FULLY EXPANDABLE INTERVERTEBRAL FUSION IMPLANT

Abstract

An intervertebral fusion implant for the fusion of two adjacent vertebrae includes an elongate, adjustable support body, of which the lower and upper cover surfaces are designed to bear on end-plates of the adjacent vertebrae, wherein a side bracket is provided, which is pivotable laterally about a hinge, and of which the bottom face and top face are designed to bear on the end-plates. The support body furthermore is provided, on the cover surface thereof, with a lifting plate which, by means of a lifting mechanism, is adjustable in height between a retracted state and a raised state in which the lifting plate forms a bearing for one of the end-plates. Thereby, both adaptions of width as well as of height are achieved.

Claims

1. An intervertebral fusion implant for the fusion of two adjacent vertebrae, comprising: an elongate, adjustable support body comprising lower and upper cover surfaces that are configured to bear on end-plates of the adjacent vertebrae; a side bracket that is pivotable laterally about a hinge, wherein a bottom face and a top face of the side bracket are configured to bear on the end-plates; and a lifting plate located on the lower or upper cover surface of the support body, the lifting plate being adjustable in height by a lifting mechanism between a retracted state and a raised state in which the lifting plate is spaced apart from the lower or upper cover surface and forms a bearing for one of the end-plates.

2. The intervertebral fusion implant of claim 1, wherein the lifting plate, in the retracted state, lies flush on the support body.

3. The intervertebral fusion implant of claim 1, wherein a central lifting element is provided for the lifting plate.

4. The intervertebral fusion implant of claim 1, wherein two or more lifting elements are provided for the lifting plate.

5. The intervertebral fusion implant of claim 1, wherein the lifting mechanism comprises a worm gear with worm and worm wheel.

6. The intervertebral fusion implant of claim 4, wherein the two or more lifting elements comprise worm wheels that work in opposite directions to each other.

7. The intervertebral fusion implant of claim 5, wherein the worm is configured to be insertable and removable.

8. The intervertebral fusion implant of claim 7, wherein the worm sits at the tip of an actuating instrument that is configured to be delivered from outside through an access tube.

9. The intervertebral fusion implant of claim 1, wherein the side bracket is configured as an expander with a pivoting arm and an expanding arm.

10. The intervertebral fusion implant of claim 9, wherein the expanding arm, in a working position, is locked on the support body.

11. The intervertebral fusion implant of claim 9, wherein the expanding arm comprises a spindle that is mounted on the support body, and a spindle block that is fitted onto the spindle.

12. The intervertebral fusion implant of claim 11, wherein, in a position of assembly, the spindle block is arranged on an end face of the support body.

13. The intervertebral fusion implant of claim 11, wherein the spindle is articulated on an end face of the support body.

14. The intervertebral fusion implant of claim 11, wherein an underside and a top of at least one of the pivoting arm and the spindle block are flush with the lower and upper cover surfaces, respectively, of the support body.

15. The intervertebral fusion implant of claim 9, wherein the side bracket has an aperture that comprises at least half of a lateral face of the side bracket.

16. The intervertebral fusion implant of claim 15, wherein the aperture leaves free an access to the worm gear at least in the expanded state of the side bracket.

17. The intervertebral fusion implant of claim 9, wherein the side bracket is configured as a frame construction, and the support body is formed with corresponding recesses into which the side bracket fits in the retracted state.

18. The intervertebral fusion implant of claim 1, wherein the support body and the side bracket form a right-angled triangle in the expanded state.

19. The intervertebral fusion implant of claim 18, wherein a length of the support body and a length of a hinge for the side bracket are configured such the support body and the hinge form an isosceles triangle in the expanded state.

20. The intervertebral fusion implant of claim 18, wherein the side bracket has a length of approximately 0.8 to 1.1 times a length of the support body.

