US20050278036A1

US20050278036A1 - Method for restoration of human or animal bone anatomy, and expansible prosthetic implant allowing implementation of this method

Info

Publication number: US20050278036A1
Application number: US10/951,766
Authority: US
Inventors: Alain Leonard; Jean Oglaza; Christian Renaud
Original assignee: Ceravic SAS
Current assignee: Vexim SAS
Priority date: 2004-06-09
Filing date: 2004-09-29
Publication date: 2005-12-15
Also published as: EP1778136A2; JP4620120B2; AU2005251536B2; US20210022884A1; US20160302943A1; JP2008501462A; US10098751B2; JP2011005264A; FR2871367B1; CN101031259A; CN103622766A; PL1778136T4; JP2013078639A; CA2567274A1; FR2871367A1; CA2567274C; PL1778136T3; CN103622766B; KR20070068338A; EP2572680B1

Abstract

A method for restoration of human or animal bone anatomy includes introduction into a bone of an expansible implant according to a single determined plane intrinsic to the implant, positioning the expansible implant in the bone in order to make the expansion plane intrinsic to the implant correspond with a bone restoration plane, opening out the implant in the bone restoration plane with a view to forming a cavity inside the bone, and injecting a filling material into the cavity containing the implant. The implant includes a single determined expansion plane intrinsic to the implant, a device for positioning the implant in the bone, and a device for opening out the implant in the expansion plane.

Description

The present invention relates to the field of surgery, and prosthetic implants, more particularly to methods for restoration of human or animal bone anatomy, and to prosthetic bone implants.
Various causes can be at the root of bone compression, in particular osteoporosis which causes for example natural vertebral compression under the weight of the individual, but also traumas, occasionally the two causes being combined. These bone compressions can essentially affect the vertebrae but also concern other bones, such as the radius or the femur for example.
Several vertebroplasty techniques are known for effecting a vertebral correction i.e. to make a vertebra re-adopt its shape or initial anatomy, or a shape similar to the latter, as closely as possible.
A technique is known for example comprising introduction of an inflatable balloon into a vertebra, then introducing a fluid under pressure into the balloon placed in the vertebra in order to force the cortical shell of the vertebra, and in particular the lower and upper vertebral plateaus, to re-adopt a corrected shape under the effect of the pressure. This technique is known by the name of kyphoplasty. Once the osseous cortical shell has been corrected, the balloon is then deflated, then withdrawn from the vertebra in order to be able to inject a cement into the latter which is intended to impart, to the corrected vertebra, sufficient mechanical resistance for the correction to have a significant duration in time. A notable disadvantage of such a method resides in its numerous manipulations, in particular inflation, and in the necessity to withdraw the balloon from the patient's body. Furthermore the expansion of a balloon is relatively poorly controlled because it has a volume, i.e. multi-directional; now it can be clearly prejudicial to the operation and therefore to the patient to exert a large pressure in unsuitable directions which might involve the risk of bursting of the cortical, in particular the lateral part of the latter connecting the lower and upper plateaus of a vertebra.
Vertebral implants exist furthermore which are intended to fill a cavity in a vertebra, but the latter adopt a radial expansion principle obtained by formation of a plurality of points which stand normally to the longitudinal axis of the implant under the effect of contraction of the latter. Such implants impose too high a pressure on the end of the points which is capable of piercing the material on which the points are supported. Furthermore, this very high pressure can cause bursting of the tissues or organ walls, such as a bone cortical for example. For this reason, these implants have the function of filling an already formed cavity because they cannot form a cavity and are use surrounded by a stitch, tissue or a balloon which makes their use all the more complicated. Furthermore, the radial expansion of such implants does not allow a particular expansion direction to be favoured.
The present invention allows these disadvantages to be reduced and other advantages to be provided. More precisely, it comprises a method for restoration of human or animal bone anatomy, characterised in that it comprises the following steps:

- introduction, into a bone, the shape of which is to be restored, of an expansible implant according to a single determined plane intrinsic to said implant,
- positioning said expansible implant in said bone in order to make said expansion plane intrinsic to said implant correspond with a bone restoration plane,
- opening out said expansible implant in said bone restoration plane with a view to forming a cavity inside said bone,
- injecting a filling material into said cavity containing said implant with a view to filling the latter.

