FR2943530A1 - Prosthetic disc for being interposed between adjacent vertebrae to replace damaged intervertebral disc at origin between vertebrae, has plates that are associated, such that sliding surfaces cooperate with each other by sliding in rotation - Google Patents

Abstract

The disc has an intermediate body comprising a sliding surface of a revolution shape around to a point. A connecting unit connects the intermediate body with a plate, so that the intermediate body is comprised inside a space defined by plans passing respectively by four faces of two couple lateral faces (24, 26). Another plate comprises a contact surface that contacts with a vertebra and comprises another sliding surface of revolution shape around the point. The plates are associated, such that sliding surfaces cooperate with each other by sliding in rotation.

Description

PROSTHETIC DISCALE TO BE INTERPOSED BETWEEN TWO CONSECUTIVE VERTEBERS

The present invention relates to disc prostheses adapted to be interposed between two consecutive vertebrae in replacement of the intervertebral disc located originally between these two vertebrae. It is already known prostheses discs capable of being implanted between two consecutive vertebrae to replace a damaged intervertebral disc, but they are actually not versatile, that is to say do not allow to perform the replacement of the intervertebral disc while by allowing a certain freedom of rotation of the two vertebrae between which they are implanted and generally does not offer the choice to the Practitioner of the implantation path, whether anterior or posterior. Also, the object of the present invention is to provide a disc prosthesis adapted to be interposed between two consecutive vertebrae instead of the intervertebral disc situated originally between these two vertebrae, which satisfactorily satisfies the objectives defined above. and which, while being of a relatively simple structure, can therefore be implemented both anteriorly and posteriorly. More specifically, the present invention relates to a disc prosthesis adapted to be interposed between two first and second consecutive vertebrae to replace the intervertebral disk located at the origin between these two vertebrae, characterized in that it comprises at least one assembly comprising: a first plate comprising a first contact surface capable of coming into contact with the first vertebra, this first plate being delimited by at least two pairs of opposite lateral faces, these opposite lateral faces being substantially perpendicular to the first surface; contact, • an intermediate body, said intermediate body having a first sliding surface of a shape of revolution around at least a first point and radius R, • means for linking said intermediate body with the first plate of way that this body is understood inside the space delimited by the plans p respectively by the four faces of the two pairs of opposite side faces, and • a second plate having a second contact surface adapted to come into contact with the second vertebra and having a second sliding surface of a shape of revolution around at least a second point and radius R, said first and second plates being associated so that the first and second sliding surfaces cooperate with one another by sliding in rotation. Other features and advantages of the present invention will appear in the course of the following description given with reference to the accompanying drawings for illustrative but not limiting purposes, in which: FIGS. 1 and 2 are two diagrammatic cross-sectional views respectively longitudinal and transverse orthogonal a first embodiment of the disc prosthesis according to the invention comprising a single set of its constituent elements, more particularly adapted for anterior implantation, the section according to FIG. 1 being referenced II in FIG. 2 and the section according to FIG. FIG. 2 being referenced II-II in FIG. 1, FIGS. 3 and 4 show, in perspective view, a second embodiment of the disc prosthesis according to the invention in accordance with the representation in FIGS. 1 and 2, FIG. 3 represents the disc prosthesis in its complete configuration and FIG. 4 represents the prosthesis. 3, but in which one of the elements has been removed, in this case the first plate, to better resorb the structure of such a disc prosthesis; FIG. 5 represents a cross-sectional view of A third embodiment of the disc prosthesis according to the invention more particularly adapted for posterior implantation, and FIG. 6 is a cross-sectional schematic sectional view of an improved embodiment of the disc prosthesis according to the invention. , capable of being applied to the embodiments according to FIGS. 1 to 5.

