HK1170654B - Intervertebral disc prosthesis - Google Patents

Description

Intervertebral disc prosthesis

This application is a divisional application of a patent application entitled "intervertebral disc prosthesis" filed on 2005, 12/14/10, and having application number 200580047633.7.

Technical Field

The present invention relates to intervertebral disc prostheses intended to replace fibrocartilaginous discs, ensuring the junction between the vertebrae of the spine.

Background

Various types of intervertebral disc prostheses are known in the prior art. Many prostheses, as exemplified by patent applications WO 02089701 and WO 2004/041129, comprise lower and upper plates forming a cage around a central core. The partial prosthesis allows the upper plate to rotate with respect to the central core and optionally allows the central core to slide with respect to the lower plate. The sliding of the central core with respect to the lower plate is an essential feature, since it must allow the core to be positioned spontaneously in the desired position, thus reducing the constraints imposed on the prosthesis during the movements of the patient in which the prosthesis is installed. The displacement of the core in cooperation with the cooperation of the at least one plate near the uneven surface allows a gradient between the plates of the prosthesis, which facilitates the mobility of the patient in whom the prosthesis is fitted. The displacement of the core also prevents it from deforming under load when subjected to primary constraints. The partial prosthesis has bone anchoring means for attaching the prosthesis to the vertebrae between which the prosthesis is to be inserted.

However, the size of the vertebrae varies greatly from person to person for the same vertebra at a given position in the spinal column, but for a given person this depends on the position of the vertebrae in the spinal column between which the prosthesis is to be inserted. The dimensions of the intervertebral disc prosthesis must be adapted to the vertebrae between which the prosthesis is to be inserted, depending on the person and the position of the vertebrae in the vertebral column. In addition, depending on the spinal disorder of the patient in which the prosthesis is installed, a prosthesis that corrects the disorder is sometimes preferred. The prosthesis can therefore be used to correct vertebral inclination defects such as lordosis. Thus, to adapt the prosthesis to as many cases as possible, a large number of prostheses with different plate sizes and inclinations must be envisaged. The main inconvenience of a large number of prostheses is the high manufacturing costs and the high level of inventory. In this context, it is advantageous to provide a prosthesis having a structure that is suitable for vertebrae of different sizes and with different inclinations of the plates. The prosthesis may reduce inventory levels and manufacturing costs.

Disclosure of Invention

The object of the present invention is to propose an intervertebral disc prosthesis which allows limited movement of the different parts of the prosthesis with respect to each other and which comprises a core for limiting the displacement thereof in at least one direction. The same prosthesis can be adjusted at low cost to fit vertebrae of different sizes.

This object is achieved by an intervertebral disc prosthesis having at least three parts including an upper plate, a lower plate and a core movable at least with respect to one of the plates, characterized in that it comprises two anatomic adaptation elements, each of which has, on the one hand, a surface for contact with the surface of a vertebra and, on the other hand, a surface at least a part of which has a surface for contact with at least a part of a plate, the anatomic adaptation elements being mounted with respect to at least a part of the plates, the anatomic adaptation elements being fixed to each plate via fixation means.

According to another feature, the anatomic adaptation elements are crowns that surround each plate and respectively prolong its upper and lower surfaces to present contact surfaces of the prosthesis with the adjacent vertebrae that are larger than when there are no anatomic adaptation elements, crowns of anatomic adaptation elements of different sizes being adjustable on the plates to adapt them to vertebrae of different sizes.

According to another feature, the anatomic adaptation elements are plates, called anatomic, which cover the plates and respectively elongate their upper and lower surfaces to provide contact surfaces of the prosthesis with the adjacent vertebrae which are larger than when there are no anatomic adaptation elements, the plates of the anatomic adaptation elements of different sizes being adjustable on the plates to adapt them to the vertebrae of different sizes.

According to another feature, the anatomic adaptation elements symmetrically prolong the upper and lower surfaces of the respective upper and lower plates, so that the surfaces extend equally on the different sides of the plates, anterior, posterior and lateral.

According to another feature, the anatomic adaptation elements symmetrically prolong the upper and lower surfaces of the respective upper and lower plates so that the surface has a greater extension on at least one of the front, rear and lateral edges of the plates than on the other edge.

According to another feature, the upper surface of the core is in contact with at least a portion of the lower surface of the upper plate, and the lower surface of the core is in contact with at least a portion of the upper surface of the lower plate.

According to another feature, at least one portion of the surface of at least one plate is concave and complementary to the convex surface of the core when in contact therewith.

According to another feature, at least one portion of the surface of at least one plate is plane and complementary to the plane of the core when in contact therewith.

According to another feature, the co-operating male and female means located in the vicinity of the edges of at least one plate and of the core limit, without excessive friction, the translation of the core with respect to this plate along an axis substantially parallel to the plate and limit or inhibit the rotation of the core with respect to this plate about an axis substantially perpendicular to the plate.

According to another feature, the dimensions of each male co-operating means are slightly smaller than those of each female co-operating means so as to allow a slight clearance between the core and the plate on which the co-operating means are mounted.

According to another feature, the dimensions of each male co-operating means are substantially the same as those of each female co-operating means so as to avoid any clearance between the core and the plate on which the co-operating means are mounted.

According to another feature, the cooperation means of the plate are female cooperation means cooperating with male cooperation means of the core.

According to another feature, the male co-operating means of the core are blocks located on both sides of the core, and the female co-operating means of the plate are four walls located in pairs on each of the two sides of the plate.

According to another feature, the fixation means of the anatomic adaptation elements on the plates of the prosthesis are removable, allowing the exchange of the anatomic adaptation elements fixed in a mobile manner to the plates of the prosthesis.

According to another feature, the fixation means of the anatomic adaptation elements on the plates are fixation means present on the anatomic adaptation elements and complementary to the fixation means present on the plates of the prosthesis.

