing the vertebrae.

In one MIS technique, a relatively small incision is made through the back to expose the vertebrae and pedicle screws are affixed to the pedicles of adjoining vertebrae using cannulated or tubular sleeve extenders. The rod is then transversely passed down through the sleeve extenders, laid into the slots of the receiving heads of the screws and secured using the set screws of the receiving heads, typically externally threaded members received by the internally threaded receiving heads. The rod joins all the pedicle screws and therefore the vertebrae in a fixed and rigid manner. Because the rod is inserted in a non-axial direction, there is still excessive damage to the muscles and other tissue because a slit must be provided, and recovery time is lengthened and healing pain is increased.

In another MIS technique, one or more short incisions or stab incisions are utilized for insertion of the pedicle screws. An example of this system is described in U.S. Pat. No. 7,1888,626, issued Mar. 13, 2007 to Foley et al., the disclosure of which is incorporated herein by reference. The sleeve extenders are joined and secured, and a swinging rod inserter is connected to this assembly of extenders. The rod inserter delivers a rod through the skin and tissue in an arced pathway and into the receiving heads of the pedicle screws. A problem with this system is that the pedicle screws are often not aligned in a linear manner and may also vary in height. The more out of alignment the receiving heads are, the more difficulty there is in using the swinging rod inserter to deliver the rod. Another problem with this system is that the rod is not restrained or guided along the insertion path in and between the pedicle screws.

In still another MIS technique, a guide wire, suture, cable or similar flexible member is first passed down through a sleeve extender and then through the pedicle screws. The leading end of the guide wire is then passed out through the last sleeve extender or through another incision. Examples of this technique are described in U.S. Pat. No. 6,821,277, issued Nov. 23, 2004 to Teitelbaum, and in U.S. Patent Application Publication No. 2008/0015582, published Jan. 17, 2008 in the name of DiPoto et al., the disclosure of both being incorporated herein by reference.

It is an object of this invention to provide an improved system having a guide wire, suture, cable or similar flexible member as part of a spinal fixation MIS procedure, the guide wire being connected to a collar member for ready mounting onto a pedicle screw.

SUMMARY OF THE INVENTION

An improved guide wire assembly as a component of a system, set of instrumentation and method comprising the combination and use of plural pedicle screws affixed to the pedicles of vertebrae, one or more rods for connecting pedicle screws to each other in a relatively rigid manner, and instrumentation means to direct insertion of the rod into the pedicle screws, such means comprising a guide wire and instrumentation to position the guide wire in and between the receiving heads of the pedicle screws, whereby the guide wire is positioned in and between the receiving heads of the pedicle screws implanted into the vertebrae, and the rod subsequently mounted onto the free end of the guide wire and inserted through the skin and tissue in a generally axial direction and guided into the receiving heads of the pedicle screws along the guide wire, all using minimally invasive surgical incisions. The rod is then secured to the pedicle screws using setscrews that mate with the receiving heads of the pedicle screws.

The improved guide wire is provided with connection means that allows the guide wire to be easily mounted onto any standard pedicle screw or other instrumentation, such as for example a ring or collar member that is slipped onto the threaded shaft of the screw beneath the receiving head prior to insertion of the screw into the pedicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view showing representative prior art pedicle screws, sleeve extenders and a fixation rod.

FIG. 2 is an exploded view showing the guide wire and collar member in relation to a pedicle screw.

FIG. 3 is view of an alternative embodiment for the collar member and guide wire.

FIG. 4 is a view showing insertion of the fixation rod along the guide wire and into the pedicle screws.

FIG. 5 is a view showing the fixation rod secured in place on the pedicle screws with the remainder of the guide wire cut off.

DETAILED DESCRIPTION OF THE INVENTION

In general, the invention comprises an improved guide wire having a mounting collar that is used with a system, set of instrumentation and method comprising the combination and use of plural pedicle screws implanted into vertebrae, at least one rod for connecting and bridging the pedicle screws and vertebrae in a relatively rigid manner, and instrumentation means to optimize insertion of the rod into the pedicle screws, such means comprising a guide wire and instrumentation to position the guide wire in the pedicle screws, whereby the screws are implanted into the vertebrae, the guide wire positioned in the screws and the rod subsequently guided into the pedicle screws along the guide wire, all using minimally invasive surgical (MIS) incisions.

Pedicle fixation in MIS is accomplished by creating a single incision or multiple, relatively short, percutaneous incisions, such incisions for example being less than 10 millimeters in length for stab incisions or from about 2 to 4 centimeters in length for standard scalpel incisions, as opposed to creating a long incision, often referred to as an open incision, which may cover 10 or more centimeters. The MIS incisions allow for pedicle screws 11 to be inserted into each desired vertebral pedicle by cutting or making one or multiple short incisions, temporarily positioning tubular distraction cannulas to provide access through the tissue to each of the vertebral pedicles, drilling into the vertebra and inserting a threaded pedicle screw 11 using a drive tool and/or a screw sleeve extender or tower 12. Most preferably, the pedicle screws 11 utilized in this invention comprise a threaded shaft 31 extending from a rod-receiving head 32, the head 32 having opposing slots 33, and rod-securing members 34, such as an externally threaded set screw mating with internal threads of the rod-receiving head 32, wherein the head 32 is mounted to the shaft 31 in a manner that allows the head 32 to swivel and rotate. With this structure, the head slots 33 can be aligned to better receive the fixation rod 22 after the screws 11 have been implanted into the vertebrae. The sleeve extenders 12 are temporarily connected to the pedicle screws 11 and are removed once the fixation rod 22 has been secured to the pedicle screws 11. The sleeve extenders 12 are tubular members preferably having opposing longitudinal slots 16 at least at their distal ends. Most preferably, the slots 16 extend over the majority of the length of the sleeve extenders 12 with only short. bridging sections 17 provided, whereby for example the profile of the sleeve extender 12 is that of an “H” when viewed laterally through aligned slots 16. Such devices, instrumentation and techniques are known in the art, and an illustration is provided as FIG. 1 herein.

