INTERMEDIATE VIRUS CAGE

Description

Domaine technique

[0001] The present invention relates to intersomatic cages suitable for interposing between two vertebrae in replacement of the intervertebral disc originally located between these two vertebrae, of the type comprising an element having the general shape of a substantially cylindrical disc and means of locking this element with at least one of the two vertebrae in order to obtain the fixation of the cages by osteosynthesis.

[0002] Interbody cages are known in which the means for locking the disc to at least one of the two vertebrae between which it is placed consist of one or two blades capable of pivoting so that their ends are embedded in the bony elements of the vertebrae. Such an embodiment with two parallel blades substantially perpendicular to the planes of the opposite faces of the disc is, for example, described and illustrated in FR2965169, US2011 / 035007, FR3029770, and FR2955483. WO 2021 / 162754 A1 describes an implant intended for a surgically created joint or cavity, comprising a blade with helical torsion.

[0003] The interbody cage according to the document referenced above gives good results, but may sometimes not meet all the needs of Practitioners depending in particular on different pathologies which affect the patients they have to treat, Practitioners also experiencing, in some cases, difficulties in making the blades penetrate the cortical bone of the vertebrae.

[0004] The present invention aims to produce an interbody cage which largely overcomes the aforementioned disadvantages of prior art cages.

[0005] More specifically, the present invention relates to an interbody cage suitable for being interposed between two vertebral bodies as a replacement for the intervertebral disc originally located between these two vertebrae according to at least one of the attached claims.

[0006] Other features and advantages of the invention will become apparent from the following description given with reference to the accompanying drawings, which are by way of illustration but in no way limiting, in which: There [ Fig. 1 ] represents a schematic cross-sectional view of an embodiment of the interbody cage according to the invention, The [ Fig. 2 ] represents a schematic cross-sectional view of another embodiment of the interbody cage according to the invention, The [ Fig. 3 ] represents a cavalier perspective view of another embodiment of the interbody cage.

[0007] It is specified that, in this description, if the adverb "sensiblement" is associated with a qualifier of a given means, this qualifier must be understood in the strict or approximate sense.

[0008] The present invention relates to an interbody cage suitable for being interposed between two vertebral bodies as a replacement for the intervertebral disc originally located between these two vertebrae, a disc which is damaged or the site of a disease.

[0009] These cases are well known to Practitioners and will not be further developed here, especially since they do not fall within the scope of the present invention.

[0010] Such a cage includes an element having the general shape of a disc 10, figures 1-3 This disc comprises two opposing surfaces 11 and 12 that are substantially parallel, and a lateral wall 13 connecting the two opposing surfaces. These two opposing surfaces are capable of coming into contact with the two vertebral bodies, respectively, and define essentially two planes called "facial planes" containing these two surfaces. These facial planes are considered parallel, or equivalent to two parallel planes, because the two surfaces 11 and 12 may be strictly parallel or exhibit a very slight angle relative to each other, depending on the specific therapy recommended by the practitioner.

[0011] The cage further comprises means for locking the element 10 with at least one of the two vertebral bodies, advantageously both. These locking means comprise at least a first portion of a blade 21 and a second portion of a blade 22, it being specified, as will be explained below, that these two portions may belong to a single blade according to the invention, or to two different blades, according to an unclaimed embodiment.

[0012] The cage, therefore, like the cages of the prior art, includes means for controlling the movement of these first and second portions of the blade between two positions Pr, Ps. The first position Pr is that in which the first and second portions of the blade 21, 22 are entirely contained within the space defined between the two facial planes, and the second position Ps is that in which these first and second portions of the blade 21, 22 emerge at least partially from this space.

[0013] According to an essential feature of the invention, the means for controlling the movement of the first and second portions of the blade 21, 22 between the first position Pr and the second position Ps are arranged to control the movement of these first and second portions of the blade according to a non-zero phase shift so that one of the first and second portions of the blade emerges, at least partially from the space between the two facial planes, before the other portion of the blade.

[0014] According to another feature of the invention, the displacement phase shift of these first and second portions of blade 21, 22 between the two positions Pr, Ps is one of the following three phase shifts: spatial phase shift, temporal phase shift, a combination of these spatial and temporal phase shifts.

[0015] As mentioned above, these first and second portions of blade 21, 22 can be defined on a single blade 23, 24 ( figures 1 et 2 ).

[0016] In the embodiment according to the figure 1 This single blade 23 is symmetrical with respect to a first straight line D1, and the means for controlling the movement of the first and second portions of this blade 23, namely the ends of the blade, comprise: a rotation shaft 123 with axis of rotation 124 and means for securing the blade 23 to the shaft 123. This shaft is mounted in a cooperative manner with respect to the element 10 so that its axis of rotation 124 is advantageously substantially parallel to the opposite faces 11, 12, but eccentric with respect to these two faces, that is to say, so that it is located at a different distance from these two faces. In the embodiment according to the figure 1 The rotation axis 124 is closer to face 11 than to face 12 (as illustrated by the two distance values). a < b ).