According to another feature, the anatomic adaptation elements are fixed to the plates by means of contact, on the one hand, with at least a portion of the surface facing at least a portion of the plates and, on the other hand, with complementary fixation means present on the plates of the prosthesis.

According to another feature, the fixation means of the anatomic adaptation elements on the plates consist in male fixation means present on the anatomic adaptation elements, cooperating with female fixation means present on the plates of the prosthesis and vice versa.

According to another feature, the female fixation means present on the plates of the prosthesis are plane surfaces situated at the edges of the plates of the prosthesis.

According to another feature, the female fixation means present on the plates of the prosthesis are recesses made in the edges of the other plate of the prosthesis.

According to another feature, the female fixation means present on the plates of the prosthesis are recesses made in the edges of the female co-operating means of the plates of the prosthesis.

According to another feature, the female fixation means present on the plates of the prosthesis are flat surfaces present on the edges of one plate and recesses formed in the female co-operation means present on the edges of the other plate of the prosthesis.

According to another feature, the female fixation means present on at least one of the plates of the prosthesis are a flat surface present on at least a first edge of one of the plates and a recess formed in at least a second edge of the plate of the prosthesis, the second edge geometrically facing the first edge of the plate.

According to another feature, at least one of the female fixation means present on the plates of the prosthesis comprises at least one notch to allow blocking of the male fixation means of the anatomic adaptation elements on this female fixation means.

According to another feature, the fixation means of the anatomic adaptation elements on the plates consist in female fixation means present on the anatomic adaptation elements and cooperating with male intermediary means that can also cooperate with the female fixation means present on the plates of the prosthesis.

According to another feature, the anatomic adaptation elements are fixed to the plates by means of, on the one hand, at least a part of their upper and lower surfaces in contact with at least a part of the respective upper and lower plates, and, on the other hand, by means of male intermediary means in contact with female fixation means present on the anatomic adaptation elements and with female fixation means present on the plates of the prosthesis.

According to another feature, the male intermediary means have fastening means which block the male intermediary means in a position cooperating with the female fixation means on the anatomic adaptation elements and with the female fixation means on the plates of the prosthesis.

According to another feature, the male intermediary means are sliding plates in the female fixation means on the anatomic adaptation elements, to cooperate with the female fixation means on the plates of the prosthesis, the fastening means of the male intermediary means being at least one irregularly shaped portion located on at least one side of the plates and intended to cooperate with at least one opening in the female fixation means on the anatomic adaptation elements and/or in the female fixation means on the plates, so as to block the male intermediary means in a position of cooperation with the female fixation means on the anatomic adaptation elements and with the female fixation means on the plates of the prosthesis.

According to another feature, the fastening means of the male intermediary means are holes in the male intermediary means and in the female fixation means of the anatomic adaptation elements, the holes in the female fixation means of the anatomic adaptation elements being able to receive fastening pins blocking the male intermediary means in a position of cooperation with the female fixation means of the plates of the prosthesis.

According to another feature, the median planes representing the upper and lower surfaces of each anatomic adaptation elements are substantially parallel or form an acute angle, the inclination of which makes it possible to adapt the overall shape of the prosthesis to the anatomy of the spinal column or to possibly correct inclination defects of the vertebrae of the patient in whom the prosthesis is used.

According to another feature, the same anatomic adaptation elements can be assembled with different plates whose upper and lower surfaces are at different angles.

According to another feature, the angle between the upper surface of the upper plate and the lower surface of the lower plate is produced by angling the median planes representing the upper and lower surfaces of the lower plate and/or of the upper plate, or by limiting, by the co-operating means, the movement of the core about a position that tilts at least one of the plates.

According to another feature, the same plate can be assembled with cores of different thickness and/or size and/or shape.

According to another feature, the anatomic adaptation elements consist of movable osseous anchorage elements fixed to the anatomic adaptation elements during the fixation of the anatomic adaptation elements to the plates, the insertion of the prosthesis between the vertebrae and the possible adjustment of the relative position between the different elements of the prosthesis.

According to another feature, the movable osseous anchorage element of the anatomic adaptation elements is provided with at least one plate equipped with cuts oriented to prevent the plate from being removed after insertion into the vertebrae, the distal end of the plate having a portion curved to fold over it and intended to act as a hook to interlock with the edge of an opening made near the periphery of the anatomic adaptation elements.

According to another feature, the portion of the movable bone anchoring element of the anatomic adaptation elements, on which the plate with the cut-out is bent and folded, is coextensive with a second plate also equipped with a cut-out oriented to prevent the removal of the plate after its insertion in the vertebrae.

According to another feature, the anatomic adaptation elements comprise movable osseous anchorage elements in the form of at least one winglet inserted in a groove of the adjacent surface of the vertebrae between which the prosthesis is to be implanted, said winglet comprising a cut-out oriented to prevent the prosthesis from exiting the housing between the vertebrae, the distal end of the winglet having a portion curved to fold over it and intended to act as a hook to interlock with the edge of the opening near the periphery of the anatomic adaptation elements.

According to another feature, the winglet further comprises a pin which is dimensioned to be tightly inserted into the slot of the anatomic adaptation elements and/or plates.

Drawings

Other features and advantages of the present invention will become more apparent from the following description, taken in conjunction with the accompanying drawings, in which:

figure 1 shows an exploded perspective view of the different elements of a prosthesis according to an embodiment of the invention,

figure 2 shows an exploded perspective view of the different elements of a prosthesis according to another embodiment of the invention,

figure 3 shows a perspective view of a prosthesis according to another embodiment of the invention.

