EP0773747A1

EP0773747A1 - Dynamic implanted vertebral orthesis

Info

Publication number: EP0773747A1
Application number: EP94922924A
Authority: EP
Inventors: Jean-Raymond Martin
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-08-27
Filing date: 1994-07-15
Publication date: 1997-05-21
Also published as: CA2170276C; WO1995005783A1; FR2709246A1; FR2709246B1; AU7265994A; CA2170276A1; US5672175A

Abstract

The invention relates to a dynamic implanted vertebral orthesis preserving at least partially the natural physiological mobility of vertabrae by effecting and maintaining a correction of the relative position of the vertabrae and/or the efforts exerted on the vertabrae, without osteosynthesis, graft or arthrodesis, and comprising anchoring elements (1, 2, 3) fixed to the vertabrae and holding means (4a, 4b, 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b) which are associated to the anchoring elements (1, 2, 3) and which maintain the vertebrae with respect to each other in a corrected position, characterized in that the means (4a, 4b, 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b) have or are comprised of elastic return means exerting elastic return forces whose orientation and intensity are determined in order to maintain the vertebrae in a correct position against natural deformation forces or to reduce the efforts exerted on the vertebrae while preserving their mobility.

Description

DYNAMIC IMPLANTED VERTEBRAL ORTHESIS

The present invention relates to a dynamic implanted vertebral orthosis making it possible to perform and maintain a correction of the relative position of the vertebrae and / or static and dynamic forces exerted on the vertebrae for the treatment of a deformation of the spine, congenital or acquired, in particular idiopathic or other, such as kyphoscoliosis, or post-traumatic, tumor, infectious, degenerative, or other instability of the spine.

Spinal osteosynthesis devices are already known which make it possible to treat scoliotic deformations, consisting of anchoring elements in the vertebrae such as hooks or intrapedicular screws, and rods or frames fixed on the anchoring elements to impose a position relative to the different vertebrae. These rigid or semi-rigid osteosynthesis devices rigidify the spine in the corrected position and are always associated with bone grafting and arthrodesis of the vertebrae. Consequently, the installation of such an osteosynthesis device has the effect of permanently suppressing the natural physiological mobility of the vertebrae. Thus, these known osteosynthesis devices, if they largely solve the problems associated with scoliotic deformation, necessarily create a handicap for the patient. This handicap is all the more penalizing as it is definitive and imposed on patients who are generally young and in period of growth. They are an obstacle to the subsequent growth of the spine.

Furthermore, the known osteosynthesis devices still pose numerous problems with regard to the positioning and the reliability of the anchoring elements which support high stresses taking into account the subsequent rigidity, and during the fixing of the rods, plates or frames, to the anchoring elements which must be carried out simultaneously with the reduction of deformation. Various semi-rigid osteosynthesis devices have thus been proposed to solve these drawbacks by preserving a certain elasticity favoring the fusion of the subsequent bone graft and facilitating the positioning of the anchoring elements or reducing the stresses transmitted to the anchoring elements. . For example, FR-A-2 689 750 proposes such an osteosynthesis device in which the rods have flexibility with a high elastic limit. The elasticity thus preserved in the arthrodesis area promotes the fusion of the bone graft. However, the problems related to the stiffening of the column persist after this fusion. Also, US-A-4 836 196 describes a spacing device disposed between anchoring elements and a stiffening structure making it possible to reduce the stresses transmitted between the vertebral body and the structure. Also, US-A-4,573,454 describes a device with an extensible structure composed of a frame in two telescopic parts one inside the other, with a view to promoting subsequent growth despite the stiffening of the column. However, this problem is only partially solved when the column portions fixed respectively to each of the parts of the structure are themselves stiffened without possible growth.

