Intervertebral prosthesis or disk prosthesis

Abstract

An intervertebral prosthesis or disk prosthesis comprising a front side, a rear side, an upper side which can be placed on the base plate of vertebral body, a lower side which can be placed on the base plate of a vertebral body, a right side, a left side, a cavity which can receive a fluid hydraulic osteocementum, an opening in the cavity and several outlets out from the cavity. The total of the transversal surfaces of the outlets S.sub.V on the front side, the total of the transversal surfaces of the outlets S.sub.H on the rear side, the total of the transversal surfaces of the outlets S.sub.R on the right side and the total of the transversal surfaces of the outlets on the left side satisfy the following conditions: S.sub.L>S.sub.R or S.sub.R>S.sub.L or S.sub.H>S.sub.V or S.sub.V>S.sub.H.

Claims

1. A surgical method comprising: implanting an intervertebral implant between an upper vertebra and a lower vertebra, wherein the intervertebral implant includes: a cavity defined by a body having a first end engaged with a delivery tool, the first end having an inlet opening for receiving a flowable material; a top surface in contact with at least a portion of the upper vertebra; a bottom surface in contact with at least a portion of the lower vertebra; a second end opposite the first end; a first lateral side being substantially straight and having a first length extending between the first and second ends, a first height extending between the top and bottom surfaces, and at least one opening; and a second lateral side being substantially straight and having a second length extending between the first and second ends, a second height extending between the top and bottom surfaces, and at least one opening, wherein the first length is substantially the same as the second length and the first height is substantially the same as the second height, and conveying a volume of flowable material to the intervertebral implant using the delivery tool, such that the flowable material flows asymmetrically out of the implant and into a surrounding disc space defined between the upper and lower vertebrae.

2. The method of claim 1, wherein: the at least one opening of the first lateral side has a combined cross-sectional area A1; the at least one opening of the second lateral side has a combined cross-sectional area A2; and A1 is not equal to A2 thereby providing that the flowable material emerges asymmetrically from the implant through said openings.

3. The method of claim 2, wherein A1 is greater than A2 so that the volume of flowable material emerging through the first side is greater than the volume of flowable material emerging through the second side.

4. The method of claim 1, wherein the cavity extends from the inlet opening towards the second end.

5. The method of claim 1, wherein the implant has a rectangular cross section.

6. The method of claim 1, wherein a cross-sectional area of the cavity decreases as the distance from the inlet opening increases.

7. The method of claim 1, wherein a cross-sectional area of the cavity decreases in one of a wedge-shape or a conical shape.

8. The method of claim 1, wherein the top surface and the bottom surface converge towards the second end.

9. The method of claim 1, wherein the flowable material comprises osteocementum.

10. A surgical method comprising: placing an implantable intervertebral cage in a disc space defined between an upper vertebra and a lower vertebra, wherein the cage includes: a first end engaged with a delivery tool, the first end having an inlet opening for receiving flowable material; a second end opposite the first end, the second end being closed so that flowable material cannot emerge therefrom; a top surface in contact with at least a portion of the upper vertebra; a bottom surface in contact with at least a portion of the lower vertebra; and first and second substantially straight sidewalls having equal lengths and having at least one opening formed therein through which flowable material can emerge from the cage; and delivering flowable material to a cavity of the cage using the delivery tool such that the flowable material delivered to the cavity flows asymmetrically out of the cage and into the surrounding disc space.

11. A surgical method comprising: placing an implantable intervertebral cage in a disc space defined between an upper vertebra and a lower vertebra, wherein the cage includes: a first end engaged with a delivery tool, the first end having an inlet opening for receiving flowable material; a second end opposite the first end, the second end being closed so that flowable material cannot emerge therefrom; a top surface in contact with at least a portion of the upper vertebra; a bottom surface in contact with at least a portion of the lower vertebra; and first and second substantially straight sidewalls having equal lengths and having at least one opening formed therein through which flowable material can emerge from the cage; and delivering flowable material to a cavity of the cage using the delivery tool such that a greater amount of flowable material emerges from the cage into a first lateral portion of the disc space than into a second lateral portion of the disc space opposite to the first lateral portion.

12. The method of claim 11, wherein: the at least one opening of the first lateral side has a combined cross-sectional area A1; the at least one opening of the second lateral side has a combined cross-sectional area A2; and A1 is not equal to A2 thereby providing that the flowable material emerges asymmetrically from the implant through said openings.

13. The method of claim 12, wherein A1 is greater than A2 so that the volume of flowable material emerging through the first sidewall is greater than the volume of flowable material emerging through the second sidewall.

14. The method of claim 11, wherein the cavity extends from the inlet opening towards the second end.

15. The method of claim 11, wherein the cage has a rectangular cross section.

16. The method of claim 11, wherein a cross-sectional area of the cavity decreases as the distance from the inlet opening increases.

