Patent Publication Number: US-11045325-B2

Title: Expansible intersomatic cage

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119 to French Patent Application No. FR1660474 filed in FRANCE on Oct. 27, 2016, which is incorporated herein by reference. 
     BACKGROUND 
     The present application relates to the field of intervertebral cages and generally to the field of implants intended to be implanted between two adjacent vertebrae, to at least partly supplant an intervertebral disc to re-establish the height of the intervertebral space and the lordosis of the spinal segment, and more particularly to expansible vertebral implants of the intersomatic cage or corpectomy cage type. 
     To remedy certain pathologies, sometimes it is sought to obtain fusion of at least two adjacent vertebrae, for example when at least one of their adjacent intervertebral discs is lesioned. 
     From the prior art diverse arthrodesis techniques are known based on diverse types of implants, such as for example, intersomatic cages inserted into the place of a disc for re-establishing the height and the lordosis of the segment and for promoting bone growth (arthrodesis), to secure together two adjacent vertebrae. 
     Such devices are for example illustrated in French patent application FR1651637, which shows intersomatic cages giving the possibility of supplanting an intervertebral disc. 
     Further, to maximize the stability and graft volume contained in such implants and therefore the quality of the fusion, the latter have to cover a volume which is as close as possible to the volume occupied by the lesioned vertebral disc. The implants of the prior art therefore generally have a very large volume allowing their implantation relatively invasive for the patient. 
     One approach, used for reducing the size of the implants during their implantation and therefore their invasivity due to the necessary degradation during the route first, has been the use of expansible cages as for example described in European patent EP1699389 B1. Such cages, once they are implanted, are deployed by the surgeon, to cover a volume approaching the volume of an intervertebral disc, while having a profile allowing it to follow the lordosis of the vertebral column, thereby improving comfort for the patient and stability of the cage. 
     Nevertheless, this type of expansible cages includes a certain number of drawbacks. In particular, during their expansion, the surgeon has to exert an excessive pressure on the implant, notably because its expansion is simultaneously accomplished on two axes orthogonal with each other. Further, it is more difficult for the surgeon to observe a specific lordosis or to control the lordosis obtained. Finally, this type of implant does not rest or only very little on the cortical bone of the vertebra, but on a softer portion of the bone at the centre of the intervertebral space, which reduces its stability and has a risk of sinking. 
     In addition, for some devices disclosed in the prior art, the expansion of this type of cages is limited. Indeed, the final volume of the expanded cage is substantially identical to or a little greater than the initial volume. 
     Moreover, these implants often have a mechanism within the cage for allowing deployment. This mechanism occupies a significant portion of the graft space, and prevents the insertion of many grafts, which is detrimental to good fusion of the vertebrae. 
     SUMMARY OF THE DISCLOSURE 
     The object of the present application is therefore to propose an expansible intervertebral implant, for example of the intersomatic cage or corpectomy cage type, giving the possibility of overcoming at least one portion of the drawbacks of the prior art, by proposing an alternative implant having increased stability and reliability and easier expansion for surgeon, while observing the lordosis of the patient. 
     For this purpose, the application relates to an expansible intervertebral implant intended to be implanted in a space between two adjacent vertebrae to supplant at least partly an intervertebral disc. In various embodiments, such an intervertebral implant may be characterized in that said implant comprises:
         an elongated body along a longitudinal axis (X) comprised between a proximal end and a distal end, the latter being defined as being the end intended to penetrate first into said intervertebral space,   at least one flexible arm mounted in the vicinity of the distal end of the longitudinal body, which may be moved between:
           a folded-back position, in which said arm is positioned substantially parallel to the axis (X) and runs along the body,   a deployed position, in which said arm is not parallel to the axis (X) and away from the body to expand said implant along an axis (Y), by assuming the general shape of a circular arc,   
           a means for deployment of said flexible arm for deploying the latter from the folded-back position to the deployed position, by the sliding of a proximal portion of said flexible arm with respect to the body inducing an increase in the space occupied by the implant, greater than the space of the implant in the folded-back position.       

     According to a special feature, said implant may be provided with one or several flexible arm pairs in nitinol. 
     According to a special feature, the arms of each of the pairs may be positioned on either side of the elongated body. 
     According to a special feature, said flexible arms of each pair may be positioned according to axial symmetry, along the axis (X). 
