Instrumentation and methods for performing distraction arthrodesis si joint fusion

Abstract

Devices and methods for generating fusion between two bones to promote healing are provided, including instrumentation and methods for performing distraction arthrodesis SI joint fusion. Said instruments include a joint finder, working cannula, and a plunger delivery device wherein implantation of a spacer to promote fusion does not require the spacer to be impacted with a hammer. Said methods include the steps of locating the entrance to the sacroiliac joint with a guide wire, distracting the joint with a joint finder, inserting a working cannula to hold the joint in a distracted state, drilling a cavity in the sacroiliac joint at the distal end of the working cannula, and inserting a spacer into the prepared cavity of said sacroiliac joint.

Description

[0001] INSTRUMENTATION AND METHODS FOR PERFORMING DISTRACTION ARTHRODESIS SI JOINT FUSION

[0002] Field of the Invention

[0003] The present invention relates to a device and method for generating fusion between two bones to promote healing. The invention finds particular utility in the ability to insert a distraction arthrodesis implant within the sacroiliac joint in a minimally invasive fashion so as to stabilize and promote fusion of the joint. While the invention has application throughout the body, its utility will be illustrated in the context of repair between two bony elements such as the pelvis and the sacrum.

[0004] Background

[0005] Orthopedic implants are used for a variety of disorders including age related degeneration, trauma, congenital and idiopathic deformities as well as pathologic fractures.

[0006] Non-surgical treatments, such as medication, rehabilitation and exercise can be effective, however, many fail to relieve the symptoms associated with these disorders. Surgical treatment of these disorders includes correction, fusion, and fixation using implantable devices. As pail of these surgical treatments, orthopedic constructs often use structural spacers, screws, cages or wedges to restore alignment and stabilize the surgical site in anticipation of healing or fusion.

[0007] In the field of orthopedics, it is common to join together two or more bones and hold them in place so as to minimize motion and promote healing or fusion across the bony elements. This is commonly accomplished using structural spacers, cages, wedges, or screws. Structural spacers, cages, or wedges (together referred to as “spacers”) are placed between two bony elements and act as a bridging element to provide structural support to the gap between the two bony elements while the two bones fuse. The adjacent bone may fuse onto, thru, or around the spacer.

[0008] In some cases, it is beneficial to use force to distract and create a gap between the two bones prior to inserting the spacer. Following distraction and insertion of the spacer, the distraction force is removed, and the ligaments connecting the two bones contract applying a compressive load on the spacer. This is referred to as ligamentotaxis, and the use of ligamentotaxis to promote fusion is referred to as distraction arthrodesis.

[0009] In orthopedics it is common to use a guidewire to find the entrance to a joint, and then use a joint finder to distract the joint. A working cannula fits over the joint finder and creates a pathway to implant the spacer while maintaining the joint distraction. Typically, a drill or broach is used to create a recessed cavity within the joint to accept the spacer. The spacer is then implanted using a mallet or hammer to drive the graft into the recess. This hammering force may damage the spacer if it is manufactured from allograft, autograft, or xenograft materials. Additionally, this force is uncomfortable for the patient and may cause adjacent trauma.

[0010] In the case of sacroiliac joint fusion, these procedures may be performed in doctors’ offices under light sedation, and patients may not tolerate the forces required to hammer in an implant while under light sedation. Thus, there exists a clinical need for orthopedic instruments to deliver spacers to a site within a joint without the need for a hammer or mallet to forcefully drive the implant. Summary

[0011] The present invention provides novel orthopedic instruments and a novel method of implantation of a spacer between two bony elements to enable fusion and healing. The method docs not utilize hammering forces to implant the spacer.

[0012] The spacer used with the novel orthopedic instruments may be autograft, allograft, xenograft, metallic, polymeric, or ceramic. The implant may have a round cross-section or a rectangular cross-section. It may have smooth sides or one or more anti-migration features.

[0013] The novel orthopedic instrumentations are designed to implant the spacer in a minimally invasive fashion. The instrumentation includes one or more guidewires, a joint finder, a working cannula, a drill bit, a plunger, a universal instrument handle, and a strike plate.

[0014] In one embodiment, the plunger has an external thread, and the working cannula has a mating internal thread. This allows the plunger to thread within the working cannula and convert rotational displacement to linear displacement to advance the spacer forward and out of the working cannula without the use of a hammer or other impaction device.

