DE20314708U1 - spinal implant - Google Patents

Description

SPINE IMPLANT

The invention relates to a spinal implant for bridging the gap between the end surfaces of two vertebral bodies with variable height.

With such implants, which are either inserted as intervertebral implants directly between two adjacent vertebral bodies or as vertebral body replacement implants to bridge a missing vertebral body between the adjacent vertebral bodies, it is necessary to adapt these implants to the exact dimensions of the gap to be bridged. In individual cases, this means that relatively large implants have to be used, the introduction of which into the body requires large openings.

This applies, for example, when known rigid implants of this type are used (US 4,843,757). Implants are also known whose height can be changed after insertion in order to facilitate insertion and to achieve an adjustment to the desired height when inserted. For example, implants are known that increase the distance between two implant halves by means of movable cams (US 4,863,476) or that allow a change in the height by rotating the implant in situ (US 5,443,514).

In other implants, a wedge-shaped intermediate part can be inserted between two pivotally connected end plates (US

A 57 641 u

16 September 2003

u-214/248

6,102,950), a similar construction is known from WO 00/74605. There are also implants that have deformable ribs like an expansion dowel that can be curved by an adjustment mechanism (US 5,059,193, WO 00/44319).

In all cases, these implants are relatively complex in design, and height adjustment is not easily feasible once the implant is inserted into the body and is therefore difficult to access.

It is an object of the invention to design a generic spinal implant in such a way that its height can be easily adjusted and that the structure is relatively simple.

This object is achieved according to the invention in a spinal implant of the type described at the outset in that it has a plurality of spacer elements arranged next to one another, which in a low position run obliquely to a horizontal plane which is arranged essentially parallel to the end surfaces of the vertebral bodies, and which in a high position are erected relative to the low position and run at least approximately perpendicular to the horizontal plane.

Simply pivoting or raising the spacer elements from the slanted low position to the upright high position results in a change in the construction height. This raising of the spacer elements can be done easily using suitable instruments, even when the implant is inserted into the body.

A 57 641 u
16 September 2003
u-214/248

It is advantageous if the spacer elements run parallel to each other.

In a preferred embodiment, the spacer elements are pivotally connected to at least one support body, which forms a contact surface for the end surface of a vertebral body. Such a support body can optionally only be provided at one end of the spacer elements, while on the opposite side the spacer elements with their free edges form the contact surface for the vertebral bodies. However, it is also possible for such support bodies to be provided on both sides of the spacer elements. The spacer elements then form links between the support bodies, which increase the distance between the support bodies when erecting.

The spacer elements can be designed as steering arms; in another embodiment, the spacer elements are designed as plates.

In another embodiment, it is provided that the end edges of the spacer elements at least at one end of the spacer elements together form a contact surface for the end surface of a vertebral body; it is particularly advantageous if this is the case at both opposite end edges of the spacer elements, i.e. if the spacer elements together form the implant and no additional support body is provided for the vertebral bodies.

The spacer elements can be of equal length so that the support surfaces formed by them are essentially flat, but it is also possible

A 57 641 u
16 September 2003
u-214/248

that the spacer elements are of different lengths and therefore form a non-flat contact surface. This makes it possible to adapt the contour of the contact surface formed by the spacer elements to the end surface of the vertebral bodies.

The spacer elements can be rounded in the area of their edges forming a contact surface so that these surfaces roll along the end surfaces of the vertebral bodies when the spacer elements are erected and do not dig into them.

Normally the spacer elements are made in one piece, but in a preferred embodiment it can also be provided that the spacer elements have an upper part and a lower part which are connected to one another in an articulated manner, and that the lower part and upper part run diagonally in opposite directions in the low position and are stretched in comparison to the low position in the high position. Such a design has the advantage that the end edges forming the contact surface or the support bodies carried by the spacer elements are not displaced against one another when erecting in the horizontal plane, so they do not have to slide along the end surfaces of the vertebral bodies, but can remain permanently in contact with the end surfaces, while the construction height is changed by stretching the spacer elements.

In a particularly preferred embodiment, the spacer elements are plates lying flat against one another. When erected, these plates slide against one another and form a stack of upright plates. To erect the plates, at least one of the plates can be

A 57 641 u
16 September 2003
u-214/248

tension member should be provided. In the erected state, the distance between the panels parallel to the horizontal plane is greater than in the folded state, and this can be used to erect the panels by tensioning them together.