     According to a special feature, said flexible arm pairs may be made with a single piece of nitinol which crosses the body and for which both portions jut out from the body forming said arms. 
     According to a special feature, said implant may be provided with a means for locking said flexible arm in its deployed position. 
     According to a special feature, said longitudinal body along an axis (X) may comprise at least two sub-portions superposed on each other and bound together at least in proximity to the proximal end by at least one connecting means and/or one joint. 
     According to a special feature, the implant may comprise at its proximal end a base bound to both sub-portions of the longitudinal body, by said connecting means and/or said joint. 
     According to a special feature, each of said sub-portions may include at least one flexible arm. 
     According to a special feature, said implant may be provided with a means for expansion of the body along an axis (Z) substantially orthogonal to the axes (X) and (Y). 
     According to a special feature, the means for expansion of the body along the axis (Z), may move the distal ends of both sub-portions away from each other. 
     According to a special feature, said means for expansion of the longitudinal body comprises at least one lockable connecting rod in a deployed position when said implant is expanded along the axis (Z). 
     According to a special feature, once the implant is expanded in the axis (Z), the arms on a same side of the body ( 2 ) may cooperate with each other so as to be at least partly superposed, while remaining in contact. 
     According to a special feature, the longitudinal body may be provided with at least one aperture at its proximal end, said aperture being configured so as to form at least one passage for:
         at least one tool cooperating with:
           said deployment means of said at least one arm, for deploying the latter, at least from the folded-back position to the deployed position,   and optionally, said means ( 3 ) for expansion of the distal end of the longitudinal body along an axis (Z) substantially orthogonal to the axes (X) and (Y),
 
and/or
   
           at least one anchoring device ( 7 ) configured for securing said implant to the adjacent vertebrae (V 1  and V 2 ).       

     According to another embodiment, the expansible intervertebral implant intended to be implanted in a vertebral segment may comprise:
         an elongated body ( 2 ) along a longitudinal axis (X) comprised between a proximal end and a distal end, the latter being defined as being the end intended to penetrate first into said intervertebral space, said elongated body comprises at least two sub-portions superposed on each other ( 2   a ,  2   b ) and bound together at least in proximity to the proximal end by at least one connecting means and/or a joint ( 6 ),   at least one flexible arm ( 21 ) on each of said sub-portions ( 2   a ,  2   b ) mounted in the vicinity of the distal end of the longitudinal body, which may be moved between:
           a folded-back position, in which said arm ( 21 ) is positioned substantially parallel to the axis (X) and runs along the body,   a deployed position, in which said arm ( 21 ) is not parallel to the axis (X) and away from the body to expand said implant along an axis (Y), by assuming the general shape of a circular arc,   
           a means for deployment of said flexible arm ( 21 ) for deploying the latter from the folded-back position to the deployed position, a means ( 3 ) for expansion of the body along an axis (Z) substantially orthogonal to the axes (X) and (Y).       

     It will be noted that the term “substantially” is regularly used in the present description, notably relating to a feature such as an orientation or a direction, so as to indicate that the relevant feature may in fact be slightly different and not be exactly as designated (for example, the expression “substantially perpendicular” should be interpreted as “at least approximately perpendicular” since it may be possible to select an orientation which is not exactly perpendicular to be able to nevertheless fulfill substantially the same function). 
     Further, terms like the term “substantially” used in the present application may also be interpreted as defining that a technical feature may be “in general” (“generally”) and often “preferably”, as indicated, but that other embodiments or configurations may be within the scope of the present disclosure. Thus, the terms such as “significantly”, “substantially” or “approximately” used with reference to certain technical features may be omitted in the present application but it will be clear for one skilled in the art that the definitions of these technical features are not limited, even in the absence of such terms, may in fact only be limited functionally if the function targeted by the technical feature may be obtained by an approximately identical or similar feature. 