The method according to the invention allows an intra-osseous cavity to be created thanks to the expansion of the implant, using a favoured expansion direction. The filling material can be injected with a relatively low pressure thanks to the implant which remains in place, which allowed the creation of a distinct precise cavity, and the preservation of the dimensions of the thus created cavity.
According to an advantageous feature, the method according to the invention comprises opening out said expansible implant in said bone restoration plane, by a determined value between a minimum thickness of the implant before any expansion of the latter and a maximum thickness of the implant after its maximum expansion.
This feature allows the expansion value of the implant to be controlled, for example with a view to a given vertebral correction.
According to an advantageous feature, the step comprising opening out said expansible implant comprises opening out a first and a second opposite plate, forming respectively a first and a second support surface in said bone.
This feature allows the pressure which is exerted by the implant on the tissues in contact with the latter to be reduced, by increasing the contact or support surface on said tissues, and allows the latter to be spread more easily with a view to forming the cavity without piercing them.
According to an advantageous feature, said first and second support surfaces in said bone have respectively a length which is substantially equal to the length of said implant.
This feature allows optimisation of the ratio of the support length on the tissues to the length of the implant. The closer this ratio is to one, the more the implant will be usable in places of a small length with a view to creating the most precise cavity possible. One advantage of the implant according to the invention is to allow the creation of the largest possible cavity for a given implant length in order to allow a bone correction in tiny parts of a bone, and in order to allow the introduction of a filling material according to the lowest possible injection pressure with a view to avoiding infiltration of the filling material into inappropriate tissues such as blood vessel walls for example.
According to an advantageous feature, said first and second plates form first and second support surfaces which are continuous over their length respectively.
This feature, because of the continuity of the support surfaces, allows a contribution to reducing the pressure on the retracted tissues, and to the creation of a cavity, the contours of which are continuous, making its contribution therefore to reducing the injection pressure of the filling material.
According to an advantageous feature, said first and second plates form respectively continuous smooth support surfaces.
According to an advantageous feature, said first and second plates form respectively partially cylindrical support surfaces, one generator of which is parallel to a longitudinal axis of said expansible implant.
According to an advantageous feature, the step comprising opening out said first and second plates comprises raising the latter by support under the plates.
This feature allows the ratio corresponding to the length of the support surfaces to the length of the implant to be increased and to make it tend towards one, as will be explained in more detail further on with the description of an embodiment of the invention. Furthermore, this feature allows the thrust forces to be distributed under the plate in order to reduce the cantilever.
According to an advantageous feature, the step comprising injecting a filling material into said cavity containing said implant with a view to filling the latter comprises injecting an ionic cement, in particular a phosphocalcic cement, an acrylic cement or a compound of the latter.
The invention relates also to an expansible implant which can take part in restoration of human or animal bone anatomy, characterised in that it comprises:

- a single determined expansion plane, intrinsic to said implant,
- means for positioning the expansible implant in said bone in order to make said expansion plane intrinsic to said implant correspond with a bone restoration plane,
- means for opening out the expansible implant in said expansion plane intrinsic to said implant, with a view to forming a cavity inside said bone.

