DE9413778U1 - Intervertebral implant - Google Patents

Description

Dreiss, Hosenthien,

D-70188 STUTTGART PATENT ATTORNEYS HANSLANGOSCHt

GEROKSTRASSE 6 EUROPEAN PATENT ATTORNEYS Dipl.-lng. (1963-1981)

tr {0711)247961 (4 UNITS) REPRESENTATIVES AGREE TO EUROPE'S UWEDREEISS

FAX (07t1)247164 REPRESENTATIVES ASSIGNED _TO THE EUROPEAN PATENT OFFICE Prof. Dr.jur, Dipl.-lng. M. Sc.

HEINZHOSENTHIA

lurVisitors Or.-ing. Oipl.-lng.

JÖRN FUHLENDORF Dipl.-lng.

JOSEFSTEIMLE Dip!.-Ing.

Applicant:

SCHÄFER micomed GmbH
Schuraannweg 70

D-73614 Schorndorf

3967 033 S/mz 26.08.94 (WP 94/2)

Title: Intervertebral implant

Description

The invention relates to an intervertebral implant for use between two vertebral bodies of a spine with an upper and a lower contact surface and a support unit connecting the contact surfaces to one another.

The individual vertebrae of the spine have, among other things, a vertebral body, a vertebral arch, a spinous process, two transverse processes and two upper and two lower articular processes. The vertebrae are connected to each other via intervertebral discs (disci intervertebralis) that are attached to their vertebral bodies (corpus vertebrae). These intervertebral discs consist of fluid-rich fibrocartilage and connect the individual vertebral bodies to each other. The size of the intervertebral discs decreases from

Postbank Stuttgart 50771-705 (bank code 600 100 70) · Dresdner BanK Stuttgart 1919 854 00 (bank code 600 300 00) S.W.i.F.T.-aclress DFlES DE FF SOO

ID: DE 147507237

top to bottom in accordance with the load occurring in the human body. The intervertebral discs act as elastic buffers and absorb shocks with a spring. It is known that the intervertebral discs can become displaced or that the inner gelatinous core (nucleus pulposus) can protrude through tears in the connective tissue-like, cartilaginous outer ring (annulus fibrosus). The intervertebral disc can then partially enter the intervertebral foramina (foramina intervertebralia) or the spinal canal. In addition, this prolapse can be medial or dorsal, medial or lateral. Such prolapses occur most frequently in the L ₄ -L ₅ , L ₅ -S ₁ and C ₆ -C ₇ vertebrales. If such prolapses are not treated, irreversible pressure damage to nerve roots or transverse lesions occur. If symptomatic physiotherapy, eg physical therapy or massage, does not promise success, the discus intervertebralis must be surgically removed. It is then possible to implant an artificial intervertebral disc or to osteosynthesize the two vertebrae using a rigid intervertebral implant.

EP 392 076 Al discloses an artificial intervertebral disc that consists of an upper and lower contact surface and an elastic intermediate layer. Anchor bolts protrude from the contact surface, over which the artificial

The intervertebral disc is fixed to the vertebral bodies. It has been shown to be disadvantageous that due to the elastic intermediate layer between the two contact surfaces, optimal synthesis of the two vertebrae cannot be achieved.

US 5,192,327 describes a rigid intervertebral implant that is also inserted between two vertebral bodies for osteosynthesis. With this implant, the two vertebrae must be placed at a predetermined distance from each other in order to insert the implant. If the distance between the two vertebrae is too great, the implant can easily slip or not hold.

The invention is therefore based on the object of providing an intervertebral implant with the structure mentioned above, which on the one hand is easy to insert between the vertebral bodies, but which ensures optimal support of the two adjacent vertebrae.

This object is achieved according to the invention in that the implant has a modular structure and the contact surfaces are formed by contact disks which can be joined to a support unit immediately before implantation so that the implant has a height corresponding to the location of use.

