WO2009040840A1

WO2009040840A1 - Intersomatic cage, pliers for intersomatic cage, kit for insertion of an intersomatic cage

Info

Publication number: WO2009040840A1
Application number: PCT/IT2007/000682
Authority: WO
Inventors: Giuseppe Sala; Paolo Guerra
Original assignee: Sintea Biotech S.P.A.
Priority date: 2007-09-28
Filing date: 2007-09-28
Publication date: 2009-04-02

Abstract

An intersomatic cage (4), suitable for being inserted in an interdiscal space, pliers (20) for gripping the cage (4), a kit for inserting the cage (4) and the relative method of insertion. The cage (4) allows a steady and safe grip, in al the insertion steps and ensures quick release of the gripping pliers (20) following the insertion of the cage (4) in the interdiscal space.

Description

DESCRIPTION

INTERSOMATIC CAGE, PLIERS FOR INTERSOMATIC CAGE, KIT FOR INSERTION OF AN INTERSOMATIC CAGE

5 [0001] The present invention relates to an intersomatic cage, preferably of the reabsorbing type, pliers for gripping and inserting said cage, a kit for the insertion of an intersomatic cage and the relative method of insertion. [0002] As is known, in vertebral surgery stabilisation systems are widely used for treating the degenerative disc pathology. The known devices are currently made of

10 a titanium alloy, such material being biocompatible and non-toxic over time. Nevertheless, titanium alloy prostheses have problems due to stress-shielding phenomena and to subsidence as well as to the wear and degeneration of surrounding and adjacent tissues, with consequent alteration of the vertebral column bio-mechanics over time.

15 [0003] Prostheses of a biocompatible and bio-reabsorbing polymeric material such as PDLLA 70:30 have been used to obviate such disadvantage. Such prostheses restore the functional continuity of the vertebral column and since they are completely reabsorbed over time, they favour a total arthrodesis process. In other words, they allow achieving a complete arthrodesis without the presence of

20 permanent prosthesis implants.

[0004] In any case, the intersomatic cages of the prior art have some disadvantages.

[0005] In fact, said cages have very small sizes and must be inserted between two adjacent vertebral bodies. Therefore, they must be gripped with special pliers

25 and inserted between the vertebral bodies after sprain of the same by special spraining devices. The insertion step is quite critical since it is necessary to avoid the excessive spraining of the vertebral bodies for preventing damages to the surrounding tissues and nervous structures. The insertion must therefore occur forcing the prosthesis between the vertebral bodies, typically by hammering and strong actions.

[0006] The prior art prostheses are provided with coupling means with the pliers that do not allow an always steady and safe gripping of the prosthesis. [0007] In fact, with the prior art prostheses the detachment of the prosthesis from the pliers in the insertion step is not infrequent; such detachment may be hazardous and makes the insertion step very slow and delicate.

[0008] The problem of the present invention is to provide an intersomatic cage which should solve the disadvantages mentioned with reference to the prior art. [0009] Such disadvantages are solved by a cage in accordance with claim 1 , pliers in accordance with claim 17, a kit in accordance with claim 26 and a method in accordance with claim 29.

[0010] Other embodiments of the present invention are described in the subsequent claims.

[0011] Further features and the advantages of the present invention will appear more clearly from the following description of preferred non-limiting embodiments thereof, wherein:

[0012] figure 1 shows a perspective view of an intersomatic cage according to an embodiment of the present invention;

[0013] figure 2 shows a plan view of the cage of figure 1 , from the side of arrow Il of figure 1 ; [0014] figure 3 shows a side view of the cage of figure 1 , from the side of arrow III of figure 1;

[0015] figure 4 shows a section view of the cage of figure 1 , along the section line IV-IV of figure 3;

[0016] figure 5 shows a section view of the cage of figure 1, along the section line V-V of figure 3;

[0017] figures 6a and 6b show perspective views of gripping pliers for intersomatic cages according to different possible embodiments of the present invention;

[0018] figure 7 shows a plan view of a portion of the pliers of figure 6; [0019] figures 8-10 show partial section views of successive steps of gripping of the intersomatic cage by the pliers of figure 6;

[0020] figures 11-12 show perspective views of steps of insertion of a cage between two adjacent vertebral bodies;

[0021] figure 13 shows a perspective view of different trials of a kit for inserting an intersomatic cage according to the present invention.