     It should be noted that in this disclosure, reference will be made generally to a primary axis X, a secondary axis Y and a tertiary axis Z. The X, Y, and Z axes generally will be configured substantially orthogonal to each other, with the axis X corresponding to the direction along which an implant will travel during insertion into the patient, for example as depicted in  FIG. 1A . In addition, generally references in this disclosure may contemplate that the primary axis X is a horizontal axis, the secondary axis Y is a lateral axis and the tertiary axis Z is a vertical axis considered with respect to the insertion path of an implant, but such directions are for ease of reference only and impose no limitations on the use, orientation, implantation, or other aspect of any embodiment within the scope of this disclosure. For example, in some preferred embodiments, the intervertebral implant  1  comprises a body  2  extending longitudinally along a primary axis X, between a proximal end and a distal end, so generally in this disclosure, the distal end may refer to the end by which the implant is introduced to the intervertebral space and the proximal end may refer to the end by which the implant is held during its implantation. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       Other features, details and advantages of the object of the application will become apparent upon reading the description which follows with reference to the appended figures, in which the sets of  FIGS. 1A to 1E, 2A to 2E, 3A to 3D, 4A to 4D, 5A to 5D, 6A to 6C and 7A to 7E , correspond to different illustrations of various embodiments of an implant described in the present application. 
         FIGS. 1A, 1B, and 1C  are perspective illustrations of an embodiment of the implant with all its components in a first insertion configuration, then in a second configuration with the implant horizontally expanded, and finally in a third configuration with the implant expanded vertically, respectively, and  FIGS. 1D and 1E  are respectively a longitudinal and transverse sectional view of the illustration of an embodiment of the implant illustrated by  FIGS. 1A and 1C , along the plane  1 D- 1 D of  FIG. 1E  and along the plane  1 E- 1 E of  FIG. 1D , respectively; 
         FIGS. 2A and 2B  are perspective illustrations of an embodiment of an implant in an insertion configuration and in a deployed configuration, respectively,  FIG. 2C  is a sectional view along the plane  2 C- 2 C of the embodiment of an implant illustrated by  FIG. 2D , and  FIGS. 2D and 2E  are respectively a sectional view along the planes  2 D- 2 D and  2 E- 2 E of the embodiment of an implant illustrated by  FIG. 2C ; 
         FIGS. 3A, 3B, and 3C  are perspective illustrations of an embodiment of the implant with all components in an insertion configuration, with the implant horizontally expanded and with the implant horizontally and vertically expanded in a deployed configuration, respectively, and  FIG. 3D  illustrates a perspective view of expansion means when the arms of the implant are deployed; 
         FIGS. 4A and 4B  are perspective illustrations of an embodiment of the implant with all components in an insertion configuration and with the implant horizontally expanded, respectively,  FIG. 4C  is an illustration of the embodiment of  FIGS. 4A and 4B  in a configuration deployed vertically, and  FIG. 4D  is a perspective illustration of the embodiment of  FIG. 4C  disposed on a vertebra V; 
         FIGS. 5A, 5B, and 5D  are perspective illustrations of an embodiment of the implant with all components in an insertion configuration, with the implant horizontally expanded and with the implant horizontally and vertically expanded in a deployed configuration with anchors installed, respectively, and  FIG. 5C  is an illustration of a portion of the embodiment illustrated by  FIG. 5B ; 
         FIGS. 6A, 6B, and 6C  are perspective illustrations of an embodiment of the implant with all components in an insertion configuration, with the implant horizontally expanded and with the implant horizontally and vertically expanded in a deployed configuration, respectively, and 
         FIGS. 7A, 7B, and 7C  are perspective illustrations of an embodiment of the implant with all components in an insertion configuration, with the implant horizontally expanded and with the implant horizontally and vertically expanded in a deployed configuration, respectively, and  FIGS. 7D and 7E  are respectively a longitudinal and transverse sectional view of embodiments illustrated by  FIG. 7A  along the plane  7 D- 7 D and  FIG. 7D  along the plane  7 E- 7 E, respectively. 
     
    
    
     DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS 
     Many combinations of the features of diverse embodiments may be contemplated without departing from the scope of the application; one skilled in the art will select one depending on the economic, ergonomic or dimensional constraints or other considerations which may be observable or applicable to a given deployment. 
     The sets of  FIGS. 1A to 1E, 2A to 2E, 3A to 3D, 4A to 4D, 5A to 5D, 6A to 6C, and 7A to 7E  depict various non-limiting embodiments of the present application. The various features of these embodiments may be mixed and combined in alternative more general embodiments, without any limitation. All of these embodiments include those not illustrated, and should be considered as fully within the scope of this disclosure. In addition, a person skilled in the art can possibly make use of the two other applications filed on the same day as the present application, by the same applicant, so as to ascertain possible functional and/or structural features which would be insufficiently detailed or not detailed in the present application. In other words, the entirety of these two other applications (description, claims and figures) can therefore be considered, if need be (depending on the applicable law), as being incorporated in the present application by reference. 
