AU2002300439B2 - Deployment device for bone anchor - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Deployment device for bone anchor The following statement is a full description of this invention, including the best method of performing it known to us: Freehills Carter Smith Beadle Melbourne\004114747 ,004114609 2 DEPLOYMENT DEVICE FOR BONE ANCHOR REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority of 09/086,508, filed on May 28, 1998 which is a continuation-in-part of U.S. Application Serial No. 08/595,772, filed on February 2, 1996 (Attorney Docket: 0383311-0040) and of Application Serial No. 08/814,149, filed on March 10, 1997 (Attorney Docket: 0383311-0070) and, thereby, of U.S. Application Serial No. 08/163,130 (now U.S. Patent No.

5,725,529) filed on December 6, 1993 (Attorney Docket: 0383311-0019) and, thereby of U.S. Application Serial No. 08/765,445 (now U.S. Patent No. 5,268,001) filed on September 25, 1991 (Attorney Docket: 0383311-0018) and, thereby, of U.S. Application Serial No. 08/588,025 (now abandoned) filed on September 1990 (Attorney Docket: 0383311-0043).

BACKGROUND OF THE INVENTION The present invention is directed to a bone anchor for attaching tissue to bone, and more particularly to a device for deploying such an anchor in bone. More specifically, the invention is directed to a bone anchor which employs a "floating" washer that conforms to the angle of the bone surface to hold tissue in place, and to a deployment device having a plunger-like configuration that facilitates deployment of such an anchor.

Soft tissue, such as tendon, may become detached from a patient's bone as a result of injury or a medical procedure. In either case, the tissue must be reattached in order to permit healing. Medical devices used to perform this function are known as bone anchors.

Traditionally, bone anchors were merely tacks or nails that were hammered through a patient's soft tissue and directly into the patient's bone. Anchors of this type, however, had many deficiencies. For example, they were prone to coming out of the bone, particularly in cases where patients were relatively active. In addition, because the anchors were hammered directly into the bone, deployment was difficult and could sometimes result in hairline fractures.

In recent times, more sophisticated bone anchors have been developed which alleviate some of the problems mentioned above. For example, many bone anchors now include prongs or something similar, which reduce the changes that the anchor 004114602 3 Swill dislodge from the bone. Likewise, bone anchors have now been developed which can be inserted into pre-formed holes in bone, rather than being hammered.

When affixing tissue directly to bone, it is often desirable to deploy the bone 00 anchor at an angle that is normal to the bone surface. If this is not done, then sufficient contact may not be achieved with the surrounding tissue to hold the tissue s in place. Understandably, achieving such placement can be difficult when the Sanchors are placed endoscopically.

In addition to the foregoing, the force required to deploy a conventional bone anchor often makes deployment problematic. Driving a tack or nail-like anchor into S 10 bone, for example, is difficult if the surgeon does not have adequate leverage on the bone to counterbalance the force of impact.

Thus, there exists a need for a bone anchor which does not need to be deployed at a precise angle in order to attach tissue to bone reliably, and a device for deploying such an anchor which does not require a surgeon to impart substantial counterforce against the device during bone anchor deployment.

In view of the foregoing, an object of at least a preferred embodiment of the invention is to provide improved devices for deploying such anchors.

The foregoing prior art discussion does not constitute an admission of common general knowledge.

SUMMARY OF THE INVENTION The present invention addresses the foregoing objects by providing a deployment tool that permits the bone anchor to be deployed without application of unnecessary counterforce.

Thus, according to the present invention there is provided an apparatus for deploying a bone anchor into a bone, the bone anchor having a housing which stores a rivet, an expandable sleeve which is frangibly coupled to the housing and into which the rivet is inserted, and a washer which floats relative to the expandable sleeve, the apparatus comprising: an outer tube having a bore therethrough and proximal and distal ends, the distal end being adapted to hold the housing of the bone anchor; and 004665970 4 O a rod, which is slidably disposed within the bore of the tube, and which is N adapted to push the rivet from the housing and into the expandable sleeve so as to force the expandable sleeve to expand into bone; cwherein the housing is forced to break away from the rivet when the rivet is partially and not fully forced into the expandable sleeve.