Figures 4A and 4B show a bottom view and a cross-sectional view taken along the plane A-A of figure 4A, respectively, of an upper plate fitted with a anatomic adaptation elements according to an embodiment of the invention, figures 4C and 4D show a plan view and a cross-sectional view taken along the plane B-B of figure 4C, respectively, of an upper plate fitted with an anatomic adaptation elements according to an embodiment of the invention,

figure 5A shows a bottom view of the anatomic adaptation elements equipped upper plate according to an embodiment of the present invention, figures 5B and 5C show cross-sections of the anatomic adaptation elements equipped upper plate according to an embodiment of the present invention, taken along the plane C-C and the plane D-D shown in figure 5A,

figures 6A and 6B show a partial bottom view of the upper plate fitted with anatomic adaptation elements according to two different embodiments of the invention,

figures 7A and 7B show perspective views of a lower plate equipped with anatomic adaptation elements according to two different embodiments of the invention.

Figures 8A and 8B show, respectively, a bottom view of the part of the lower plate equipped with the anatomic adaptation elements with their fixation means open and a cross-section along the plane E-E shown in figure 8A, figures 8C and 8D show, respectively, a bottom view of the same embodiment as shown in figures 8A and 8B and a cross-section along the plane F-F shown in figure 8C, but with their fixation means closed and locked,

figures 9A and 9B show, respectively, a partial bottom view of the lower plate with the anatomic adaptation elements fitted and with the fixation means thereof open, and a section along the plane G-G shown in figure 9A, and figures 9C and 9D show, respectively, the same embodiment as shown in figures 9A and 9B, and a section along the plane H-H shown in figure 9C, but with the fixation means of the anatomic adaptation elements according to an embodiment of the invention closed and locked,

figures 10A and 10B show respectively a prosthesis comprising a bone anchoring device according to an embodiment of the invention and a perspective view of a bone anchoring device according to this embodiment,

fig. 11A and 11B show a prosthesis comprising a bone anchoring device according to an embodiment of the invention, in perspective view and in section along the plane I-I shown in fig. 11A, respectively.

Detailed Description

The intervertebral disc prosthesis according to the invention comprises an upper plate (1) connected to a lower plate (2) by means of a core (3), each plate (1, 2) being equipped with anatomic adaptation elements (11,22) allowing to adapt the overall dimensions of the prosthesis to the dimensions of the vertebrae between which it is intended to be inserted. Thus, thanks to the anatomic adaptation elements (11,22), a single unit consisting of two plates (1, 2) and a core (3) can be used for vertebrae of different sizes, which greatly reduces the costs of manufacturing the prosthesis and its variants. The prosthesis according to the invention has the advantage that the anatomic adaptation elements (11,22) of the simple components it comprises can be varied in size to suit the different vertebrae of the spinal column, for example to adapt the thickness of the prosthesis to the intervertebral space and/or to adapt the inclination of the plates (1, 2) of the prosthesis to the inclination of the vertebrae of the patient. Although the anatomic adaptation elements (11,22) allow the prosthesis to be adapted to vertebrae of different sizes, it is naturally possible to use plates (1, 2) and cores (3) of different sizes and shapes, if desired.

The two anatomic adaptation elements (11,22) of the prosthesis according to the invention are an upper element (11) and a lower element (22). The upper element (11) is, on the one hand, in contact at least partially with the lower surface of the first vertebra (110) and, on the other hand, in contact at least partially with the lower surface (111) of the upper plate (1). The lower element (22) is at least partially in contact, on the one hand, with the lower surface (220) and, on the other hand, with the upper surface (222) of the second vertebra, and with a portion of the lower plate (2). Each of the two anatomic adaptation elements (11,22) is fixed to the plates (1, 2) by respective fixation means (113, 223).

The core (3) has a slight thickness (3 to 15 mm, depending on the vertebrae between which the prosthesis is to be inserted). For better absorption of the constraints, the core may be made of a compressible material such as polyethylene, which mimics the physical properties of the elasticity of a natural intervertebral disc.

In all possible embodiments of the invention, the core (3) has a convex portion on at least a portion of at least one of its upper (30) and lower (34) surfaces. In the embodiment shown in fig. 1 to 9, the upper surface (30) of the core (3) is a convex portion complementary to the concave portion (140) of the lower surface (14) of the upper plate (1), while the lower surface (34) of the core (3) is a planar portion complementary to at least one portion of the plane of the upper surface (24) of the lower plate (2). The concave portion (140) of the lower surface (14) of the upper plate member (1), as particularly visible in fig. 4A, 4B, 5A, 5B and 5C, has a circular periphery. In other possible embodiments (not shown), the lower surface (34) of the core (3) is a convex portion, complementary to a concave portion of the upper surface (24) of the lower plate (2), while the upper surface (30) of the core (3) is a planar portion, complementary to at least one planar portion of the lower surface (14) of the upper plate (1). In other embodiments (not shown), the concave surface is located on a portion of one of the upper (30) and lower (34) surfaces of the core (3) cooperating with the convex surface located on a portion of the surface of one of the plates (1, 2). In a different possible embodiment of the invention (not shown), the non-convex or non-concave surface of the core (3) may be, for example, slightly concave or convex, respectively.

In the embodiment shown in figures 1 to 9, the concave portion (140) of the lower surface (14) of the upper plate (1), complementary to the convex portion of the core (3), can tilt the upper plate (1) when the patient with the prosthesis is bent over. The cooperation between the concave portion (140) and the convex portion (34) provides an attachment surface to the prosthesis, due to the inclination of the upper plate (1) with respect to the core (3). The centre of the connection is naturally the tip of the convex surface (34) of the core (3). In the embodiment shown, the lower surface of the core (3) and the upper surface of the lower plate (2) are plane, so as to allow clearance for the core (3) to translate with respect to the lower plate (2) along an axis substantially parallel to the lower plate (2) and to rotate about an axis substantially perpendicular to the lower plate (2). The inclination of the upper plate (1) and the clearance of the core allow the core (3) to move towards a desired position to absorb the constraints imposed on the prosthesis during the movement of the patient in whom the prosthesis is installed. The movement between the upper plate (1) and the core (3) and the clearance of the core (3) with respect to the lower plate (2) thus allow the patient to move and optionally eliminate the drawbacks of prosthesis positioning. The voids also have the effect of preventing the prosthesis from wearing too quickly due to constraints applied to the prosthesis.