[0022] With reference to the above figures, reference numeral 4 generically denotes an intersomatic cage suitable for being arranged between two adjacent vertebral bodies 8, 10 that determine an interdiscal space. [0023] Cage 4 comprises a cage body 12 having a prevailing cross extension X- X, substantially parallel to a side insertion direction of cage 4 in the interdiscal space.

[0024] Advantageously, the cage body 12 has a seat 16 for allowing the gripping of cage 4 by gripping means 18, such as pliers 20.

[0025] Advantageously, seat 16 is positioned at a side end 24 of the cage body 12, relative to said prevailing cross extension X-X, and is open on the side of said side end 24 so as to be accessible by the gripping means 18, 20 external to cage 4.

[0026] At said seat 16, the cage body 12 comprises a protuberance 30 suitable for allowing a gripping of cage 4 according to a shape coupling with said gripping means 18, 20.

[0027] According to an embodiment, seat 16 seats a protuberance 30 on the overall having a prism configuration, suitable for allowing gripping cage 4 with gripping means 18, 20, according to a shape coupling.

[0028] Seat 16 is delimited inwards of the cage body 12, that is, opposite the side end 24, by a support wall 34, facing the side end 24 of the cage body 12 and suitable for ensuring a stop for the gripping means 18, 20 of cage 4. [0029] The support wall 34 determines a support surface 38 incident with a centre line plane 40 of the cage body 12, said centre line plane 40 being perpendicular to the prevailing cross extension X-X. [0030] Preferably, the support surface 38 forms an incidence angle 41 with the centre line plane 40, on the side of the cage body 12 arranged in front direction of the spinal tract in a configuration of insertion of cage 4 in the interdiscal space. [0031] Preferably, protuberance 30 extends perpendicularly to said support wall 34. [0032] According to an embodiment, protuberance 30 at a jointing portion with the support wall 34 comprises at least one recess 44 so as to form at least one undercut 46.

[0033] Preferably, protuberance 30 determines a pair of undercuts 46, respectively facing a front portion 50 and a back portion 52 of the cage body 12. [0034] Preferably, said protuberance comprises an abutment plane 56, substantially parallel to said support wall 34.

[0035] Seat 16 has an axial extension smaller than the axial thickness of the cage body 12, so as to be axially delimited by at least one shelf 60 of the cage body 12; by axial direction it is meant a direction perpendicular to the side insertion direction and substantially parallel to a portion of vertebral column wherein cage 4 is inserted.

[0036] Preferably, protuberance 30 is axially delimited by a pair of shelves 60 of the cage body 12, said shelves 60 forming axial guides for the insertion of gripping means 18, 20 of cage 4. [0037] According to an embodiment, the cage body 12 comprises at least one opening 64 extending along said prevailing cross extension X-X, passing through the cage body 12 along said axial direction.

[0038] The cage body is axially delimited by a pair of bases 68, suitable for abutting against the vertebral plates of adjacent vertebral bodies 8, 10; preferably, at at least one base 68, the cage body 12 comprises fixing elements 70 that extend from said base 68, suitable for favouring the primary stability of cage 4, in a configuration of insertion of cage 4 in the interdiscal space. For example, said fixing elements 70 have a triangular or trapezoidal configuration.

[0039] Preferably, the cage body 12 comprises, relative to a section plane parallel to said axial direction and perpendicular to said side prevailing extension X-

X, a wedge section, said wedge having a diverging profile moving from the front portion 50 to the back portion 52 of the cage body 12.

