WO2014068510A2

WO2014068510A2 - Intervertebral prosthesis, particularly for percutaneous mini-invasive surgery procedures

Info

Publication number: WO2014068510A2
Application number: PCT/IB2013/059813
Authority: WO
Inventors: Gabriele CORTINOVIS; Luigi Tarricone; Stefano Caselli
Original assignee: Redemed S.R.L.
Priority date: 2012-11-02
Filing date: 2013-10-31
Publication date: 2014-05-08
Also published as: ITAR20120035A1; WO2014068510A3

Abstract

An intervertebral prosthesis (1 ), particularly for percutaneous mini- invasive surgery procedures, having the particularity that it comprises a plurality of mutually articulated segments (21-28). More precisely, the segments (21-28) are movable from an active configuration, in which they are arranged with respect to each other so as to form a disk-like body (2), to an insertion/extraction configuration, in which the segments (21-28) are substantially mutually aligned, and vice versa.

Description

INTERVERTEBRAL PROSTHESIS, PARTICULARLY FOR PERCUTANEOUS MINI-INVASIVE SURGERY PROCEDURES

The present invention relates to an intervertebral prosthesis, particularly for percutaneous mini-invasive surgery procedures.

Currently, several pathologies affecting the spinal column and particularly the intervertebral discs are known in the medical field.

Some of these pathologies cause a degeneration of the fibrous capsule of the intervertebral disc, which reduces its elasticity and is damaged, releasing part of the nucleus pulposus. This phenomenon is commonly known as hernia.

There are also other pathologies of the progressive type that entail the thinning, over time, of the intervertebral disc because of the loss of its capacity to retain water inside it. This thinning also often causes the thinning of the facet capsules, with consequent pain. In some cases, this thinning can cause the reduction of the medullary cavity, with a high risk of chronic claudication.

In many cases, the progressive deterioration of the intervertebral disc requires the implantation of an intervertebral prosthesis that substantially replaces the disc itself.

Currently, two fundamental types of intervertebral prostheses are available.

A first type of prosthesis has the main function of facilitating the fusion of two adjacent vertebra. These prostheses comprise generally one or two bodies made of osteoconductive material that are placed, by means of a surgical procedure, in opposite positions between two adjacent vertebrae. The materials used for the provision of the two bodies facilitate the growth and adhesion of bone tissue so as to cause the fusion of the two vertebrae, which can no longer move with respect to each other. This type of prosthesis is applied generally at the level of the lumbar vertebrae, which are the ones subjected to the highest load constituted by body weight. A second, more modern type of intervertebral prosthesis instead has the function of replacing a deteriorated disk while preserving mutual mobility between the two adjacent vertebrae. These prostheses comprise two plates, which are structured to be fixed on the opposite faces of two adjacent vertebrae, between which an articulated structure is interposed which allows physiological relative movements between the two adjacent vertebrae. The articulated structure can be constituted for example by a spherical joint structured to allow coplanar sliding between the two plates. This allows maintaining the natural mobility of the vertebrae and alleviating, at the same time, the pain due to contact between the vertebrae.

Prostheses of this second type, however, have some serious drawbacks.

One of the main functions of the intervertebral disc is to cushion the loads to which the vertebrae are subjected. Said prostheses, however, are usually made of titanium and polyethylene, and therefore the main function of cushioning loads is lost, with consequently iatrogenic damage situated at the articular facet level, such as for example arthrosis. Moreover, since they are substantially prismatic or cylindrical bodies the cross-section of which is comparable to that of an intervertebral disc, they can be implanted only by accessing the spinal column from an anterior direction. Access from a posterior direction is in fact prevented by the presence of the vertebral cavity and of the dura mater, which enclose the spinal cord, as well as by the articular facets, and by numerous bone structures. The implantation of a prosthesis of this type therefore requires operating the patient in the anterior part and moving aside the internal organs, as well as the aorta, in order to expose the spinal column, cutting into the anterior ligament of the spinal column. Therefore, these are extremely traumatic operations that are not free from risks, also in view of the fact that they expose the aorta to possible traumas and lacerations.

The anterior surgical access path, moreover, involves serious risks of urinary incontinence and retrograde ejaculation.

Moreover, it is clear that in case of failure of the procedure, the removal of these prostheses is very complicated and often requires two surgical accesses, the first one to remove the prosthesis and the second one to stabilize the adjacent vertebrae.

