WO2019159074A1 - Intervertebral implant device comprising a bone implant matrix - Google Patents

Abstract

There is described an intervertebral implant device (1) having a substantially prismatic shape and formed by a bone implant matrix. There is also described the use of a bone implant matrix in neurosurgery.

Description

INTERVERTEBRAL IMPLANT DEVICE COMPRISING A BONE

IMPLANT MATRIX

Cross-Reference to related applications

This patent application claims priority from Italian patent application no. 102018000002658 filed on 13/02/2018, the entire disclosure of which is incorporated herein by reference.

Technical Field

The present invention relates to an intervertebral implant device having a substantially prismatic shape and formed by a bone implant matrix. The present invention also relates to the use of a bone implant matrix in neurosurgery.

Prior art

The spinal column is formed by vertebrae separated from one another by cartilaginous intervertebral discs. These discs form a "cushion" between adjacent vertebrae, providing resistance to compression along the axis that supports the spinal column, but allowing limited movement between the vertebrae to provide flexibility. Injuries, diseases or other degenerative problems can cause deterioration or dislocation of one or more intervertebral discs. This type of damage can cause the compression of adjacent nerve roots, giving rise to often very debilitating chronic pain.

A certain number of devices and methods have been proposed to replace damaged intervertebral discs and to stabilize the spinal column .

One approach used, known as arthrodesis, consists in inserting a hollow cage made of biocompatible material, typically titanium, porous tantalum or titanium-peek, into the intervertebral space. Before implantation, the cavity of the cage is filled with autologous bone material or other bone regenerating substances.

However, this approach has numerous disadvantages.

The first disadvantage consists of the fact that the procedure requires very long immobilisation and subsequent rehabilitation times. In particular, after surgery, the patient is obliged to use a brace (collar) for at least four weeks and subsequently to follow a rehabilitation programme for at least ninety days up to six months, to recover the functional movement of the neck .

The second disadvantage consists of the fact that, even when the surgery is completely successful, a foreign body (the cage) remains permanently implanted in the patient.

The third disadvantage consists of the fact that the hollow cage often slips out of the implant seat ( "pull-out" phenomenon) , causing serious consequences, such as obstruction and damage of the airways when the surgery involves the cervical vertebrae. Naturally, in these cases urgent surgery is required. In other cases, due to the thin walls of the cage, following a trauma or abnormal movement, vertebral body collapse can occur, again with serious consequences for the health of the patient and further surgery is required.

The fourth disadvantage consists of the fact that the conventional cage is not radiopaque: therefore positioning of this device is extremely difficult.

Finally, the material with which the cage is filled is generally autologous bone taken from the iliac crest of the patient. The amount of bone contained in the cage is limited and is not ideal. Furthermore, the sensitivity of the donor site (acute post operative or persistent pain, paraesthesia, haematomata and superficial and deep infections) associated with the bone harvested from the iliac crest represents a frequent complication .

Therefore, there is the need to develop devices and methods to replace and/or stabilise damaged intervertebral discs that overcome the aforesaid disadvantages.

Some materials that can replace and promote the regeneration of bone tissue in case of trauma or degeneration have been developed. One of these materials, used in the field of dentistry and maxillofacial surgery, is described in EP2358407.

Object of the invention

An object of the present invention is to produce an intervertebral implant device that solves the aforementioned drawbacks in a simple, effective and economic manner.

The aforesaid object is achieved by the present invention as it relates to an intervertebral implant device as defined in claim

1.

Another object of the present invention is to provide a bone implant matrix for use in neurosurgery.

The aforesaid object is achieved by the present invention as it relates to a bone implant matrix for use in neurosurgery as defined in claim 7.

Brief description of the drawings

For a better understanding of the present invention a preferred embodiment is described below, purely by way of non-limiting example and with reference to the accompanying drawings, wherein :

- Fig. 1 is a perspective view of an intervertebral implant device according to the present invention;

- Fig. 2 is a side elevation view of the device of Fig. 1; - Fig. 3 is a top view of the device of Figs. 1 and 2;

- Fig. 4 is a front elevation view of the device of the Figs. 1, 2 and 3;

- Fig. 5 is a section along the line V-V of Fig. 4;

- Fig. 6 is an X-ray of a patient treated with the conventional "peek cage" technique;

- Fig. 7 is an X-ray of a patient treated with the device according to the present invention.