According to an advantageous feature, the implant according to the invention comprises means for controlling a determined expansion value, between a minimum thickness of the implant before any expansion of the latter and a maximum thickness of the implant after its maximum expansion.
According to an advantageous feature, the implant according to the invention comprises a first and a second plate which are opposite and able to form respectively a first and a second support surface in said bone, which surfaces are intended to be moved away one from the other along said single expansion plane during the expansion of the implant.
According to an advantageous feature, said first and second opposite plates form first and second support surfaces which are able to be moved along a perpendicular to a longitudinal axis of said expansible implant during the expansion of the latter.
According to an advantageous feature, said first and second support surfaces in said bone have respectively a length which is substantially equal to the length of said implant.
According to an advantageous feature, said first and second plates form first and second support surfaces which are continuous over their length respectively.
According to an advantageous feature, said first and second plates form respectively continuous smooth support surfaces.
According to an advantageous feature, said first and second plates form respectively partially cylindrical support surfaces, one generator of which is parallel to a longitudinal axis of said expansible implant.
According to an advantageous feature, the implant according to the invention comprises a first and a second support for each of said first and second plates, which are situated under the latter respectively.
According to an advantageous feature, said first and second plates comprise respectively a first and a second cantilever wing, the respective attachment zones of which are situated at the level of said first and second supports.
According to an advantageous feature, said first and second cantilever wings have respectively a length corresponding substantially to the maximum displacement value of one of said first or second plates in said single expansion plane.
According to an advantageous feature, said means for positioning the expansible implant in said bone in order to make said expansion plane intrinsic to said implant correspond with a bone restoration plane, comprise engagement means allowing orientation of said implant angularly about a longitudinal axis.
The invention relates also to an application of an expansible implant according to the invention in order to produce a bone fracture reduction.
Other features and advantages will appear in the text which follows of two embodiments of an expansible implant according to the invention and two embodiments of a method for restoration of human or animal bone anatomy according to the invention, accompanied by the annexed drawings, examples given by way of illustration and non-limiting.
FIG. 1 represents a perspective view of a first embodiment of an expansible implant according to the invention, in resting position, i.e. not opened out.
FIG. 2 represents the example of FIG. 1, in opened-out position.
FIG. 3 represents a lateral view of the example according to FIG. 1.
FIG. 4 represents a view in section according to the line I-I of FIG. 3.
FIG. 5 represents a view in section according to the line II-II of FIG. 3.
FIG. 6 represents an end view according to F of the example according to FIG. 1.
FIG. 7 represents a view from above of the example according to FIG. 1.
FIG. 8 represents a perspective view of a second embodiment of an expansible implant according to the invention, in resting position, i.e. not opened out.
FIG. 9 represents the example of FIG. 8, in opened-out position.
FIG. 10 represents a lateral view of the example according to FIG. 8.
FIG. 11 represents a view in section according to the line III-III of FIG. 10.
FIG. 12 represents a view in section according to the line IV-IV of FIG. 10.
FIG. 13 represents a view in section according to the line V-V of FIG. 10.
FIG. 14 represents a view in section according to the line VI-VI of FIG. 10.
FIG. 15 represents an end view according to G of the example according to FIG. 8.
FIG. 16 represents a view from above of the example according to FIG. 8.
FIGS. 17 to 29 represent schematically the different steps of a first embodiment of a method for bone restoration according to the invention.
FIGS. 30 to 32 represent schematically steps of a second embodiment of a method for bone restoration according to the invention.
The expansible implant 1 represented in FIGS. 1 to 7 which can take part in restoration of human or animal bone anatomy, comprises:

- a single determined expansion plane 2, intrinsic to the implant,
- means 3 for positioning the expansible implant in the bone allowing the expansion plane intrinsic to the implant to correspond with a bone restoration plane,
- means 4 for opening out the expansible implant in the single expansion plane 2, with a view to forming a cavity inside the bone, and advantageously:
- means 5 for controlling a determined expansion value, between a minimum thickness A of the implant before any expansion of the latter and a maximum thickness B of the implant after its maximum expansion,
- a first 6 and a second 7 opposite plate which are able to form respectively a first 8 and a second 9 support surface in the bone intended to be moved apart one from the other along the single expansion plane 2 during expansion of the implant 1.