Irrespective of the embodiment, the core (3) also has male or female cooperating means (33) respectively complementary to the female or male cooperating means (23) of at least one of the plates (1, 2). Male and female co-operating means (23, 33) located in the vicinity of the edges of at least one of the plates (1, 2) and the core (3) limit, without excessive friction, the translation of the core (3) with respect to the plates (1, 2) along an axis substantially parallel to the plates (1, 2) and limit or inhibit the rotation of the core (3) with respect to the plates (1, 2) about an axis substantially perpendicular to the plates (1, 2). The dimensions of the male co-operating means (33) are slightly smaller than those of the female co-operating means (23) to allow a slight clearance between the core (3) and the plates (1, 2) in which they are mounted. Conversely, the male co-operating means (33) may also be substantially the same size as the female co-operating means (23) to prevent a clearance between the core (3) and the plates (1, 2) in which they are mounted.

In the embodiment shown in fig. 1 to 3, the core (3) has male cooperation means (33) complementary to the female cooperation means (23) on the lower plate (2). The male co-operating means (33) of the core (3) are, for example, snaps or blocks of substantially parallelepiped shape, present on the side edges of the core (3), as shown particularly visually in fig. 1 to 3. The female cooperation means (23) are, for example, four walls located in pairs on each of the two side edges of the lower panel (2). The wall can be bent towards the centre of the prosthesis to cover at least part of the male co-operating means (33) of the core (3) and avoid lifting the core (3) and the upper plate (1). The co-operating means (23, 33) also prevent the ejection of the prosthesis when the chip (3) is over-constrained on the prosthesis. In another embodiment (not shown), the dimensions of the male co-operating means (33) of the core (3) are substantially the same as the dimensions of the female co-operating means (23) of the lower plate (2) so as to avoid clearance when the core (3) is translated and rotated with respect to the lower plate (2). In the latter case, the prosthesis only allows the inclination of the upper plate (1) with respect to the core (3). In another embodiment (not shown), the core (3) has female co-operating means, for example complementary recesses of male means on the lower plate (2). The male means on the lower plate (2) may consist of two blocks or two projecting edges curved towards the interior of the prosthesis on both sides of the lower plate (2) and facing each other. The ledge may be replaced, for example, by a block having a hole to which the hasp is secured by a pin passing through the hole. In another embodiment (not shown), the lower plate (2) has a rounded bottom end. By complementation, the lower surface of the core (3) has a well below it. The dimensions of the bottom semicircular end of the plate (2) and the well of the core (3) can be adjusted according to the desired result by choosing to have little or no play in the core (3) in translation and rotation. In other embodiments (not shown), the co-operating means may be located on the core (3) and the upper plate (1) instead of on the lower plate (2).

A first embodiment will now be described with reference to fig. 1. In this embodiment, the upper anatomic adaptation elements (11) and the lower anatomic adaptation elements (22) are plates, called anatomic, which cover the upper plate (1) and the lower plate (2), respectively. The upper (222) and lower (111) surfaces of the upper (11) and lower (22) anatomic adaptation elements have a framework that houses the lower (2) and upper (1) plates, respectively. In another embodiment, each of the upper (222) and lower (111) surfaces of the anatomic adaptation elements may be planar and comprise stops which, for the previous frames, prevent the lower plate (2) and the upper plate (1), respectively, from moving with respect to the anatomic adaptation elements. The upper (222) and lower (111) surfaces of the lower (22) and upper (11) anatomic adaptation elements, respectively, extend the upper (10) and lower (20) surfaces of the upper (1) and lower (2) plates, respectively, to provide a contact surface of the prosthesis with the adjacent vertebrae which is larger than when the anatomic adaptation elements (11,22) are absent. The different dimensions of the anatomic plates of the anatomic adaptation elements (11,22) are adaptable to a single unit made of the two plates (1, 2) and the core (3) to provide a good contact between the prosthesis and the vertebrae of different dimensions.

In the embodiment of the prosthesis according to the invention shown in fig. 2, the anatomic adaptation elements (11,22) are crowns that surround the upper plate (1) and the lower plate (2). In this embodiment, the edges of the upper (10) and lower (20) surfaces of the upper (1) and lower (2) plates are inclined and complementary to the respective lower (111) and upper (222) inner edges of the upper (11) and lower (22) crowns, respectively. The edges of the plates (1, 2) and the inclined shape of the anatomic adaptation crowns (11,22) cooperate with the fixation means (113, 223) of the anatomic adaptation elements to keep the anatomic adaptation crowns (11,22) fixed to the plane of the upper plate (1) and lower plate (2) of the prosthesis, respectively. Anatomic adaptation crowns (11,22) respectively prolong the upper (10) and lower (20) surfaces of the upper (1) and lower (2) plates to provide a contact surface between the prosthesis and the adjacent vertebrae which is greater than when no anatomic adaptation elements (11,22) are present. As with the previously described anatomic plates (11,22), the single unit made of the two plates (1, 2) and the core (3) is adjustable to suit the vertebrae of different sizes, thanks to the different sizes of the crowns of the anatomic adaptation elements (11, 22).

In all embodiments of the invention, the anatomic adaptation elements (11,22) may extend symmetrically or asymmetrically the upper (10) and lower (20) surfaces of the upper (1) and lower (2) plates, respectively. Thus, for example, the anterior edge of the anatomic adaptation elements (11,22) may have a greater contact surface with the vertebrae than the posterior edge, so that the centre of attachment of the prosthesis (described above) is centred with respect to the natural axis of the spinal column, i.e. eccentric to the portion 2/3-1/3 of the posterior vertebrae.