Also, reducing deformation during installation of the device ¹ osteosynthesis still poses problems. Indeed, the reduction of the deformation must be able to be carried out at the same time of the installation of the vertebral instrumentation, and this in the three dimensions. In particular, during scoliosis, it is necessary not only to replace the vertebrae in the same sagittal plane, but also to restore the kyphosis and / or lordosis while performing a derotation of the vertebrae. Cotrel-Dubousset type osteosynthesis devices partially solve this problem. They consist of two posterior bilateral stems bent during the intervention, immediately before their fixation in anchoring elements according to the lateral deviation, then rotated to place their curvature in a sagittal plane in order to restore kyphosis or lordosis at least partially and to derotate the vertebrae. The correction is limited by the fact that it is carried out only by the rod of the concavity which is turned first. The rod placed in the convexity is mode 1lée on the correction obtained and has only a stabilizing effect during its insertion. The two rods are then connected to each other by transverse traction devices stabilizing the assembly in position. However, the curvature of the stems essentially determined according to the lateral deviation to be corrected does not necessarily correspond to an appropriate correction of the kyphosis or lordosis. In addition, these devices are considered to be among the most sophisticated and rigid. As a result, the installation is extremely delicate and the bone structure is sometimes too fragile to withstand the mechanical stresses generated. Whether these devices are rigid or semi-rigid, they are in all cases associated with a graft and therefore result in the suppression of any movement: this results in a concentration of forces at the ends of the instrumented area with development at these levels of disco-ligament degeneration or arthritis overload.

In addition to Cotrel-Dubousset devices, two other types of osteosynthesis devices are used to treat deformities of the spine. These are, on the one hand, Roy-Camille's plates and pedicle screw devices and their improvements, and, on the other hand, Luque devices with sub-lamar wires and their improvements. The Roy-Camille devices are reserved for small amplitude corrections concerning a limited number of vertebrae, and do not allow efficient derotation. Luque devices can cause serious neurological complications given the passage wires passing under the vertebral lamina near the spinal cord.

None of the known osteosynthesis devices allows correction of a deformation while at least partly preserving the natural physiological mobility of the vertebrae and the subsequent possibilities of growth.

Furthermore, various elastic intervertebral devices are also known which make it possible to treat degenerative, lumbar instabilities. These devices generally consist of intervertebral ligaments or springs (sometimes accompanied by wedges) interposed between the spinous processes or between intrapedicular screws. These ligaments or springs exert traction forces tending to bring the vertebrae closer together and to reduce their relative mobility. These known devices therefore also considerably limit the natural physiological mobility of the instrumented vertebrae. Furthermore, elastic ligaments quickly lose their mechanical qualities because they are subjected to very high tensile forces. In addition, these devices are unable to carry out a correction of deformation, in particular given their excessive flexibility in bending in the frontal plane. Also, after their installation, it is not possible to vary the elasticity of the implanted device.

The invention therefore aims to overcome the drawbacks of all known devices by proposing a new implanted vertebral orthosis preserving at least in part the natural physiological mobility of the vertebrae and allowing, without osteosynthesis, grafting or arthrodesis, to perform and maintain a correction of the relative position of the vertebrae and / or reduce the forces exerted on the vertebrae for the treatment of a congenital or acquired deformation of the spine, in particular idiopathic or other, such as kyphoscoliosis, or post-spinal instability traumatic, tumor, infectious, degenerative, or other. Thus, the invention aims to propose a new category of implanted dynamic vertebral orthosis which, unlike known osteosynthesis devices, can be subsequently modified or even removed, and preserves the natural physiological mobility of the vertebrae not only when it is implanted, but also after its subsequent removal.

The invention also aims to provide an implanted vertebral orthosis which preserves the growth potential of the spine. The invention also aims to propose an implanted vertebral orthosis which can subsequently be removed, in particular at the end of the growth period when the risks of worsening or recurrence of the deformation or instability have disappeared.

The invention also aims to propose an implanted vertebral orthosis which can be applied with the least possible risk of damage to the nervous system. The invention also aims to propose an implanted vertebral orthosis transmitting to the anchoring elements fixed on the vertebrae the lowest possible mechanical stresses, and in particular mechanical stresses the value of which is strictly limited to that necessary for maintaining the correction of deformation and / or application of the desired forces on the vertebrae.