[0040] Advantageously, said cage is made of a biocompatible and/or bio- reabsorbing polymeric material. [0041] The present invention relates to pliers 20 for intersomatic cage 4, suitable for allowing the gripping and insertion of an intersomatic cage in an interdiscal space.

[0042] According to an embodiment, pliers 20 comprise a pair of handles 74 for gripping pliers 20; preferably said handles 74 are mechanically connected to rods 78 provided with gripping fingers 82 counter shaped relative to said protuberance 30 of cage 4, so as to ensure a safe gripping of cage 4.

[0043] Advantageously, the gripping fingers 82 are counter shaped relative to undercuts 46 determined by protuberance 30 of cage 4, so as to surround and clamp protuberance 30 in a closed configuration of pliers 20. [0044] According to an embodiment, a first gripping finger 82' have an 'L' configuration so as to allow the concurrent placing of finger 82' on a first undercut 46' of protuberance 30 and on the abutment plane 56 of protuberance 30.

[0045] A second gripping finger 82" is counter shaped relative to a second undercut 46" opposite the first gripping finger 82' and the first undercut 46'. [0046] According to an embodiment of the present invention, the gripping fingers 82 are angled relative to handles 74, so that in a gripping configuration of cage 4 with pliers 20, handles 74 are angled relative to said prevailing cross extension direction X-X (figure 6a).

[0047] Preferably, the gripping fingers 82 are angled relative to handles 74, so that in a gripping configuration of cage 4 with pliers 20, said handles 74 are substantially perpendicular relative to the prevailing cross extension direction X-X and parallel to a front-back direction determined by the vertebral bodies that form the interdiscal space of insertion of cage 4 (figure 6a).

[0048] According to a further possible embodiment of the present invention, the gripping fingers 82 are substantially parallel to handles 74, so that in a gripping configuration of cage 4 with pliers 20, handles 74 are substantially parallel relative to said prevailing cross extension direction X-X (figure 6b). [0049] In this way, in a gripping configuration of cage 4 with pliers 20, said handles 74 are substantially perpendicular relative to a front-back direction determined by the vertebral bodies that form the interdiscal space of insertion of cage 4.

[0050] Preferably, at least one of said handles 74 comprises, opposite the gripping fingers 82, a plate 86 suitable for allowing the abutment on pliers 20 with a hammer, for favouring the insertion of cage 4 in the interdiscal space according to a front-back direction.

[0051] Advantageously, pliers 20 comprise screw means 90 engaged with holes of said handles 74, so as to allow spreading and clamping handles 74 and gripping fingers 82 without exerting manual pressure on handles 74. [0052] The present invention relates to a kit for the insertion of an intersomatic cage 4 in an interdiscal space, the kit comprising at least one cage 4 and at least one pair of pliers.

[0053] Preferably, the kit for inserting an intersomatic cage comprises elements for spraining vertebral bodies suitable for allowing a spacing between adjacent vertebral bodies 8, 10 and the subsequent insertion of an intersomatic cage 4 in the interdiscal space determined thereinbetween.

[0054] Preferably, the kit comprises trials 100 suitable for favouring the selection of the intersomatic cage to be inserted in an interdiscal space (figure 13). [0055] The method of insertion of an intersomatic cage 4 in an interdiscal space determined by two adjacent vertebral bodies 8, 10 shall now be described. The method comprises the steps of spraining two adjacent vertebral bodies 8, 10 that determine an interdiscal space beforehand. An intersomatic cage 4 is gripped at a side end 24 with pliers 20 suitable for making a shape coupling with protuberance 30 of seat 16.

[0056] The pliers are clamped with screw means 90 that clamp the gripping fingers 82 of pliers 20 on the protuberance of the seat. The steps of coupling of fingers 82 on protuberance 30 are for example illustrated in figures 8-10. [0057] The cage is then moved laterally in the proximity of the interdiscal space and is positioned at the opening of the interdiscal space so as to arrange the front portion or end 50 of the cage body 12, preferably having smaller thickness than the back portion or end 52, at such opening.