According to selected embodiments, the intervertebral disc prosthesis according to the invention may, for example, correct a lordotic defect. An angle is required between the upper and lower surfaces of the prosthesis that contact the adjacent vertebrae. This angle can be obtained by manufacturing an upper plate (1) with an angle formed in the median plane representing the lower (14) and upper (10) surfaces. Another possibility is that the median plane of the lower plate (2) representing the lower (20) and upper (24) surfaces forms an angle. Another possibility is that the median plane of at least one of the anatomic adaptation elements (11,22) represents the lower and upper surfaces, forming an angle. Thus, a single unit made of two plates (1, 2) and a core (3) can be used to guide or not to guide lordosis, depending on the anatomic adaptation elements (11, 12) associated therewith. In the embodiment shown in fig. 3, the lower surface (220) of the lower anatomical plate (22) forms an angle with the upper surface (222). Another possibility to obtain this angle is a slightly offset position of the core (3) with respect to the centre of the prosthesis. The slightly offset position of the core (3) can be maintained by, for example, adjustable positioning of the male and female cooperating means (23, 33) therebetween. If the surgeon desires, for example, that the prosthesis guides lordosis remaining within a certain range of values, he chooses a prosthesis with a core (3) that is slightly free in translation and rotation with respect to the lower plate (2) around a position that causes a slight permanent inclination of at least one of the plates, thanks to the precise adjustment of the co-operating means (23, 33) between the core (3) and the lower plate (2). Thus, according to selected embodiments, the median planes representing the upper (110, 222) and lower (111, 220) surfaces of each anatomic adaptation elements (11,22) may be substantially parallel or form an acute angle. The inclination obtained by this angle allows to adjust the overall shape of the prosthesis to suit the structure of the spinal column or to possibly correct the inclination defects of the vertebrae of the patient to whom the prosthesis is applied. The same anatomic adaptation elements (11,22) can be assembled with different plates (1, 2), the upper (10, 24) and lower (14, 20) surfaces of said plates (1, 2) forming different angles. Instead, plates (1, 2) with upper (10, 24) and lower (14, 20) surfaces parallel are assembled with anatomic adaptation elements (11,22) with upper (110, 222) and lower (111, 220) surfaces forming different angles. The angle between the upper surface (10) of the upper plate (1) and the lower surface (20) of the lower plate (2) can be produced by representing that the lower surface (20, 14) of the lower plate (2) and/or of the upper plate (1) forms an angle with the median plane of the upper surfaces (24, 10), or by limiting the movement of the core (3) by the cooperating means (23, 33) about a position that tilts at least one of the plates (1, 2).

Fig. 1 to 3 show a movable bone anchoring device (60) of an anatomic adaptation elements (11, 22). The bone anchoring means (60) can be fixed to the anatomic adaptation elements (11,22) when fixing it to the plates (1, 2), in particular when inserting a prosthesis between the vertebrae. This feature allows the surgeon to easily position the prosthesis between the vertebrae and then insert the bone anchoring device (60) once the prosthesis has been correctly positioned. In the embodiment shown in fig. 1, the mobile bone anchoring means (60) are plates (61) provided with cuts (62) that prevent their removal after insertion into the vertebrae. The plates (61) may be replaced by, for example, nail-shaped rods with or without cut-outs preventing the plates from being removed. The distal end of the plate member (61) has a portion (63) bent and folded thereon. The curved portion (63) forms a hook shape intended to interlock with the edges (16,26) of the opening near the periphery of the anatomic adaptation elements (11, 22). The edges (16,26) of the openings form an interlocking rod shape of the bone anchoring device (60). In fact, the curved portion (63) allows the bone anchoring device (60) to clasp the rods (16,26) of the anatomic adaptation elements (11, 22). The rod may be replaced by any equivalent means that can clasp the bone anchoring device (60). In the embodiment shown in figures 1 to 9, the rods (16,26) are positioned on the anterior edge of the anatomic adaptation elements (11,22) to allow the surgeon to use it after the prosthesis has been inserted between the vertebrae through an anterior device (by entering the vertebrae from the anterior face). If implantation of the prosthesis is to be accomplished by a posterior device, the anatomic adaptation elements (11,22) may have a stem (16,26) at their posterior edge. If implantation of the prosthesis is to be accomplished by a posterior device, the anatomic adaptation elements (11,22) may have a stem (16,26) on at least one of their sides. In the embodiment shown in figures 2 to 3, the hook-shaped portion (63) of the plate (61) with the cut-out, bent over, of the movable bone anchoring means (60) of the anatomic adaptation elements (11,22) is coextensive with a second plate (61) also equipped with a cut-out (62) that prevents the plate (61) from being removed after insertion into the vertebrae. In the embodiment shown in fig. 2, the second plate (61) is shorter than the first plate, whereas in the embodiment shown in fig. 3, the second plate (61) is longer than the first plate. The bone anchoring device (60) is locked to the rods (16,26) so that it has a variable angle facilitating the attachment of the prosthesis. In fact, depending on the obstacles, the surgeon may choose the angle at which it is desired to introduce the bone anchoring device (60) into the vertebrae. In addition, the bone anchoring means (60) can be inserted after positioning the prosthesis between the vertebrae so that the relative position of the different elements (1, 2, 3) of the prosthesis can be adjusted. In fact, the insertion of the prosthesis creates constraints on the elements of the prosthesis, which are mutually movable, and they risk being poorly positioned. Thanks to the invention, the surgeon can adjust the relative position between the prosthetic elements before determining the attachment of the prosthesis.

