Expandable spinal implant

Abstract

The present application relates to an expandable spinal implant (1) comprising two elongated implant members (20, 30). The implant members (20, 30) are rotatably coupled to a central base portion (10) and comprise a first end with an axis of rotation and circumferentially arranged gear teeth (23, 33). The gear teeth (23) of the first elongated implant member (20) is interlocked into said gear teeth (33) of the second elongated implant member (30).

Claims

1. An expandable spinal implant comprising a first elongated implant members and a second elongated implant member, said elongated implant members being rotatably coupled to a central base portion, said implant members comprising a first end with an axis of rotation and circumferentially arranged gear teeth, wherein the gear teeth of said first elongated implant member are interlocked into said gear teeth of the second elongated implant member, wherein said base portion is a body in the form of a segmental arc and said elongated implant members are coupled to said base portion at an apex of said segmental arc.

2. The expandable spinal implant of claim 1, wherein the elongated implant members are in the shape of a segmental arc and substantially abut with said base portion along their entire length in an initial and unexpanded configuration.

3. The expandable spinal implant of claim 1, wherein said elongated implant members and the central base portion form a substantially X-shaped footprint in an expanded configuration.

4. The expandable spinal implant of claim 1, wherein the elongated implant members and the central base portion are substantially straight and form a substantially K-shaped footprint in an expanded configuration.

5. The expandable spinal implant of claim 1, comprising at least one pocket for receiving bone graft material.

6. The expandable spinal implant of claim 1, comprising elongated implant members of unequal length.

7. The expandable spinal implant of claim 1, comprising a dowel having a ball head at one end, said ball head cooperating with a first channel located on the inside of said first elongated implant member, such as to impart motion onto said first elongated implant member for rotating said first elongated implant member relative to said central base structure around its axis of rotation.

8. The expandable spinal implant according to claim 1, wherein the elongated implant members and the central base portion each comprise a lower surface and an upper surface, said upper surface and said lower surface of said elongated implant members and of said central base portion being flush with each other.

9. The expandable spinal implant according to claim 8, wherein the upper surfaces and the lower surfaces of said elongated implant members and of said central base portion being arranged at an angle to each other, said angle preferably being from 0 to 15.

10. The expandable spinal implant according to claim 8, wherein the lower surfaces and the upper surfaces of said elongated implant members and of said central base portion are parallel to each other.

11. A kit comprising multiple expandable spinal implants of claim 1, wherein the expandable spinal implants have at least one of: incremental thicknesses between 8 and 20 mm, elongated implant members with varying lengths or elongated implant members with varying widths.

12. A kit according to claim 11, wherein the expandable spinal implants have varying angles between the lower surfaces and the upper surfaces of said elongated implant members and of said central base portion, said angles preferably varying from 1 to 15.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings used to explain the embodiments show:

(2) FIG. 1 a first embodiment of an expandable spinal implant according to the present invention in an exploded view;

(3) FIG. 2 the expandable spinal implant according to FIG. 1 in an assembled configuration;

(4) FIG. 3a, 3b the expansion of the expandable spinal implant according to FIG. 1;

(5) FIG. 4a, 4b the expandable spinal implant according to FIG. 1 arranged on a vertebral body;

(6) FIG. 5a-5b a second embodiment of an expandable spinal implant according to the present invention comprising a dowel;

(7) In the figures, the same components are given the same reference symbols.

PREFERRED EMBODIMENTS

(8) FIG. 1 shows a first embodiment of the expandable spinal implant 1 in an exploded view. The expandable spinal implant 1 comprises a first elongated implant member 20, a second elongated implant member 30, a central base portion 10, two hinge-pins 60, 61 and a dowel 40.

(9) Each of the elongated implant members 20, 30 comprises an axis of rotation at a first end. Each axis of rotation is defined by a corresponding bore 21, 31 into which one of the two hinge-pins 60, 61 is inserted. Furthermore, the elongated implant members 20, 30 each comprise a recess 22, 32 extending through the elongated implant member 20, 30 and intersecting with the bores 21, 31 wherein each recess 22, 32 is substantially perpendicularly arranged in reference to the respective axis of rotation defined by each bore 21, 31. Said first ends of the elongated implant members 20, 30 are of a half cylindrical shape and comprise a set of gear teeth 23, 33, circumferentially arranged around the axis of rotation defined by bores 21, 31. The gear teeth 23, 33 are arranged on both sides of the recesses 22, 32. Towards a second end, the elongated implant members 20, 30 each comprise a pocket 24, 34 extending from a top surface 50 to a bottom surface 51, wherein the pockets 24, 34 are shaped to receive bone graft material or a bone graft substitute, to promote bone ingrowth. Both elongated implant members 20, 30 are in the general shape of a segmental arc.

(10) The central base portion 10 is a block shaped element in the general shape of a segmental arc which comprises, like the elongated implant members 20, 30, a top surface 50 and a bottom surface 51. At the apex 14 of the segmental arc, the central base portion comprises a part 15 with a top side 52 and a bottom side 53 which are spaced apart from the upper surface 50 and the lower surface 51, respectively, of the central base portion 10. The part 15 comprises two substantially parallel through-bores 11.1, 11.2, extending form the top side 52 to the bottom side 53 of the part 15. Said through bores 11.1, 11.2 are configured to each receive one of the two hinge-pins 60, 61 such as to rotatably couple each of the elongated implant members 20, 30 to said central base portion 10.