[0015] The disclosure contemplates all combinations of any one or more of the foregoing aspects and / or embodiments, as well as combinations with any one or more of the embodiments set forth in the detailed description and any examples.

[0016] Brief Description of the Drawings

[0017] FIG. 1 is a schematic drawing showing a spacer formed in accordance with the present invention. FIG. 1 A is a schematic drawing showing an alternative spacer formed in accordance with the present invention.

[0018] FIG. 2 is a schematic drawing showing the components of the novel instrument kit formed in accordance with the present invention.

[0019] FIG. 2A is a schematic drawing showing guide wires that are included in the instrument kit formed in accordance with the present invention.

[0020] FIG. 3 is a schematic drawing showing the joint finder formed in accordance with the present invention.

[0021] FIG. 3A is a schematic drawing showing the joint finder being inserted with the aid of a universal handle.

[0022] FIG. 3B is a schematic drawing showing an alternative configuration of the joint finder formed in accordance with the present invention.

[0023] FIG. 4 is a schematic drawing showing the working cannula formed in accordance with the present invention.

[0024] FIG. 4A is a schematic drawing showing the working cannula being inserted over the joint finder.

[0025] FIG. 4B is a schematic drawing showing an alternative working cannular formed in accordance with the present invention.

[0026] FIG. 5 is a schematic drawing showing a strike plate formed in accordance with the present invention. FIGS. 5A and 5B are schematic drawings showing the strike plate engaging with the working cannula formed in accordance with the present invention.

[0027] FIGS. 5C and 5D are schematic drawings showing an alternative strike plate and its engagement with the working cannula formed in accordance with the present invention.

[0028] FIGS. 6 and 6A are schematic drawings showing a drill bit formed in accordance with the present invention.

[0029] FIG. 7 is a plunger delivery device formed in accordance with the present invention.

[0030] FIGS. 8 and 8 A are schematics showing how the delivery device plunger and working cannula can be used to implant a spacer in accordance with the present invention.

[0031] FIG. 9 is a schematic showing how the strike plate can be used to aid in removal of the working cannula in accordance with the present invention.

[0032] FIG. 10 is a schematic shows an alternative method to remove the working cannula in accordance with the present invention.

[0033] FIGS. 11 through 15 are schematics showing the steps of inserting a spacer using the instruments presented in accordance with the present invention.

[0034] Detailed Description

[0035] Looking first at FIG. 1 there is shown a spacer 100 formed in accordance with the present invention. The spacer is round in cross-section. Spacer 100 may have a lead in chamfers 110 to aid in initial insertion. Additionally, spacer 100 may have a cannulation 120 allowing it to be inserted over a guide wire. It should be appreciated that spacer 100 may have anti-migration ridges or teeth to aid in initial fixation of the spacer.

[0036] In a preferred embodiment, spacer 100 is manufactured from allograft bone. Spacer 100 may be 100% cortical bone, 100% cancellous bone, or a combination of both. Allograft spacer 100 may have one or more cortical surfaces 130 and have a cancellous midsection.

[0037] In an alternative preferred embodiment and now looking at FIG. 1A, spacer 100 is manufactured from allograft bone. Spacer 100 is cylindrical in nature and has a central cannulation 120. The spacer has a single cortical surface 130. The remainder of spacer 140, is made from dense cancellous bone.

[0038] In a preferred embodiment, spacer 100 has a diameter between 7mm and 15mm, and most preferably a diameter between 7 and 10mm. In a preferred embodiment spacer 100 is between 15 and 30mm in length and most preferably between 22 and 27mm in length. In a preferred embodiment the cortical surface is between 0.5 and 5mm in thickness and most preferably between 1mm and 3mm in thickness.

[0039] Alternatively, spacer 100 may be made from autograft bone, xenograft bone, a polymer such as PEEK or PEKK, or metallic such a titanium or a titanium alloy.