WO2006/051547 relates to an intervertebral prosthesis that can be implanted in order to replace a damaged intervertebral disc by means of a mini-invasive surgical procedure. In particular, this prosthesis is composed of mutually separate parts that can be assembled directly in situ in order to form a disk-like structure. These parts are inserted, one by one, by means of an adapted insertion device, between the two vertebrae of interest, so as to mutually interlock to form the disk-like structure.

This prosthesis of the known type, however, is not free of drawbacks, including the fact that its implantation requires an anterior surgical access, which entails the known problems of moving aside the internal organs described earlier and the fact that a posterior surgical access is in any case greatly limited by the presence of bone structures, such as the articular facets, and of the vertebral canal.

The aim of the present invention is to provide an intervertebral prosthesis, particularly for percutaneous mini-invasive surgery procedures, that obviates the drawbacks and overcomes the limitations of the background art, allowing implantation with a posterolateral access to the spinal column, safeguarding moreover the external fibrous annulus of the disc and the posterior ligament and, if need be, to be able to remove it with a simple procedure.

Within this aim, an object of the present invention is to provide an intervertebral prosthesis that can be implanted much more quickly and less traumatically than prostheses of the known type, using the surgical technique used every day for the positioning of intervertebral spacers adapted for vertebral fusion. Another object of the present invention is to provide an intervertebral prosthesis that allows maintaining physiological mobility between two adjacent vertebrae.

A further object of the invention is to provide an intervertebral prosthesis that is capable of giving the greatest assurances of reliability and safety of use.

This aim and these and other objects that will become more apparent hereinafter are achieved by an intervertebral prosthesis, particularly for percutaneous mini-invasive surgery procedures, characterized in that it comprises a plurality of mutually articulated segments, said segments being movable from an active configuration, in which said segments are arranged with respect to each other so as to form a disk-like body, to an insertion/extraction configuration, in which said segments are substantially mutually aligned, and vice versa.

Further characteristics and advantages will become more apparent from the description of a preferred but not exclusive embodiment of an intervertebral prosthesis, illustrated by way of non-limiting example with the aid of the accompanying drawings, wherein:

Figure 1 is a perspective view of an intervertebral prosthesis, particularly for percutaneous mini-invasive surgery procedures, according to the present invention, in its active configuration;

Figure 2 is a perspective view of the prosthesis of Figure 1 in its insertion/ extraction configuration ;

Figure 2a is an enlarged-scale detail view of a portion of the prosthesis shown in Figure 2;

Figures 3 to 10 are views of a sequence of steps of the implantation of the prosthesis between two adjacent vertebrae, according to a first implantation method;

Figure 1 1 is a view of the prosthesis shown in the previous figures provided with a cutting and removal device; Figure 12 is a perspective view of a variation of the intervertebral prosthesis shown in the previous figures, according to the invention;

Figure 13 is a view of a pair of adjacent vertebrae in which a device for the insertion of the prosthesis of Figure 12 is inserted;

Figures 14 to 16 are views of a sequence of steps of the implantation, between two adjacent vertebrae, of the prosthesis of Figure 12, according to a second implantation method, which uses the insertion device of Figure 13.

With reference to the cited figures, the intervertebral prosthesis, particularly for percutaneous mini-invasive surgery procedures, generally designated by the reference numeral 1 , comprises a plurality of segments, designated in the cited figures by the reference numerals 21 to 28, which are mutually articulated so as to be movable from an active configuration, in which they are arranged with respect to each other so as to form a disk-like body 2, as shown in Figure 1 , to an insertion/extraction configuration, in which the segments 21 to 28 are substantially mutually aligned, as shown in Figure 2, and vice versa.

As will be described in more detail hereinafter, in their insertion/extraction configuration the segments 21 to 28 form an articulated and flexible succession of concatenated elements.

Advantageously, each segment 21 to 28 is made of an elastomeric material, such as for example silicone.

It should be stressed that the use of an elastomeric material, particularly silicone, allows simulating the elastic behavior of an intervertebral disc regarding the absorption of compression stresses, rotations about three perpendicular axes, and the relative sliding movements between two adjacent vertebrae between which it is interposed.