It is first of all specified that, in the figures, the same references designate the same elements, whatever the figure on which they appear and whatever the form of representation of these elements. Similarly, if elements are not specifically referenced in one of the figures, their references can be easily found by referring to another figure. It is also stated that the figures essentially represent three embodiments of the object according to the invention, but that there may be other embodiments that meet the definition of this invention. It is furthermore specified that, when, according to the definition of the invention, the object of the invention comprises "at least one" element having a given function, the embodiment described may comprise several of these elements. Conversely, if the embodiment of the object according to the invention as illustrated has several elements of identical function and if, in the description, it is not specified that the object according to this invention must obligatorily comprise a number particular of these elements, the object of the invention may be defined as comprising "at least one" of these elements.

Lastly, it is specified that when, in the present description, an expression defines, by itself, without a specific particular mention concerning it, a set of structural characteristics, these characteristics may be taken, for the definition of the object of the protection requested, when technically possible, either separately, or in full and / or partial combination. With reference to the appended figures, the present invention relates to a disc prosthesis adapted to be interposed between two first and second consecutive vertebrae schematically illustrated at VI and V2, to replace the intervertebral disk situated at the origin between these two vertebrae and which has revealed to have been damaged for any reason whatsoever. This prosthesis comprises at least one set E1, E2, Figures 1 to 4 showing embodiments of the disc prosthesis comprising a single set, Figure 5 showing an embodiment of the disc prosthesis comprising two sets. Each set E1, E2 comprises a first plate 10 having a first contact surface 11 adapted to come into contact with the first vertebra VI and delimited by at least two pairs 24, 26 of opposite side faces, these opposite lateral faces being substantially perpendicular to the first contact surface 11, the first plate 10 being accordingly entirely comprised in the space delimited by the planes passing respectively by its four lateral faces.

The prosthesis further comprises an intermediate body 30, this intermediate body having a first sliding surface 12 of a shape of revolution around at least a first point 29 and radius R, and means for linking the intermediate body 30 with the first plate 10 so that the intermediate body is included within the space delimited by the planes passing respectively by the four faces of the two pairs 24, 26 of opposite side faces. It is specified that, in the sense of the present invention, the sliding surface 12 which is of a shape of revolution around at least a first point 29 and radius R, may be spherical, and in this case the first point 29 is unique in being the center of the spherical or cylindrical surface, and in this case it is of revolution around a multitude of points 29 defining an axis of rotation. It is also provided, for this set El, E2, a second plate 20 having a second contact surface 21 adapted to come into contact with the second vertebra V2. This second plate further comprises a second sliding surface 28 of a shape of revolution around at least a second point 29 and of the same radius R. In use, as illustrated in the figures, the first and second plates 10, 20 are associated so that the first and second sliding surfaces 12, 28 cooperate on one another by sliding in rotation, around and around the common point 29. Very preferably as the one more particularly illustrated in the figures, these means to bind the intermediate body 30 with the first plate 10 are constituted by the fact that the first plate 10 and the intermediate body 30 are made in one piece. In addition, it is also very advantageous for the set E1, E2 to have means 50 for firmly connecting the first plate 10 with the first vertebra V1. According to an embodiment which is particularly advantageous, these means 50 defined above, are constituted by a core 56, at least one blade 51 mounted integral on the core 56 and means for mounting the core 56 in rotation relative to the first plate 10 about a rotation axis 34 substantially perpendicular to the two faces of one 26 of the two pairs 24, 26 of opposite side faces (in the illustrated embodiments, this pair of opposing faces is the pair 26), of so that it is able to take any position between two first and second positions P1, P2 shown in Figure 2, respectively in broken lines (for P1) and in continuous lines (for P2). The blade 51 is fixedly mounted on this core 56 so that, when the core 56 is in its first position P1, the blade 51 is completely included in the half-space delimited by a plane passing through the first contact surface 11 and comprising the first plate 10, and that when the web 56 moves from the first position P1 to the second P2, the blade 51 moves in a partial groove 52 made in the first plate 10 to emerge from the first face contact 11 to be able to anchor in the first vertebra VI. According to a preferred embodiment, the means for mounting the core 56 in rotation between the first and second positions P1, P2 are constituted by a through-hole 57 formed in the first plate 10, the core 56 then being mounted in rotation in the piercing through 57 so that it overflows on both sides of this through breakthrough by two parts of non-zero length. In this case, in order to properly bind the first plate 10 with the vertebra VI and to avoid that it undergoes for example undesired lateral movements, it is very advantageous for the prosthesis to have, as can be seen in FIG. 1, two blades 51 respectively fixed on the two parts of the core 56 which protrude on either side of the through-hole 57. As will be described hereinafter, this blade 51 (or these two blades) may furthermore to be mounted in cooperation with a longitudinal rib 82 to ensure a very good hold in X and Y by. compared to the first vertebra V1. According to a more particularly advantageous embodiment for posterior implantation, the first sliding surface 12 is formed on the intermediate body 30 so that the first point 29 is outside the space between the two planes 70, 71 passing respectively by one of the two pairs 24, 26 opposite side faces, namely the torque 24. This structural feature allows for a set El, E2 having a lateral size less than, for example, the embodiments according to Figures 1 to 4, and to be able to associate, as described hereinafter, two sets E1, E2 for a disc prosthesis embodiment such as that illustrated in FIG. 5. In the embodiment illustrated in FIG. 5, the disc prosthesis comprises two sets El , E2 associated and having substantially symmetrical structures from one another with respect to a plane of symmetry 91. The prosthesis according to this embodiment comp furthermore, means 90 for associating the two sets E1, E2 so that the first rotation points 29 of these two sets are merged. These means 90 for associating the two sets E1, E2 may be constituted by the second vertebra V2 itself. However, much more preferably, they advantageously consist of a prosthesis wedge 92 interposed between the two sets El, E2 in association with means 93 for releasably securing said prosthesis wedge 92 with the first plate 10 of each together El, E2.