     More particularly,  FIGS. 1A to 1D  schematically illustrate the concept, object of the application, an intervertebral implant as a cage which expands horizontally and optionally vertically so that the volume occupied initially in the intervertebral space is less than the occupied volume in its final position of use. The distribution of the upper and lower contact areas of the implant with the vertebral endplates is then more reliable (balanced), i.e. the support on the periphery of the plates and the anterior portion are maximized since the cortical bone is denser therein at these localizations, thereby giving the possibility of better supporting the load and the implantation. 
     In various embodiments, the implant  1  comprises a body  2  of elongated shape along an axis X, with the body comprising a proximal end and a distal end. In some embodiments, the body  2  may comprise at least one flexible arm  21 . In various embodiments, one or both ends of the flexible arm  21  may be pivotally mounted to the body  2  an pivot around a pivot axis  22  such as illustrated for example in  FIGS. 5A to 5D, 6A to 6C, and 7A to 7D . In various embodiments, one or both ends of the flexible arm  21  may be slidably mounted to the body  22  using a loose attachment such as illustrated for example by orifices  220  depicted in  FIGS. 1A to 1E and 2A to 2E  or by lugs  211  depicted in  FIGS. 3A to 3C . In various embodiments, one point of flexible arms  21  may be rigidly attached or integral with the body  2  such as illustrated for example in  FIGS. 1A to 1F, 2A to 2E, 3A to 3C, and 4A to 4D . In various embodiments, the respective flexible arms  21  may be formed in one piece with portions disposed on opposite sides of the body  2 , for example, such as illustrated for example in  FIGS. 7A to 7E . In various embodiments, one or more different types of attachment means, such as those described herein, may be used in the same implant. 
     In other words, the implant  1  may comprise an elongated body  2  along an axis X, comprising a proximal end and a distal end. The distal end is often defined as the end which is first introduced into the intervertebral space, alternatively the proximal end is the one inserted last and also the one with which the implant is held. It will be noted that this conventional definition depends on the implantation route. Said body  2  may be provided with at least one flexible arm  21 , which may be pivotally mounted  22 , as illustrated in  FIGS. 5A to 5D , in one piece with the body  2  or attached on the latter, without any hinge or joint, as shown in the other figures. The flexible arm moves between a folded-back position and at least one deployed position. 
     In the folded-back position, the arm  21  may be positioned along the body  2 , close to or alongside, i.e. substantially parallel to the axis X to minimize the dimensions of the implant for its implantation in the patient, thus giving the possibility of reducing the invasiveness of the surgical operation. In certain embodiments, the arms  21  are juxtaposed against the body  2  when the implant is in the insertion configuration. 
     In the deployed position, i.e. the final position of use, a portion of the distal end  210  of the arm  21  slides along the body  2 . The implant  1  is then deployed along an axis Y substantially perpendicular to the body  2 , by the fact that the arm  21  is deformed so as to become arched. Thus, the implant occupies a larger space, while allowing increased stability and reliability, since the surface, in contact with the bone of the vertebrae, in particular the cortical bone is greater than in the folded-back position. In other words, the implant has gained in volume and in contact surface by the sliding of a portion of the distal end of the arm and by the deformation of the arm. This deformation may be elastic or plastic depending on the material making up the arm. This deployment is not a redistribution of the initial volume of the implant, but actually an increase in the latter. 
     According to various embodiments, a portion of the proximal end  210  of the arm  21  may be locked or retained in at least one deployed position, by locking means, for example the portion may be:
         inserted and captured in at least one orifice  220  of the body, as shown for example in  FIGS. 1D and 2C , or   hooked-up to the body  2  via at least one retainer or catch element, as shown for example by a lug  211  in  FIGS. 3A to 3C , or   free, along the body  2 , as shown in  FIGS. 5A to 5D .       

     When the proximal end  210  of the arms  21  is free, the latter may be hooked-up or placed in proximity to the proximal end of the implant  1  to arch the flexible arms, for example as illustrated in  FIGS. 5B and 5D . 
     Thus, according to various embodiments, the deployment of the implant may be adjustable, for example by means of several positions of the locking means (orifices  220 /lug  211 ), or of several of the adjustable positions, for example, a screw or other control means which controls the sliding of the proximal end of the arm (not illustrated). 