According to another aspect, there is provided an apparatus and bone anchor combination, comprising bone anchor having a housing which stores a rivet, an expandable sleeve which is frangibly coupled to the housing and into 0which the rivet is inserted, and a washer which floats relative to the expandable N 10 sleeve, prior to deployment: an outer tube having a bore therethrough and proximal and distal ends, the distal end being adapted to hold the housing of the bone anchor; and a rod, which is slidably disposed within the bore of the tube, and which is adapted to push the rivet from the housing and into the expandable sleeve so as to force the expandable sleeve to expand into bone; wherein forcing the rivet into the expandable sleeve causes the washer to be forced into a fixed position relative to the rivet so that the washer is substantially parallel to a surface of the bone and causes the housing to break away from the expandable sleeve.

In accordance with yet another aspect of the present invention, there is provided a method for deploying a bone anchor into a bone, the bone anchor having a housing which stores a rivet, an expandable sleeve which is frangibly coupled to the housing and into which the rivet is inserted, and a washer which floats relative to the expandable sleeve prior to deployment, the method employing apparatus comprising: an outer tube having a bore therethrough and proximal and distal ends, the distal end being adapted to hold the housing of the bone anchor; and a rod, which is slidably disposed within the bore of the tube, and which is adapted to push the rivet from the housing and into the expandable sleeve so as to force the expandable sleeve to expand into bone; the method comprising: 004665970 4A O attaching the bone anchor to the distal end of the housing; and Spushing the rivet from the housing with the rod and into the expandable sleeve to force the expandable sleeve to expand into bone, wherein forcing the rivet into the expandable sleeve causes the washer to be forced into a fixed position relative to the rivet so that the washer is substantially parallel to a surface of the bone and causes the housing to break away from the expandable sleeve.

SIt will be understood that the term "comprises" or its grammatical variants as N used herein is equivalent to the term "includes" and is not to be taken as excluding the presence of other elements or features.

A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiments thereof in connection with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention may be attained by reference to the drawings, in which: Figure 1 is a close-up view of a bone anchor in accordance with the present invention, in which the bone anchor's rivet is not deployed; Figure 2 is a close-up view of a bone anchor in accordance with the present invention, in which the bone anchor's rivet is deployed; Figure 3 shows a bone anchor deployment device in accordance with the present invention; Figure 4 shows an outer tube of the bone anchor deployment device shown in Figure 3; Figure 5 shows an inner rod of the bone anchor deployment device shown in Figure 3; and Figures 6 through 12 show a process for deploying the bone anchor shown in S004114602 Figure 1 into a bone using the bone anchor deployment device shown in Figure 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Figures 1 and 2 are close-up, cut-away views of a bone anchor according to the present invention. As shown in Figure 1, bone anchor 1 includes housing 2, expandable sleeve 4, rivet 6, floating washer 7, breakable flanges 9, and threading In preferred embodiments of the invention, some or all of these components are made of a bioabsorbable material which dissolves in a patient's body over a period of time leaving little or no trace. Alternatively, bone anchor 1 may be made of other biocompatible materials, such as conventional plastics or the like.

Rivet 6 is comprised of head 11, elongate body 12, tapered tip 14, and a centerbore (not shown) running therethrough. Head 11 is located at the proximal end of rivet 6 and has a diameter which is greater than that of either elongate body 12 or tapered tip 14. Head 11 also includes undersurface 15. Undersurface 15 can be formed with a spherical radius or, alternatively, angled relative to a longitudinal axis of the elongate body. Thus, as shown in the illustration, the undersurface is angled relative to plane 16 which, as shown in Figure 1, bisects elongate body 12 at a right angle. Preferably, undersurface 15 is angled at 45 degrees; although other angles may be used. Elongate body 12 includes annular ribs 8 on an outer surface thereof, which are adapted to aid in maintaining rivet 6 in sleeve 4. It should be noted, however, that elongate body 12 need not include annular ribs in order to perform its function. Tapered tip 14 is located at the distal end of rivot 6, and has a diameter which decreases gradually from the diameter of elongate body 12 to less than that of inner bore 19 of expandable sleeve 4.