[0017] In the embodiment according to the figure 2 The single blade 24 is asymmetrical with respect to a second line D2. In this cage embodiment applying the invention as defined above, the two blade portions 21, 22 are defined at each end of the single blade 24, which is asymmetrical with respect to this second line D2. In this case, the axis of rotation 124 defined above can be located equidistant from the two faces, but it is possible that it may be eccentric with respect to these two faces.

[0018] In the (unclaimed) embodiment according to the figure 3 , the two portions of blade 21, 22 are defined on two different blades respectively, namely a first blade 31 and a second blade 32.

[0019] In this embodiment, the means for controlling the movement of the first portion of the blade and the second portion of the blade comprise: first and second shafts 46, 47 mounted to rotate relative to the element 10 around respectively a first axis 48 and a second axis 49; means for securing the first and second blades 31, 32 with respectively these first and second shafts 46, 47, for example by making a single piece or by welding or the like, so that their planes make a determined angle with respect to the first and second axes (for example 90°, or less but not zero); and means for driving in rotation these first and second shafts, for example a drive gear 50 mounted in cooperation with respectively these first and second shafts.

[0020] This gearing consists of a mechanical system composed of at least one first and a second toothed wheel (or similar) 51, 52 meshed together (or driven for example by a non-slipping belt), the two toothed wheels being respectively mounted in a fixed cooperation with the rotation shafts 46, 47; and means 35 for controlling the rotation of at least one of the first and second shafts.

[0021] Advantageously, at least one of the two gears 51, 52 is mounted removably on its shaft, so that it can be changed if necessary. It is also possible for the entire assembly, including the blades, shafts, etc., to be mounted removably relative to element 10 so that the whole assembly can be replaced if necessary.

[0022] The operation of such a cage and its advantages are evident from the description given above.

[0023] They can, however, be summarized as follows. The cage is inserted between two vertebrae, with the blade(s) oriented so that portions 21 and 22 are in the first position (Pr). This technique is widely known to practitioners. Then the blade(s) are rotated using a suitable instrument, which is itself well-known. Since the blade portions are out of phase in their rotation, first one of the two, for example, the first portion of blade 22, penetrates the cortical bone of one of the vertebrae. Then, still using the same rotational command of the shaft(s) supporting the blade(s), the second portion of blade 23 penetrates the cortical bone of the other vertebra.

[0024] Due to the phase difference between the penetration of the two blade portions into the vertebrae, the force (or, as technicians call it, the "torque") that the practitioner must exert is significantly less than that which would have been required if both blade portions had penetrated the cortical bone simultaneously. This advantage undoubtedly facilitates the implantation of such an interbody cage, and therefore the practitioner's work, ultimately benefiting the patient.

[0025] The disc 10 can be made for example of Titanium, Peek (i.e. polyetheretherketone) or similar, and as for the blades and shafts they are made for example of Titanium or stainless steel or similar.

[0026] It is also clearly stipulated that such a cage may contain one or more blades, although it usually only contains two ( figure 3 ).

[0027] For the purposes of this description, "blade portion" means one of the ends of such a blade. However, such a portion may consist, for example, of at least one tooth or similar feature located laterally on the edge of the blade, or even of a combination of the end of the blade and a tooth.

Claims

1. Interbody cage suitable for being positioned between two vertebral bodies to replace an intervertebral disk originally located between these two vertebrae, said cage comprising: • an element in the general shape of a disk (10), having two substantially parallel opposing faces (11, 12) and a side wall (13) connecting said two opposing faces, said two opposing faces being suitable for respectively coming into contact with the two vertebral bodies, said two opposing faces substantially defining two facial planes containing said two faces, • means for locking said element (10) to at least one of the two vertebral bodies, said locking means comprising at least a first blade portion (21) and a second blade portion (22), and means for controlling movement of the first blade portion and the second blade portion between two positions, the first position (Pr) being the position in which the first blade portion and the second blade portion (21, 22) are entirely contained in the space defined between the two facial planes, and the second position (Ps) being the position in which said first blade portion and said second blade portion (21, 22) emerge from said space, said the first blade portion and the second blade portion between two positions being arranged to control the movement of said first blade portion and said second blade portion according to a non-zero phase shift such that one of the first blade portion and the second blade portion emerges from said space before the other blade portion, characterized in that the first blade portion and the second blade portion (21, 22) are defined on a single blade (23, 24), said single blade (21, 23) being rigidly connected to a rotating shaft (123) having a rotational axis (124) such that the plane of said single blade forms a non-zero angle with said rotational axis, said rotating shaft being mounted in engagement with respect to the element (10) such that the rotational axis of said rotating shaft is substantially parallel to said opposing faces (11, 12).

2. Cage according to claim 1, characterized in that said non-zero angle is a right angle.

3. Cage according to claim 1, characterized in that said single blade (23) is a symmetrical blade.

4. Cage according to claim 1, characterized in that the two blade portions (21, 22) are defined at each end of a single asymmetrical blade (24).