More precisely, each segment 21 to 28 has a prismatic shape, with a substantially triangular or rectangular base, so as to extend between two planes that are substantially parallel and perpendicular to the longitudinal axis of the disk-like body 2 that they define in their active configuration. However, in order to improve the ergonomics of the intervertebral prosthesis 1 , the upper and lower faces of each individual segment 21 to 28 are such as to form, in their active configuration, a disk-like body 2 that has an upper surface 2b and a lower surface 2c that are mutually inclined at an angle that coincides substantially with the angle formed by the lower articular surface (I) with the upper articular surface (S) of two adjacent vertebrae. This angle can vary according to the level of the spinal column to be treated.

Conveniently, the upper surface 2b of the disk-like body 2 is formed by the upper faces of the segments 21 to 28 that, in the closed configuration of the disk-like body 2, are mutually contiguous and coplanar. In the same way, the lower surface 2c of the disk-like body 2 is formed by the lower faces of the segments 21 to 28 that, in the closed configuration of the disklike body 2, are mutually contiguous and coplanar.

In the proposed embodiment of the intervertebral prosthesis 1 , the disk-like body 2 comprises eight segments 21 to 28.

As is clearly visible in Figure 1 , in the proposed embodiment the disklike body 2 has advantageously an elongated shape with an anterior portion and a posterior portion that are longer than the two lateral portions. A first segment 21 and a fifth segment 25 are intended therefore to define, in the active configuration, the anterior portion and the posterior portion of the disk-like body 2. A third segment 23 and a seventh segment 27 are intended instead to define, again in the active configuration, the lateral portions of the disk-like body 2. Finally, a second segment 22, a fourth segment 24, a sixth segment 26 and an eighth segment 28 are intended to define portions which are rounded on their lateral surface and mutually link the other segments 21 , 23, 25 and 27, having a substantially triangular base different from the other segments, which have a rectangular base.

With the exception of the two end segments 21 and 28, which are mutually disconnected, the segments 21 to 28 are mutually separated by partial notches formed in the thickness of the disk-like body 2. These notches are formed along planes that are substantially vertical, i.e., substantially at right angles to the upper surface 2b or lower surface 2c of the disk-like body 2. The partial notches do not separate completely the segments 21 to 28 from each other, but leave intact intermediate portions, designated in the cited figures by the reference numerals 21a to 28a, for connection between each pair of segments 21 to 28.

More precisely, said intermediate portions 21a to 28a are formed at the outer lateral faces of the segments 21 to 28 that form the outer lateral surface 2a of the disk-like body 2 so as to form a hinge coupling between each pair of segments 21 to 28, allowing them to perform mutual rotations about a rotation axis that is substantially parallel to the longitudinal axis of the disklike body 2.

Advantageously, the intermediate portions 21a to 28a cited above, being monolithic with the segments 21 to 28, are made of the same elastomeric material so as to keep, in the absence of external stresses, the segments 21 to 28 in the active configuration due to the elastic properties of the elastomeric material.

In fact, the elastomeric material tends, in an inactive condition, to make the segments 21 to 28 assume their active configuration, forming the disk-like body 2.

As a consequence, in the insertion/extraction configuration of the segments 21 to 28, the elastomeric material of the intermediate portions 21a to 28a is elastically deformed. Therefore, in order to allow keeping the segments 21 to 28 in the open insertion/extraction configuration it is necessary to apply a divaricating force, for example at the two end segments 21 and 28.

The intervertebral prosthesis 1 according to the present invention comprises moreover a plurality of upper and lower plate-like bodies, designated in the cited figures respectively by reference numerals 31 to 38 W

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and 41 to 48 respectively, advantageously made of osteoconductive material.

These upper plate-like bodies 31 to 38 and these lower plate-like bodies 41 to 48 are associated respectively with the upper and lower surfaces of the segments 21 to 28.

In the active configuration of the segments 21 to 28, the upper and lower plate-like elements are mutually contiguous and coplanar, forming a continuous upper surface la and a continuous lower surface lb of the intervertebral prosthesis 1.

More precisely, the upper plate-like bodies 31 to 38 and the lower plate-like bodies 41 to 48 are mutually independent so as to be disconnected from each other.

In this manner, the segments 21 to 28 are free to assume their own configurations, the active configuration or the insertion/extraction configuration, without being hindered by the presence of the plate-like bodies.

Conveniently, the osteoconductive material of which the plate-like bodies are made preferably has a trabecular structure and allows in a short time to achieve a good anchoring thereof to the lower articular surface (I) and to the upper articular surface (S) of two adjacent vertebrae.