As seen in Figure 6, there is a gap between the upper wall 98 of the prosthesis wedge 92 which is opposite the second vertebra V2. To prevent the bone body of this second vertebra from deforming and filling this space, it is advantageous to give the upper wall 98 of the prosthesis block 92 a shape of revolution of radius R and having as its center the common point 29 defined above, and to position, between the second plates of the two sets and in the space defined above, an intermediate shim 100 having a friction surface 101 on the upper wall 98 of the complementary prosthesis wedge of this wall. As for the fastening means 93, they are constituted for example by sliding interlockings 94 of any shape whatsoever, FIG. 5 giving an example, which is trapezoidal, but which could be circular, etc., among several possible ones. are in themselves within the realm of normal knowledge of a person skilled in the art. It is also very advantageous that the first and second contact surfaces 11, 22 respectively of the first and second plates 10, 20, each comprise projecting portions 80, 81 capable of anchoring in the vertebrae VI, V2, as shown in FIGS. pimples or the like. It is also advantageous that, more particularly the first contact surface 11, that of the first plate 10 which incorporates one or two pivoting blades 51, further comprises at least one longitudinal rib 82 substantially parallel to the axis 34, a height greater than that of the pins, the blade 51 being substantially in the axis of the rib when it is in its second position P2 so that, having in addition a shape and dimensions that make it overflow from the longitudinal rib 82 when it is in its second position P2, as illustrated in particular in Figure 2, the combination of each blade 51 with the longitudinal rib 82 corresponding contributes to the perfect maintenance of the first plate 10 X and Y, as mentioned before. The blade 51 (or both blades) prevents the sliding of the first plate 10 along the axis 34, and the longitudinal rib 82 prevents its sliding in a direction perpendicular to this axis, Figures 1 and 2.