Prior to deployment of bone anchor 1, rivet 6 is housed in housing 2, as shown in Figure 1. Housing 2 is preferably cylindrical in shape and includes threading 10 at first open end 20. Threading 10 is adapted to connect bone anchor 1 to a bone anchor delivery device, such as that described in detail below. Housing 2 is integrally coupled with expandable sleeve 4 via flanges 9, which are sized to break in response to either downward or upward pressure against head 11 so as to disconnect free) housing 2 from expandable sleeve 4.

Expandable sleeve 4 includes inner bore 19, as noted above, and is fabricated of a material which is capable of expanding into an interference fit with a bone S004114602 6 hole. Inner bore 19 has a diameter that is less than the diameter of elongate body 12, but which is greater than or equal to a diameter of tapered tip 14. As a result of these dimensions, expandable sleeve 4 is able to receive rivet 6, distal-end-first. As described in more detail below, expandable sleeve 4 expands as elongate body 12 moves into expandable sleeve 4, eventually resulting in the arrangement shown in Figure 2, in which expandable sleeve 4 is fully expanded. When bone anchor 1 is deployed in a hole in a bone, this expansion results in an interference fit between expandable sleeve 4 and the bone. To aid in expansion, expandable sleeve 4 also may include radial or longitudinal slots (not shown) which runs all or part-way along expandable sleeve 4. In addition, a membrane may also be included on the slot, which permits expansion while, at the same time, guarding against breakage of expandable sleeve 4.

The outer surface of expandable sleeve 4 includes annular ribs or threads 17 along at least a portion thereof. Annular ribs or threads 17 contact sides of a bone hole into which bone anchor 1 is implanted and, when expandable sleeve 4 is expanded, assist in maintaining bone anchor 1 in the bone. This feature of the invention is described in more detail below.

Disposed around the outer surface of expandable sleeve 4 is washer 7.

Washer 7 may be of any shape, it may be elliptical, circular, etc., and may include ridges or other protrusions on its undersurface for improved contact with tissue or bone. When bone anchor 1 is not deployed in a bone, washer 7 "floats", meaning that it is capable of at least longitudinal motion and limited angular motion relative to expandable sleeve 4. Washer 7 may be capable of lateral motion relative to expandable sleeve 4 as well. Thus, referring to Figure 1, washer 7 is capable of longitudinal motion along line 22 and of angular motion at, angles 23 and 24.

This longitudinal motion and angular rotation is possible when expandable sleeve 4 is fully unexpanded and, preferably, also when it is fully expanded. Washer 7 also has a top surface 25 which abuts with undersurface 15 of rivet 6, and which may or may not be angled or radiused relative thereto. In the embodiment shown in Figures 1 and 2, top surface 25 of washer 7 is not angled or radiused.

Bone anchor 1 is deployed into a hole in a bone using a plunger-like deployment device, such as that shown in Figure 3. As shown in Figure 3, bone S004114602 7 anchor deployment device 26 is comprised of tube 27 and rod 29. These components may be fabricated of any material; although stainless steel is used in the preferred embodiment. Tube 27, which is shown in Figure 4, has a bore (not shown) therethrough for receiving rod 29. At distal end 30, the inner surface of tube 27 includes threading (not shown). This threading is adapted to mate with threading of a bone anchor, such as bone anchor 1, in order to hold the housing of the bone anchor substantially immobile during deployment. Tube 27 also includes shaped handle 31 at its proximal end. Handle 31 interacts with knob 32 of rod 29 so as to limit the motion of rod 29 relative to tube 27.

In this regard, rod 29, which is shown in Figure 5, is removably disposed within the bore of tube 27 and is slidable therein. That is, rod 29 can be removed from tube 27 merely by sliding rod 29 out of tube 27. In addition, rod 29 is capable of sliding within tube 27 such that distal end 34 of rod 29 extends out from tube 27 (see Figure This feature of rod 29 makes it possible for rod 29 to move within at least a portion of the housing of a bone anchor connected to tube 27, as described in more detail below. As noted above, rod 29 also includes knob 32, which contacts handle 31 of tube 27 in order to limit the motion of distal end 34 relative to tube 27.