[0040] Looking now at FIG. 2, there is shown the novel instrumentation 200 for implanting the spacer 100. Novel instrumentation 200 includes a joint finder 300, a working cannula 400, a strike plate 500, a drill bit 600, a plunger delivery device 700, and a universal handle 340. Additionally, and now looking at FIG. 2A, guide wires 290 are showing. Two different style guide wires may be included in the instrument kit. Guidewire 290A has a pointed tip 294A. Pointed tip 294A may be a pencil point or a 3 faced trocar point. Additionally, guidewire 290A may have a groove 292A located the length of the spacer 100 from the tip of 294A of the guidewire. This ensures the guidewire is located deep enough in the joint to allow the spacer to be fully implanted. Additionally, guidewire 290B may be included in the instrument kit. Guide wire 290B has blunt ends. It should be appreciated that guidewire 290B may also have a groove located the length of the spacer from the tip of the guidewire like guide wire 290A.

[0041] Instruments 200 and 290 are packaged to form a complete instrument kit. The complete instrument kit is packaged and terminally sterilized so that no cleaning or sterilization is required at the site of surgery prior to surgery. The complete instrument kit may be fully disposable or may be returned to the vendor for re-processing, cleaning, packaging, and sterilization. Additionally, the complete instrument kit may include ancillary supplies to assist with the surgery including but not limited to suture, a scalpel, and sterile drapes.

[0042] Looking now at FIG. 3 a joint finder 300 is shown. Joint finder 300 has a distal end 310 that is necked down to create two parallel faces. The distance between the two parallel faces is greater than the distance between the sacrum and the ilium. Thus, when the joint finder is pushed into the joint, it creates distraction between the sacrum and the ilium. Joint finder 300 may have a central cannulation 320. Central cannulation 320 allows it to be slid over a guide wire 290 to make it easier for the joint finder to find it way into the joint. The distal end of the joint finder has a feature 330 designed to rigidly attach it to a separate handle. Looking now at FIG. 3A, handle 340 is shown. Handle 340 attaches to feature 330. Handle 340 may be a fixed handle or in a preferred embodiment can exhibit ratcheting action. Handle 340 allows the physician to apply significant downward force on the joint finder, while also allowing for rotational motion of the joint finder to aid in it being able to be pressed into and distract the joint. Handle 340 allows for enough force to be exerted on the joint finder that a hammer may not be necessary to position the joint finder within the body.

[0043] Looking at FIG. 3B, an alternative joint finder 300 is shown. The joint finder has a main body 311 that is manufactured from a radiolucent material such as aluminum or plastic. The joint finder 300 has a distal end 310 with two parallel faces. The faces may have two radiopaque markers 312a and 312b. Radiopaque markers 312a and 312b can be made from a more dense material like stainless steel or tantalum. The distance between radiopaque marker 312a and 312b is equivalent to the length of the spacer 100.

[0044] Looking now at FIG. 4a working cannula 400 is shown. Working cannula 400 has a central cannulation 405 that is sized so that joint finder 300 fits within the cannulation. In use, working cannula 400 is slid over joint finder 300 and following final placement of the working cannula, the joint finder is removed. Working cannula 400 has two cutouts. Cutout 410 abuts the sacrum and cutout 420 abuts the ilium. Between the two cutouts are Fingers 430. Fingers 430 have two parallel faces 435. This distance between these faces is the same as the distance between joint finder faces 310.

[0045] Additionally, the distal end of the working cannula has an internal thread region 440. This thread mates with a plunger delivery device 700 (shown later). On the top surface of the working cannula there are two fingers 450. These fingers engage a strike plate (shown later) and can be used to provide downward pressure on the working cannula and allow for the working cannula to be rotated slightly within the joint. There is also a cross hole 460 that runs through the working cannula. These holes can be used to help remove the working cannula. Looking now at FIG. 4A the working cannula 400 is shown slid over the joint finder 300. The handle 340 must be removed from the joint finder to allow the working cannula to fit over it; however, the handle can be re-installed on the joint finder to help with its removal.

[0046] FIG. 4B shows an alternative working cannula 400. This working cannula has atop surface that does not have the two fingers 450 shows in FIG. 4. This flat surface allows a strike plate (shown later) to provide downward pressure on the working cannula.

[0047] Looking now at FIG. 5, a strike plate instrument 500 is shown. Strike plate 500 has a distal gripping area 510 and a distal flange region 520. Distal flange 520 is a larger cross-section than distal gripping area 510. Strike plate 500 has a central cannulation 530 that is sized to allow it to slide over the working cannula. The cannulation is smaller at the flange region so that it creates a step within the cannulation. Thus, the strike plate can slide over the working cannula, but the working cannula cannot slide through the strike plate. There are two tab regions 540 that are adjacent to the central canulation at the distal flange. These two tabs 540 engage the two fingers 450 of the working cannula. When nested together, the strike plate can be used to generate rotational movement of the working cannula, which may be beneficial for its insertion and removal.