The implant 1 adopts for preference a cylindrical shape with a transverse circular exterior section, and can advantageously be manufactured from a tubular body 24, made of biocompatible material, for example titanium.
The implant 1 comprises a first 20 and a second 21 end adopting respectively the shape of a transverse section of the tubular body 24, intended to be brought one towards the other with a view to allowing opening out of the implant, as represented in FIG. 2. To this end, the two ends 20, 21 are connected to each other by a first 22 and second 23 rectilinear arm, which are parallel when the implant is not opened out, formed longitudinally in the tubular body 24 and able to be folded under the effect of bringing the ends 20 and 21 one towards the other, whilst distancing the first 6 and second 7 opposite plates from the longitudinal axis 10 of the tubular body 24.
As represented in FIGS. 4 and 5, in order to allow their opening out in a single plane 2, the arms 22 and 23 are diametrically opposite and thus determine a single expansion plane 2 passing through the longitudinal axis 10 of the tubular body 24.
The arms 22, 23 are formed from a transverse recess 40 of the tubular body, traversing the tubular body 24 throughout, and extending over the length of the tubular body between the two ends 20 and 21 of the implant 1. As represented in FIG. 5, the arms, 22, 23 connecting the two ends 20 and 21 adopt respectively a transverse section bounded by a circular arc 26 of the exterior surface of the tubular body 24 and the chord 27 which defines this circular arc 26 and which is included in the wall 25 forming the recess 40. The recess 40 is for example symmetrical with respect to the longitudinal axis 10.
Each arm 22, 23 is divided into three successive rigid parts which are articulated together and on the ends 20 and 21 of the implant 1 as follows: for the upper arm 22: a first rigid part 28 is connected by one end of the latter to the end 20 of the implant 1 by means of an articulation 29 and is connected by its other end to the first end of the second adjacent rigid part 30 by means of an articulation 31; the second rigid part 30 being connected by its other end to the third rigid part 32 by means of an articulation 33, the other end of the third rigid part being connected to the end 21 of the implant 1 by means of an articulation 34. The articulations 29, 31, 33 and 34 are articulations with one degree of freedom in rotation, acting respectively about axes which are perpendicular to the expansion plane 2 of the implant 1. The articulations 29, 31, 33 are advantageously formed by a thinning of the wall forming the arm in the relevant articulation zone, as represented in FIGS. 1, 2 or 3.
Each arm 22, 23, when the ends 20 and 21 of the implant are brought one towards the other, opens out such that the central rigid part 30 moves away from the longitudinal axis 10 of the implant pushed by the two adjacent rigid parts 28 and 32. As represented more particularly in FIG. 3, in order to initiate the movement of the arm in the correct direction during bringing together of the ends 20 and 21 one towards the other, it is advisable to create a suitable rotation couple of the various parts of the arm. To this end, the rigid parts of ends 28, 32 of the upper arm 22 are articulated on the ends 20 and 21 respectively of the implant 1 in the low part of the material web forming these rigid parts, and are articulated on the central rigid part 30 in an upper part of said material web forming the rigid parts 28, 32, the displacement of the articulations, creating, as soon as a force is applied to bring the ends 20 and 21 together along the longitudinal axis 10 of the implant, a rotation couple on the rigid parts of ends 28 and 32, tending to make the latter pivot towards the exterior of the implant as a result of moving the central rigid part 30 away from the longitudinal axis 10 of the implant 1.
The lower arm 23 is constructed in the same manner as the upper arm and is advantageously symmetrical to the upper arm 22 with respect to a plane which is perpendicular to the expansion plane 2 passing through the longitudinal axis 10.
The articulations of the upper 22 and lower 23 arms are therefore formed by weakened zones produced by grooves 81, respectively defining a thin web of material forming the tubular body 24, the thickness of which is determined by the depth of the grooves 81, as represented in the Figures, in order to allow plastic deformation of the material without it breaking, advantageously until the rigid parts of ends 28 and 32 of the upper arm 22, and their symmetrical ones on the lower arm 23 can adopt a position, termed extreme expansion, in which the intended rigid parts are perpendicular to the longitudinal axis 10 of the implant 1, when the ends 20 and 21 of the implant 1 are brought one towards the other such that the latter is opened up until its maximum expansion capacity. The width of the grooves 81 will be determined in order to allow advantageously such a clearance of the parts of the upper and lower arms and also in order to impart a suitable radius of curvature to the webs in order to ensure plastic deformation without rupture of the material.
The first 6 and second 7 opposite plates are respectively advantageously formed in the upper 22 and lower 23 arms, as follows: for the upper arm 22 for example, the rigid plate 6 is formed on the one hand by said central rigid part 30 and on the other hand by a material extension extending on both sides of the central part 30 in the end parts 28 and 32. In order to produce a rigid plate 6, the parts of the latter extending in the end parts 28 and 32 are separated from the latter by the production of two transverse slots 35 and 36 situated in the thickness of each end part 28 and 32 and extending longitudinally over the length of the latter, as represented in FIGS. 3 and 4. The articulations 31 and 33 and the end parts 28 and 32 form respectively a first 12 and a second 13 support for the first 6 plate, situated under the latter. The same applies to the second plate 7 by symmetry.
Hence, the first 6 and second 7 plates comprise respectively a first 16, 18 and a second 17, 19 cantilever wing, the respective attachment zones of which are situated at the level of the first 12, 14 and second 13, 15 supports. As represented in FIG. 1, 2 or 3, the first 16, 18 and second 17, 19 cantilever wings have respectively a length corresponding substantially to the maximum displacement value of one of the first 6 or second 7 plates in the single expansion plane 2.
The first 6 and second 7 opposite plates form advantageously first 8 and second 9 support surfaces, respectively having a length which is substantially equal to the length of the implant and able to be displaced perpendicularly to the longitudinal axis 10 of the expansible implant 1 during expansion of the latter. It should be noted that the first 6 and second 7 plates form advantageously first 8 and second 9 continuous smooth support surfaces over their length respectively. Because of the preferential production of the implant 1 in a tubular body 24, the first 6 and second 7 plates form respectively advantageously partially cylindrical support surfaces, one generator 11 of which is parallel to the longitudinal axis 10 of the expansible implant 1.