Moreover, the same upper plate-like bodies 31-38 and lower plate-like bodies 41-48 can be provided, at their faces that are opposite the ones associated with the segments 21 to 28, with a surface provided with a plurality of protruding bodies 50, conveniently shaped like a cone, a pyramid or other pointed structure, adapted to facilitate the grip of the intervertebral prosthesis 1 to the bone surfaces of the adjacent abutment vertebrae.

In this manner, once the intervertebral prosthesis 1 has been implanted and the correct space has been restored, the protruding portions, or the tips, of these protruding bodies 50 are driven into the vertebral body, giving a primary stability while waiting for the bone to invade the trabecular structure of the plate-like bodies, thanks to the osteoconductive properties of the material of which they are made.

Furthermore, the intervertebral prosthesis 1 is provided with means for positioning the segments 21 to 28 which are adapted to allow the transition of the segments 21 to 28 from the insertion/extraction configuration to the active configuration and vice versa, indeed during the implantation or removal of the intervertebral prosthesis 1 into or from the patient.

More precisely, these positioning means comprise an external wire 60, for connecting all the segments 21 to 28, which is associated with the outer lateral surface 2a of the disk-like body 2 so as to protrude respectively from the first segment 21 and from the last segment 28 with two end portions 61 adapted to be manipulated for the transition of the segments 21 to 28 from the active configuration to the insertion/extraction configuration and vice versa.

In the proposed embodiment, the external connecting wire 60 is embedded perimetrically in the segments 21 to 28 proximate to the external lateral surface 2a, more precisely through the intermediate portions 21a to 28a. The relative rotation among the segments 21 to 28 is facilitated by the presence of the external connecting wire 60: pulling the end portions 61 of the wire facilitates the rotation of the segments 21 to 28 with respect to the corresponding intermediate portions 21 a to 28a, providing the active configuration.

In fact, the simultaneous traction of both of the two end portions 61 is adapted to move the segments 21 to 28 to their active configuration, whereas the traction of only one of the two end portions 61 allows uncoiling the segments 21 to 28 in order to bring them to their open insertion/extraction configuration starting from the closed active configuration.

Preferably, the disk-like body 2 has an annular shape. The annular shape in fact facilitates the elastic return of the segments 21 to 28 to the active configuration.

Advantageously, the segments 21 to 28 can be divided, transversely to the direction of their thickness, into at least two portions made of elastomeric materials of different hardness. In other words, the disk-like body 2 can be constituted by the overlap of two or more layers of elastomeric materials having different characteristics. In this manner it is possible to give the prosthesis distinguished and progressive elastic properties. By using for example two layers with different hardness it is possible to obtain a prosthesis that opposes an increasing resistance to the movement between the two adjacent vertebrae as the extent of the movement itself increases. Likewise, the elastomeric insert can be adapted to the necessary space both in terms of height and with different angles.

With reference to Figures 3 to 10, which show a vertebra above which a prosthesis according to the present invention is inserted, a first method for implanting the intervertebral prosthesis 1 is described hereinafter.

Before proceeding with the description of the implantation referenced above, it should be stressed that the vertebra above the intervertebral prosthesis 1 is not shown for the sake of greater clarity of the figures.

The intervertebral prosthesis 1 , according to the present invention, thanks to the possibility of assuming an insertion/extraction configuration, can be implanted in a substantially easier and less traumatic manner than prostheses of the known type.

In fact, the intervertebral prosthesis 1 , in the insertion/extraction configuration, can be introduced between two adjacent vertebrae from a region that is posterior and lateral to said vertebrae.

Insertion between the two adjacent vertebrae can be performed with the aid of a tubular element, not shown, which is shaped so as to contain the prosthesis in its open configuration. This tubular element has a trapezoidal cross-section which facilitates its insertion between two contiguous vertebrae, allowing also, by means of a leverage effect, their divarication. In this manner, a sufficient operating space is provided for the positioning of the intervertebral prosthesis 1 between two contiguous vertebrae. More precisely, the intervertebral prosthesis 1 can be inserted, while it is inside the tubular element, behind the two adjacent vertebrae, from the same side of the two adjacent vertebrae. By making the prosthesis move forward progressively outside the tubular element, the segments 21 to 28, as they exit from the tubular element, move elastically into the closed configuration, moving progressively closer to the adjacent segment. The prosthesis is therefore arranged progressively in its closed configuration, shown in its final form in Figure 10. The implantation of the intervertebral prosthesis 1 requires therefore only the provision of a small access path for the tubular element from a posterior and/or lateral region with respect to the affected vertebrae and a slight divarication of the affected vertebrae in order to allow the intervertebral prosthesis 1 to be arranged freely in its closed configuration.