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The modular design of the implant provides the significant advantage that the implant is available in individual parts before it is installed and is only assembled to fit perfectly immediately before insertion. The contact discs are connected to a support unit that determines the distance between the two vertebrae. According to the invention, the contact discs can be connected to a large number of support units so that there is always an implant available that can be inserted exactly between the two vertebrae.

The intervertebral implant according to the invention can not only replace intervertebral discs, but also bridge entire vertebrae. This is particularly necessary if an entire vertebra has been surgically removed due to spondylitis, for example. The two contact discs are adjusted with the corresponding support unit to a distance that essentially corresponds to the surgically removed vertebra and the intervertebral discs. The intervertebral implant according to the invention therefore serves as a placeholder for intervertebral discs and/or entire vertebrae.

In a further development, at least one contact disc is designed as a ring. This design has the advantage that the implant fits better to the

adjacent vertebrae and can be more easily surrounded by bone tissue.

A simple joining of the intervertebral implant according to the invention is achieved in that the contact discs have receptacles for the support unit on their sides facing each other. In addition, the contact discs can have receptacles for further support units on their sides facing away from each other. In this way, not just two but several contact discs can be connected to each other, whereby a tower-like structure can be built up. In this way, several vertebrae can also be bridged.

Optimal anchoring of the intervertebral implant with the front sides of the adjacent vertebrae is achieved by providing the contact discs with a surface contour that differs from the smooth surface, e.g. a ribbing, serration or similar, at least on their opposite front surfaces. Slipping of the implant is thus almost impossible.

According to the invention, the support unit consists of several rods. This structure has the significant advantage that it is relatively simple, has a low weight, can easily be penetrated by bone tissue and is easy to store due to the simple components.

According to the invention, the receptacles consist of vertical recesses in particular. The rods of the support unit are inserted or driven into these recesses and are held there by a press fit. The implant according to the invention can be constructed very quickly and the height of the implant can be adjusted precisely using rods of different lengths.

In a further development, the support unit is provided with a fine-mesh grid, particularly made of titanium or biocompatible plastic. This fine-mesh grid promotes the filling of the implant with spongiosa.

The modular design has the significant advantage that several support units of different lengths, in particular several rods of different lengths, are available, so that almost any construction height can be achieved with the implant according to the invention. An optimal adaptation is achieved by the fact that the support disc has a wedge shape in the ventral-dorsal vertical section. This wedge shape enables an optimal adaptation to the neighboring vertebrae.

In another embodiment, the contact discs are parallel to each other. This is particularly advantageous in the thoracic region of the spine, as the individual vertebrae there are almost parallel to each other.

Further advantages, features and details emerge from the following description, in which particularly preferred embodiments are shown in detail with reference to the drawing. The features mentioned in the claims and the description and shown in the drawing can each be essential to the invention individually or in any combination. The drawing shows:

Figure 1 is a plan view of the intervertebral implant according to the invention;

Figure 2 is a perspective view, partially exploded, of the intervertebral implant according to the invention;

Figure 3 shows a section III-III according to Figure 2; and Figure 4 shows a section IV-IV according to Figure 1.

Figure 1 shows a top view of a ventral intervertebral implant, designated as a whole with 1, which has a cross-sectional shape that approximates the cross-section of a vertebral body. Accordingly, the ventral side 2 of the intervertebral implant is convex, whereas the dorsal side 3 is flat. It is also conceivable that this dorsal side 3 is concavely curved.

ring-shaped or oval cross-sectional shapes are conceivable. Between these two sides 2 and 3, a breakthrough 4 can be seen, which promotes filling of the implant 1 with spongiosa. In addition, receptacles 6 designed as blind holes 5 can be seen, in which a support unit 7 (Figure 2) can be anchored. A total of ten to twelve such receptacles are provided.

