Intervertebral disk prosthesis and method for producing an intervertebral disk prosthesis

Abstract

The invention relates to an intervertebral disk prosthesis (10), comprising a caudal plate (20), a cranial plate (30), and an elastic core (40) formed between the caudal plate (20) and the cranial plate (30), wherein the caudal plate (20) has a cavity (25) on the side (21) facing the cranial plate (30), wherein the core (40) is integrally connected to the cavity (25) in the caudal plate (20).

Claims

1. An intervertebral disk prosthesis (10), comprising a caudal plate (20), a cranial plate (30), and an elastic core (40) formed between the caudal plate (20) and the cranial plate (30), characterized in that the caudal plate (20) has a cavity (25) on a side (21) facing the cranial plate (30), wherein the core (40) is integrally connected to the cavity (25) of the caudal plate (20), wherein the core (40) is injected or cast into the cavity (25) and the cranial plate (30) is not connected to the core (40), wherein a side of the core (52) facing the cranial plate (30) is arched in shape in a longitudinal direction (L) and a transverse direction (Q), wherein the cranial plate (30) has at least two guiding pins (34), which movably engage with a guiding contour (50) of the core (40), and the guiding contour (50) of the core (40) is formed as at least two curved cavities (51), wherein the core has an elliptical groove, with the at least two curved cavities being formed within the groove, wherein the core (40) is injected or cast into the cavity (25) by means of a plastic injection molding method or vacuum casting method, and wherein the caudal plate (20) has an edge area and an edge section on the side facing the core, which serves for sealing in the molding tool.

2. The intervertebral disk prosthesis (10) according to claim 1, characterized in that the core (40) has viscoelastic properties and/or is made of an elastomer.

3. The intervertebral disk prosthesis (10) according to claim 1, characterized in that a side (22) of the caudal plate (20) facing a bone and/or a side (31) of the cranial plate (30) facing a bone have a tooth system (32) and/or corrugation (29).

4. The intervertebral disk prosthesis (10) according to claim 1, characterized in that in the cavity (25) of the caudal plate (20), an undercut (28) is formed at least in sections.

5. A method for producing an intervertebral disk prosthesis (10) according to claim 1, characterized by the method steps of: a) providing the caudal plate (20) comprising a cavity (25), b) injecting or casting an elastic material into the cavity (25), and forming the elastic core (40).

6. The method according to claim 5, characterized in that prior to step b), the caudal plate (20) is put into a mold.

7. The method according to claim 5, characterized by c) applying the cranial plate (30) onto the core (40) such that at least one guiding pin of the at least two guiding pins (34) of the cranial plate (30) movably engages with a guiding contour (50) of the core (40).

Description

(1) The invention will be explained below in more detail on the basis of a plurality of exemplary embodiments with reference to the attached schematic drawings.

(2) Shown are in:

(3) FIGS. 1a-1b several views of an intervertebral disk prosthesis according to the invention in accordance with a first exemplary embodiment;

(4) FIGS. 2a and 2b various views of an intervertebral disk prosthesis according to the invention in accordance with a second exemplary embodiment;

(5) FIGS. 3a-3c several views of an intervertebral disk prosthesis according to the invention in accordance with a third exemplary embodiment; and

(6) FIG. 4 an exploded view of an intervertebral disk prosthesis according to the invention in accordance with a fourth exemplary embodiment.

(7) The same reference numerals will be used in the following description for identical parts or parts of identical action.

(8) In FIGS. 1a and 1b, an intervertebral disk prosthesis 10 according to a first exemplary embodiment is illustrated. In FIG. 1a, an exploded view of the individual components of the intervertebral disk prosthesis 10 is illustrated. In FIG. 1b, on the other hand, a cross-section of the intervertebral disk prosthesis 10 is illustrated.

(9) It should be pointed out that the individual elements of the intervertebral disk prosthesis 10 in the actually fixed or produced state cannot be disassembled as shown in FIG. 1a. Above all, this is not readily possible because of the production method according to the invention.

(10) The intervertebral disk prosthesis 10, for example, is a cervical intervertebral disk prosthesis. This intervertebral disk prosthesis comprises a caudal plate 20, a cranial plate 30, and a viscoelastic core 40 formed between the caudal plate 20 and the cranial plate 30. The caudal plate 20 has a cavity 25 on the side 21 facing the cranial plate 30. As illustrated in particular in FIG. 1b, the cavity 25 has an undercut 28.

(11) The core 40 is integrally connected to the cavity 25 of the caudal plate 20. The viscoelastic core is in particular injected or cast into the cavity 25. The viscoelastic core is a core of elastomer, such as silicone or PCU, for example.

(12) Within the scope of the production method according to the invention, the caudal plate 20 having the cavity 25 as well as the undercut 28 can first be made available. The caudal plate 20, for example, is put into an injection molding tool. Subsequently, the viscoelastic material can be injected or cast into the caudal plate.

(13) On the lower side or the side 22 facing the bone, the caudal plate 20 has a corrugation 29 at least in sections. In the illustrated example, the corrugation 29 is not formed over the entire lower side 22. Rather, an edge section 23 is formed over the entire circumference which serves as a supporting surface in the injection molding tool. After the caudal plate 20 is put into the injection molding tool, a molding tool is subsequently applied upon so as to be able to form the viscoelastic core 40 thereafter. The edge area 27 of the side 21 of the caudal plate 20 serves in this case as the supporting surface for the molding tool. The edge area 27 serves for sealing within the injection molding tool.