For example, the tension member can pass through openings in the plates.

The tension member can be, for example, a thread, a wire, a band, a rod or a bar, and it is advantageous if the bar has a profile for securing a pressure element that can be moved on it. Such a pressure element can be formed, for example, by a disk through which the bar passes, so that the disk can be moved on the bar in the tensioning direction, but is then prevented from sliding back by the profile.

The panels can have interlocking projections and recesses that guide the panels against each other in the transverse direction and allow them to be moved freely in the direction from their upper edge to their lower edge. The panels are thus held in a stack and secured against sideways movement, but they can be moved against each other in their vertical extension to be erected without the guide getting in the way. For example, these projections and recesses can be designed as ribs and grooves into which the ribs engage.

It is advantageous if the spacer elements and/or, if applicable, the support bodies, tension members and pressure elements are made of a resorbable material

A 57 641 u
16 September 2003
u-214/248

so that the implant gradually dissolves and is reabsorbed by the body as a bony bridge forms between the vertebral bodies supported by the implant.

In a further preferred embodiment, the spacer elements have hook-shaped projections on the front and back, which are engaged behind by corresponding hook-shaped projections on the adjacent spacer elements, preferably the hook-shaped projections engage behind one another with some play. The hook-shaped projections hold the spacer elements together to form a chain-like component, so that they are also held in place to a certain extent in the axial direction. Nevertheless, the spacer elements can be pivoted between the pivoted low position and the upright high position.

The following description of preferred embodiments of the invention serves to explain in more detail in conjunction with the drawing. They show:

Figure 1: a schematic side view of an implant inserted into the intervertebral space between two vertebral bodies in a low position;

Figure 2: a view similar to Figure 1 with the implant in the raised position;

Figure 3: a perspective view of the implant of Figures 1 and 2 in low position;

··

·

-7-

A 57 641 u
16 September 2003
u-214/248

Figure 4: a view similar to Figure 3 of a modified embodiment of an implant with a double thread tensioning element;

Figure 5: a perspective view of a further embodiment of an implant with upper and lower support bodies and with spacer elements pivotably connected to them;

Figure 6: a view similar to Figure 3 of a further preferred embodiment of an implant with pivotable spacer elements;

Figure 7: a side view of two mutually displaceable spacer elements of an implant with longitudinal guide elements;

Figure 8: a plan view of the front of a plate-shaped spacer element of Figure 7;

Figure 9: a plan view of the back of a plate-shaped spacer element of Figure 7;

Figure 10: a longitudinal sectional view of the further embodiment of an implant with interlocking spacer elements by hook-shaped projections in the low position;

Figure 11: a front view of the implant of Figure 10 and

•t ·

A 57 641 u
16 September 2003
u-214/248

Figure 12: a view similar to Figure 10 with the implant in the raised position.

The invention is discussed using the example of an intervertebral implant, but it is understood that a similar construction can also be used for a vertebral body replacement implant.

The implant 1 shown in Figures 1 to 3 comprises a plurality of rectangular, plate-shaped spacer elements 2 which are arranged next to one another in the manner of a stack, flat against one another. All spacer elements 2 have a continuous slot 5 in the middle, running in the direction from the lower edge 3 to the upper edge 4. A rod 6 is pushed through all the slots 5 of the spacer elements 2, which has a head-shaped thickening 7 at one end and onto which a disk-shaped pressure element 8 is pushed from the other side.

The spacer elements 2 are rounded at the lower edge 3 and at the upper edge 4, the lower edges 3 together form a lower contact surface and the upper edges 4 together form an upper contact surface of the implant. The dimensions of the implant are selected so that the implant can be inserted into the intervertebral space 9 between two vertebral bodies 10, 11, whereby the contact surfaces formed by the upper edge and the lower edge rest on the end surfaces 12, 13 of the vertebral bodies 10, 11.

To insert the implant 1, the plate-shaped spacer elements 2, which preferably consist of a resorbable material, are placed at an angle to

A 57 641 u
16 September 2003
u-214/248

a horizontal plane which runs essentially parallel to the end surfaces 12, 13 of the vertebral bodies 10, 11 and in which the rod 6 lies (Figure 1). In this oblique arrangement, the distance between the contact surfaces formed by the upper edge and the lower edge is small, and this position is therefore referred to as the low position.