It is clear that the prosthesis may comprise other bone anchoring means (60) than those described above, without departing from the scope of the present invention. To give non-limiting examples, the bone anchoring means (60) may comprise winglets fixed to the prosthesis as shown in patent application WO03/039400 or studs driven into the vertebrae through the anatomic adaptation elements as shown in patent application WO 04/041129. Fig. 10A, 10B, 11A and 11B illustrate an embodiment of the anchoring device (60). The bone anchoring device (60) according to the present embodiment consists of winglets comprising a hook-shaped portion (63) bent folded over such that the winglets are adaptable to the anatomic adaptation elements. The hooked portion (63) of the winglet, as shown particularly visually in figure 10B, allows the anchoring device (60) to interlock with the edge (16,26) of the opening near the periphery of the anatomic adaptation elements (11,22), as shown particularly visually in figures 11A and 11B. The edges (16,26) of the opening form a stem on which a bone anchoring device (60) is interlocked, as described above. The winglet also comprises a pin (64) (or dowel) insertable into a slot present on the surface of the plate and/or the anatomic adaptation elements to which the winglet is to be fixed, as shown particularly visually in figure 11B. The dimensions of the slot (65) and the pin (64) are adjustable to secure the pin (64) to the slot (65). For example, the pin (64) may be substantially conical with the larger diameter of the taper at the base of the pin and the smaller diameter at the end thereof. The side walls of the slot (65) are adjustable, cooperating with the taper of the pin (64), so that the pin can be inserted tightly into the slot, thereby fixing the bone anchoring device (60) to the anatomic adaptation elements (11, 22). For example, the width of the surface of the groove (65) may be greater than the width of its bottom surface. The bone anchoring device (60) is fixed to the prosthesis of the invention by first interlocking the hook-shaped portion (63) to the stem (16,26) of the anatomic adaptation elements (11,22) and then rotating the bone anchoring device (60) around the stem until the pin (64) tightly protrudes into the slot (65) of the anatomic adaptation elements (11,22) and/or of the plates (1, 2). For all prostheses of the invention, the winglet (60) may be of standard dimensions, and the position of the pin (64) of the winglet (60) within the slot (65) may vary as a function of the dimensions of the anatomic adaptation elements (11, 22). Depending on the thickness of the anatomic adaptation elements (11,22), the pin (64) may only protrude into the anatomic adaptation elements (11,22) or may traverse the anatomic adaptation elements (11,22) and protrude into a slot (65) in the plates (1, 2), as shown in the example of plate (1) on figure 11 bB. Since the size (diameter) of the anatomic adaptation elements (11,22) may vary, their slot length may also vary and may be replaced by holes at a variable distance from the rods (16,26) so that the holes may receive the pins (64), but when the pins are designed to protrude into the plates, the plates should comprise slots, since the distance of the pins from the periphery of the plates depends on the size of the anatomic adaptation elements (11, 22). Once secured to the anatomic adaptation elements (11,22), the winglets (60) may cooperate with grooves drilled in the surface of the adjacent vertebrae in contact. Thus, the surgeon may slot the vertebral surfaces between which the prosthesis is to be inserted. The slots in the vertebrae are naturally oriented relative to the sagittal plane depending on the position and orientation of the winglet. The orientation should be predetermined and the orientation of the prosthesis will be set and fixed. Likewise, the depth of the groove in the vertebrae and its extension from the periphery are also predetermined as a function of the size of the winglet (60) and will allow the surgeon to adjust the relative position of the elements of the prosthesis and predict the position of the prosthesis relative to the natural axis of the vertebrae. The winglet includes a cutout (66) in a surface that will contact a bottom surface of a slot in the vertebra. The cut-out (66) of the winglet (60) will prevent the prosthesis from being ejected from the intervertebral housing, for example when the prosthesis is strongly constrained. It is clear, in particular according to fig. 11B, which shows two embodiments, that the hook-shaped portion (63) of the winglet (60) can be oriented so that it can be interlocked to the rod (16,26) by insertion into an opening near the periphery of the anatomic adaptation elements (11,22) or by insertion from outside the opening.

It is clear that the above-described bone anchoring means (60) can be specifically adapted to the anatomic adaptation elements (11,22) of the invention, but it can also be adapted to the plates of other types of intervertebral disc prostheses comprising openings near the periphery of the plates. The edges (16,26) of such openings in the plate members form a kind of rod (16,26) to which the hook-shaped parts of the two removable embodiments of the bone anchoring means (60) can be interlocked.

Figures 4 to 9 show different embodiments of the fixation means (113, 223, 15, 25) of the plates (1, 2) of the prosthesis transversally equipped with anatomic adaptation elements (11,22) and defining the anatomic adaptation elements (11,22) on the plates (1, 2). The fixation means (113, 223, 15, 25) are removable, which means that the anatomic adaptation elements (11,22) can be easily attached to the plates (1, 2) of the prosthesis and detached from the plates (1, 2) of the prosthesis. The fixation means (113, 223, 15, 25) allow to replace the anatomic adaptation elements (11,22) fixed in a movable manner to the plates (1, 2). The fixation means (113, 223, 15, 25) of the anatomic adaptation elements (11,22) on the plates (1, 2) are fixation means (113, 223) on the anatomic adaptation elements (11,22) complementary to the fixation means (15, 25) on the plates (1, 2) of the prosthesis. The anatomic adaptation elements (11,22) are fixed to the plates (1, 2) by contact, on the one hand, with at least part of their lower (111) and upper (222) surfaces, with at least part of the upper (1) and lower (2) plates, respectively, and, on the other hand, with their fixation means (113, 223) with complementary fixation means (15, 25) on the plates (1, 2) of the prosthesis. With the anatomic plates (11,22) as shown in figures 4A to 4D, the anatomic adaptation elements (11,22) are fixed to the plates (1, 2) thanks to the fact that the upper (10) and lower (20) surfaces of the upper (1) and lower (2) plates are solidly connected to the framework located on the upper (111) and lower (222) surfaces of the upper (11) and lower anatomic plates (22) respectively, through the fixation means (113, 223, 15, 25). With the anatomic crowns (11,22) as shown in figures 5A to 5C, the anatomic adaptation elements (11,22) are fixed to the plates (1, 2) thanks to the fact that the inclined portions of the upper (10) and lower (20) surfaces of the upper (1) and lower (2) plates are solidly connected to the inclined portions of the upper (111) and lower (222) surfaces of the upper (11) and lower (22) anatomic plates, respectively, through the fixing means (113, 223, 15, 25). Different embodiments of the fixation means (113, 223, 15, 25) of the anatomic adaptation elements (11,22) on the plates (1, 2) will now be described with reference to figures 4 to 9. It is clear that the fixing means are given by way of example and can be replaced by any equivalent means without departing from the scope of the invention. Also, the invention allows the use of any combination of the different fastening means (113, 223, 15, 25) described below.