21. An instrument set for an intervertebral fusion implant that comprises an elongate, adjustable support body comprising lower and upper cover surfaces that are configured to bear on end-plates of adjacent vertebrae, a side bracket that is pivotable laterally about a hinge, wherein a bottom face and a top face of the side bracket are configured to bear on the end-plates, and a lifting plate located on the lower or upper cover surface of the support body, the lifting plate being adjustable in height by a lifting mechanism between a retracted state and a raised state in which the lifting plate is spaced apart from the lower or upper cover surface and forms a bearing for one of the end-plates, wherein the instrument set comprises: a guide tube, an actuating rod, and a coplanar sighting tube arranged at an angle on the guide tube such that the sighting tube intersects an axis of the guide tube in front of a mouth of the guide tube.

22. The instrument set as claimed in claim 21, wherein a tongue for engaging in the support body of the intervertebral fusion implant is arranged on the guide tube at the front end.

23. The instrument set of claim 21, wherein the actuating rod has a thread at its front end, the thread being configured as a spindle for an actuating device of the side bracket.

24. The instrument set of claim 21, further comprising a worm spindle for actuating the lifting mechanism, wherein the sighting tube is configured to receive the worm spindle.

25. The intervertebral fusion implant of claim 3, wherein the implant is configured to prevent the central lifting element from rotating.

26. The intervertebral fusion implant of claim 5, wherein and the worm wheel sits on the lifting element.

27. The intervertebral fusion implant of claim 7, wherein the worm is configured to be inserted centrally between two lifting elements that re provided for the lifting plate.

28. The intervertebral fusion implant of claim 12, wherein the spindle block forms a continuation of a contour of the support body.

29. The intervertebral fusion implant of claim 13, wherein, in the position of assembly, the spindle protrudes in the longitudinal direction of the support body.

30. The intervertebral fusion implant of claim 15, wherein the aperture comprises at least two thirds of the lateral face of the side bracket.

31. The intervertebral fusion implant of claim 16, wherein the aperture leaves free an access to the worm gear also in the retracted state.

32. The instrument set of claim 21, wherein the sighting tube intersects an axis of the guide tube in front of a mouth of the guide tube at a distance corresponding to 0.5 to 1.0 times a length of the support body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention is explained in more detail below with reference to the attached drawing in which advantageous illustrative embodiments are depicted. In the drawing:

[0036] FIG. 1 shows a schematic view of an intervertebral fusion implant according to the invention in the intervertebral space between vertebral bodies;

[0037] FIG. 2 shows plan views and a partially perspective representation of the intervertebral fusion implant in the position of assembly, in the working position, and in an intermediate position;

[0038] FIG. 3 shows an exploded view of the intervertebral fusion implant with inserted worm gear;

[0039] FIG. 4 shows a view of an instrument set; and

[0040] FIG. 5 shows a detail of the attachment of an insertion instrument to the intervertebral fusion implant.

DETAILED DESCRIPTION OF THE INVENTION

[0041] An illustrative embodiment of an intervertebral fusion implant according to the invention, designated in its entirety by reference number 1, is provided for implantation in an intervertebral space 91 between two immediately adjacent vertebral bodies 9, 9′. In a physiologically intact vertebral column, an intervertebral disk 90 is located in the intervertebral space between the vertebrae. This intervertebral disk 90 may undergo degeneration as a result of disease or wear, with the result that it has to be at least partially resected. In order to achieve sufficient support of the intervertebral space 91, despite the loss of intervertebral disk material, and to thereby prevent collapse of the vertebral column, the intervertebral fusion implant 1 is inserted into the intervertebral space 91. It provides a supporting action and thus facilitates fusion of the adjacent vertebrae 9, 9′ in a natural way through bone growth.

[0042] In the following explanation of the structure and function of the illustrative embodiment of the intervertebral fusion implant 1, reference is made to FIGS. 2 and 3. The intervertebral fusion implant comprises a support body 2, with a side bracket 3 which is arranged pivotably thereon via a hinge 30. The side bracket 3 is formed in two pieces, with a pivoting arm 31, which has the hinge 30 at one end thereof, and an expanding arm 32, which is connected in an articulated manner to the other end of the pivoting arm 31 via a second hinge 36. The expanding arm 32 comprises a spindle 33 and a spindle block 34. The spindle block 34 is cuboid and has the hinge 36 on its edge facing toward the support body 2.