[0058] The cage is then inserted in a front-back direction hitting with a hammer on plate 86 arranged on a gripping handle 74 of pliers 20 so as to force the insertion of the cage in said interdiscal space, through a rotation of the cage relative to an axis of rotation parallel to the portion of vertebral column wherein the cage is inserted.

[0059] Then, once the cage has been positioned in the interdiscal space, the pliers are extracted, acting on the screw means 90 in so as to spread the gripping fingers 82 of pliers 20, and release and extract the pliers from the cage. [0060] As we can appreciate from the description, the cage, the pliers, the kit and the method of the present invention allow overcoming the disadvantages of the prostheses of the prior art.

[0061] In particular, the intersomatic cage allows restoring the height of the intervertebral disc providing a support to the front column and ensuring stability to the operated portion. [0062] Advantageously, the cage comprises a seat that allows the autologous bone grafting; in this way it is possible to achieve an arthrodesis by the growth of a bone bridge between two adjacent vertebras. Such arthrodesis process moreover, is facilitated by the re-absorption of the cage in a time interval ranging between 16 and 18 months. [0063] The reabsorbing intersomatic cage stabilises the lumbar rachis in a safe manner, since the cage consists of a single body that has no disconnected parts and thus does not exhibit intrinsic kinematic characteristics.

[0064] Advantageously, the cage comprises a gripping seat suitable for ensuring a steady and safe grip of the cage also subsequent to the operations for inserting the prosthesis in the interdiscal seat.

[0065] In fact, thanks to the seat shaping, the cage can be gripped by the pliers so as to oppose the rotation and side movements first, in particular perpendicular, relative to the side insertion of the cage.

[0066] Moreover, the undercuts on the protuberance of the cage seat oppose the rotation and the extraction of the cage from the pliers according to a direction substantially parallel to the direction of insertion of the cage.

[0067] Advantageously, the gripping fingers of the pliers are counter shaped relative to the protuberance of the cage seat, so as to ensure a safe gripping of the cage. [0068] Advantageously at the handles and/or rods the pliers comprise an abutment plane that allows easily hitting with a hammer on the pliers so as to favour the insertion of the cage in the interdiscal seat.

[0069] The screw clamping system allows gripping the cage with a safe grip without the need of manually clamping the pliers on the cage; thus the surgeon can grip the pliers with the cage without having to exert any manual clamping pressure on the pliers handles and without the risk of accidental release of the pliers. [0070] Moreover, the screw clamping system also allows a safe release of the pliers subsequent to the completion of the insertion of the prosthesis in situ. In fact, spreading the gripping fingers of the pliers, it is possible to extract the same with great rapidity and there is no risk, as it happens in the prior art prostheses, that the pliers could lock on the cage after positioning the latter in the interdiscal seat. [0071] Moreover, the shelves that delimit the seat ensure an axial locking of the pliers on the cage.

[0072] A man skilled in the art may make several changes and adjustments to the cages and to the pliers described above in order to meet specific and incidental needs, all falling within the scope of protection defined in the following claims.

Claims

1. lntersomatic cage (4), suitable for being inserted in an interdiscal space between two adjacent vertebral bodies (8, 10)₁ comprising a cage body (12) having a prevailing cross extension (X-X), substantially parallel to a side insertion direction of the cage (4) in the interdiscal space, the body (12) having a seat (16) for allowing the gripping of the cage (4) by gripping means (18, 20), characterised in that said seat (16) is arranged at a side end (24) of the cage body (12), relative to said cross prevailing extension (X-X), the seat (16) is open on the side of said side end (24) so as to be accessible by gripping means (18, 20) external to the cage (4), and comprises a protuberance (30) suitable for allowing a gripping of the cage (4) according to a shape coupling with said gripping means (18, 20).

2. lntersomatic cage (1) according to claim 1, wherein the seat (16) seats a protuberance (30) on the overall having a prism configuration, suitable for allowing the gripping of the cage (4) with gripping means (18, 20), according to a shape coupling.