Finally, rod 29 includes a centerbore (not shown) which is capable of receiving a guide wire, such as a K-wire and/or the like.

Figures 6 through 12 explain operation of both bone anchor 1 and deployment device 26 in the context of deploying a bone anchor into a bone during an endoscopic or other surgical procedure. To initiate such a procedure, a K-wire is inserted through the tissue tendon) and into the bone at which a bone anchor is to be deployed. A hole is then formed in the bone at that location, via a drill bit or other cutting device disposed at the distal end of the K-wire. In this regard, hole 37 can be formed by any conventional means. In preferred embodiments of the invention, however, a drill bit or other cutting device (not shown) is slid over Kwire 36 so as to secure the drill bit to K-wire 36 in order to drill hole 37. Thereafter, the drill is removed from K-wire 36. In these embodiments of the invention, a drill guide which is used with such a drill may take the place of the K-wire entirely. The following, however, assumes that a K-wire is used. The result of these steps is shown in Figure 6, namely K-wire 36 in hole 37.

S004114602 8 After, before or during formation of hole 37 in bone 39, a bone anchor, such as that shown in Figure 1, is installed in a bone anchor deployment device, such as that shown in Figure 3. Specifically, with reference to Figure 6, housing 2 of bone anchor 1 is screwed into inner threads of tube 27 on deployment device 26. Once this has been done, bone anchor deployment device 26 and bone anchor 1 are slid over K-wire 36 via respective throughbores of sleeve 4, rivet 6 and rod 29. This is shown in Figure 6.

Next, as shown in Figure 7, expandable sleeve 4 on bone anchor 1 is inserted through soft tissue 40 and into hole 37 of bone 39. Since expandable sleeve 4 is not expanded at this stage of the deployment process, little actual pressure is required on the part of the surgeon in order to insert expandable sleeve 4 into hole 37. As shown in Figure 7, rod 29 may also be moved into contact with rivet 6 at this point by pressing down on knob 32. This pressure may be applied by any means, such as by a surgeon "squeezing" handle 31 and knob 32 together using one hand in a syringe-like manner. Alternatively, hammer blows may be applied to knob 32 while holding tube 27 in place.

In any event, following insertion of expandable sleeve 4 into hole 37; additional pressure is applied to knob 32 to begin initial deployment of rivet 6 into expandable sleeve 4. Specifically, downward pressure is applied to rivet 6 by sliding rod 29 downwards relative to tube 27 so as to force rod 29 into housing 2 and to force rivet 6 out of housing 2 and into expandable sleeve 4. Since housing 2 is held substantially immobile by tube 27, and since housing 2 is connected to sleeve 4, the process of deploying rivet 6 has little or no effect on the bone. That is, the downward force applied to rivet 6 is not significantly imparted to bone 39 because rivet 6 moves within housing 2 and sleeve 4, both of which are held in place by tube 27. As a result, bone 39 moves little during initial deployment of rivet 6.

As shown in Figures 8 and 9, as rivet 6 is deployed into expandable sleeve 4, expandable sleeve 4 expands within hole 37. This expansion results in an interference fit between bone anchor 1 (meaning rivet 6 and expandable sleeve 4) and bone 39. Annular ribs 17 on expandable sleeve 4 strengthen this interference fit by coming into relatively tight contact with the sides of hole 37. In addition, annular S004114602 9 ribs 18 on rivet 6 also enhance the reliability of the interference fit by reducing the chances that rivet 6 will come out of expandable sleeve 4.

The initial deployment process depicted in Figure 6 through 9 causes rivet 6 to be moved substantially, but not completely, into hole 37 of bone 39. That is, as shown in Figure 9, following initial deployment, there is still a space 42 between rivet 6 and a bottom of hole 37. Moreover, as also shown in Figure 9, following initial deployment, washer 7 is not firmly sandwiched between head 11 of rivet 6 and tissue 40 on bone 39. Since washer 7 is preferably firmly sandwiched between head 11 and tissue 40 in order for bone anchor 1 to function properly, additional steps are performed in order to complete deployment.