After insertion into the intervertebral space 9, the plate-shaped spacers 2 are raised so that they are essentially perpendicular to this horizontal plane and thus perpendicular to the rod 6. This can be achieved relatively easily by pushing the pressure element 8 onto the rod 6 and clamping it against the head-shaped thickening 7. This inevitably leads to the plate-shaped spacers 2 being raised until they lie flat against one another over their entire height and thus reach a maximum construction height of the implant 1; this position is therefore referred to as the raised position (Figure 2). The pressure element 8 can be secured in a suitable manner after the clamping process, for example by profiling the rod 6, which can have screw threads or grooves, or by clamping the inner edge of an opening in the pressure element 8 to the rod 6.

The plate-shaped spacer elements 2 can be secured against lateral displacement relative to one another, for example by means of longitudinal grooves 14 on one side of the spacer elements 2 and by means of ribs 15 engaging in these on the opposite side, the longitudinal grooves 14 and the ribs 15 run from the upper edge to the lower edge, so that the relative displacement of the plate-shaped

A 57 641 u
16 September 2003
u-214/248

Spacer elements 2 are easily possible, but they are secured transversely to this direction of displacement (Figures 7 to 9).

Instead of a rod 6, another tension member can be used to clamp and erect the plate-shaped spacer elements 2, for example a thread or a wire. However, it is also possible for the spacer elements 2 to be erected using a separate instrument. The threads, bands or wires then only serve to hold the erected implant together. In the embodiment of Figure 4, which is constructed similarly to that of Figures 1 to 3 and in which the same parts have the same reference numerals, instead of the central slots 5, a total of four such slots 16 are arranged in each plate-shaped spacer element 2 near the corner points. A loop 17 of a thread is guided through two of these slots 16, and a separate thread is used on the top and bottom. The spacer elements 2 can also be erected using these threads 17, so that the implant is transferred from the low position to the high position.

In the embodiment of Figure 5, in which corresponding parts again have the same reference numerals, the plate-shaped spacer elements 2 are not mounted flat against each other, but are each pivotably connected to a plate-shaped support body 19 or 20 by a pivot bearing 18 at the lower and upper ends, so that when the spacer elements 2 pivot, they act like parallel links that change the distance between the two support bodies 19, 20 (Figure 5). In Figure 5, the implant is in the low position with the

- 11 A
57 641 u
16 September 2003
u-214/248

Lines are shown, an upright position is indicated with dash-dotted lines.

The embodiment of Figure 6 corresponds largely to that of Figures 1 to 3, corresponding parts have the same reference numerals. While in the embodiments of Figures 1 to 3 the plate-shaped spacer elements 2 are formed in one piece, in the embodiment of Figure 6 the spacer elements 2 are divided into an upper part 21 and a lower part 22, the upper part and lower part are pivotally connected to one another, the pivot axis runs transversely to the rod 6 passing through the spacer elements 2 and lies in the horizontal plane. In the low position the upper part 21 and lower part 22 are arranged at an angle in opposite directions, if the upper part and lower part are raised using the rod 6, the spacer elements 2 stretch and thereby increase the height of the implant.

In addition to the two-part spacer elements 2, a closing element 23 can be provided, which is supported on the upper edge and the lower edge of the last spacer element 2 and thus enables all spacer elements 2 to be clamped together by the rod 6 and a pressure element that can be moved thereon.

This division of the spacer element 2 could also be used in a design according to Figure 5, where it is also possible to use spacer elements in the form of handlebars instead of the plate-shaped spacer elements 2. The handlebars do not necessarily have to run parallel to each other, it can also be provided that the handlebars are 180° apart from each other.

- 12A
57 641 u
16 September 2003
u-214/248

are twisted, so that the buckling of these links or spacer elements 2 occurs in opposite directions.