Advantageously, it is possible, for example as illustrated in FIG. 6, that the set E1, E2 also comprises, mounted in association with the second plate 20, a plate 151 capable of taking two positions, a first position represented in dashed line in which this lamella 151 does not emerge from the second contact surface 22, and a second position shown in continuous lines in which it emerges and enters the second vertebra V2, and means for controlling the passage of the lamella 151 from its first position to the second. According to a particularly advantageous embodiment, these means for controlling the passage of the blade 151, from its first position to the second, include the blade 51 integral with the core 56. Indeed, as shown in Figure 6, the blade 51 and the slat 151 are mounted relative to each other so that, from the position in which the blade 51 is in its first position P1, a rotation of the core 56 in the dextral direction of about four Twenty degrees drive the blade 51 until it meets the blade 151 and pushes it from its first to its second position. The core 56 is then turned approximately one hundred and eighty degrees in the direction mesestrorsum, to pass the blade 51 in its second position P2, Figures 2 and 6 for the locking of the first plate 10 with the first vertebra VI as described above. The disc prosthesis according to the invention as described above is used as follows: When the intervertebral disk between two consecutive vertebrae VI and V2 is damaged and the practitioner decides to replace it with a disc prosthesis while retaining A certain mobility between the two vertebrae relative to each other, it can implement disc prosthesis 25 according to the invention in two ways. The first way is for example the following: If it wants to implant a disc prosthesis according to the invention comprising only one set El, E2, it implants for example a prosthesis according to the embodiments illustrated in Figures 1 to 4 In this case, because of the lateral size of this assembly, its implantation between the two vertebrae can generally be carried out only by the anterior way.

The disc prosthesis having been implanted, the second plate 20 retains a certain freedom of rotation with respect to the first plate 10 by pivoting on the sliding surface 12 of the intermediate body 30 as previously explained and illustrated in FIG. This allows the spine to maintain relative flexibility and allows the patient to recover at least some of the movement he could do before the intervertebral disc was damaged. The second way is for example the following: If the practitioner prefers to implant the disc prosthesis posteriorly, he will choose a prosthesis according to the third embodiment illustrated in Figure 5. In this case, he introduces and implants the two sets El, E2 which have substantially identical structures and symmetrical to each other with respect to a plane, but with a reduced lateral size. Their implantation can therefore be done posteriorly, respectively by two separate paths located on either side of the spinal cord, to position them as shown in Figure 5. This technique is called, by those skilled in the art, "pose bilateral ".

Since the point of rotation 29 is situated outside the space between the two planes 70, 71 defined above, it is relatively easy for the practitioner to find the two respective implantation positions of the two sets E1 and E2, for that they are symmetrical to each other with respect to the plane 91 and that their two points of rotation 29 are merged, Figure 5. As a result, the two sets E1 and E2, which then have the same point of 29 rotate, behave as a single disc prosthesis giving the two second plates 20 a certain freedom of rotation relative to the first two plates 10, and therefore a certain freedom of rotation of the second vertebra V2 relative to the first VI, as illustrated in broken lines Vr in FIG. 5. This disc prosthesis structure comprising two sets implanted in association, each of which does not have the disadvantage of a large lateral bulk, allows implantation by the posterior path whose benefits are known, which is of great benefit to the patient on the therapeutic level and to the practitioner whose operative work is facilitated.

However, for greater safety, the Practitioner can implant, between the two sets E1, E2, a prosthesis wedge 92 which also has a reduced lateral space requirement, to remotely hold the two sets E1, E2 and to be certain. that they will remain constantly well positioned relative to each other with their points of rotation 29 together. This block of prosthesis can be implanted, also by the posterior way, prior to the implantation of the two sets El, E2.

Claims (12)