The implant 1 represented in FIGS. 1 to 7 can therefore be advantageously obtained from machining a tube section, for example according to the shapes and geometries described above.
The means 3 for positioning the expansible implant in the bone which allow the expansion plane 2 intrinsic to the implant to correspond with a bone restoration plane, comprise engagement means allowing orientation of the implant angularly about the longitudinal axis 10, for example two flat surfaces 37, 38 which are formed on the cylindrical surface with a circular section of the end 20 for example, with a view to allowing a rotational engagement of the implant 1.
The means 4 for opening out the expansible implant in the single expansion plane 2, with a view to forming a cavity inside the bone, comprise end parts 28 and 32 of the upper arm 22 and the symmetrical end parts on the lower arm 23, allowing opening out of the upper 6 and lower 7 plates, and an implant carrier 71 allowing the ends 20 and 21 of the implant to be brought together when it is implanted, and as will be described further on with the description of an example of the method according to the invention, describing an example of the application of the implant. The implant carrier 71, by being supported on the end 20 for example, must allow the end 21 to be brought near, by pulling on the latter or by being supported on the end 21, for example, by bringing together the end 20 by pushing on the latter. To this end, the distal end 21 for example comprises advantageously a hole 39 threaded along the longitudinal axis 10 in order to allow the engagement of the implant carrier 71. The proximal end 20 comprises for its part a boring 80 along the longitudinal axis 10 in order to allow the passage of a core of the implant carrier 71 as will be explained further on.
The control means 5 are provided by the implant carrier which comprises advantageously means for millimetric control of the bringing together of the ends 20 and 21 one towards the other of the implant 1, preferably by means of a method by screwing (not shown), allowing the expansion to be stopped at any moment as a function of requirements. On the other hand, the control means are also provided by the articulations of the arms 22 and 23, more specifically by the thickness of the material webs defining the latter which, deforming in the plastic region, allow the expansion to preserve substantially a determined opening-up position of the arms, apart from elastic shrinkage which is very minor in practice.
It will be noticed that the expansion of the plates 6 and 7 of the implant, and their stabilisation once opened up, can be achieved by adapting to the encountered bone geometry because the implant 1 allows a non-parallel displacement of the plates 6 and 7 and, at the end of the displacement, allows a definitive position of the plates in a non-parallel state if necessary as a function of the bone anatomy.
In FIGS. 8 to 16 relating to the description of a second embodiment of an expansible implant 101 according to the invention, the elements which are functionally identical to those of FIGS. 1 to 7 relating to the first implant example 1 comprise respectively the same numerical reference with the addition of the number 100 and therefore will not be described further. Reference will be made to the description which precedes for these elements.
The represented implant 101 differs from the implant 1 by the absence of the wing on the plates 106 and 107, as represented more particularly in FIG. 9 and by the presence of a parallelogram system 141 on one of the end parts 128 or 132 of each of the arms 122 and 123, in the represented example on the end part 128 of the upper arm 122 connected to the end 120 of the implant 101 and of its symmetrical one on the lower arm 123. The parallelogram systems have the function of ensuring displacement of the plates respectively of each of the arms 122 and 123, parallel to the longitudinal axis 110 of the implant. To this end, as represented in FIG. 9, the end part 128 of the arm 122 and of its symmetrical one 123 is split, just as its articulations 131 and 129 respectively over the central part 130 and over the end 120 of the implant in order to form a parallelogram which is deformable during displacement of the corresponding plate.
The articulations of the deformable parallelogram 141 are produced in the same manner as the other articulations 131, 133, 134 of the arm 122, as represented in FIGS. 8 to 16, and according to an appropriate geometry as explained above, more particularly as represented in FIGS. 11 to 14, with a view to creating force couples on the various parts 129, 130, 132 of the arm allowing the desired displacements when bringing together the ends 120 and 121 of the implant 101.
In order to obtain a deformable parallelogram 141, the end part 128 of the arm is divided into three longitudinal levers, i.e. two lateral levers 142 and a central lever 143 forming two sides of the deformable parallelogram 141, the two other sides of the parallelogram being formed respectively by an extension 144 of the central part of the arm 122, placed in the axis of extension of the central lever 143, and by a double extension 145 of the end 120 of the implant 101, extending parallel to the longitudinal axis 110 of the implant and placed in the axis of extension of the two lateral levers 142, as represented in FIG. 8 for example.
It should be noted that the arms 122 and 123 are symmetrical with respect to a plane which is perpendicular to the plane of expansion 102 passing through the longitudinal axis 110 of the implant 101 in order to obtain, during the expansion of the implant, the displacement of the two plates 106 and 107 in a manner parallel to the longitudinal axis 110 of the implant 101.
The implant 101 will advantageously be able to be provided with two plates brought together (not shown), for example adopting the shape, in particular the length, of the plates 6 and 7 of the implant 1 described above, comprising wings extending beyond the central part of the arms 22 or 23, with a view to extending the length of the central part of the arms 122 or 123 without otherwise extending the length of the implant. Hence, the implant 101 would adopt a similar configuration to that of the implant 1 and would differ only from it by its supplementary capacity to force the plates to be opened out parallel to the longitudinal axis of the implant, which finds applications in specific fracture reductions for which the fragments of bone must be moved apart in a parallel manner. The plates which are brought together can be joined at their central part of the respective arm by welding for example.
A first example of the method according to the invention for restoration of human bone anatomy which uses an expansible implant, for example according to the invention, in particular as described above, will now be described by means of FIGS. 17 to 29. It concerns more precisely a method for bone restoration of a vertebra by a posterolateral route, with fracture reduction.
The method comprises the following steps:

- introduction, into a vertebra 60, the shape of which is to be restored, an expansible implant 1 according to a single determined plane 2 intrinsic to the implant: in order to effect this operation, it is necessary to:
  - place percutaneously a pin 61, for example of the Kirschner pin type, comprising a threaded end 62, by a posterolateral route, in order that the threaded end 62 comes to be screwed into the cortical 63 opposite the cortical 64 which is traversed by the pin, as represented in FIG. 17;
  - introduce a first dilatation tube 65 around the pin 61 until the end of the first tube 65 comes to be supported upon the exterior surface of the cortical 64, as represented in FIG. 18;
  - introduce a second dilatation tube 66 around the first dilatation tube 65 until the end of the second tube 66 comes to be supported on the exterior surface of the cortical 64, as represented in FIG. 19;
  - introduce a third dilatation tube 67 around the second dilatation tube 66 until the end of the third tube 67 comes to be supported on the exterior surface of the cortical 64, as represented in FIG. 20; the tube 67, at its end in contact with the bone cortical 64, has teeth 68 in order to obtain anchorage of the tube in the cortical 64;
  - withdraw the first and second dilatation tubes 65 and 66, as represented in FIG. 21, leaving in place only the pin 61 surrounded by the tube 67, which are separated from each other by a tubular space 68;
  - pierce the proximal cortical 64 and the spongy matter 70 forming the interior of the vertebra 60 by means of a drill 69 guided by the pin 61, as represented in FIG. 22, the spongy matter being pierced as far as the distal third approximately, then withdraw the drill 69 and the pin 61;
  - fix the implant 1 on an implant carrier 71 and introduce the assembly into the tube 67 until abutting against the bottom of the piercing, as represented in FIG. 23; to this end, the implant carrier will be able to comprise a sheath, at one end of which the proximal end 20 of the implant will be fixed with its rotational engagement means 3, and on the inside of which a core is able to slide, a core, the distal end of which is intended to be screwed into the distal end 21 of the implant 1; the implant carrier comprises in addition handling means with millimetric control of the core with respect to the sheath, termed compression system, allowing the core to be slid into the sheath so as to bring the ends of the implant one towards the other;
- positioning of the expansible implant 1 in the vertebra 60 in order to make the expansion plane 2 intrinsic to the implant correspond with a bone restoration plane, i.e. in this case, making the implant carrier 71 turn with the implant 1 which is fixed at its end in the vertebra 60, until the expansion plane 2 is parallel to the mechanical axis of the vertebra, as represented in FIG. 24;
- opening out of the expansible implant 1 in the bone restoration plane with a view to forming a cavity 72 inside the vertebra 60, by screwing the compression system (not represented) intending to bring the ends 20 and 21 of the implant one towards the other in order to open out the opposite plates 6 and 7, advantageously forming respectively a first 8 and a second 9 support surface in the vertebra 60, which surfaces are continuous over their length which is substantially equal to the length of the implant 1, as represented in FIG. 25; in the course of the expansion, control of the reduction of the fracture thanks to the millimetric control means, and after having obtained the desired expansion, for example of a determined value between a minimum thickness of the implant before any expansion of the latter and a maximum thickness of the implant after its maximum expansion, then freeing of the implant carrier 71 by unscrewing it from the implant 1, then extraction of the tube 67, as represented in FIG. 26, merely the implant in opened-out position remaining in place in the vertebra 60; the expansion of the implant in the vertebra is achieved by support under the plates allowing the thrust force to be distributed over the length of the plates under the latter, allowing thus a sufficient length of the plates to be provided whilst limiting an excessive dimensioning of the thickness of the latter in order to resist flexion; it will be noted therefore that the implant according to the invention adopts a ratio of spatial requirement in length (not opened out) to length of elevator plate which is extremely optimised, allowing best use of the limited intra-osseous spaces with a view to fracture reduction, for example;
- injection into the cavity containing the implant 1 of a filling material 74, for example an ionic cement, in particular a phosphocalcic cement, an acrylic cement or a compound of the latter with a view to filling the cavity; for this, introduce the needle of the injector 73 into the tube 67 until the end of the needle reaches the distal orifice 39 of the implant 1, as represented in FIG. 27; then inject the filling material in order to obtain optimal filling of the cavity 72 created by the expansion of the implant; continue the injection in a retrograde manner as far as the proximal orifice 64 of the vertebra 60, as represented in FIG. 28; then withdraw the needle from the injector 73 and the tube 67, as represented in FIG. 29.