Specifically, in order to complete deployment of bone anchor 1, deployment device 26 must be removed from K-wire 36 and housing 2 must be disconnected from expandable sleeve 4. One advantage of the present invention is that these actions may be performed concurrently. More specifically, as noted above, bone anchor 1 includes flanges 9 which break when sufficient force is applied thereto. In the present invention, this force may comprise either contact with head 11 during downward movement of rivet 6 into expandable sleeve 4, or contact with head 11 during upward movement of tube 27. In this regard, to break flanges 9 during upward movement of tube 27, downward pressure is retained on rod 29 and upward pressure is applied to tube 27.

In any event, as shown in Figure 10, once flanges 9 break, deployment device 26, with housing 2 still attached thereto, can be slid off of K-wire 36, leaving rivet 6, washer 7, and expandable sleeve 4 within bone 39. Final deployment then can begin by disconnecting rod 29 from tube 27 by sliding rod 29 out of tube 27) and sliding rod 29 back over K-wire 36, as shown in Figure 11. Washer 7 is then set in place by applying a force to knob 32 of rod 29 by way of hammer blows or the like. Because this additional force can be applied via hammer blows or the like, the need for a surgeon to exert counterforce during final deployment is reduced.

The additional force applied above causes rivet 6 to move substantially all the way into hole 37, thereby resulting in firm contact between head 11 and washer 7. As a result of this contact, head 11 forces washer 7 against tissue 40 so that 004114602 washer 7 is firmly sandwiched between head 11 and tissue 40. In this regard, since washer 7 floats relative to bone surface, head 11 forces washer 7 against tissue so that washer 7 is substantially parallel to a surface of bone 39, so that washer 7 is disposed at an angle that substantially conforms to a surface of the underlying bone (see Figure 12). The angle or radii of the undersurface of head 11 described above facilitates this placement. As a result, washer 7 is able to hold tissue 40 in place. Thus, by using a floating washer in this manner, the invention reduces the need to implant the bone anchor at a precise angle relative to the bone.

The present invention has been described with respect to particular illustrative embodiments. It is to be understood that the invention is not limited to the above-described embodiments and modifications thereto, and that various changes and modifications may be made by those of ordinary skill in the art without departing from the spirit and scope of the appended claims.

Claims (11)

1. An apparatus for deploying a bone anchor into a bone, the bone anchor having a housing which stores a rivet, an expandable sleeve which is frangibly coupled to the housing and into which the rivet is inserted, and a washer which floats relative to the expandable sleeve, the apparatus comprising: an outer tube having a bore therethrough and proximal and distal ends, the distal end being adapted to hold the housing of the bone anchor; and a rod, which is slidably disposed within the bore of the tube, and which is adapted to push the rivet from the housing and into the expandable sleeve so as to force the expandable sleeve to expand into bone; wherein the housing is adapted to break away from the rivet when the rivet is partially and not fully forced into the expandable sleeve.

2. An apparatus according to claim 1, wherein the proximal end of the tube includes a tube handle and the distal end of the tube includes threading on an inner surface of the tube, the threading being adapted to hold the housing in place; wherein the rod has a proximal end and a distal end, the proximal end of the rod having a knob and the distal end of the rod adapted to contact the rivet in the housing; and wherein the rod knob is adapted to contact the tube handle during deployment of the bone anchor so as to limit motion of the distal end of the rod relative to the tube.

3. An apparatus according to claim 1 or claim 2, wherein the rod includes a centerbore which is capable of receiving any of a guide wire, guide pin and K-wire.