Moreover, once the segments 21 to 28 are about to be arranged in the active configuration, it is possible to grip the end portions 61 of the external connecting wire 60 and pull them in order to ensure that said segments 21 to 28 assume the desired active configuration. In this manner, one prevents the presence of any residues of biological material between the vertebral bodies, and particularly between the segments 21 to 28, from being able to hinder correct complete closure, by elastic return of the disk-like body 2 between the segments 21 to 28.

Moreover, as already mentioned, the external connecting wire 60 can be used advantageously also for the possible recovery/removal of the intervertebral prosthesis 1.

In fact, by gripping and pulling an end portion 61 of the connecting wire 60, optionally through the tubular element described above, the segments 21 to 28 uncoil, passing from the closed active configuration to the open insertion/extraction configuration, substantially by performing in reverse the steps of insertion of the intervertebral prosthesis 1 shown in Figures 3 to 10. As shown by way of example in Figure 1 1 , the prosthesis 1 can comprise a cutting and removal device 80 connected detachably to a distal segment 21 of the prosthesis 1 , which is adapted to cut and remove at least one portion of a damaged intervertebral disc.

Said cutting and removal device 80 comprises advantageously a tubular body 81 that comprises a cutting edge 82 and defines a volume 83 for collecting the biological material of the damaged intervertebral disc.

During the insertion of the prosthesis 1 between the two adjacent vertebrae, in fact, the cutting and removal device 80 moves forward by cutting and removing the part of the damaged disc that it encounters along its path, accumulating part of this biological material inside the volume 83 and pushing the remaining part outside the intervertebral space. Moreover, since the cutting and removal device 80 is connected detachably to the prosthesis 1 , if necessary it is removed from the prosthesis 1 so as to allow it to assume its active configuration, i.e., the disk-like shape.

In addition to the first method for implanting the prosthesis, described above, a second implantation method is presented hereinafter which uses, as an alternative to said tubular element through which the prosthesis is pushed in its insertion/extraction configuration, an adapted insertion device 100, shown in Figure 13, arranged between a pair of adjacent vertebrae V and V.

Figures 12 and 14 to 16 show the intervertebral prosthesis 1', which is a variation of the intervertebral prosthesis 1 and comprises the segments 2Γ- 28'.

The insertion device 100 is adapted to guide the insertion of the vertebral prosthesis Γ between two adjacent vertebrae V and V. It comprises a lower plate 102 and an upper plate 104 that are mutually connected by a cross-member 106. The lower plate 102 is adapted to engage the upper articular surface S of a first vertebra V, while the upper plate 104 is adapted to engage the lower articular surface I of a second vertebra V. The insertion device 100 defines a U-shaped insertion trajectory 101 for the prosthesis 1' around the cross-member 106.

Moreover, the insertion device 100 can comprise, along the insertion trajectory 101 , at least one guiding channel 108, 1 18 adapted to engage at least one guiding body 1 10, 120 formed in at least one segment of the prosthesis Γ. Said at least one guiding channel 108, 1 18 coupled to the at least one guiding body 1 10, 120 is adapted to assist the elastic return of the segments 2 T-28' of the prosthesis to the active configuration, i.e., to the disk-like shape.

In particular, the device 100 can comprise a first guiding channel 108, provided in the lower plate 102 and adapted to engage at least one lower guiding body 1 10, which is formed in at least one segment 2Γ-28' of the prosthesis , and protrudes from the lower surface of the segment itself, as shown in Figure 12. Advantageously, multiple segments 22', 23', 24', 26', 27' and 28' comprise a corresponding lower guiding body 1 10.

In addition or as an alternative to the first guiding channel 108, the device 100 can comprise a second guiding channel 1 18, formed in the cross- member 106 and adapted to engage at least one lateral guiding body 120, which is formed in at least one segment 2 Γ-28' of the prosthesis and protrudes from the inner lateral surface of said segment, as shown in Figure 12. Advantageously, multiple segments 2 Γ, 23', 25' and 27' comprise a corresponding lateral guiding body 120.

