BONE ANCHOR ASSEMBLY

Abstract

A suture anchor including a sleeve with an optional solid tip and a threaded, hollow interior portion. A transverse hole passes through a distal end of the sleeve. An inner screw with a flat distal end and threads disposed on an outer surface and a driver head extension monolithically connected with a proximal end of the inner screw are also provided.

Claims

1. A suture anchor comprising: a sleeve with a solid tip and a threaded, hollow interior portion; a transverse hole passing through a distal end of the sleeve; an inner screw with a flat distal end and threads disposed on an outer surface; and a driver head extension monolithically connected with a proximal end of the inner screw.

2. The suture anchor of claim 1, wherein the driver head extension is configured to break off with a predetermined amount of torque.

3. The suture anchor of claim 1, wherein the sleeve is provided with a plurality of slits on the proximal end.

4. The suture anchor of claim 3, wherein the number of slits is four.

5. The suture anchor of claim 1, wherein the transverse hole is provided just above the solid tip of the sleeve.

6. The suture anchor of claim 1, wherein the inner screw has a wider portion near the proximal end between the threads and the driver head extension.

7. The suture anchor of claim 1, wherein the sleeve has a series of radial projections on an outer surface.

8. The suture anchor of claim 1, wherein the inner screw includes a square head.

9. The suture anchor of claim 8, wherein the driver head extension includes a square head of the same shape and size as the inner screw.

10. The suture anchor of claim 1, wherein the suture anchor is composed of a bio-absorbable material.

11. A suture anchor comprising: a sleeve with a hollow interior portion; a transverse hole passing through a distal end of the sleeve; an inner screw with a flat distal end and threads disposed on the outer surface; a driver head extension monolithically connected with a proximal end of the inner screw.

12. The suture anchor of claim 11, wherein the interface between the inner screw and the driver head extension is undercut.

13. The suture anchor of claim 12, wherein the driver head extension is configured to break off at the interface with a predetermined amount of torque.

14. The suture anchor of claim 13, wherein the inner screw remains removable after the driver head extension has been broken off.

15. The suture anchor of claim 11, wherein the inner screw has a wider portion sized to engage an expandable portion of the sleeve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, wherein:

[0031] FIG. 1 shows an exploded view of the anchor before insertion of the inner screw;

[0032] FIG. 2 shows an exploded view of the anchor of a different design before insertion of the inner screw;

[0033] FIG. 3 shows a view of the anchor with suture prior to insertion into the bone;

[0034] FIG. 4 shows the anchor as it would appear implanted into the bone, but before the screw has been locked in place; and

[0035] FIG. 5 shows the anchor after being implanted and after the full torque has been applied to lock the screw in place shearing the undercut distal end of the inner screw off.

[0036] FIG. 6 shows the anchor assembly connected to a driver and suture as part of an arthroscopy.

DETAILED DESCRIPTION

[0037] The exemplary suture anchor of FIG. 1 includes an inner screw 2 which is integrally connected to a square-shaped driver extension 3 and an anchoring sleeve 1A. In describing the suture anchor assembly, the term distal refers to the direction in which the suture anchor is inserted, i.e., towards the interior of the bone, and the term proximal refers to a direction away from the bone and towards the surgeon, opposite the distal direction.

[0038] The inside of the sleeve 1A is provided with threads or a durable material which engage the threads of the inner screw. The sleeve itself contains an eyelet for receiving the suture thread. The sleeve in FIG. 1 is smooth on the outside for application to a pre-drilled hole in the bone. This exemplary embodiment can be applied to very hard bone tissue where expansion of the proximal end is sufficient.

[0039] The sleeve 1A can also contain two or more slits beginning at a proximal end and continuing about a on third of the length of the sleeve. This slit allows the sleeve to expand upon complete insertion of the inner screw 2. The distal end of the sleeve beyond the eyelet is solid, providing a surface for the suture to be clamped against.

[0040] The anchor assembly can be manufactured from polyether-ether ketone, polylactic acid, lactide, homopolymers and copolymers of glycolide, dioxanone, caprolactone, trimethylene carbonate, and other bio-absorbable and bio-degradable polymers, for example. Alternatively, non-corrosive alloys and metals could be used.