A second example of the method according to the invention for restoration of human bone anatomy, which uses an expansible implant for example according to the invention, in particular such as the one described above, will now be described by means of FIGS. 30 to 32. It concerns more precisely a method for bone restoration of a vertebra by a transpedicular route, with fracture reduction.
The second method example is similar to the first and differs from the latter by the penetration route of the implant into the vertebra 60 which is now produced in a transpedicular manner, as represented in FIG. 30, by replacing the posterolateral route used for the first method. As a result, only some steps of the second method have been represented in FIGS. 30 to 32 in order to show the different route used for the introduction of the implant 1 into the vertebra. For FIGS. 30 to 32, elements identical to those of the first method example have the same numerical references, and those Figures correspond respectively to the steps of FIGS. 24, 25 and 28 of the first method example. Concerning the step represented in FIG. 32, the latter differs slightly from FIG. 28 by the position of the needle of the injector 73, closer to the distal end of the implant in FIG. 32.

Claims

1. Method for restoration of human or animal bone anatomy, characterised in that it comprises the following steps:

introduction, into a bone (60), the shape of which is to be restored, of an expansible implant (1, 101) according to a single determined plane (2, 102) intrinsic to said implant,

positioning said expansible implant in said bone in order to make said expansion plane intrinsic to said implant correspond with a bone restoration plane,

opening out said expansible implant in said bone restoration plane with a view to forming a cavity (72) inside said bone,

injecting a filling material into said cavity containing said implant (74) with a view to filling the latter.

2. Method according to claim 1, characterised in that it comprises opening out said expansible implant (1, 101) in said bone restoration plane, by a determined value between a minimum thickness of the implant before any expansion of the latter and a maximum thickness of the implant after its maximum expansion.