If the insertion device 100 is available, the method for implanting the intervertebral prosthesis Γ comprises the steps described hereinafter.

First of all, the insertion device 100 is inserted between two adjacent vertebrae V and V, preferably from a posterior and lateral region with respect to said vertebrae V and V.

The prosthesis is then arranged in the insertion/extraction configuration, in which the segments 2 Γ-28' are substantially mutually aligned, and is inserted in the insertion device 100 along the insertion trajectory 101. During insertion in the insertion device 100, the prosthesis 1 ' tends to assume the active configuration, i.e., the disk-like shape, and in particular the segments 2 Γ-28¹, due to the elastic return caused by the elastomeric material of which the prosthesis is made, tend to make the prosthesis bend and make the prosthesis Γ recover a substantially disk-like shape, which progressively forms around the cross-member 106 of the insertion device 100, along the trajectory 101.

When the prosthesis Γ is almost completely inserted in the insertion device 100, it is possible to remove said insertion device 100, and the prosthesis Γ can finally assume the active configuration, in which all the segments 2 -28" are arranged so as to form the disk-like body 2'.

The presence of the guiding channel 108, 1 18 in the insertion device 100 and of the guiding bodies 1 10, 120 provided in the prosthesis itself assists the elastic return of the segments 2Γ-28" to the active configuration, guiding the insertion of the prosthesis along the trajectory 101.

The relative dimensions between the cross-section of the guiding channel 108, 1 18 and the space occupation of the guiding body 1 10, 120, combined with the yielding of the elastomeric material of which the prosthesis Γ is made and with the elastic return effect of the prosthesis , allow each individual segment 2 Γ-28" of the prosthesis to follow the trajectory 101 along the guiding channel 108, 1 18 along the entire U-shaped path.

Advantageously, removal of the device 100 is facilitated by the presence of an escape extension 109 of the channel 108 formed in the plate 102, so that the lower guiding bodies 1 10 do not hinder removal of the device 100.

Said second implantation method also can comprise the steps of cutting and removing at least part of the damaged intervertebral disc by means of the cutting and removal device 80, during the insertion of the prosthesis along the trajectory 101.

In practice it has been found that the intervertebral prosthesis, W

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particularly for percutaneous mini-invasive surgery procedures, according to the present invention achieves the intended aim and objects since it can be implanted by means of percutaneous mini-invasive surgery procedures.

Another advantage of the intervertebral prosthesis according to the invention resides in the fact that it can be implanted percutaneously by means of a posterior, lateral or posterolateral surgical access.

A further advantage of the intervertebral prosthesis according to the invention resides in the fact that it ensures both good stability and good mobility of the vertebral joint.

Another advantage of the intervertebral prosthesis according to the invention resides in the fact that it can be adapted to the different characteristics of the implantation site.

A further advantage of the intervertebral prosthesis according to the invention resides in the fact that it can be removed easily with single-access mini- invasive surgery procedures.

The intervertebral prosthesis, particularly for percutaneous mini- invasive surgery procedures, thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

All the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements.

The disclosures in Italian Patent Application no. AR2012A000035, from which this application claims priority, are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. An intervertebral prosthesis (1), particularly for percutaneous mini- invasive surgery procedures, characterized in that it comprises a plurality of mutually articulated segments (21 -28), said segments (21-28) being movable from an active configuration, in which said segments (21-28) are arranged with respect to each other so as to form a disk-like body (2), to an insertion/extraction configuration, in which said segments (21 -28) are substantially mutually aligned, and vice versa.

2. The intervertebral prosthesis (1) according to the preceding claim, characterized in that said segments (21-28) are made of an elastomeric material.

3. The intervertebral prosthesis (1) according to claims 1 or 2, characterized in that said disk-like body (2) has an annular shape that is adapted to facilitate the elastic return of said segments (21-28) to said active configuration.

4. The intervertebral prosthesis (1) according to one or more of the preceding claims, characterized in that said segments (21-28) are divided, transversely to the direction of their thickness, into at least two portions made of elastomeric material of different hardness, so as to give the prosthesis differentiated and progressive elastic properties.

5. The intervertebral prosthesis (1) according to one or more of the preceding claims, characterized in that it comprises a plurality of upper platelike bodies (31-38) and a plurality of lower plate-like bodies (41-48), which are associated respectively with the upper and lower surfaces of said segments (21-28), said upper plate-like bodies (31 -38) and said lower platelike bodies (41-48) being independent of each other so as to be disconnected from each other.

