INTERVERTEBRAL DISC IMPLANT

Abstract

Intervertebral disc implant comprising a prosthetic nucleus of a hydrogel. The prosthetic nucleus comprises a porous inner core embedded in the hydrogel, e.g., with sections with open cells and sections with closed cells. The porous inner core can for example be made of a 3D printable hydrogel or bio-ink. The prosthetic nucleus further comprises a jacket enclosing the porous inner core and the embedding hydrogel.

Claims

1. An intervertebral disc implant comprising a prosthetic nucleus of a hydrogel, wherein the prosthetic nucleus comprises a porous inner core embedded in the hydrogel.

2. The intervertebral disc implant according to claim 1, wherein the porous inner core has a structure with open cells.

3. The intervertebral disc implant according to claim 2, the structure of the porous inner core further comprising closed cells.

4. The intervertebral disc implant according to claim 3, wherein the closed cells form a posterior wall.

5. The intervertebral disc implant according to claim 1, wherein the porous inner core is made of a hydrogel or bio-ink.

6. The intervertebral disc implant according to claim 5, wherein the porous inner core is made by a rapid prototyping process.

7. The intervertebral disc implant according to claim 6 wherein the rapid prototyping process comprises stereolithography, fused deposition modelling, laminated object modelling, selective laser sintering, and/or 3D printing.

8. The intervertebral disc implant according to claim 1, wherein the prosthetic nucleus further comprises a jacket enclosing the hydrogel and the porous inner core.

9. The intervertebral disc implant according to claim 7, wherein the jacket is made of a fibrous material.

10. The intervertebral disc implant according to claim 8, wherein the jacket is at least partly coated with a bio-coating.

11. The intervertebral disc implant according to claim 10 wherein the bio-coating comprises mesenchymal stem cells.

12. The intervertebral disc implant according to claim 1 further comprising and a fusion cage comprising a porous body of a non-compressible bio-compatible material.

13. The intervertebral disc implant according to claim 12 wherein the non-compressible bio-compatible material comprises PEEK, titanium, and/or carbon materials.

14. An intervertebral disc implant connectable to two adjacent vertebrae defining an intervertebral disc space, the implant comprising a prosthetic nucleus of a hydrogel, wherein the prosthetic nucleus comprises a porous inner core embedded in the hydrogel and a fibrous scaffold plate connected or connectable to two vertebrae defining an intervertebral disc space, the fibrous scaffold plate extending along at least a part of a contour of the intervertebral disc space.

15. The intervertebral disc implant according to claim 14, wherein the fibrous scaffold plate is configured to connect to the two adjacent vertebrae.

16. The intervertebral disc implant according to claim 15 wherein the fibrous scaffold plate is configured to connect to the two adjacent vertebrae by a mechanical connection.

17. The intervertebral disc implant according to claim 14, wherein the fibrous scaffold plate comprises a bio-coating.

18. The intervertebral disc implant according to claim 17 wherein the bio-coating comprises a platelet rich plasma.

19. A fusion cage for spinal fusion, comprising a porous body of a non-compressible bio-compatible material.

20. The fusion cage according to claim 19 wherein the non-compressible bio-compatible material comprises EEK, titanium, and/or carbon materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1: shows an exemplary embodiment of an intervertebral disc implant in transversal cross section;

[0049] FIG. 2: shows the porous core of the implant of FIG. 1;

[0050] FIG. 3A:shows an exemplary embodiment of a fibrous scaffold plate at a posterolateral side of a lumbar intervertebral disc space;

[0051] FIG. 3B:shows a fibrous scaffold plate at an anterior side of a lumbar intervertebral disc space;

[0052] FIG. 3C:shows a fibrous scaffold plate at a lateral side of a lumbar intervertebral disc space;

[0053] FIG. 3D:shows a fibrous scaffold plate at an anterior a side of a cervical intervertebral disc space.

DETAILED DESCRIPTION

[0054] FIG. 1 shows a transversal cross section of an intervertebral disc implant 1 in an intervertebral disc space 2 between two vertebrae 3A, 3B. The intervertebral disc implant 1 replaces a nucleus pulposus (NP) of a natural intervertebral disc. The natural NP serves to space the vertebrae 3A, 3B and to absorb and hydraulically distribute pressure and impact loads. To mimic this, the intervertebral disc implant 1 has a prosthetic nucleus 4 of a flowable and biocompatible hydrogel 2 in a jacket 5 of a fibrous PET material, biasing the hydrogel of the prosthetic nucleus 4 into a desired shape, e.g., to support lordotic shaping.

[0055] The prosthetic nucleus 4 further comprises a porous inner core 6 fully embedded in the biocompatible hydrogel 2. The biocompatible hydrogel 2 forms an outer layer around the porous inner core 6. The porous inner core 6 has a section 6A with open cells or pores absorbing the biocompatible hydrogel which supports structural integrity of the intervertebral disc implant 1. The porous inner core 6 also has a section 6B with closed cells forming a posterior wall blocking passage of vertebral fracture fragments through the intervertebral disc implant 1 to the spinal cord (not shown). The closed cell section 6B and the open cell sections 6A form an integral part and the transition between the sections may not be a sharp as shown in the drawing. In fact the all sections will comprise open cells and closed cells but the closed cell section 6B will typically have a higher density of closed cells than the open cell sections 6A.