[0048] Looking now at FIG. 5A the working cannula 400 is shown with the strike plate 500 slide over and engaged on the working cannula fingers 450 (Shown in FIG. 5B). It should be appreciated that the strike plate can slide up and down on the working cannula. This allows the strike plate to function as a slide hammer and can be used to tap the working cannula into the joint without the need for a hammer. FIGS. 5C and 5D show an alternative strike plate 500. This strike plate does not have the two tabs 540 and is meant to be used with the working cannula presented in FIG. 4B.

[0049] Looking now at FIG. 6 a drill bit 600 for creating a cavity in the two bones of the joint is shown. Drill bit 600 has one or more distal cutting flutes 610, a central shaft 620, and a drive engagement feature 630. In a preferred embodiment drill bit 600 is cannulated so that it can be used over a guide wire to confirm and control its angulation and positioning. Additionally, drill bit 600 may have an integrated drill stop to limit its forward advancement. It should be appreciated that other tools may be used to create the cavity for holding the spacer. Other tools include but are not limited to end mills, broaches, and saws. Looking now at FIG. 6A, the drill bit 600 is shown attached to handle 340. This allows the handle to be used to rotate and advance the drill bit into bone.

[0050] Looking now at FIG. 7, plunger delivery device 700 is shown. Plunger delivery device 700 may be fully cannulated to allow it to operate over a guidewire. Plunger delivery device 700 has a distal tip 710 designed to engage and put pressure against spacer 100. Distal end tip 710 may have a mating feature for connecting to the spacer or may have a smooth flat surface for pressing against the top surface of the spacer. On the proximal end of the plunger delivery device is a mating feature 720 for connecting the delivery device to a handle 340. Between the distal end tip 710 and proximal drive feature 720 is a threaded region 730 sized to engage the threaded region of the working cannula 440 and a shaft 740 that is sized to slide within the working cannula cannulation.

[0051] Looking now at FIG. 8 the implantation of spacer 100 is shown. If a guidewire (not shown) were being used it would be aligned with the central axis of all the instruments and spacer. Spacer 100 is placed through the cannulation of the strike plate 500 and down the working cannula 400. Plunger delivery device 700 is connected to handle 340, and the plunger delivery device slides down the working cannula. When the threaded region of the delivery device 730 begins to mesh with the threaded region 440 of the working cannula, the physician can grip the strike plate 500 and apply downward pressure on the strike plate (and working cannula) while turning the handle clockwise. This advances the plunger delivery device and drives the spacer 100 into the prepared cavity. Looking now at FIG. 8A, the plunger delivery device is shown fully threaded into the working cannula, and the spacer 100 is fully seated in the prepared cavity. It should be appreciated that unlike other methods for delivering a spacer into the sacroiliac joint the method shown in this invention accomplishes the placement without using a hammer to impact the spacer into the cavity.

[0052] After implantation of the spacer the instruments can be removed. Looking now at FIG. 9 a method for removing the instruments is shown. The strike plate 500 can be used to tap against the underside of the handle 340 to help remove the working cannula from within the joint. Alternatively, and now looking at FIG. 10, the working cannula can be removed from the joint by first unthreading the plunger delivery device 700, removing the strike plate 500, and placing the handle mating feature 720 through the cross hole 460 of the working cannula. The plunger delivery device can then be used to pull up on the working cannula to remove it.

[0053] Looking now at FIG. 11 the method of implanting spacer 100 is shown. First the sacroiliac joint 1100 is located. The sacroiliac joint is made up of the sacrum 1110 and the ilium 1120. A guidewire 290 is advanced through the skin and guided via tactile feel and fluoroscopy into the sacroiliac joint. When the guidewire is within the sacroiliac joint a joint finder 300 is slid over the guidewire until it abuts the sacroiliac joint. At this point downward pressure (with the aid of a handle 340) is applied to the joint finder and it is pressed into the sacroiliac joint, distracting the joint. With the joint finder within the joint, and now looking at FIG. 12, the working cannula can be inserted over the joint finder. The strike plate 500 may be used to help provide downward pressure on the working cannula to drive it into the joint. With the working cannula fully in the joint, the joint finder can be removed. At this point, the guidewire may stay in the joint, or may be removed.