(11) The dowel 40 comprises a ball-head 41 and a threaded shaft 42. The ball-head 41 is engaged within a first channel 25 located on the inside of the first elongated implant member 20. The first channel 25 includes an opening 26 connecting said channel 25 to the outside and allowing the passage of the dowel 40 into said first channel 26. The threaded shaft 42 is engaged within a second channel 12 which comprises an internal thread cooperating with the threaded shaft 42.

(12) FIG. 2 shows the expandable spinal implant 1 in an assembled state. The two elongated implant members 20, 30 are rotatably coupled to the central base portion 10 by means of the two hinge-pins 60, 61 which are introduced into the bores 21, 31 of the elongated implant members 20, 30, and through the through bores 11.1, 11.2 of the central base portion 10. The part 15 of the central base portion 10 is arranged within the recesses 22, 32 of the elongated implant members 20, 30. Both elongated implant members 20, 30 may only rotate around their rotation axis defined by the bores 21, 31. The sets of teeth 23, 33 are interlocked. As a result, upon actuation or rotation of the first elongated implant member 20, the second elongated implant member 30 will be actuated or rotated.

(13) Note that the two elongated implant members 20, 30 are in the initial, unexpanded configuration. In this initial configuration, both elongated implant members 20, 30 abut onto the central base portion 10 along their entire length.

(14) FIGS. 3a and 3b show the expansion of the expandable spinal implant 1 according to FIG. 2. In a first initial and unexpanded configuration, the elongated implant members 20, 30 are abutting the central base portion 10 on their entire length. The expandable spinal implant 1 has a substantially elongated, curved and narrow footprint in said first initial configuration, as shown in FIG. 3a. Upon actuation of the first elongated implant member 20, both elongated implant members 20, 30 rotate outwards, resulting in a second, expanded configuration as shown in FIG. 3b. This rotation is caused by the interaction of the gear teeth 23, 33 with each other. Hence, a rotation movement of one of said elongated implant members 20, 30 is transmitted by means of the gear teeth 23, 33 to the other elongated implant member 20, 30. In the second configuration the elongated implant members 20, 30 impart a generally X-shaped footprint to the expandable spinal implant 1.

(15) In a variant, the elongated implant members 20, 30 may have a different length, for instance the first elongated implant member 20 may be longer than the second elongated implant member 30.

(16) FIGS. 4a and 4b show the expandable spinal implant 1 arranged on a vertebral body 2. The expandable spinal implant 1 is thereby placed on the endplate 3 of the vertebral body 2 and occupies the intervertebral space 4 which would normally be occupied by the intervertebral disc. The adjacent vertebra on the other side of the intervertebral space 4 is not shown as it would cover the expandable spinal implant 1 in the perspective of the figure. FIG. 4a shows the expandable spinal implant 1 in the first, unexpanded configuration. In the second, expanded configuration, the elongated implant members 20, 30 are positioned close to the outer perimeter of the endplate 3 of the vertebral body 2, where the bone is denser, and withstands higher loads, as shown in FIG. 4b.

(17) FIGS. 5a and 5b show the actuation mechanism of the expandable spinal implant 1 in more detail. In both figures, the first elongated implant member 20 is shown in a cut-away view.

(18) In the first, unexpanded configuration of the expandable spinal implant 1, as shown in FIG. 5a, the ball head 41 of the dowel is located within the first channel 25 in a form-fitting manner. Linear movement of the dowel 40 within the second channel 12 will entail a rotational movement of the first elongated implant member 20 relative to the central base portion 10 by means of the interaction of the ball head 41 with the first channel 25. Further, the threaded shaft 42 comprises a drive 43. The threaded shaft 42 cooperates with the internal thread located in said first channel 12. By turning the dowel 40 via the drive 43, a linear translation of the dowel 40 will be caused by the cooperation of the threaded shaft 42 with the internal thread. Access to said drive 43 is made possible through the second channel 12, e.g. for a suitable instrument (not shown). In the embodiment shown, the drive 43 is configured as hexagonal drive, however, other drive types may also be used, such as e.g. a torx-drive. The base portion 10 further includes an attachment portion 16 configured to be coupled to an insertion instrument (not shown). In the initial configuration, the dowel 40 is located at a retracted position within the second channel 12 and protrudes out of central base portion 10.

(19) FIG. 5b shows the expandable spinal implant 1 in the second, expanded configuration. In this configuration, the dowel 40 is located at an extended position within the second channel 12. By the translational movement of the dowel 40 from the retracted position as shown in FIG. 5a to said extended position, the ball head 41 pushed onto walls of the first channel 25 of the elongated member 20. This pushing force is translated in a rotational movement of the first elongated implant member 20, as its first end is coupled to the central base portion 10 by means of the first hinge-pin 60. Mediated by the engagement of the gear teeth 23, 33 the second elongated implant member 30 is likewise rotated.