     The implant  1  is provided with a means for deployment of said at least one arm from the folded-back position to the deployed position. This deployment means may have different shapes depending on the selected embodiment. However, its role is to reduce the distance between the proximal end of the arm and the distal end of the body to arch the arm, i.e. give it the general shape of a circular arc. This transformation may be achieved by means of sliding of a portion or “reserve” of the proximal end of the arm along the body. It is by handling this “reserve” of material (i.e. by totally or partly using it) that the practitioner expands more or less the implant, along the axis Y orthogonal to the body  2 , to optimally occupy the intervertebral space depending on the morphology of each patient. 
     In various embodiments used, such as for example in the sets of  FIGS. 1, 2 and 4 , the locking means of the deployment may be achieved by shape cooperation between the orifice  220  and the proximal end  210  of the arm. The orifice  220  having such an adjusted configuration that the proximal end  210  cannot move within it without intervention of an external force. In some of these types of embodiments, the free end  210  may have an expanded profile, configured for example as a bulb or a lip as shown in  FIG. 2C . In various other embodiments, such as for example in figure set  3  in which the locking means of the deployment is achieved by shape cooperation between the lug  211  and a groove  2111  in the proximal end  210  of the arm, for example using a friction fit to both retain the proximal end  210  to the body  2  and prevent movement of free end  210  when no external force is applied. 
     In various embodiments, for example as illustrated in the sets of  FIGS. 6 and 7 , a wedge  212  sliding along the axis X and crossing the body  2 , allows deployment. When the wedge slides towards the distal end, the distance between the proximal end of the arm and the distal end of the body is found to be reduced, thereby allowing arching of the arm  21 , as shown in  FIGS. 6A and 6B . In this type of embodiment, the locking of the deployment may be obtained by immobilizing the wedge, for example by means of a screw, a lug or any type of abutment or other means of limiting movement of the wedge. 
     In various other embodiments, the arms  21  may be formed of a material having shape memory, with one position of the arm stable in the expanded state and locking means used to maintain the arms  21  in an insertion configuration, or may be formed of a material having a bistable shape memory, with arm positions that are stable both in the expensed state and in the insertion configuration. 
     According to diverse embodiments, said implant may be provided with locking means giving the possibility of locking the arm in its deployed position, this locking means may coincide with or be additional to the shape cooperation between the orifice  220  or the lug  211 , and the reserve of the distal end of the arm. 
     In certain embodiments, the arm  21  may be made of a flexible material, for example nitinol. In some of these embodiments, the arm is stressed in the folded-back position. In other embodiments, it is in the folded-back position that the arm is at rest. Depending on the case, when the practitioner raises or adds at least partly the stress, the arm is released from the stress, allowing the latter to re-assume its deployed position or to be stressed to assume the deployed position and its arched shape as shown by  FIGS. 1A-B ,  2 A-B,  3 A-B,  4 A-B,  5 A-B,  6 A-B,  7 A-B. 
     In other words, in some of these embodiments, the arm may be stressed in the folded-back or insertion position and may have a tendency to assume the expanded or deployed position. In another of these embodiments, the arm may be stressed in the expanded or deployed position and may have a tendency to assume the folded-back or insertion position. In some other of these embodiments, the arm may exhibit bistability, and have a tendency to assume either the expanded or deployed position or the folded-back or insertion position. During deployment in many of these types of embodiments, force may be applied or removed to cause the arm to move from a stressed position to the stable position that the arm has a tendency to assume. 
     In various embodiments, such as for example illustrated by  FIGS. 4A to 4D , fins  23  may be positioned along the body  2  of the implant. Such fins contribute to the deployment and to maintaining the flexible arms in their deployed position, in certain embodiments, the fins can, through shape memory or another spring action, help in the deployment and the retention in the deployed position of the flexible arms  21 . In some of these embodiments, the fins are also in nitinol. These fins  23  may be also compressed along the body  2  by the flexible arms  21 . These fins also allow generation of the contact surface with the vertebral bodies, thus said implant better resists the compression forces without however interfering with the occurrence of the fusion. 
     In various embodiments, examples of which are illustrated by the figures of the present application, said body  2  may preferably comprise at least one arm  21  in the vicinity of its distal end, i.e. the end which is the first in contact with the patient during the implantation of the implant. 
     In various embodiments, the implant may comprise an even number of arms  21 , for example, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22 or further 24 preferably distributed symmetrically along the body  2  of the implant. 