[0054] Looking now at FIG. 13, a drill bit 600 is used to create a cavity 640 in the sacroiliac joint. Drill bit 600 is sized to fit within the cannulation of the working cannula. Drill bit 600 has a drive engagement feature 630 for connecting to a handle 340. This allows the drill bit to be rotated and driven into the bone. Cavity 640 is sized to receive spacer 100. The cavity may be slightly smaller than the spacer so as to create a press fit or interference fit between the two.

[0055] Looking now at FIG. 14, the implantation of the spacer 100 is shown. Spacer 100 is placed into the cannulation of the working cannula, and the plunger delivery device can be placed into the cannulation behind the spacer. Looking now at FIG. 15, advancing the plunger delivery device by threading it into the working cannula advances the spacer until it is fully seated in the prepared cavity. With the spacer implanted, the instrumentation can be removed.

[0056] For ease of representation, FIGS. 11-15 do not show the strike plate. It is recommended that the strike plate be placed on the working cannula prior to inserting the spacer and the plunger delivery device. This allows the physician to apply a downward pressure on the working cannula while the spacer is implanted. Modification Of The Preferred Embodiments

[0057] It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.

[0058] What is claimed is:

Claims

CLAIMS1. Instrumentation for performing sacroiliac joint fusion, said instruments including a joint finder, working cannula, and a plunger delivery device wherein implantation of a spacer to promote fusion does not require the spacer to be impacted with a hammer.

2. Instrumentation according to claim 1 that is provided in sterile single use disposable kits.

3. Disposable kits according to claim 2 that contain RFID tags to track their location.

4. Instrumentation according to claim 1 that also includes guidewires.

5. Guidewires according to claim 4 that have a notch the positioned the length of the spacer from the distal end of the guidewire.

6. Instrumentation according to claim 1 that also include a strike plate that slides on the working cannula, can provide downward pressure on the working cannula, and rotation of the working cannula.

7. Instrumentation according to claim 1 wherein the plunger delivery device threads into the working cannula.

8. Instrumentation according to claim 1 wherein a handle is provided that can attach to the joint finder, drill bit, and plunger delivery device.

9. A spacer according to claim 1 that is circular in cross-section.

10. A spacer according to claim 1 that is cannulated.

11. A spacer according to claim 1 that is made from allograft human bone.

12. A spacer according to claim 1 made from a polymer such as PEKK.

13. A spacer according to claim 1 made from a metal such as a titanium alloy such asTi-6Aluminum-4Vanadium.

14. A method of performing SI Joint fusion, said method including the steps of: locating the entrance to the sacroiliac joint with a guide wire, distracting the joint with a joint finder, inserting a working cannula to hold the joint in a distracted state, drilling a cavity in the sacroiliac joint at the distal end of the working cannula, and inserting a spacer into the prepared cavity of said sacroiliac joint.

15. The method according to claim 14 wherein said spacer is implanted into said prepared cavity without the use of impaction forces.

16. The method according to claim 14 wherein said spacer is implanted into said prepared cavity by rotating a threaded delivery plunger within a mating threaded working cannula to linearly translate the spacer to within said prepared cavity.

17. The method according to claim 14 wherein said instrumentation is provided in sterile single-use disposable instrument kits.

18. Disposable kits according to claim 17 that contain RFID tags to track their location.

19. The method according to claim 14 that also includes the use of guidewires.

20. The guidewires according to claim 19 that have a notch the positioned the length of the spacer from the distal end of the guidewire.

21. The method according to claim 14 that also include a strike plate that slides on the working cannula, can provide downward pressure on the working cannula, and rotation of the working cannula.

22. The method according to claim 14 wherein the plunger delivery device threads into the working cannula.

23. The method according to claim 14 wherein a handle is provided that can attach to the joint finder, drill bit, and plunger delivery device.

24. The method according to claim 14 wherein said spacer is circular in cross-section.

25. The method according to claim 14 wherein said spacer is cannulated.

26. The method according to claim 14 wherein said spacer is made from allograft human bone.

27. The method according to claim 14 wherein said spacer is made from a polymer such as PEKK.

28. The method according to claim 14 wherein said spacer is made from a metal such as a titanium alloy such as Ti-6Aluminum-4Vanadium.

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