In some embodiments, the fixation means (113, 223, 15, 25) of the anatomic adaptation elements (11,22) on the plates (1, 2) are male fixation means (113, 223) located on the anatomic adaptation elements (11,22) and cooperating with female fixation means (15, 25) located on the plates (1, 2) of the prosthesis. The female fixation means (15, 25) on the plates (1, 2) of the prosthesis may be, for example, a plane (15, 25) on the edges of the plates (1, 2) of the prosthesis, or a groove (15, 25) made in the edges (15, 25) of the plates (1, 2) of the prosthesis or in the edges of the female co-operation means (23) of the plates (1, 2) of the prosthesis.

In the embodiment shown in figures 4A and 4B, on the rear side of the lower surface (111), the fixation means (113) of the anatomic plate (11) are projecting edges shaped and sized to receive a portion (15) of the rear side of the lower surface (14) of the upper plate (1). On the front side of the lower surface (111), the fixing means (113) of the anatomical plate (11) are pins having a rotation axis equipped with a catch, which is rotatable about this axis and receives a portion (15) of the rear side of the lower surface (14) of the upper plate (1), as shown particularly visually in figures 4A and 4B. Fig. 4A to 4C show the right latch in the open position and the left latch in the closed position. In the embodiment shown in figures 4C and 4D, on the rear side of the lower surface (222), the fixing means (223) of the lower anatomic plate (22) are projecting edges shaped and sized to be inserted in the openings (25) made in the cooperating means (23) of the lower plate (2). On the front side of the lower surface (222), the fixing means (223) of the upper anatomic plate (22) are pins with a rotation axis equipped with a snap on to receive a groove (25) in the part of the lower plate (2) rear edge co-operating means (23). The latch shown in figures 4A to 4D may be held in the closed position by fastening means (55) such as those located on the plates (1, 2) of the prosthesis. For example, as shown in figure 4C, a notch (55) in a groove (25) on a portion of the cooperating means (23) of the lower plate (2) prevents the pin (223) of the lower anatomical plate (22) from pivoting.

In the embodiment shown in fig. 5A to 5C, the front and rear edges of the upper anatomic adaptation crown (11) have fixing means (113) in the form of projecting edges cooperating with plane portions (15) located at the edges of the lower surface (14) of the upper plate.

In the embodiment shown in figures 6A to 9D, the fixation means (113, 223, 15, 25) of the anatomic adaptation elements (11,22) on the plates (1, 2) are female fixation means (113, 223) on the anatomic adaptation elements (11,22) cooperating with male intermediary means (50), the male intermediary means (50) also cooperating with female fixation means (15, 25) on the plates (1, 2) of the prosthesis. The anatomic adaptation elements (11,22) are fixed to the plates (1, 2) by contact, on the one hand, with at least a portion of their upper (111) and lower (222) surfaces, with at least a portion of the upper (1) and lower (2) plates, respectively, and, on the other hand, with their male intermediary means (50), with the female fixation means (113, 223) on the anatomic adaptation elements (11,22) and with the female fixation means (15, 25) on the plates (1, 2) of the prosthesis. The male intermediary means (50) are sliding plates (50) located in female fixation means (113, 223) on the anatomic adaptation elements (11,22) to cooperate with female fixation means (15, 25) located on the plates (1, 2) of the prosthesis. The plate (50) is parallelepiped-shaped and may include flaps (500) on its sides, as shown particularly schematically in fig. 7A. The tab (500) of the male intermediary device (50) is complementary in shape to the female fixation devices (113, 223) on the anatomic adaptation elements (11,22) with the runners on which the tab (500) can slide and to the female fixation devices (15, 25) on the plates (1, 2) of the prosthesis. The complementary shape of the wings (500) of the plate (50) and the runners of the female fixation means (113, 223) on the anatomic adaptation elements (11,22) and of the female fixation means (15, 25) on the plates (1, 2) prevents the plate (50) from disengaging from the female fixation means (113, 223, 15, 25) before being blocked by the fastening means (55).

The male intermediary means (50) has fastening means (55) blocking the male intermediary means (50) in a position cooperating with the female fixation means (113, 223) on the anatomic adaptation elements (11,22) and the female fixation means (15, 25) on the plates (1, 2) of the prosthesis. The fastening means (55) are, for example, at least one irregularly shaped portion (55) located on at least one side of the plate (50) and are intended to cooperate with at least one opening (550) in the female fixation means (113, 223) of the anatomic adaptation elements (11,22) and/or in the female fixation means (15, 25) of the plates (1, 2). The opening (550) may be complementary to the shape of the male intermediary device (50) or its fastening device, as shown in fig. 6A and 6B.