     In various embodiments, each pair of arms may be made in a single piece  21  of nitinol, having the general shape of a strip, which crosses the longitudinal body of the implant along an axis orthogonal to the implant, the single piece of nitinol being secured to the body of the implant in its middle, to obtain on either side of the body two flexible arms  21   a  and  21   a  having substantially the same size and the same profile and two proximal ends  210 . In other words and for the sake of understanding, it will then be considered that the free ends of the single piece  21  in nitinol are two proximal ends  210  and that the portions of the single piece in nitinol housed in the body are the distal ends. However, the arms  21   a  of each pair may be distinct and each attached on one side of the body  2 . 
     Nevertheless, embodiments with an odd number of arms  21  are quite possible. In this case, it may be preferable that the arms be positioned alternately on either side of the body  2  of the implant, such as a zigzag. 
     In various preferred embodiments, the arms (e.g.,  21 ,  21   a , or  21   b ) comprise a strip-shaped portion, of flexible or resilient material, having opposing broad surfaces and edges connecting the opposing broad surfaces. Flexibility and/or resilience, preferably is limited to a bending deformation of the strip such that its longitudinal axis forms a curve in a plane perpendicular to a broad surface of the strip. Preferably, such strips are generally rigid in flexing, twisting or other deformations in other directions, including directions generally parallel to the broad surfaces of the strip. Such rigidity may enhance the ability of the implant to support the compressing forces imposed by the adjacent vertebrae. 
     In various embodiments, illustrated for example by  FIGS. 7A to 7E , the pair of arms  21  may comprise of a single piece of nitinol for which the free ends are pivotally mounted  22  on either side of the distal end of the body, as clearly shown in  FIG. 7D . The middle of the single part of nitinol is then, in this configuration, not attached to the body  2 , but sliding through the latter along the axis X. Such embodiments may have a deployment means comprising the central portion  214  of the single nitinol part forming the arm  21 , with translation of this central portion  214  toward the distal end of the implant  1 , to expand the arm  21  on each side of the body  2  during lateral deployment. 
     According to diverse embodiments, said longitudinal body may comprise two sub-portions  2   a  and  2   b  positioned on each other. Both sub-portions are generally bound together through at least one joint  6 . Preferably, this joint is found at the proximal end of the body, i.e. on the side closest to the vertebral spines when said implant is implanted in a patient, via a posterior route. More specifically, this joint may give the possibility of binding a base to both sub-portions  2   a  and  2   b . This is by this phase that the practitioner may hold the implant. 
     Said joint  6  allows a movement of both sub-portions  2   a  and  2   b  and in particular of their respective distal ends along an axis Z substantially orthogonal to the axes X and Y. 
     In diverse embodiments, said joint  6  may be provided with fins (not shown) which are deployed according to a movement following the axis Y. Such a deployment, gives the possibility of enlarging the volume occupied by the implant in the intervertebral space and promote stability of the latter. Moreover, these fins also give the possibility of better containing a graft inserted into the implant (in order to promote bone growth and arthrodesis) and of avoiding its migration towards the nerve roots or of the dura mater. Such fins may be in nitinol. 
     In certain embodiments, the implant  1  has means  3  for expanding the longitudinal body along an axis Z orthogonal to the axes X and Y. In particular said expansion means  3  allows the distal ends of the sub-portions  2   a  and  2   b  to move away from each other. Such a feature allows observance of the lordosis of the vertebral column. Further, the expansion along the axis Z may be modulated by the surgeon during the implantation so as to perfectly correspond to lordosis of the patient. 
     According to diverse embodiments, the expansion means may, depending on the embodiments, include:
         At least one scissor lift structure or a small connecting rod formed for example with arms  151  and with an axis  25  having preferably at least a locking position, for example by means of shape cooperation  250  of the arms  151 . This small connecting rod, in various embodiments, may also comprise an abutment  8 , which may be provided with a thread, which cooperates with a tool held by the practitioner to facilitate deployment of the implant along the axis Z.   At least one wedge. This wedge  3  according to the embodiments, slides along the body  2  in at least one guide  67  having a mating shape with a portion  66  of the wedge  3 .       

     Further, when the implant expands along the axis Y and Z, the expansions may be:
         sequential, for example a first expansion along the axis Y, and then a second expansion along the axis Z or further a first expansion along the axis Z, followed by a second expansion along the axis Y, or   simultaneous, i.e. the expansion along the axis Y is concurrent with the expansion along the axis Z.       