REVENDICATIONS1. Disc prosthesis adapted to be interposed between two first and second consecutive vertebrae (VI, V2) in replacement of the intervertebral disk situated at the origin between these two vertebrae, characterized in that it comprises at least one set (E1, E2) comprising: a first plate (10) comprising a first contact surface (11) adapted to come into contact with the first vertebra (V1), said first plate being delimited by at least two pairs (24, 26) of opposite lateral faces, these opposite side faces being substantially perpendicular to the first contact surface (11), • an intermediate body (30), said intermediate body having a first sliding surface (12) of a shape of revolution around at least one first point (29) and radius R, • means for linking said intermediate body (30) with the first plate (10) so that said intermediate body (30) is included within the space limited by the planes passing respectively through the four faces of the two pairs (24, 26) of opposite side faces, and 20 • a second plate (20) having a second contact surface (21) adapted to come into contact with the second vertebra (V2) and having a second sliding surface (28) of a shape of revolution about at least a second point (29) and radius R, said first and second plates (10, 20) being associated so that the first and second sliding surfaces (12, 28) cooperate with one another by rotational sliding. 2. Disc prosthesis according to claim 1, characterized in that the means for linking said intermediate body (30) with the first plate (10) are constituted by the fact that said first plate (10) and said intermediate body (30) ) are made in one piece. 3. disc prosthesis according to one of claims 1 and 2, characterized in that said assembly (E1, E2) comprises means (50) for connecting said first plate (10) with the first vertebra (V1). 4. disc prosthesis according to claim 3, characterized in that the means (50) for connecting said first plate (10) with the first vertebra (V1) are constituted by: • a core (56), • means for mounting said core (56) rotated relative to said first plate (10) about an axis of rotation (34) substantially perpendicular to the two faces of one (26) of the two pairs (24, 26) of opposite side faces so that this core is able to take any position between two first and second positions (P1, P2), • at least one blade (51) integral with said core (56), said blade (51) being mounted in cooperation with said core (56) so that in the first position (P1) said blade (51) is fully within the half-space defined by a plane passing through the first contact surface (11) and comprising the first plate (10) , and that when the web (56) passes from the first (P1) to the second position (P2), said The blade (51) moves in a partial groove (52) made in the first plate (10) to emerge from the first contact face (11) to be able to anchor in the first vertebra (VI). 5. Disc prosthesis according to claim 4, characterized in that the means for mounting said core (56) in rotation between the two first and second positions (P1, P2) are constituted by a through hole (57) made in the first plate (10), said core (56) being rotatably mounted in said through-hole (57) so that it opens on either side of this through-hole. 6. disc prosthesis according to claim 5, characterized in that said assembly (E1, E2) comprises two blades (51) respectively fixed on the two parts of said web (56) opening on either side of said through-hole . 7. disc prosthesis according to one of the preceding claims, characterized in that said first sliding surface (12) is formed on the intermediate body (30) so that the first point (29) is outside the space between two planes (70, 71) passing respectively through one (24) of the two pairs (24, 26) of opposite side faces. 8. Disc prosthesis according to claim 7, characterized in that it comprises: • two sets (E1, E2), the two sets having structures substantially symmetrical to each other with respect to a plane called " symmetry "(91), and • means (90) for associating the two sets (E1, E2) so that the first points (29) of the two sets are merged. 9. Disc prosthesis according to claim 8, characterized in that the means (90) for associating the two sets (E1, E2) consist of a prosthesis wedge (92) interposed between the two sets (E1, E2). and means (93) for releasably securing said shim (92) with the first tray (10) of each assembly (E1, E2). 10. Disc prosthesis according to claim 9, characterized in that the means (93) for releasably fixing said shim (92) with the first plate (10) of each set (E1, E2) are constituted by interlocking sockets. slide (94). 11. Disc prosthesis according to one of the preceding claims, when it depends on claim 4, characterized in that the first and second contact surfaces (11, 22) each comprise projecting parts (80, 81) adapted to anchor in said vertebrae (VI, V2), and that the first contact surface (11) further comprises at least one longitudinal rib (82) substantially parallel to said axis (34), said blade (51) being substantially in the axis of said rib when said soul is in its second position (P2). 12. Disc prosthesis according to one of the preceding claims, characterized in that said set (E1, E2) comprises a blade (151) mounted in association with the second plate (20), the blade (151) being adapted to take two positions, a first position in which it does not emerge from the second contact surface (22), and a second position in which it emerges from this second contact surface (22) and enters the second vertebra (V2), and means for controlling the passage of the lamella (151) from its first position to the second.