Detailed description of the invention

With reference to Figs. 1 to 5, an intervertebral implant device according to the present invention is indicated with 1. The device 1 has a substantially prismatic shape with a substantially trapezoidal profile with top 2 and bottom 3 faces having a substantially isosceles trapezoidal profile with a rectilinear short base and a convex curvilinear long base and rectilinear oblique sides joined by rounded edges. The top face 2 is convex upwards and the bottom face 3 is flat. The front face 4 is curvilinear convex and the side faces 5, 6 and the back face 7 are substantially flat and joined by rounded edges.

Advantageously, the device is formed by a bone implant matrix.

In a preferred embodiment, the bone implant matrix comprises the matrix described in EP2358407 (Smartbone® manufactured by

Industrie Biomediche Insubri SA) , i.e.,

a) a base matrix treated with

b) a reinforcing mixture as a homogeneous coating, finely dispersed on the whole surface of the matrix, said reinforcing mixture containing at least a polymer and at least an additional component selected from cell nutrients, cell-growth promoters, cell-adhesion promoters, osteo-inductors, osteo-integrators, substances which are able to promote cell-rooting and cell growth, by stimulating cell proliferation and tissue integration, wherein the base matrix is a demineralised, non- demineralised, acellularized bovine bone matrix, the polymer of the reinforcing mixture is a biodegradable polyester or co polymer thereof, the substance, which is able to promote cell rooting and cell growth being selected from the group consisting of gelatine, hydrolysed gelatine and wherein the reinforcing mixture is obtained starting from two solutions, each of them made of a soluble polymer, which is the biodegradable polyester or co-polymer thereof, and an agent, which is the gelatine or hydrolysed gelatine, promoting cell engraftment, growth and proliferation, and tissue integration, respectively, immiscible with each other, but made partially miscible by adding an alcohol or another proper solvent to each of them; in order to obtain a fine and homogeneous molecular dispersion of the components.

The terminology used corresponds to that used in the aforesaid patent. Therefore, the description thereof should be referred to for any definitions and specifications.

In a preferred and alternative embodiment to the one above, the bone implant matrix comprises at least one material selected from the group consisting of (cadaveric, donor or autologous) human bone, (bovine, swine, equine or reindeer) bone, natural materials (biocorals or wood derivatives), synthetic materials (bioglasses, hydroxyapatites, calcium phosphates, tricalcium phosphates, betatritricalcium phosphates, aliphatic polyesters), collagen, gelatine, and mixtures thereof.

As visible in Figs. 4 and 5, the front face 4 of the device 1 comprises a hole 8 adapted to receive a tool for manipulating the device.

In a preferred embodiment, the top face 2 and/or the bottom face 3 of the device 1 have/has a texturized surface, i.e., a surface characterised by ridges and furrows. This type of surface minimises the possibility of the device sliding sideways after it has been inserted into the implant seat . In an alternative preferred embodiment, the top face 2 and/or the bottom face 3 of the device 1 have/has a smooth surface. A surface of this type is simpler and less expensive to produce.

The present invention also relates to the use in neurosurgery of the matrix described in EP2358407, i.e., a bone implant matrix comprising :

a) a base matrix treated with

b) a reinforcing mixture as a homogeneous coating, finely dispersed on the whole surface of the matrix, said reinforcing mixture containing at least a polymer and at least an additional component selected from cell nutrients, cell-growth promoters, cell-adhesion promoters, osteo-inductors, osteo-integrators, substances which are able to promote cell-rooting and cell growth, by stimulating cell proliferation and tissue integration, wherein the base matrix is a demineralised, non- demineralised, acellularized bovine bone matrix, the polymer of the reinforcing mixture is a biodegradable polyester or co polymer thereof, the substance which is able to promote cell rooting and cell growth being selected from the group consisting of gelatine, hydrolysed gelatine and wherein the reinforcing mixture is obtained starting from two solutions, each of them made of a soluble polymer, which is the biodegradable polyester or co-polymer thereof, and an agent, which is the gelatine or hydrolysed gelatine, promoting cell engraftment, growth and proliferation, and tissue integration, respectively, immiscible with each other, but made partially miscible by adding an alcohol or another proper solvent to each of them; in order to obtain a fine and homogeneous molecular dispersion of the components.