The structure of the intervertebral implant 1 can be seen in Figure 2. It is clear that the support unit 7 consists of several rods 8 that are anchored in the receptacles 6. In the embodiment of Figure 2, the rods 8 have the same length, but they can also be of different lengths. To anchor the rods 8, receptacles 6 are provided on both the top and bottom of the contact disks 10 that form contact surfaces 9.

In section III-III, which is shown in Figure 3, it is clearly visible that the receptacles 6 provided on the top and bottom are opposite each other and are designed as blind holes 5. The rods 8 are driven into these receptacles 6. By using several support disks 10, a tower-like structure can be achieved.

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From Figures 3 and 4 it can be seen that the front surfaces of the contact disks 10 have a toothing 11, which ensures an optimal hold on the neighboring vertebrae. For the sake of simplicity, this toothing 11 is not shown in Figures 1 and 2. The wedge shape of the contact disk 10 can be clearly seen from Figure 4. In this way, even vertebrae that are at an angle to one another can be optimally connected to one another.

The modular design of the intervertebral implant 1 according to the invention ensures that by using rods 8 of the appropriate length, whereby the implant 1 is assembled immediately before installation, the free space between the vertebrae to be connected is optimally filled and the remaining vertebrae of the spine can retain their original position. The rods 8 can be held in the receptacles 6, for example, by means of a press fit, caulking, screwing or the like. The presence of a large number of receptacles 6 means that the rods 8 can be installed in the most suitable places, whereby only four or five rods are used at a time. A fine-mesh net or grid can be inserted into the interior space surrounded by the rods 8, which promotes the filling of the implant 1 with spongiosa.

Claims (15)

• II".. &idigr;&iacgr;*·»&idigr; · *··♦··♦« Protection claims 1. Intervertebral implant for use between two vertebral bodies of a spine with an upper and a lower contact surface and a support unit connecting the contact surfaces to one another, characterized in that the implant (1) has a modular structure and the contact surfaces are formed by contact disks (10) which can be joined to such a support unit (7) immediately before implantation so that the implant (1) has a height corresponding to the place of use. 2. Intervertebral implant according to claim 1, characterized in that at least one contact disc (10) is designed as a ring. 3. Intervertebral implant according to claim 1 or 2, characterized in that the contact discs (10) have receptacles (6) for the support unit (7) on their mutually facing sides. 4. Intervertebral implant according to one of the preceding claims, characterized in that the contact discs (10) are arranged at their opposite Sides have holders (6) for additional support units (7). 5. Intervertebral implant according to one of the preceding claims, characterized in that the contact discs (10) are provided at least on their sides facing away from each other with a surface contour that deviates from the smooth surface, e.g. a corrugation, toothing (11) or the like. 6. Intervertebral implant according to one of the preceding claims, characterized in that the support unit (7) consists of several rods (8). 7. Intervertebral implant according to one of claims 3 to 7, characterized in that the receptacles (6) consist of in particular vertical depressions or blind holes (5). 8. Intervertebral implant according to claim 6 and 7, characterized in that the rods (8) and the blind holes (5) form a press fit. 9. Intervertebral implant according to one of the preceding claims, characterized in that the support unit (7) has a fine-mesh grid, in particular made of titanium or biocompatible plastic. 10. Intervertebral implant according to one of the preceding claims, characterized in that it is constructed from two or more contact disks (10) and a support unit (7) located between two contact disks (10). 11. Intervertebral implant according to one of the preceding claims, characterized in that the size of the contact discs (10) is adapted to the size of the vertebrae. 12. Intervertebral implant according to one of the preceding claims, characterized in that several support units (7) of different lengths are available. 13. Intervertebral implant according to one of the preceding claims, characterized in that the contact disc (10) has a wedge shape in the ventral-dorsal vertical section. 14. Intervertebral implant according to one of claims 1 to 12, characterized in that the contact discs (10) are parallel to one another. 15. Intervertebral implant according to one of the preceding claims, characterized in that it consists of titanium and/or biocompatible plastic.