WO2009001387A1

WO2009001387A1 - Filling gel for intervertebral nucleus, prosthesis for intervertebral nucleus, method of nucleoplasm

Info

Publication number: WO2009001387A1
Application number: PCT/IT2007/000467
Authority: WO
Inventors: Giuseppe Sala; Paolo Guerra
Original assignee: Sintea Biotech S.P.A.
Priority date: 2007-06-28
Filing date: 2007-06-28
Publication date: 2008-12-31

Abstract

A filling gel (4) for intervertebral nucleus suitable for being inserted in an intervertebral nucleus for restoring, by infiltration in pathological discal seat, the natural functions of a partly damaged pulpous nucleus. The invention further relates to a nucleus prosthesis suitable for integrally replacing a discal nucleus, as well as a method of nucleoplasty for fixing and/or replacing an intervertebral nucleus.

Description

DESCRIPTION

"FILLING GEL FOR INTERVERTEBRAL NUCLEUS, PROSTHESIS FOR INTERVERTEBRAL NUCLEUS, METHOD OF NUCLEOPLASM"

[0001] The present invention relates to a filling gel for intervertebral nucleus, a prosthesis for intervertebral nucleus and a relative method of nucleoplasty.

[00023 As known, the intervertebral disc is a structure arranged between adjacent vertebral bodies, mainly consisting of fibrous cartilage organised into different hierarchical levels. Its complex architecture supervises the function of connecting mean, elastic shock absorber as well as transmission of loads allowing the flexibility of the vertebral column.

[0003] The structure consists of a highly hydrated jelly-like material located centrally, that is, the pulpous nucleus, and on an external side, the fibrous anulus, consisting of layers or lamellas of collagen fibres having variable configuration and arrangement from the inside towards the periphery.

[0004] The pulpous nucleous is a deformable but incompressible gel consisting of type Il collagen and proteoglycans (GAG), capable of maintaining a water balance by the direct intake of liquids from the outside. The hydrophilic properties of proteoglycans depend, besides the amount, especially on their water exchange capability, a feature that is altered in the disc degeneration.

[0005] The nucleus hydrophily causes a state of continuous vertebral "pre- compression" that increases the resistance to mechanical stresses. [0006] The intervertebral disc acts as a hydrostatic cushion whose intradiscal pressure increases with the increase of the hydration of the pulpous nucleus and decreases as it decreases. The dehydration of the pulpous nucleus caused by the involutional ageing processes removes about 15-20% of water and reduces the intradiscal pressure by 30%.

[0007] Such reduction of the water contents and the consequent decrease of the intradiscal pressure cause an increase of the compression on the anulus with obvious risks of degeneration and fissuration of the anulus lamellas.

[0008] Any alteration of the pulpous nucleus causes therefore a weakening of the entire discal structure and, for bio-mechanical causes, alterations of the adjacent structures that are overloaded.

[0009] The degeneration of the intervertebral disc is one of the main causes of lumbar suffering.

[0010] At present, treatments are known in the art that envisage the use of pharmacological therapy, physiokinesi therapy and surgical aids.

[0011] The two main surgical operations known to date for the treatment of the degenerated disc are nucleotomy in the case of damaged pulpous nucleus, discectomy in the case of a total degeneration of the entire disc, and the fusion between vertebral bodies.

[0012] At present, as regards nucleotomy, the alternative solution envisages the replacement of the pulpous disc with an artificial one.

[0013] The nucleus prostheses present on the market exhibit considerable difficulties related both to problems of the traditional prosthesis implants, as a failure due to wear and degeneration of the materials, and to the difficulty of surgical access.

[0014] Although these known surgical techniques provide quite satisfactory clinical results, they alter the biomechanics of the spine leading to an increasingly faster degeneration of the surrounding tissues and adjacent discs. [0015] In the orthopaedics field and in vertebral surgery there is a great interest in the development of new techniques capable of providing the repair or regeneration of the intervertebral pulpous nucleus with non invasive surgical techniques. [0016] The object of the present invention is to solve the disadvantages mentioned with reference to the prior art.

[0017] Such disadvantages are solved by a filling gel in accordance with claim 1 , by a nucleus prosthesis in accordance with claim 13 and by a method of nucleoplasty in accordance with claim 18. [0018] Other embodiments of the present invention are described in the subsequent claims.

[0019] Further features and the advantages of the present invention will appear more clearly from the following description of preferred non-limiting embodiments thereof, wherein: [0020] figure 1 shows a perspective view of a nucleus prosthesis according to an embodiment of the present invention;

[0021] figures 2 and 3 show perspective partially dissected views of intervertebral nucleus prostheses according to further embodiments of the present invention; [0022] figures 4 and 5 show perspective views of steps of a method of nucleoplasty according to the present invention.

[0023] With reference to the above figures, reference numeral 4 generally denotes a filling gel for intervertebral nucleus suitable for being inserted in an intervertebral nucleus. [0024] Advantageously, said filling gel 4 comprises type Il equine collagen and proteoglycans.