To date, the aforesaid matrix has mainly been used in dentistry and maxillofacial surgery. Even if its use in the orthopaedic field was cited in EP2358407 as potentially advantageous, its use in a particularly delicate sector such as neurosurgery has never been suggested or tested. The complexity of operations on the spinal column must be underscored: the use of an alternative device to the conventional cage is therefore an innovative and cutting edge approach, even only for the ethical implications linked to the testing thereof.

The use of the aforesaid matrix in neurosurgery is preferably applied to vertebral surgery, more preferably to surgery in the cervical area.

Preferably, the matrix is implanted in the intervertebral space.

Even more preferably, the implanted matrix has a substantially prismatic shape with a substantially trapezoidal profile with top and bottom faces having a substantially isosceles trapezoidal profile with a rectilinear short base and a convex curvilinear long base and rectilinear oblique sides joined by rounded edges, the top face being convex upwards and the bottom face being flat, the front face being curvilinear convex and the side and back faces being substantially flat and joined by rounded edges.

In use, the surgeon positions the device 1 in the intervertebral space by means of a suitable manipulation tool. The device 1 is fixed to the manipulation tool by means of a self-tapping screw (not illustrated) that is inserted into the hole 8 on the front face 4 of the device 1. Once the device 1 has been inserted in place, the correct positioning thereof is verified by means of X-ray. The self-tapping screw is then unscrewed from the hole 8 by means of the manipulation instrument and the instrument with the screw are extracted from the body of the patient.

Depending on the site of use and on the size of the patient, the device can be suitably sized. With reference to Figs. 2 and 3, a table is provided below with the sizes (in mm) of different embodiments of the device 1 that can be used in male or female, adult or paediatric patients.

If necessary, the device 1 of the most suitable size can be milled before implantation so as to have the ideal shape and size for the patient.

Comparative example between the prior art device (peek cage) and the device according to the present invention

Fig. 6 shows an X-ray of a patient treated with the conventional "peek cage" device. The sizeable metal plate to avoid "pull out" of the cage is highlighted. The vertebral bodies are weakened by the screws inserted to lock the plate. The "peek cage" is not radiopaque except for the three "markers" obtained with holes in a hollow area of the cage.

Fig. 7 instead shows an X-ray of a patient treated with a device according to the present invention. The X-ray was taken 7 days after the surgery. The absence of locking plates can be noted, as the porosity of the device is such as to allow rapid integration by the surrounding tissue. From an analysis of the properties of the intervertebral implant device 1 according to the present invention the advantages that can be obtained using it are evident.

In particular, due to the device 1 according to the present invention, after surgery the patient can be discharged after twenty-four hours, uses the brace (collar) for a much shorter time (from ten days to two weeks) compared to conventional techniques and no rehabilitation is required, with enormous advantages for the quality of life of the patient and a significant saving of economic resources for the health service.

The fact that the device 1 according to the invention is made of a material more similar to bone and not of two materials, of which one (for example the titanium) undoubtedly cannot be replaced by regenerated bone enables much more efficient integration than is possible with prior art devices. In time, the device 1 is completely replaced by regenerated bone.

Due to the shape and to the material of the device 1 according to the invention, the forces are distributed optimally and the risk of fracture in the areas of interest is minimised.

Moreover, the device 1 according to the invention is not subject to the phenomenon of "pull-out". After a period of time from thirty to approximately sixty days, the device 1 is completely integrated with the vertebrae and twelve months after surgery it has been totally replaced by regenerated bone.

Moreover, the device 1 according to the invention represents the only known device that can be made to measure. Besides being available in different models of variable sizes, it can also be modelled by means of milling, in cases in which there is a very limited space between the vertebral bodies or the space has not been correctly evaluated in advance. Furthermore, the device 1 according to the invention is radiopaque and can therefore be positioned under fluoroscopic guidance, i.e., using a radiographic machine.