     In various embodiments, nevertheless without being limiting, a sequential expansion beginning with the axis Y may be preferred. Indeed, due to the stresses on the vertebrae and on the vertebral column generally, it may be easier to perform an expansion along the axis Y than an expansion along the axis Z and the expansion along the axis Y may be better informed if the implant has not yet expanded in height. 
     In embodiments, the arms  21  may be provided with a structure  213  allowing their extension along an axis substantially parallel to the axis Z, for example a meshing compressed beforehand, as illustrated by the set of  FIGS. 5A to 5D  or a structure of the accordion/fan type. Thus, with such structures, the compression forces which are undergone by the implant are distributed on the whole of the latter, reinforcing its stability. These flexible extensions further give the possibility of restricting the access to the graft space by the sides of the implant and of well containing the graft which will subsequently be injected within the implant. 
     In embodiments, the arms  21   a  and  21   b  on a same side of the body  2  may have a complementary profile between them so that they superpose, at least partly, while remaining in contact when the implant is deployed in the axis Z, as shown by  FIG. 1C . Thus, the stability of the implant is reinforced. In certain embodiments, the curvature of the arms may be asymmetrical so that only one portion of the upper arm  21   a  rests on a portion of the lower arm  21   b . Such a configuration gives the possibility of enlarging the space occupied by the arms and thus gives the possibility of better distribution of the stresses and therefore improves the stability of the implant. 
     In embodiments, said longitudinal body may be preferably provided with an aperture at its proximal end, to let through a tool actuating said deployment means of said at least one arm, (in order to move said arm from the folded-back position to the deployed position), and/or, said expansion means of the distal end of the longitudinal body along an axis Z orthogonal to the axes X and Y, and/or let through at least one anchor or anchoring device  7  configured for securing the implant to the adjacent vertebrae (V). Further, the aperture allows introduction of a graft to promote bone growth and thereby reinforce the stability of the implant. In certain embodiments, the aperture may be formed by the profile of both sub-portions  2   a  and  2   b  of the body, or have in the base which comprises at least one joint  6 , allowing expansion of the distal end of the body along the axis Z. 
     In embodiments, the anchoring device  7  may be replaced or complemented by anchors  31  integrated to the expansion means  3 , in particular when the latter is a small connecting rod, for example as shown in  FIGS. 2D and 2E . 
     In embodiments, the implants are provided with apertures, for example right through, to promote bone growth in their inside. These apertures thus give the possibility of reinforcing the anchoring and the stability of the implant, in the long run, by arthrodesis. 
     Further, regardless of the embodiment, the arm may comprise on the surfaces in contact with the bone, a profile promoting the frictional forces, such as of teeth, notches or other irregularities, to guarantee the maintaining of the arm in its deployed position. 
     It will easily be understood upon reading the present application that the particularities of the present application, as generally described and illustrated in the figures, may be arranged and designed according to a great variety of different configurations. Thus, the description of the present application and the relating figures are not provided for limiting the scope of the application but simply illustrate selected embodiments. 
     One skilled in the art will understand that the technical characteristics of a given embodiment may in fact be combined with characteristics of another embodiment unless the opposite is explicitly mentioned or unless it is obvious that these characteristics are incompatible. Further, the technical features described in a given embodiment may be isolated from the other features of that embodiment unless the opposite is explicitly mentioned. In particular, the embodiments described in the present application, although they are detailed with reference to illustrative and non-limiting figures, in which the implant may be designed for a posterior approach implantation, are not limited to a particular vertebral level or to a particular implantation route. It is therefore clear that these features could be adapted to a cervical, or lumbar implantation, and by the different routes of traditional approaches (anterior, posterior, lateral etc.). The arrangement of the various components of the implant is then modified to allow such an implantation, and so that the expansion of the implant is suited to its position in the spine and complying with the configuration of the latter. For example, in the case of an implantation by an anterior route, it may be easily possible to consider having a gripping means of the implant allowing said implant to be held at its distal end (i.e. the end opposite to the joint  6 ), and allowing actuation of the deployment means, preferably thanks to a traction, to expand the cage in one or two dimensions. 
     It should be obvious for those skilled in the art that the present application allows embodiments under many other specific forms without departing from the field defined by the scope of the appended claims, they should be considered as an illustration and the application should not be limited to the details given above.