[0025] According to an embodiment, the filling gel 4, in non hydrated conditions, comprises a percentage by weight of collagen between 30% and 40%.

[0026] According to a possible embodiment, the filling gel 4, in non hydrated conditions, comprises a percentage by weight of proteoglycans comprised between

50% and 60%.

[0027] The filling gel 4 for intervertebral nucleus prostheses, in hydrated conditions, comprises a percentage by weight of water comprised between 85% and 95%. [0028] Preferably, the filling gel according to the present invention comprises a percentage by weight of water equal to 90%, in hydrated conditions.

[0029] According to an embodiment, the filling gel 4 in hydrated conditions comprises percentages by weight of collagen and proteoglycans comprised between 5% and 15%. [0030] Preferably, the filling gel 4 in hydrated conditions comprises a percentage by weight of collagen and proteoglycans equal to 10%.

[0031] According to a further embodiment of the present invention, the filling gel

4 comprises a mixture of type Il equine collagen, proteoglycans and hydrogel.

Preferably, the amount of hydrogel is not less than 50% by weight of gel. Said hydrogel can comprise for example polyvinyl-alcohol (PVA) and/or polyvinyl- pirrolidone (PVP) or a mixture thereof.

[0032] Advantageously, the filling gel 4 for intervertebral nucleus prostheses is a purified gel so as to not exhibit any type of immune response.

[0033] The present invention advantageously relates to an intervertebral nucleus prosthesis 8 comprising filling gel 4 having the features described above. [0034] According to a possible embodiment, the nucleus prosthesis 8 is entirely made of the filling gel 4 comprising type Il equine collagen, proteoglycans and hydrogel according to the embodiments described above.

[0035] Said prosthesis may be entirely composed of the filling gel 4, in hydrated or non hydrated conditions, or according to a further embodiment it may consist of a containment pocket 12 that internally encloses the filling gel 4.

[0036] The containment pocket 12 may be made of a waterproof material, so as to form an incompressible prosthesis which always ensures the proper volume and the proper consistency required over time. [0037] According to a preferred embodiment, the containment pocket 12 is made of a material suitable for allowing the absorption of water, such as for example type

Il equine collagen, so as to always ensure proper hydration of the filling gel contained therein and thus the proper interdiscal pressure.

[0038] According to a possible embodiment, the containment pocket 12 exhibits a plurality of microporosities 16, suitable for allowing the passage and the absorption of water inside the filling gel 4. The containment pocket 12, thanks to microporosities 16, allows therefore proper hydration of the filling gel while allowing the combination of the cells making up the nucleus with the biological filling gel.

[0039] The method of nucleoplasty according to the present invention will now be described.

[0040] A method of nucleoplasty according to the present invention comprises the steps of solidarising a cannula 24 to the cortical of a vertebral body 20, preferably having a catching end 28 and an injection end 32. [0041] The injection end 32 penetrates into the seat of the intervertebral nucleus; the filling gel comprising type Il equine collagen, proteoglycans and hydrogel according to the embodiments described above is then injected.

[0042] According to a possible method, filling gel in non hydrated form is injected and then a step of hydration of the gel is carried out directly into the seat of the intervertebral nucleus, by injections for example of saline. [0043] According to a further embodiment of the present invention, filling gel 4 in hydrated form is directly injected.

[0044] Advantageously, filling gel 4 that has been previously subjected to a purification process for annulling the immune response thereof is injected.

[0045] According to a further possible method of nucleoplasty in accordance with the present invention, a prosthesis of nucleus 8 is inserted into the nucleus seat, comprising a containment pocket that internally encloses the filling gel.

[0046] In particular, the nucleotomy is carried out in a first step, i.e. the removal of the nucleus from the relative seat.

[0047] Then, the insertion of the prosthesis or of the filling gel is carried out by infiltration through the anulus fibres.

[0048] As can be appreciated from the description, the filling gel for intervertebral nucleus, the prosthesis of intervertebral nucleus and the method of nucleoplasty of the present invention allow overcoming the disadvantages of the prior art.

[0049] In particular, the filling gel according to the present invention reproduces the mechanical features of the biological nucleus.

[0050] Moreover, the filling gel exhibits the same hygroscopicity as the biological nucleus and therefore the nucleus can receive the necessary hydration over time; thanks to the achievement of the necessary hydration, the intradiscal pressure is maintained within biologically acceptable values and the anulus is not overloaded. The risks of degeneration and fissuration of the anulus lamellas are therefore prevented.

[0051] The method of nucleoplasty is especially advantageous as it is extremely little invasive. In fact, it is possible to inject directly a predetermined amount of filler into the damaged nucleus so as to restore proper volume and proper shape of the nucleus.