A braided guide wire, cable, suture or similar flexible member 13, preferably or stainless steel or titanium, is provided, the guide wire 13 being of sufficient length to extend through all of the implanted pedicle screws 11 and the out through the skin of the patient. The guide wire 13 is preferably provided with a short lead or tip member 14 on one end in order to facilitate threading the wire 13 through the pedicle heads 32. One end of the guide wire 13, to be referred to as the affixed. end 18, is attached to a collar or ring member 35 that receives the shaft 31 of the pedicle screw 11, such that the collar member 35 is positioned adjacent the head 32 of the first or outermost of the implanted pedicle screws 11 and is held in place between the head 32 and the vertebra. The collar member 35, which is preferably annular but may also be C-shaped, is placed onto the shaft 31 prior to implantation of the pedicle screw 11. The guide wire 13 may be permanently affixed. to the ring member 35, as shown in FIG. 2, or may be joined in a releasable manner, such as shown in FIG. 3, where the affixed end 18 of the wire 13 is provided with a hook member 36 that is temporarily secured to an eyelet 37 on the ring member 35.

The guide wire 13 is then threaded in known manner such that it extends through all the pedicle slots 33 and between the pedicle screw heads 32 with its free end 19 disposed externally to the patient. The lead member 14 may be curved to better accomplish this. The cannulated fixation rod 22 is then passed through the pedicle screws 11 using the guide wire 13 to generally direct its movement through the screws 11, as shown in FIG. 4. The guide wire 13 is then cut at the end of the rod 22 and the free end 19 portion removed, with the remaining portion left within the patient, as shown in FIG. 5, or the wire 13 is cut adjacent the affixed end 18 and the majority of the wire 13 is removed, or the wire 13 is released by removing the hook 36 from the collar eyelet 37 and the full length of guide wire 13 is removed.

It is understood that equivalents and substitutions to certain elements and steps set forth above may be obvious to those skilled in the art, and therefore the true scope and definition of the invention is to be as set forth in the following claims.

Claims

1. In a spinal fixation system comprising the combination of plural pedicle screws affixed to the pedicles of vertebrae, said pedicle screws having receiving heads, a fixation rod connecting said pedicle screws to each other in a relatively rigid manner, and a guide wire directing insertion of said fixation rod into said pedicle screws, wherein said guide wire is positioned in and between said receiving heads of said pedicle screws implanted into the vertebrae, whereby said rod is mounted onto said guide wire and inserted through skin and tissue in a generally axial direction and guided into said receiving heads of said pedicle screws along said guide wire, and rod securing members that mate with said receiving heads of said pedicle screws, whereby said rod is secured to said pedicle screws using said rod securing members;

the improvement comprising a collar member adapted to receive one of said pedicle screws, said collar member being connected to said guide wire, whereby said collar member is mounted to said one of said pedicle screws prior to affixation of said one of said pedicle screws.

2. The improvement of claim 1, wherein said guide wire is permanently connected to said collar member.

3. The improvement of claim 1, wherein said guide wire is releasably connected to said collar member.

4. The improvement of claim 3, wherein said collar member comprises an eyelet and said guide wire comprises a hook member.

5. A spinal fixation system comprising the combination of plural pedicle screws affixed to the pedicles of vertebrae, said pedicle screws having receiving heads, a fixation rod connecting said pedicle screws to each other in a relatively rigid manner, a guide wire directing insertion of said fixation rod into said pedicle screws, a collar member connected to said guide member, wherein said collar member is mounted onto one of said pedicle screws and further wherein said guide wire is positioned in and between said receiving heads of said pedicle screws implanted into the vertebrae, whereby said rod is mounted onto said guide wire and inserted through skin and tissue in a generally axial direction and guided into said receiving heads of said pedicle screws along said guide wire, and rod securing members that mate with said receiving heads of said pedicle screws, whereby said rod is secured to said pedicle screws using said rod securing members.

6. The system of claim 5, wherein said guide wire is permanently connected to said collar member.

7. The system of claim 5, wherein said guide wire is releasably connected to said collar member.

8. The system of claim 7, wherein said collar member comprises an eyelet and said guide member comprises a hook member.

9. A spinal fixation assembly comprising the combination of plural pedicle screws affixed to the pedicles of vertebrae, said pedicle screws having receiving heads, a fixation rod connecting said pedicle screws to each other in a relatively rigid manner, a guide wire, and a collar member connected to said guide wire and mounted onto one of said pedicle screws, said guide wire positioned in and between said receiving heads of said pedicle screws, and rod securing members that mate with said receiving heads of said pedicle screws, whereby said rod is secured to said pedicle screws using said rod securing members.

10. The assembly of claim 9, wherein said guide wire is permanently connected to said collar member.

11. The assembly of claim 9, wherein said guide wire is releasably connected to said collar member.

12. The assembly of claim 11, wherein said guide wire further comprises an eyelet disposed in said collar member and a hook member.