6. The intervertebral prosthesis (1) according to one or more of the preceding claims, characterized in that said upper plate-like bodies (31-38) and said lower plate-like bodies (41-48) have, at their faces that are opposite 2014/068510

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the ones associated with said segments (21-28), a surface provided with a plurality of protruding bodies (50) that are adapted to facilitate the grip of said intervertebral prosthesis (1) to the bone surfaces of the adjacent abutment vertebrae.

7. The intervertebral prosthesis (1) according to one or more of the preceding claims, characterized in that said upper plate-like bodies (31-38) and said lower plate-like bodies (41-48) have a trabecular structure made of osteoconductive material.

8. The intervertebral prosthesis (1) according to one or more of the preceding claims, characterized in that it comprises intermediate portions

(21a-28a) for the connection of said segments (21-28), which are formed at the outer lateral faces of said segments (21-28) that form the outer lateral surface (2a) of said disk-like body (2) so as to form a hinge coupling between each pair of said segments (21-28), allowing them to perform mutual rotations about a rotation axis that is substantially parallel to the longitudinal axis of said disk-like body (2).

9. The intervertebral prosthesis (1 ) according to one or more of the preceding claims, characterized in that said intermediate portions (21a-28a) are made of said elastomeric material so as to keep, in the absence of external forces, said segments (21-28) in said active configuration by the elastic properties of said elastomeric material.

10. The intervertebral prosthesis (1) according to one or more of the preceding claims, characterized in that it comprises means for positioning said segments (21-28), which are adapted to allow the transition of said segments (21-28) from said active configuration to said insertion/extraction configuration and vice versa.

1 1. The intervertebral prosthesis ( 1 ) according to one or more of the preceding claims, characterized in that said means for positioning said segments (21-28) comprise at least one external connecting wire (60) which is associated with said outer lateral surface (2a) so as to protrude respectively from the first and the last of said segments (21-28) with two end portions (61) adapted to be manipulated for the transition of said segments (21-28) from said active configuration to said insertion/extraction configuration and vice versa.

12. The intervertebral prosthesis (1) according to one or more of the preceding claims, characterized in that it comprises a cutting and removal device (80) connected detachably to a distal segment (21) of said prosthesis (1) adapted to cut and remove at least one portion of a damaged intervertebral disc.

13. The intervertebral prosthesis (1) according to claims 12, characterized in that said cutting and removal device (80) comprises a tubular body (81) that comprises a cutting edge (82) and defines a volume (83) for collecting said at least one portion of said damaged intervertebral disc.

14. An insertion device (100) adapted to guide the insertion of an intervertebral prosthesis (Γ) according to one or more of claims 1 to 13, between two adjacent vertebrae (V, V), characterized in that it comprises a lower plate (102) and an upper plate (104) mutually connected by a cross- member ( 106), said lower plate (102) engaging the upper articular surface (S) of a first vertebra (V), said upper plate (104) engaging the lower articular surface (I) of a second vertebra (V), said insertion device (100) defining an insertion trajectory (101) for said prosthesis (Γ).

15. The insertion device (100), according to claim 14, characterized in that it comprises, along said insertion trajectory (101) of said prosthesis (Γ), at least one guiding channel (108, 1 18) adapted to engage at least one guiding body (1 10, 120) formed in at least one segment (2 Γ-28") of said prosthesis (Γ), said at least one guiding channel (108, 1 18) assisting said elastic return of said segments (2 Γ-28¹) of said prosthesis (Γ) to said active configuration.

16. A method for implanting an intervertebral prosthesis ( ), according to one or more of claims 1 to 13, characterized in that it comprises the steps of:

- introducing an insertion device (100), according to one or more of claims 14 and 15, between two adjacent vertebrae (V, V);

- arranging said prosthesis ( ) in said insertion/extraction configuration, in which said segments (2 Γ-28') are substantially mutually aligned;

- inserting said prosthesis (Γ) in said insertion device (100) along said insertion trajectory (101 );

- removing said insertion device (100), said prosthesis ( ) assuming said active configuration, in which said segments (2Γ-28') are mutually arranged so as to form a disk-like body (2').

17. The method for implanting an intervertebral prosthesis ( ), according to claim 16, characterized in that it comprises the steps of cutting and removing at least one portion of a damaged intervertebral disc by means of said cutting and removal device (80).