3. lntersomatic cage (4) according to claim 1 or 2, wherein said seat (16) is delimited inwards of the cage body (12) by a support wall (34), facing said side end (24) of the cage body (12) and suitable for ensuring a stop for gripping means (18, 20) of said cage (4).

4. lntersomatic cage (4) according to claim 3, wherein said support wall (34) determines a support surface (38) incident with a centre line plane (40) of the cage body (12), said centre line plane (40) being perpendicular to the prevailing cross extension (X- X).

5. lntersomatic cage (4) according to claim 4, wherein said support surface (38) forms an incidence angle with the centre line plane (40), on the side of the cage body (12) arranged in front direction of the spinal tract in a configuration of assembly of the cage (4) in the interdiscal space.

6. lntersomatic cage (4) according to any one of claims 3 to 5, wherein said protuberance (30) extends perpendicularly to said support wall (34).

7. lntersomatic cage (4) according to any one of claims 3 to 6, wherein said protuberance (30) at a jointing portion with the support wall (34) comprises at least one recess (44) so as to form at least one undercut (46).

8. lntersomatic cage (4) according to any one of claims 3 to 7, wherein said protuberance (30) determines a pair of undercuts (46), respectively facing a front portion (50) and a back portion (52) of the cage body (12).

9. lntersomatic cage (4) according to any one of claims 3 to 8, wherein said protuberance (30) comprises an abutment plane (56), substantially parallel to said support wall (34).

10. lntersomatic cage (4) according to any one of claims 1 to 9, wherein the seat (16) has an axial extension smaller than the axial thickness of the cage body (12), so as to be axially delimited by at least one shelf (60) of the cage body (12), said axial direction being perpendicular to the side insertion direction and substantially parallel to a portion of vertebral column wherein the cage (4) is inserted.

11. lntersomatic cage (4) according to claim 10, wherein said protuberance (30) is axially delimited by a pair of shelves (60) of the cage body (12), said shelves (60) forming axial guides for the insertion of gripping means (18, 20) of the cage (4).

12. lntersomatic cage (4) according to any one of the previous claims, wherein the cage body (12) comprises at least one opening (64) extending along said prevailing cross extension (X-X), passing through the cage body (12) along said axial direction.

13. lntersomatic cage (4) according to any one of the previous claims, wherein said cage body (12) is axially delimited by a pair of bases (68), suitable for abutting against the vertebral plates of adjacent vertebras (8, 10) and wherein at at least one base (68), the body (12) comprises fixing elements (70) that extend from said base (68), suitable for favouring the primary stability of the cage (4), in a configuration of insertion of the cage (4) in the interdiscal space.

14. lntersomatic cage (4) according to claim 13, wherein said fixing elements (70) have a triangular or trapezoidal configuration.

15. lntersomatic cage (4) according to any one of the previous claims, wherein said cage body (12) comprises, relative to a section plane parallel to said axial direction and perpendicular to said side prevailing extension (X-X), a wedge section, said wedge having a diverging profile moving from a front portion (50) to a back portion (52) of the cage body (12).

16. lntersomatic cage (4) according to any one of the previous claims, wherein said cage (4) is made of a biocompatible and/or bio-reabsorbing polymeric material.

17. Pliers (20) for intersomatic cage (4) suitable for allowing the gripping and the insertion of an intersomatic cage (4) according to any one of claims 1 to 16, wherein said pliers (20) comprise a pair of handles (74) for gripping the pliers (20), characterised in that said handles (74) are mechanically connected to rods (78) provided with gripping fingers (82) counter shaped relative to said protuberance (30) of the cage (4), so as to ensure a safe gripping of the cage.

18. Pliers (20) for intersomatic cage (4) according to claim 17, wherein said gripping fingers (82) are counter shaped relative to the undercuts (46) determined by the protuberance (30) of the cage (4), so as to surround and clamp the protuberance (30) in a closed configuration of the pliers (20).