4. An apparatus as claimed in any one of claims 1 to 3 wherein the tube is adapted to hold the housing such that the housing is substantially immobile relative to the tube and the rod is slidably movable within the tube and within at least a portion of the housing between a first location in the tube, a second location in the housing at which the rod forces the rivet out of the housing and into the sleeve, and a third location outside of the tube. 004665970 12 An apparatus and bone anchor combination, comprising a bone anchor having a housing which stores a rivet, an expandable sleeve which is frangibly coupled to the housing and into which the rivet is inserted, and a washer which floats relative to the expandable sleeve, prior to deployment: an outer tube having a bore therethrough and proximal and distal ends, the distal end being adapted to hold the housing of the bone anchor; and a rod, which is slidably disposed within the bore of the tube, and which is adapted to push the rivet from the housing and into the expandable sleeve so as to force the expandable sleeve to expand into bone; wherein forcing the rivet into the expandable sleeve causes the washer to be forced into a fixed position relative to the rivet so that the washer is substantially parallel to a surface of the bone and causes the housing to break away from the expandable sleeve.

6. An apparatus and bone anchor combination according to claim 5, wherein the proximal end of the tube includes a tube handle and the distal end of the tube includes threading on an inner surface of the tube, the threading being adapted to hold the housing in place; wherein the rod has a proximal end and a distal end, the proximal end of the rod having a knob and the distal end of the rod adapted to contact the rivet in the housing; and wherein the rod knob is adapted to contact the tube handle during deployment of the bone anchor so as to limit motion of the distal end of the rod relative to the tube.

7. An apparatus and bone anchor combination according to claim 5 or 6, wherein the rod includes a centerbore which is capable of receiving any of a guide wire, guide pin and K-wire. 004665970 13 0 8. An apparatus and bone anchor combination as claimed in any one of claims 5 to 7 wherein the tube is adapted to hold the housing such that the housing is substantially immobile relative to the tube and wherein the rod is slidably movable within the tube and within at least a portion of the housing between a first location in the tube, a second c, 5 location in the housing at which the rod forces the rivet out of the housing and into the sleeve, and a third location outside of the tube.

9. A method for deploying a bone anchor into a bone, the bone anchor having a housing which stores a rivet, an expandable sleeve which is frangibly coupled to the housing and into which the rivet is inserted, and a washer which floats relative to the expandable sleeve prior to deployment, the method employing an apparatus N-I comprising: an outer tube having a bore therethrough and proximal and distal ends, the distal end being adapted to hold the housing of the bone anchor; and a rod, which is slidably disposed within the bore of the tube, and which is adapted to push the rivet from the housing and into the expandable sleeve so as to force the expandable sleeve to expand into bone; the method comprising: attaching the bone anchor to the distal end of the housing; and pushing the rivet from the housing with the rod and into the expandable sleeve to force the expandable sleeve to expand into bone, wherein forcing the rivet into the expandable sleeve causes the washer to be forced into a fixed position relative to the rivet so that the washer is substantially parallel to a surface of the bone and causes the housing to break away from the expandable sleeve. The method according to claim 9, wherein the proximal end of the tube includes a tube handle and the distal end of the tube includes threading on an inner surface of the tube, the threading being adapted to hold the housing in place; wherein the rod has a proximal end and a distal end, the proximal end of the rod having a knob and the distal end of the rod adapted to contact the rivet in the housing; and wherein the rod knob is adapted to contact the tube handle during deployment of 004665970 14 the bone anchor so as to limit motion of the distal end of the rod relative to the tube.

11. The method according to claim 10 or 11, wherein the rod includes a centerbore which is capable of receiving any of a guide wire, guide pin and K-wire.

12. The method as claimed in any one of claims 9 to 11 wherein the tube is adapted to hold the housing such that the housing is substantially immobile relative to the tube and the rod is slidably movable within the tube and within at least a portion of the housing between a first location in the tube, a second location in the housing at which the rod forces the rivet out of the housing and into the sleeve, and a third location outside of the tube.

13. An apparatus for deploying a bone anchor into a bone, substantially as hereinbefore described with reference to the accompanying drawings.

14. An apparatus and bone anchor combination substantially as hereinbefore described with reference to the accompanying drawings. A method for deploying a bone anchor into a bone substantially as hereinbefore described with reference to the accompanying drawings. Dated 22 June 2006 Freehills Patent Trade Mark Attorneys Patent Attorneys for the Applicant/s: Ethicon, Inc.