[0043] At one end, the spindle 33 has a spherical bearing foot 35 and, at its other end, it has an actuating head 37, which is preferably designed as a hexagon socket. The spherical bearing foot 35 is mounted in a corresponding recess 25 on the end face 20 of the support body 2 and thus forms a pivot joint, wherein the recess 25 extends into the adjacent area of the lateral surface 23 of the support body 2 facing toward the expanding arm 3. The bearing foot 35 thus forms a pivot bearing, as a result of which the support body 2, which in the position of assembly bears with its end face 20 on the spindle block 34, is transferred in an arc shape, by expansion of the expanding arm 3, to its transversely oriented working position (cf. FIGS. 2a and 2b). In the position of assembly, the spindle block 34 lies flush on the end face 20 of the support body 2 and forms a continuation, of identical contour, of the cross section of the support body 2. The underside and top of the spindle block 34 are flush here with the cover and bottom of the support body 2. Moreover, the lateral face of the spindle block 34 directed away from the expanding arm 3 is flush with the corresponding opposite lateral face 22 of the support body 2. In the position of assembly, the spindle 33 lies in the longitudinal direction of the support body 2, the longitudinal direction being defined by the main axis of the support body 2 connecting the end faces 20, 21.

[0044] The expanding arm 31 of the side bracket 3 is designed as a frame construction. At the top and bottom it has a respective main strut 38, which are connected in the area of the hinge 36 by a transverse strut 39. They delimit a large central aperture 39. In the position of assembly (see FIG. 2a), the expanding arm 31 lies recessed on the support body 2, wherein the longitudinal supports 38 engage in recesses 28 formed on the top and bottom edge of the lateral face 23.

[0045] By actuation of the spindle 33, by means of turning the spindle using an actuating tool which engages on the spindle head 37, the spindle block 34 and the support body 2 are moved away from each other, as a result of which the pivoting arm 31 is released and pivots away from its position of assembly directly on the lateral face 23 of the support body 2, and at the same time the support body 2 is pivoted into a direction transverse to the spindle 33 via the pivot hinge formed by the spindle foot 35. Since the spindle block 34 is fixed by the actuating tool, it remains stationary.

[0046] A lifting plate 40 is also provided, which forms a cover 24 of the support body 2. The lifting plate 40 is actuated by a lifting mechanism 4, which has two lifting spindles 41, and two worm wheels 42 which are fitted on the lifting spindles 41 and which, on their inside, have a mating thread for screwing onto the lifting spindle 41 and, on their outside, have teeth for cooperating with a worm spindle 44. The worm wheels 42 and the worm spindle 44 form a worm gear 43, which is accessible from outside via an actuation opening 45 in the lateral face 23 of the support body 2. The worm gear 43 is arranged in the interior of the support body 2 and is provided with a covering 46. The worm gear 43 functions such that an actuating instrument with a worm spindle 44 at its front end is pushed through the aperture 39 in the expanding arm 31 and through the access opening 45 in the lateral face 23 into the interior of the support body 2, where the worm spindle 44 comes to rest centrally between the two worm wheels 42 and meshes with these. By turning the actuating instrument with the worm spindle 44, the worm wheels 42 are brought into opposing rotation, as a result of which the two lifting spindles 41 are moved upward and thus raise the lifting plate 40. The lifting plate 40 thus reaches a position spaced apart from the support body 2, the size of the space being defined by the number of revolutions of the worm spindle 44. In this way, a stepless regulation of the height of the lifting plate 40 can take place. Said lifting plate 40 can be angled to the support body 2 as indicated by the angle “α”. Said angle α can be about 2° to about 15°, preferably about 3° to about 11°, further preferably about 4° to about 8°. Said angle may correspond to the normal angle between adjacent vertebrae as it can be found in healthy persons at the intervertebral fusion site.