19. Pliers (20) for intersomatic cage (4) according to claim 17 or 18, wherein a first gripping finger (82') has an 'L' configuration so as to allow the concurrent placing of the first finger (82') on a first undercut (46') of the protuberance (30) and on the abutment plane (56) of the protuberance (30).

20. Pliers (20) for intersomatic cage (4) according to claim 17, 18 or 19, wherein a second gripping finger (82") is counter shaped relative to a second undercut (46") opposite the first gripping finger (82').

21. Pliers (20) for intersomatic cage (4) according to any one of claims 17 to 20, wherein said gripping fingers (82) are angled relative to the handles (74), so that in a gripping configuration of the cage (4) with the pliers (20), said handles (74) are angled relative to said prevailing cross extension direction (X-X).

22. Pliers (20) for intersomatic cage (4) according to any one of claims 17 to 20, wherein said gripping fingers (82) are angled relative to the handles (74), so that in a gripping configuration of the cage (4) with the pliers (21), said handles (74) are substantially perpendicular relative to said prevailing cross extension direction (X-X) and parallel relative to a front-back direction determined by the vertebral bodies (8, 10) that determine the interdiscal space of insertion of the cage (4).

23. Pliers (20) for intersomatic cage (4) according to any one of claims 17 to 20, wherein the gripping fingers (82) are substantially parallel to the handles (74), so that in a gripping configuration of the cage (4) with the pliers (21 ), the handles (74) are substantially parallel relative to said prevailing cross extension direction (X-X).

24. Pliers (20) for intersomatic cage (4) according to any one of claims 17 to 23, wherein at least one of said handles (74) comprises, opposite the gripping fingers (82), a plate (86) suitable for allowing the abutment on the pliers (20) with a hammer, for favouring the insertion of the cage (4) in the interdiscal space according to a front-back direction.

25. Pliers (20) for intersomatic cage (4) according to any one of claims 17 to 24, wherein said pliers (20) comprise screw means (90) engaged with holes of said handles (74), so as to allow spreading and clamping the handles (74) and the gripping fingers (82) without exerting manual pressure on the handles (74).

26. Kit for the insertion of an intersomatic cage (4), comprising at least one cage (4) according with claims 1 to 16 and at least one pair of pliers (20) according with any one of claims 17 to 25.

27. Kit for inserting an intersomatic cage according to claim 26, comprising elements for spraining vertebral bodies (8, 10) suitable for allowing a spacing between adjacent vertebral bodies (8, 10) and the subsequent insertion of an intersomatic cage (4) in the interdiscal space determined thereinbetween.

28. Kit for inserting an intersomatic cage according to claim 26 or 27, comprising trials (100) suitable for favouring the selection of the intersomatic cage (4) to be inserted in an interdiscal space.

29. Method of insertion of an intersomatic cage (4) in an interdiscal space between two adjacent vertebral bodies (8, 10), comprising the steps of:

- spraining two adjacent vertebral bodies (8, 10) that determine an interdiscal space,

- gripping an intersomatic cage (4) at a side end (24) with pliers (20) suitable for making a shape coupling with a seat (16) of said end of the cage (24),

- clamping said pliers (20) with screw means (90) that clamp gripping fingers (82) of the pliers on a protuberance (30) of the seat (16), - moving the cage (4) laterally in the proximity of the interdiscal space.

30. Method for inserting an intersomatic cage according to claim 29, comprising the step of hitting with a hammer on a plate (86) arranged on a gripping handle (74) of the pliers (20) so as to force the insertion of the cage (4) in the interdiscal space, according to a front-back direction.

31. Method for inserting an intersomatic cage according to claim 29 or 30, comprising the steps of inserting the cage (4) in the interdiscal space, acting on the screw means (90) so as to spread the gripping fingers (82) of the pliers, releasing and extracting the pliers (20) from the cage and from the interdiscal space.