[0052] Advantageously, the introduction of a gel or of the prosthesis according to the invention into the intervertebral nucleus allows restoring the natural functions of the tissue. [0053] Advantageously, the method of nucleoplasty according to the present invention provides a combination of the cells making up the intervertebral nucleus with the biological filling gel. The biological filling gel according to the present invention stimulates the proliferation and differentiation of the cells making up the cartilagineous tissue.

[0054] Advantageously, the filling gel according to the present invention exhibits no risks of BSE (bovine spongiform encephalopathy).

[0055] Unusually, the filling gel may be subject to purification processes without modifying its own mechanical features and at the same time so as to totally annul the immune responses resulting from other types of collagen, such as bovine collagen. [0056] In other words, the filling gel comprising type Il equine collagen can be subject to purification processes without altering its chemical-physical features, so as to reproduce in situ the anatomical properties of the pulpous nucleus, with particular reference to the intradiscal pressure.

[0057] A man skilled in the art may make several changes and adjustments to the filling gels, to the intervertebral nucleus prostheses and to the methods of nucleoplasty described above in order to meet specific and incidental needs, all falling within the scope of protection defined in the following claims.

Claims

1. Filling gel (4) for intervertebral nucleus (4) suitable for being inserted in an intervertebral nucleus characterised in that said gel (4) comprises type Il equine collagen and proteoglycans.

2. Filling gel (4) for intervertebral nucleus according to claim 1 , wherein in non hydrated conditions, said gel (4) comprises a percentage by weight of type Il equine collagen between 30% and 40%.

3. Filling gel (4) for intervertebral nucleus according to claim 1 or 2, wherein in non hydrated conditions, said gel (4) comprises a percentage by weight of proteoglycans between 50% and 60%.

4. Filling gel (4) for intervertebral nucleus according to any one of the previous claims, wherein in hydrated conditions, said gel (4) comprises a percentage by weight of water between 85% and 95%.

5. Filling gel (4) for intervertebral nucleus according to claim 4, wherein said gel comprises a percentage by weight of water equal to 90%.

6. Filling gel (4) for intervertebral nucleus according to claim 4 or 5, wherein said gel (4) in hydrated conditions comprises a percentage by weight of collagen and of proteoglycans between 5% and 15%.

7. Filling gel (4) for intervertebral nucleus according to claim 6, wherein said gel in hydrated conditions comprises a percentage by weight of collagen and of proteoglycans equal to 10%.

8. Filling gel (4) for intervertebral nucleus according to any one of the previous claims, wherein said filling gel 4 comprises a mixture of type Il equine collagen, proteoglycans and hydrogel.

9. Filling gel (4) for intervertebral nucleus according to claim 8, wherein the amount of hydrogel is not less than 50% by weight of the gel.

10. Filling gel (4) for intervertebral nucleus according to claim 8 or 9, wherein said hydrogel comprises polyvinyl-lalcohol (PVA).

11. Filling gel (4) for intervertebral nucleus according to claim 8, 9 or 10, wherein said hydrogel comprises polyvinyl-pirrolidone (PVP).

12. Filling gel (4) for intervertebral nucleus according to any one of the previous claims, wherein said gel (4) is a purified gel so as to not exhibit any immune response.

13. Intervertebral nucleus prosthesis (8) comprising filling gel (4) according to any one of claims 1 to 12.

14. Intervertebral nucleus prosthesis (8) according to claim 13, wherein said filling gel is contained within a containment pocket (12).

15. Intervertebral nucleus prosthesis (8) according to claim 14, wherein said containment pocket (12) is made of type Il equine collagen so as to allow the absorption of water by the filling gel contained therein.

16. Intervertebral nucleus prosthesis (8) according to claim 14 or 15, wherein said containment pocket (12) exhibits a plurality of microporosities (16) suitable for allowing the passage and the absorption of water inside the filling gel (4).

17. Intervertebral nucleus prosthesis (8) according to any one of claims 13 to 16, wherein said gel is a purified gel with no immune response.

18. Method of nucleoplasty for the treatment of an interdiscal nucleus at least partly degenerated, comprising the step of inserting into said nucleus a filling gel (4) according to any one of claims 1 to 12.

19. Method of nucleoplasty according to claim 18, wherein said insertion step is a step of insertion with percutaneous technique through the use of a needle or a cannula (24).

20. Method of nucleoplasty according to claim 18 or 19, wherein said filling gel is inserted into the nucleus in non hydrated condition.

21. Method of nucleoplasty according to claim 18, 19 or 20, comprising the step of hydration of the filling gel by fluid infiltration in the filling gel.

22. Method of nucleoplasty according to any one of claims 18 to 21 , wherein said filling gel (4) has been previously subjected to a purification process for annulling the immune response thereof.

23. Method of nucleopiasty for the treatment of a degenerated interdiscal nucleus, comprising the step of removing the degenerated nucleus and inserting a nucleus prosthesis into the discal seat according to any one of claims 13 to 17.