[0041] Another exemplary design of a sleeve is shown in FIG. 2 with the sleeve 1B having threads disposed on the outer surface. The threads can be replaced by simple projections and barbs for gripping soft tissue or continuous screw-like threads for a tight fit in a pre-drilled hole, for example. The sleeve can thus be changed depending on the operation without altering the rest of the assembly or substantially changing the process of inserting the anchor into the patient. This alternate sleeve can also be provided with a plurality of slits to aid expansion.

[0042] The insertion of the bone anchor requires full assembly before it can be inserted into the bone. The inner screw must be fully inserted before the now connected pieces can be screwed into the bone and the suture must be threaded through the eyelet in the sleeve.

[0043] In FIG. 3 the fully-assembled bone suture anchor is shown with a suture thread 4 in place. The suture thread 4 must be inserted though the eyelet in the sleeve 1A before the inner screw 2 is fully inserted. Once the suture is in place the inner screw 2 can be tightened such that the suture is clamped to the solid distal end of the sleeve.

[0044] The driving of the inner screw 2 and the assembly as a whole is accomplished by inserting the square head on the driver extension 3 into a corresponding opening on a driver (not shown). Once the sleeve has been inserted into the bone, the inner screw can be further tightened such that the distal end of the sleeve expands and locks the anchor into the anchoring hole. The proximal end of the inner screw may be provided with a small enlargement, an expanding element, which when fully tightened engages the expandable proximal end of the sleeve and presses it outward.

[0045] The suture anchor is configured to receive a plurality of sutures. The number of sutures passing through the eyelet results in a varying depths at which the inner screw will engage the outer sleeve. For example, if four sutures are being clamped then expansion and clamping start at approximately the same time. Alternatively, if only one suture is being clamped, then expansion may begin before the suture is fully clamped.

[0046] The assembly in FIG. 4 shows how the anchor would appear in situ after the suture anchoring operation has been completed. Additionally, the length of the inner screw and the position of an expanding element on the inner screw are selected such that the expanding element engages and expands the outer sleeve between the slits when a distal end region of the inner screw is engages the suture.

[0047] The advantage of this measure is that the clamping and the expanding processes are optimally matched to one another such that the clamping and expanding processes are undertaken simultaneously and in one moving step when the inner screw, on which the expanding element is formed, is moved to the distal end.

[0048] The driving of the inner screw should require very little torque since the initial driving through the sleeve is unimpeded. Subsequently, the clamping of the suture and the insertion of the sleeve into the pre-drilled hole in the bone should likewise require little torque. Thus, in normal operation over-driving the inner screw would only result in stripping of the inner threads, or stripping of the driving head, or over-insertion into the pre-drilled hole. All of these scenarios result in the device and the surrounding bone being damaged and perhaps immobilization of the device, preventing correction or removal.

[0049] Therefore, the inner screw 2 and driver head extension 3 are specially adapted to shear or break at a predetermined position B at a predetermined torque limit which would constitute over-driving. This prevents over-driving of the assembly which, because of its small size and precise machining, can be fragile. The drawing of FIG. 5 shows the screw after the torque limit has been reached and the breaking position can be seen neatly dividing the inner screw 2 and the driver head extension 3. The breaking position B can be selected by undercutting or otherwise weakening the screw shaft at this point.

[0050] Alternatively, the removable driver head extension can be removed once the operation is completed in the same way it is broken off during torque limiting. Furthermore, the inner screw 2, after separation from the driver head extension 3, still has a square head for additional adjustment or, if necessary, removal of the anchor.

[0051] Finally, the full assembly in operation is shown in FIG. 6. This exemplary procedure is an arthroscopy where a tendon 6 of the rotator cuff is reattached to the shoulder bone 8. The suture 4 is tied through the tendon end 5 and wound back through the anchor. Before the inner screw is completely tightened, the suture length can be adjusted. Subsequently the assembly is inserted into the pre-drilled hole 7 and driver 9 completes the tightening of the inner screw, locking the suture in place within the assembly and expanding the proximal end to secure the bone anchor in the pre-drilled hole.

[0052] The invention thus being described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.