Figures 10 to 12 show a further preferred embodiment of an implant 1 which is constructed similarly to the implant in Figures 1 to 3, corresponding parts therefore have the same reference numerals. In contrast to the simple plate-shaped spacer elements 2 in the embodiment in Figures 1 to 3, the plate-shaped spacer elements 2 in this embodiment have hook-shaped extensions 24 on the front and back, which result from a U-shaped bend in the plate-shaped spacer elements and which form a slot-shaped gap 25 between themselves and the spacer elements. The extensions extend over more than half the height of a spacer element 2. The spacer elements 2 have such an extension 24 on the front and back, with the extensions 24 starting at opposite edges of the spacer element 2 and thus being directed in opposite directions. The free ends 26 of each extension 24 penetrate into the gap 25 of the adjacent spacer element 2, so that an articulated connection is formed between adjacent spacer elements 2. The spacer elements can be pivoted into the upright position, this is made possible by a certain amount of play between the extensions 24 that penetrate into the gaps 25 and the side walls of the gap 25.

Furthermore, the same mechanisms can be used to erect the spacer elements 2 as has been discussed in the preceding embodiments.

Claims (20)

1. Spinal implant for bridging the space between the end surfaces of two vertebral bodies with variable height, characterized in that it has several spacer elements ( 2 ) arranged next to one another, which in a low position run obliquely to a horizontal plane which is arranged essentially parallel to the end surfaces ( 12 , 13 ) of the vertebral bodies ( 10 , 11 ), and which in a high position are erected relative to the low position and run at least approximately perpendicular to the horizontal plane. 2. Implant according to claim 1, characterized in that the spacer elements ( 2 ) run parallel to one another. 3. Implant according to one of claims 1 or 2, characterized in that the spacer elements ( 2 ) are pivotally connected to at least one support body ( 19 , 20 ) which forms a contact surface for the end surface ( 12 , 13 ) of a vertebral body ( 10 , 11 ). 4. Implant according to claim 3, characterized in that the spacer elements ( 2 ) are designed as steering arms. 5. Implant according to claim 3, characterized in that the spacer elements ( 2 ) are designed as plates. 6. Implant according to one of the preceding claims, characterized in that the end edges ( 3 , 4 ) of the spacer elements ( 2 ) at least at one end of the spacer elements ( 2 ) together form a contact surface for the end surface ( 12 , 13 ) of a vertebral body ( 10 , 11 ). 7. Implant according to claim 6, characterized in that the spacer elements ( 2 ) are of different lengths and thus form a non-planar contact surface. 8. Implant according to one of claims 6 or 7, characterized in that the spacer elements ( 2 ) are rounded in the region of their edges ( 3 , 4 ) forming a contact surface. 9. Implant according to one of the preceding claims, characterized in that the spacer elements ( 2 ) have an upper part ( 21 ) and a lower part ( 22 ) which are connected to one another in an articulated manner and that the upper part ( 21 ) and lower part ( 22 ) run obliquely in opposite directions in the low position and are stretched in the high position compared to the low position. 10. Implant according to one of the preceding claims, characterized in that the spacer elements are plates ( 2 ) lying flat against one another. 11. Implant according to claim 10, characterized in that at least one tension member ( 6 ; 17 ) is provided for erecting the plates ( 2 ) against each other. 12. Implant according to claim 11, characterized in that the tension member ( 6 ; 17 ) extends through openings ( 5 ; 16 ) in the plates ( 2 ). 13. Implant according to claim 11 or 12, characterized in that the tension member ( 17 ) is a thread or wire or band. 14. Implant according to claim 11 or 12, characterized in that the tension member ( 6 ) is a rod. 15. Implant according to claim 14, characterized in that the rod ( 6 ) has a profile for fixing a pressure element ( 8 ) displaceable on it. 16. Implant according to claim 15, characterized in that the pressure element ( 8 ) is a disc through which the rod ( 6 ) extends. 17. Implant according to one of claims 10 to 16, characterized in that the plates ( 2 ) have interlocking projections and recesses ( 15 , 14 ) which guide the plates ( 2 ) against each other in the transverse direction and enable them to be freely displaced in the direction from their upper edge ( 4 ) to their lower edge ( 3 ). 18. Implant according to one of the preceding claims, characterized in that the spacer elements ( 2 ) and/or optionally the support bodies ( 19 , 20 ), tension members ( 6 , 17 ) and pressure elements ( 8 ) consist of a resorbable material. 19. Implant according to one of the preceding claims, characterized in that the spacer elements ( 2 ) have hook-shaped projections ( 24 ) on the front and rear sides, which are engaged behind by corresponding hook-shaped projections ( 24 ) of the adjacent spacer elements ( 2 ). 20. Implant according to claim 19, characterized in that the hook-shaped projections ( 24 ) engage behind one another with play.