Claims

1. An intervertebral implant device (1) having a substantially prismatic shape with a substantially trapezoidal profile with top (2) and bottom (3) faces, having a substantially isosceles trapezoidal profile with a rectilinear short base and a convex curvilinear long base and rectilinear oblique sides joined by rounded edges, the top face (2) being convex upwards and the bottom face (3) being flat, the front face (4) being curvilinear convex and the side faces (5,6) and the back face (7) being substantially flat and joined by rounded edges,

wherein the device (1) is formed by a bone implant matrix.

2. The device (1) according to claim 1, wherein the bone implant matrix comprises:

a) a base matrix treated with

b) a reinforcing mixture as a homogeneous coating, finely dispersed on the whole surface of the matrix, said reinforcing mixture containing at least a polymer and at least an additional component selected from cell nutrients, cell-growth promoters, cell-adhesion promoters, osteo-inductors, osteo-integrators, substances able to promote cell-rooting and cell growth, by stimulating cell proliferation and tissue integration, wherein the base matrix is a demineralised, non-demineralised, acellularized bovine bone matrix, the polymer of the reinforcing mixture is a biodegradable polyester or co-polymer thereof, the substance, which is able to promote cell-rooting and cell growth being selected from the group consisting of gelatine, hydrolysed gelatine and wherein the reinforcing mixture is obtained starting from two solutions, each of them made of a soluble polymer, which is the biodegradable polyester or co-polymer thereof, and an agent, which is the gelatine or hydrolysed gelatine, promoting cell engraftment, growth and proliferation, and tissue integration, respectively, immiscible with each other, but made partially miscible by adding an alcohol or another proper solvent to each of them; in order to obtain a fine and homogeneous molecular dispersion of the components.

3. The device (1) according to claim 1, wherein the bone implant matrix comprises at least one material selected from the group consisting of (cadaveric, donor or autologous) human bone, (bovine, swine, equine or reindeer) bone, natural materials (biocorals or wood derivatives), synthetic materials (bioglasses, hydroxyapatites, calcium phosphates, tricalcium phosphates, betatritricalcium phosphates, aliphatic polyesters), collagen, gelatine, and mixtures thereof.

4. The device (1) according to any of claims 1 to 3, wherein the front face (4) of the device (1) comprises a hole (8) adapted to receive a tool for manipulating the device (1) .

5. The device (1) according to any of claims 1 to 4, wherein the top face (2) and/or the bottom face (3) of the device (1) have/has a texturized surface.

6. The device (1) according to any of claims 1 to 4, wherein the top face (2) and/or the bottom face (3) of the device (1) have/has a smooth surface.

7. A bone implant matrix comprising:

a) a base matrix treated with

b) a reinforcing mixture as a homogeneous coating, finely dispersed on the whole surface of the matrix, said reinforcing mixture containing at least a polymer and at least an additional component selected from cell nutrients, cell-growth promoters, cell-adhesion promoters, osteo-inductors, osteo-integrators, substances able to promote cell-rooting and cell growth, by stimulating cell proliferation and tissue integration, wherein the base matrix is a demineralised, non-demineralised, acellularized bovine bone matrix, the polymer of the reinforcing mixture is a biodegradable polyester or co-polymer thereof, the substance, which is able to promote cell-rooting and cell growth being selected from the group consisting of gelatine, hydrolysed gelatine and wherein the reinforcing mixture is obtained starting from two solutions, each of them made of a soluble polymer, which is the biodegradable polyester or co-polymer thereof, and an agent, which is the gelatine or hydrolysed gelatine, promoting cell engraftment, growth and proliferation, and tissue integration, respectively, immiscible with each other, but made partially miscible by adding an alcohol or another proper solvent to each of them; in order to obtain a fine and homogeneous molecular dispersion of the components,

for use in neurosurgery.

8. The bone implant matrix for use according to claim 7, wherein the neurosurgery is vertebral surgery.

9. The bone implant matrix for use according to claim 8, wherein the matrix is implanted in the intervertebral space.

10. The bone implant matrix for use according to claim 9, wherein the matrix has a substantially prismatic shape with a substantially trapezoidal profile with top and bottom faces having a substantially isosceles trapezoidal profile with a rectilinear short base and a convex curvilinear long base and rectilinear oblique sides joined by rounded edges, the top face being convex upwards and the bottom face being flat, the front face being curvilinear convex and the side faces and the back face being substantially flat and joined by rounded edges .