17. The method of claim 11, wherein a cross-sectional area of the cavity decreases in one of a wedge-shape or a conical shape.

18. The method of claim 11, wherein the flowable material comprises osteocementum.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and further development of the invention are described in even greater detail by means of several examples and partially diagrammatic drawings, in which

(2) FIG. 1 shows a perspective view of an inventive, lens-shaped intervertebral implant,

(3) FIG. 2 shows a longitudinal section through the intervertebral implant of FIG. 1 along the central plane VIII-VIII,

(4) FIG. 3 shows a side view from the right of the intervertebral implant of FIG. 1,

(5) FIG. 4 shows a side view from the left of the intervertebral implant of FIG. 1,

(6) FIG. 5 shows a perspective view of an inventive intervertebral prosthesis, which is secured by means of cured osteocementum,

(7) FIG. 6 shows a plan view of the intervertebral prosthesis of FIG. 5,

(8) FIG. 7 shows a perspective view of a variation of the embodiment, using two intervertebral implants, the osteocementum securing the implant in their position relative to one another as well as to prevent migrating apart,

(9) FIG. 8 shows a plan view of the two intervertebral implants of FIG. 7,

(10) FIG. 9 shows a front view of a variation of the embodiments, in which the perforated intervertebral implant has a rectangular cross section and

(11) FIG. 10 shows a front view of a variation of the embodiment, in which the perforated intervertebral implant has a circular ring-shaped cross section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(12) The intervertebral prosthesis 1, shown in FIGS. 1 and 2, consists of a rectangular hollow body and has a front side 2, a rear side 3, an upper side 4 suitable for positioning against the baseplate of a vertebral body, a lower side 5 suitable for positioning against the baseplate of a vertebral body, a right side 6, a left side 7, a cavity 8 suitable for accommodating a flowable, hydraulic osteocementum, an inlet opening 9 into the cavity 8 and several outlet openings 10; 11; 12; 13 from the cavity 8. The upper side 4 and the lower side 5 converge toward the front side 2 as well as toward the rear side 3, so that a lens-like configuration of the intervertebral prosthesis results.

(13) As can be seen from FIG. 2, the cross section of the cavity 8 decreases in the shape of a cone as the distance from the inlet opening 9 increases.

(14) As shown in FIG. 3, there are three outlet openings 12 with areas F.sub.1, F.sub.2 and F.sub.3 in the right side 6 of the intervertebral prosthesis 1, so that the sum S.sub.R of the cross sectional surfaces of the outlet openings emerging the right side 6 is S.sub.R=F.sub.1+F.sub.2+F.sub.3.

(15) As shown in FIG. 4, there are two outlet openings 13 with the areas F.sub.4 and F.sub.5 in the left side 7 of the intervertebral prosthesis 1, so that the sum S.sub.L of the cross-sectional surfaces of the outlet openings emerging for the left side 7 is S.sub.L=F.sub.4+F.sub.5.

(16) It is important that the sum S.sub.L>S.sub.R, so that more osteocementum can emerge on the left side 7 of the intervertebral prosthesis 1 from the cavity 8 through the outlet opening 13 into the intervertebral space than from the right side 6.

(17) FIGS. 5 and 6 show how the osteocementum 20, emerging from the right side 6 and the left side 7 of the intervertebral prosthesis 1, is distributed. Because the sum S.sub.L of the cross sectional areas of the outlet openings 13 emerging on the left side 7 is larger, the amount of osteocementum 20, emerging on the left side 7 and curing, is also larger than that emerging on the right side 6 and curing.

(18) FIGS. 7 and 8 show a further embodiment, which consists of two inventive intervertebral prosthesis 1, which are disposed next to one another. The two intervertebral prostheses are positioned in such a manner, that the right side 6 of the intervertebral prosthesis 1, which is disposed on the left, is oriented in the direction of the left side 7 of the intervertebral prosthesis 1, which is disposed on the right. For the intervertebral prosthesis 1, disposed on the left, the condition S.sub.L>S.sub.R applies, whereas, for the intervertebral prosthesis 1, which is disposed on the right, the reverse applies, namely S.sub.R>S.sub.L. Due to this measure, less osteocementum 20 emerges in the space between the two intervertebral prostheses 1 than emerges to the right side of the intervertebral prosthesis 1 disposed on the right and to the left side 7 of the intervertebral prosthesis 1 disposed on the left.

(19) FIG. 9 shows a variation of the embodiment of an inventive intervertebral implant 1, which has a rectangular cross section and from which a larger amount of osteocementum 40 has emerged on the right side than on the left side.

(20) FIG. 10 shows a further variation of an embodiment of an intervertebral prosthesis 1, which has a circular cross section and for which the amount of osteocementum 40 emerging on the right side through the outlet openings 12 is larger than that emerging on the left side through outlet openings 13.