In the embodiment shown in fig. 6A, the plate with the male intermediary means (50) widens towards the rear end, and the irregularly shaped part with the fastening means (55) is a cut-out located in the rear half of the plate (50). The incision (55) compresses the posterior end of the plate (50) when introduced into the female fixation device (113, 223) of the upper and/or lower anatomic adaptation elements (11,22), as shown in the left plate of fig. 6A. When the plate (50) reaches the end of the travel of the slide produced by the female means (113, 223) of the anatomic adaptation elements (11,22) and by the means (15, 25) of the plate (1, 2), this means that when it cooperates simultaneously with both female means, for example the opening (550) in the female means (113, 223) of the anatomic adaptation elements (11,22) separates the plate (50) from this point, as shown in the right plate of fig. 6A. Fig. 7B shows a perspective view of an embodiment of the fixing device in which the plate (50) is intended to be held in the female means (25) of the co-operating means (23) of the lower plate (2). The figure also shows in particular a skeleton on the anatomical plate (22) which may have a thickness greater than that of the lower plate (2). Depending on the size of the co-operating means (23, 33) of the lower plate (2) of the core (3), the truss edges may provide a peripheral stop to limit the displacement of the core (3) relative to the lower plate (2). In the embodiment shown in fig. 6B, the irregularly shaped parts of the fastening means (55) constituting the male intermediary means (50) are snaps located on the sides of the plate (50). As shown in the left panel of fig. 6B, the buckle (55) is pressed when the buckle is introduced into the slideway of the female device (113, 223). When the plates are pushed to the blocking position, the catch (55) opens naturally in an opening (550) located on the side of the female means (113, 223) of the upper and/or lower anatomic adaptation elements (11,22), as shown in the right plate (50) of figure 6B.

Fig. 7A and 8A to 8D show another alternative embodiment of the male intermediary device (50). In this embodiment, the irregularly shaped part of the plate (50) constituting the fastening means (55) of the plate (50) is a hole in the male intermediary means (50) which is prolonged by a hole (550) of the female fixation means (113, 223) of the anatomic adaptation elements (11,22), as shown particularly visually in fig. 8B. The holes (550) are intended to receive the fastening pins (55) which block the male intermediate means (50) in their position of cooperation with the female fixation means present on the plates (1, 2) of the prosthesis, as shown in figure 8C.

Fig. 9A to 9D show another alternative embodiment of the fastening means (55) of the male intermediary device (50). In this embodiment, the irregularly shaped part of the fastening means (55) which make up the plate (50) is a cut (55) in the lower surface of the plate, which cooperates with an opening (550) in the female fixation means (113, 223) of the anatomic adaptation elements, once pushed onto the female fixation means (15, 25) of the plate (1, 2), by preventing the plate (50) from being removed, as shown in figure 9D.

It will be apparent to those skilled in the art that the present invention is susceptible to embodiment in many other specific forms without departing from the scope of the invention as claimed in the present application. Accordingly, the embodiments are exemplary only, and may be modified within the scope defined by the claims, and the invention is not necessarily limited by the foregoing detailed description.

Claims (8)

1. Bone anchor (60) for anchoring an intervertebral implant in the bone tissue of a vertebra, characterized in that: said bone anchor (60) comprising a plate (61) for penetrating into the bone tissue of said vertebra to hold said implant against said bone tissue, and characterized in that said bone anchor (60) comprises three parts:

a first end portion sharpened and for first penetrating into bone tissue of the vertebra;

a second end having a portion (63) folded curvedly thereon, said portion (63) folded curvedly thereon being capable of interlocking to a means for fastening said bone anchor (60) to said intervertebral implant while allowing said bone anchor (60) to be removed from said implant;

a middle portion between the first and second end portions forming a plate having an elongated rectangular overall shape with sides provided with cuts (62) oriented to resist removal of the plate from the bone tissue.

2. Bone anchor (60) according to claim 1, characterized in that the portion (63) on which the curve is folded can be interlocked to the means for fastening on the implant, which means are formed by a rod at the edges (16,26) of an opening formed in the vicinity of the outer circumference of the implant, so that the bone anchor (60) is movable and allows the angle of the bone anchor (60) relative to the implant to be adjusted by rotation about the rod.

3. Bone anchor (60) according to any one of claims 1 and 2, characterized in that the portion (63) on which the curve is folded is coextensive with a second plate (61) also provided with a cut (62) oriented to prevent the removal of the plate (61).

4. The bone anchor (60) of claim 3, wherein the second plate is smaller than the first plate.

5. Bone anchor (60) according to claim 1, characterized in that the portion (63) bent folded thereon is able to interlock to a fastening means formed by the edges (16,26) of an opening made in the vicinity of the periphery of the plate of the intervertebral implant.

6. Bone anchor (60) according to claim 1, characterized in that the portion (63) on which the bending is folded can be interlocked to the fastening means of the anatomic adaptation elements (11,22) extending over the entire diameter and/or the entire height of the intervertebral implant.

7. System consisting of an intervertebral disc prosthesis and of a bone anchor (60) for anchoring the intervertebral disc prosthesis, characterized in that the bone anchor (60) comprises a plate (61) for penetrating into the bone tissue of the vertebrae in order to hold the intervertebral disc prosthesis against the bone tissue, and in that the bone anchor (60) comprises three parts:

a first end portion sharpened and for initial penetration into bone tissue of the vertebra;

a second end having a portion (63) bent folded thereon, said portion (63) bent folded thereon being capable of interlocking to a means for fastening said bone anchor (60) to said intervertebral disc prosthesis while allowing said bone anchor (60) to be removed from said intervertebral disc prosthesis;

a middle portion between the first and second end portions forming a plate having an elongated rectangular overall shape with sides provided with cuts (62) oriented to resist removal of the plate from the bone tissue.

8. System according to claim 7, characterized in that the fastening means of the intervertebral disc prosthesis are intended to contact the bone tissue so that the plate (61) of the anchor penetrates into the bone tissue to its second end.