(14) The undercut 28 in the cavity 25 is formed over the entire circumference. Therein, the viscoelastic material is injected, a core 40 is formed, and an integral connection of the core 40 to the caudal plate 20 is established. Thus, the material is prevented from subsequently being removable from the integral connection. Due to the integral connection of the core 40 to the cavity 25 of the caudal plate 20, no additional attachment elements or supplemental materials such as adhesives or threads, for example, are necessary. Thus, the assembly of the intervertebral disk prosthesis 10 takes place quasi during the production phase.

(15) The cranial plate 30 has a tooth system 32 on the upper side or the side 31 facing the bone. The cranial plate 30 moreover has two guiding pins 34. The guiding pins 34 are formed on a connection step 35 of the cranial plate 30.

(16) The cranial plate 30 is not connected to the core. The cranial plate 30 merely rests upon the core 40 on the side 33 facing the caudal plate 20. The guiding pins 34 engage with the guiding contour 50 of the viscoelastic core 40. The guiding core 50 in the illustrated example is formed in the form of two cavities 51. The cavities 51 are essentially formed to be curved. In particular, the cavities 51 have a kidney shape. Accordingly, torsion of the cranial plate 30 in relation to the elastic core 40 is possible. The guiding contour 50 is formed as a section of an elliptical groove 45.

(17) The elastic core 40 is moreover formed to be arched. The core 40 is in particular formed to be arched on the side 52 facing the cranial plate 30. The side 52 is formed to be arched both in the transverse direction Q and the longitudinal direction L. Due to the groove 45 forming an elliptical orbit, an elastic core 40 having a core center 41 is formed which has an elliptical shape and is arched both in the longitudinal direction L and the transverse direction Q. This also enables a tilting movement of the cranial plate 30 in relation to the elastic core 40.

(18) In FIGS. 2a and 2b, an embodiment of a cervical intervertebral disk prosthesis 10 similar to FIGS. 1a and 1b is illustrated. Hereinafter, only the differences will be dealt with. These can in particular be recognized in conjunction with the realization of the elastic core 40.

(19) In FIGS. 1a and 1b, the side 52 of the core 40 is formed to be convexly arched in the transverse direction Q and in the longitudinal direction L.

(20) In FIG. 2a, the core 40 is subdivided into a plurality of partial section. The core center 41 is convexly arched in the transverse direction Q, whereas the area outside the groove 45 is concavely arched in the longitudinal direction L. Thereby, a core center 41 is formed which distinctly protrudes beyond the circumferential section 42 of the core 40. The result is a double saddle function.

(21) As already set forth in FIGS. 1a and 1b, the caudal plate 20 is formed with a cavity 27 and having an undercut 28 over the entire circumference.

(22) A further embodiment of an intervertebral disk prosthesis 10 is illustrated in FIGS. 3a to 3c. This, in turn, is composed of a caudal plate 20, a cranial plate 30, and an elastic core 40.

(23) It can be seen in particular in FIG. 3b, that in this exemplary embodiment, as well, the elastic core 40 is injected into a cavity 25 of the caudal plate 20, with the cavity, in turn, having an undercut 28 formed over the entire circumference.

(24) The differences can in particular be recognized in the shape of the guiding pin 34′ of the cranial plate 30 and the shaping of the guiding contour 50 of the elastic core 40. The guiding contour 50 essentially has a cross shape. The guiding pin 34′ has a hereto complementary shape. The guiding contour 50 has a greater cross-section than the guiding pin 34′ so that the guiding pin 34′ can move within the guiding contour 50. As can be seen from FIG. 3b, the cavity 51 of the guiding contour 50 is formed over the entire height of the elastic core 40. The elastic core 40, in turn, is formed to be convexly arched both in the longitudinal direction L and the transverse direction Q.

(25) In FIG. 3c, the shape of the guiding contour 50, and thus the shape of the complementarily formed guiding pin 34′, are illustrated in greater detail. The cross shape 55 is followed by transverse webs 56. The transverse webs 56, in turn, are formed to be slightly arched.

(26) The guiding contours 50 and/or the core center 41 (this concerns the exemplary embodiments of FIGS. 1a to 2b) form a kind of neutral zone. Since the cavities 51 of the guiding contours 50 are greater than the engaging geometry of the guiding pins 34 and 34′, movement is permitted in cooperation with the cranial plate 30, with the cranial plate 30 being guided within the elastic core 40.

(27) The dimension of the range of motion in the neutral zone is reflected by the geometry of the guiding contour 50 and the associated cavity 51. In the neutral zone, the movement is guided mechanically via the geometry of the elastic core 40 and is performed at lowest load or counterforce. The geometry of the cavity 51 or of the guiding contour 50 within the core 40, and the inversely configured geometry of the guiding pin 34 or 34′ of the cranial plate 30 prevent the intervertebral disk prosthesis 10 from being dislocated.

(28) In FIG. 4, an additional embodiment of an intervertebral disk prosthesis 10 having a cross-shaped guiding pin 34′ and a complementarily formed cavity 51 of the guiding contour 50 is illustrated. In FIG. 4, the elastic core 40 is concavely arched both in the transverse direction Q and the longitudinal direction L. It is also conceivable for the elastic core 40, in particular the side 52, to be concavely shaped only in the longitudinal direction L or only in the transverse direction Q.

LIST OF REFERENCE NUMERALS

(29) 10 intervertebral disk prosthesis 20 caudal plate 21 side of the caudal plate 22 lower side 23 edge section 25 cavity 27 edge area 28 undercut 29 corrugation 30 cranial plate 31 upper side 32 tooth system 33 side of the cranial plate 34, 34′ guiding pin 35 connection step 40 elastic core 41 core center 42 circumferential section 45 groove 50 guiding contour 51 cavity 52 side 53 lower side 55 cross shape 56 transverse web L longitudinal direction Q transverse direction