[0056] In FIG. 1, the porous inner core 6 is shown with a substantially rectangular cross sectional shape. In sagittal cross section (perpendicular to the cross section shown in FIG. 1), the porous inner core 6 can for example be substantially wedge-shaped, so as to force the adjacent vertebrae 3A, 3B to a mutual orientation restoring the natural lordotic curvature. The porous inner core 6 is shown separately in perspective view in FIG. 2, and has relatively high side face 8 at the anterior side, a lower side face 9 at the posterior side and wedge shaped lateral side faces 10.

[0057] The foam-like structure of the porous inner core 6 with open and closed cells can for example be made by 3D-printing of a printable hydrogel or bio-ink. This also allows customized shaping of the porous inner core to optimize lordotic re-shaping.

[0058] In the shown exemplary embodiment, the closed cells 6B of porous inner core form a T-shaped or anchor shaped section with an anterior flange and a posterior flange bridged by a central web section. The open cells 6A form two oval bodies fitting between the web plate and the anterior and posterior flanges. Other distributions of open and closed cells can also be used, in particular to optimize and tailor the visco-elastic dynamics of the inner core 6 for a specific case.

[0059] The embedding biocompatible hydrogel 2 is absorbed by the open cells 6A of the porous inner core 6. To facilitate a more even distribution of the biocompatible hydrogel through the porous inner core 6, the closed cell sections 6B can be provided with channels or fenestrations 11.

[0060] The intervertebral disc implant 1 is surrounded by the annulus fibrosus (AF) 12 and sandwiched between the cartilage endplates 13A, 13B of the adjacent vertebrae 3A, 3B.

[0061] The intervertebral disc implant 1 can for example be implanted by means of a cannula (not shown). In a first step, the porous inner core 6 is inserted between the two vertebrae 3A, 3B. The porous inner core 6 is within the jacket 5 but without the hydrogel forming the outer layer 7 of the prosthetic nucleus. The porous inner core 6 comprises a cannula which is used for handling the porous inner core during insertion. In a next step, a hydrogel is injected via the cannula. The hydrogel 2 is partly absorbed by the open cells 6A of the porous inner core 6 and partly forms an outer layer around the porous inner core 6. Injection of hydrogel is stopped after sufficient hydrogel is injected to provide the desired height of the intervertebral disc space 2. In a final step, the cannula is removed.

[0062] In FIG. 1, the AF 12 is still intact. If the AF 12 also needs to be restored, a fibrous scaffold plate can be used stimulating regrowth of the AF tissue. FIGS. 3A-D show examples of such fibrous scaffold plates 30 in different positions.

[0063] In the lumbar region (FIGS. 3A-C), the AF 8 spans the full circumference of the intervertebral disc space 2 in top view. To replace an intervertebral disc in the lumbar region, the surgeon typically operates from the posterior side B. Parts of the facet joints may need to be removed to stay at safe distance from the spinal cord and reach the intervertebral disc space at a lateral side. The fibrous scaffold plate 30 can then be attached to a posterolateral corner of the two respective vertebrae.

[0064] FIG. 3B shows a fibrous scaffold plate 30′ applied at the anterior side of an intervertebral disc space 2 in the lumbar region. Such an anterior approach is exceptional since the surgeon must approach the intervertebral disc space 2 through the patient’s belly, which usually has substantial impact on the patient’s recovery. Here, a larger scaffold plate can be used, since the surgeon has better access.

[0065] FIG. 3C shows an alternative lateral approach. In this case, the surgeon approaches the intervertebral disc space 2 from the side. Due to the wedge-shape of the intervertebral disc space 2, the fibrous scaffold plate 30″ is rhomboid shaped as it needs to be higher at the anterior side than at the posterior side.

[0066] FIG. 3D shows a fibrous scaffold pate 30‴ applied in the cervical region. In this region, the intervertebral disc space 2 can be reached form the anterior side without disturbance of internal organs. Moreover, in the cervical region, the AF only spans the anterior two third of the circumference of the intervertebral disc space 2, so anterior application is the most appropriate approach.

[0067] The fibrous scaffold plates 30′, 30″, 30‴ are dimensioned in accordance with the actual anterior, posterior or lateral position. The fibrous scaffold plates are woven or non-woven plates of bio-compatible fiber material, in particular PET. In the cervical region (FIG. 3D), the fibers converge in an upward direction to mimic the lamellae structure of the anterior cervical AF tissue.

[0068] The fibrous scaffold plates are provided with eyelets 31 or similar openings for receiving fasteners to anchor the fibrous scaffold plates to the two adjacent vertebrae.