[0047] To insert and actuate the intervertebral fusion implant, an instrument set is provided, as is shown in FIG. 4. It comprises a guide tube 70 with a tongue 71 at its front end, which tongue 71 is designed to engage in a correspondingly shaped and complementary recess 27 on the spindle block 34 bearing on the end face 20 of the support body 2. By means of this form-fit connection, the support body 2 with the spindle block 34 is arranged on the guide tube 70 so as to rotate therewith. In order to fix the support body 2 with the spindle block 34 on the guide tube 70, an insertion rod 72 is provided which has a thread 73 at its front end. This thread 73 engages in a retaining thread 29, which is designed as an internal thread on the end face of the spindle block 34 directed away from the support body. By turning the insertion rod 72, a tension-resistant screw connection to the spindle block 34 and to the support body 2 is achieved.

[0048] A sighting tube 8 is arranged fixedly and in a coplanar manner on the guide tube 70. It is oriented at an angle α to the axis 78 of the guide tube, specifically in such a way that the axis 88 of the sighting tube 8 intersects the axis 78 of the guide tube 70 at a point p, which is located in front of the mouth of the guide tube 70 by a distance corresponding approximately to half the length of the support body 2. The sighting tube 8 serves to receive a rotation rod 84 which, at its rear end, has a grip 83 for rotating it and, at its front end, has the worm spindle 44. Moreover, the instrument set comprises an actuating rod 74 which, at its front end, has a hexagon 75 matching the head 37 of the spindle 33.

[0049] For the implantation, the insertion rod 72 is pushed through the guide tube 70, and the insertion rod 72, with the thread 73 at its front end, receives the support body 2 and holds the latter on the front end of the guide tube 70. Securing against rotation is additionally achieved by the tongue 71 at the front end of the guide tube 70 engaging in the recess 27 on the support body 2. By means of minimally invasive surgery, the intervertebral fusion implant 1, thus mounted on the guide tube 70 rigidly and in a manner secure against rotation, can then be introduced by the chosen access route (for example by the PLIF operating technique) to the intended site of implantation in the intervertebral space 91, until it has reached the intended site of implantation in which the anterior end face 21 of the support body 2 lies flush with the anterior margin of the cover surface 93 of the vertebra (see FIG. 2a). When the implant 1 is located at the intended site of implantation, the expanding arm 3 is expanded in a first step. For this purpose, the actuating rod 74 is pushed through the insertion rod 72, which is hollow for this purpose, until the hexagon 75 at the front end engages in the hexagon socket on the head 37 of the spindle 33. By turning the actuating rod 74, the spindle 33 is rotated, and the support body 2 is moved away from the spindle block 34 in the manner described below and the pivoting arm 31 is spread open. The spindle bock 34 remains stationary on account of its being fixed on the guide tube 70. The chosen length ratio of expanding arm 3 to support body 2 ensures that the support body 2 in the expanded state protrudes in the anterior direction (see FIG. 2b) exactly as far as in the position of assembly (see FIG. 2a). After the expansion has been completed, the actuating rod 74 can be removed. The rotation rod 84 is now pushed through the sighting tube 8. It will be noted here that, by virtue of the angle α, the sighting tube 8 targets the implantation site from the contralateral side. That is to say, if the guide tube 70 is guided to the left along the nerve tract in the vertebral column, the sighting tube 8 is located to the right. The fixed angle ensures that the sighting tube 8, with its rotation rod 84 pushed through it, maintains a sufficient distance from the sensitive nerve tract in the vertebral column. In this way, the worm spindle 44 on the rotation rod 84 can be safely pushed through the sighting tube 8 until it finally enters the support body 2 of the intervertebral fusion implant. By virtue of the angle α on the sighting tube 8, the worm spindle 44 of the rotation rod 84 passes through the aperture 39 of the pivoting arm 31 into the access opening 45 in the lateral face 23 of the support body 2 and thus comes to bear in its intended position centrally between the two worm wheels 42. By turning the rotation rod 84 by means of the grip 83, the worm spindle 44 is actuated, as a result of which the worm wheels 42 rotate and the lifting plate 40 is elevated above the lifting spindles 41. Once the lifting plate 40 has reached the desired position, the rotation rod 84 can be removed.