3. Method according to claim 1, characterised in that the step comprising opening out said expansible implant (1, 101) comprises opening out a first (6, 106) and a second (7, 107) opposite plate, forming respectively a first (7, 107) and a second (8, 108) support surface in said bone.

4. Method according to claim 3, characterised in that said first (7) and second (8) support surfaces in said bone have respectively a length which is substantially equal to the length of said implant.

5. Method according to claim 3, characterised in that said first (6, 106) and second (7, 107) plates form first (7, 107) and second (8, 108) support surfaces which are continuous over their length respectively.

6. Method according to claim 5, characterised in that said first (6, 106) and second (7, 107) plates form respectively continuous smooth support surfaces.

7. Method according to claim 3, characterised in that said first (6) and second (7) plates form respectively partially cylindrical support surfaces, one generator (11) of which is parallel to a longitudinal axis (10) of said expansible implant.

8. Method according to claim 3, characterised in that the step comprising opening out said first (6) and second (7) plates comprises raising the latter by support under the plates.

9. Method according to claim 1, characterised in that the step comprising injecting a filling material (74) into said cavity (72) containing said implant with a view to filling the latter, comprises injecting an ionic cement, in particular a phosphocalcic cement, an acrylic cement or a compound of the latter.

10. Expansible implant (1, 101) which can take part in restoration of human or animal bone anatomy, characterised in that it comprises:

a single determined expansion plane (2, 102), intrinsic to said implant,

means (3, 103) for positioning the expansible implant in said bone (60) in order to make said expansion plane intrinsic to said implant correspond with a bone restoration plane,

means (4, 104) for opening out the expansible implant in said expansion plane intrinsic to said implant with a view to forming a cavity (72) inside said bone.

11. Expansible implant according to claim 10, characterised in that it comprises means (5, 105) for controlling a determined expansion value, between a minimum thickness (A) of the implant before any expansion of the latter and a maximum thickness (B) of the implant after its maximum expansion.

12. Expansible implant according to claim 10, characterised in that it comprises a first (6, 106) and a second (7, 107) plate which are opposite and able to form respectively a first (8, 108) and a second (9, 109) support surface in said bone (60), which surfaces are intended to be moved one away from the other along said single expansion plane (2, 102) during expansion of the implant (1, 101).

13. Expansible implant according to claim 12, characterised in that said first (6, 106) and second (7, 107) opposite plates form first (8, 108) and second (9, 109) support surfaces which are able to be displaced perpendicularly to a longitudinal axis (10, 110) of said expansible implant (1, 101) during the expansion of the latter.

14. Expansible implant according to claim 12, characterised in that said first (8) and second (9) support surfaces in said bone have respectively a length which is substantially equal to the length of said implant.

15. Expansible implant according to claim 12 characterised in that said first (6, 106) and second (7, 107) plates form first (8, 108) and second (9, 109) support surfaces which are continuous over their length respectively.

16. Expansible implant according to claim 15, characterised in that said first (6, 106) and second (7, 107) plates form respectively continuous smooth support surfaces.

17. Expansible implant according to claim 12, characterised in that said first (6) and second (7) plates form respectively partially cylindrical support surfaces, one generator (11) of which is parallel to a longitudinal axis (10) of said expansible implant (1).

18. Expansible implant according to claim 12, characterised in that it comprises a first (12, 14) and a second (13, 15) support for each of said first (6) and second (7) plates, which are situated under the latter respectively.

19. Expansible implant according to claim 18, characterised in that said first (6) and second (7) plates comprise respectively a first (16, 18) and a second (17, 19) cantilever wing, the respective attachment zones of which are situated at the level of said first (12, 14) and second (13, 15) supports.

20. Expansible implant according to claim 19, characterised in that said first (16, 18) and second (17, 19) cantilever wings have respectively a length corresponding substantially to the maximum displacement value of one of said first (6) or second (7) plates in said single expansion plane (2).

21. Expansible implant according to claim 10, characterized in that said means (3, 103) for positioning the expansible implant in said bone in order to make said expansion plane (2, 102) intrinsic to said implant correspond with a bone restoration plane, comprise engagement means (37, 38, 137, 138) allowing orientation of said implant angularly about a longitudinal axis (10, 110) of said expansible implant (1, 101).

22. (canceled)