The invention also aims to propose an implanted vertebral orthosis whose characteristics can be adjusted during installation, and after implantation by transcutaneous or percutaneous adjustments, as required.

More particularly, the invention aims to propose an implanted vertebral orthosis allowing the reduction of the deformation of the spine in a precise manner in three dimensions. As such, the invention aims to propose an implanted vertebral orthosis making it possible to reduce scoliosis while preserving the natural physiological mobility of the vertebrae.

To do this, the invention relates to an implanted vertebral orthosis preserving at least in part the natural physiological mobility of the vertebrae by allowing, without osteosynthesis, grafting or arthrodesis, to effect and maintain a correction of the relative position of the vertebrae and / or efforts exerted between the vertebrae, for the treatment of a conformation of the spine, congenital or acquired, in particular idiopathic or other, such as a kyphoscoliosis, or of an instability of the post-traumatic, tumor, infectious, degenerative spine , or other, comprising anchoring elements fixed on the vertebrae and holding means associated with the anchoring elements to maintain the vertebrae relative to each other in corrected position in which the shape of the spine and / or the forces exerted on the vertebrae are corrected, characterized in that the holding means comprise or consist of elastic return means exerting forces elastic return, the orientation and value of which are determined to maintain the vertebrae in a corrected position against natural deformation forces or to reduce the forces exerted on the vertebrae while retaining their mobility. According to the invention, the orthosis comprises at least one retaining rod which is movably associated with the anchoring elements of at least one vertebra by coupling means which prevent any relative movement of sliding in horizontal translation (that is i.e. in the lateral and anteroposterior directions relative to the vertebra) but allow, after placement, a relative movement according to at least one other degree of freedom.

Thus, 1 vertebral orthosis implanted according to the invention is not an osteosynthesis device carrying out a stiffening of the spinal column. On the contrary, it constitutes a dynamic system generating correction forces for the vertebrae with respect to each other. The mobile links made by means of coupling allowing relative movements according to at least one degree of freedom makes it possible to preserve the natural physiological mobility of the vertebrae with respect to each other. The only sources of rigidity induced by the orthosis according to the invention are those which are necessary to effect and maintain a correction of the relative positions of the vertebrae. It has in fact been determined that these mobility limitations are in fact necessary and sufficient to treat the majority of deformations and instabilities. And the orthosis according to the invention is placed without a bone graft.

The number, nature, orientation and value of the elastic restoring forces and the degrees of freedom authorized by the means for coupling the retaining rods to the anchoring elements are determined as a function of the degree and the rigidity of the deformation or spinal instability.

Advantageously and according to the invention, each retaining rod is associated with the anchoring elements of a vertebra by coupling means preventing any relative movement between the retaining rod and the d ^: anchoring elements. And, the means for coupling this retaining rod to all the anchoring elements of the other vertebrae allow, after fitting, a relative movement according to at least one degree of freedom.

In the case of a correction of a lateral deviation of the spine (scoliosis), the retaining rods are preferably rigidly associated with a median vertebra by coupling means preventing any relative movement, and associated in a mobile manner according to the minus a degree of freedom relative to the anchoring elements of the other vertebrae, in particular of the end vertebrae of the deformation to be corrected.

According to the invention, the degree of freedom authorized by the means for coupling the retaining rods to the anchoring elements can be a relative longitudinal translation along a vertical axis and / or a relative rotation about an axis perpendicular to a plane. frontal and / or a relative rotation around a vertical axis and / or a relative rotation around an axis perpendicular to a sagittal plane. In particular, rotations around any horizontal axis are allowed. For example, according to the invention, in the case of the treatment of lumbar instability, the authorized degrees of freedom can be a relative longitudinal translation along a vertical axis, a relative rotation around an axis perpendicular to a frontal plane, and relative rotation about a vertical axis. In the case of treatment for scoliosis, provision is also made for relative rotation about an axis perpendicular to a sagittal plane. Thus in the latter case, any rotation around a horizontal axis is authorized. According to the invention, these degrees of freedom are provided for all the means for coupling the retaining rods to the anchoring elements of all the instrumented vertebrae except one.

According to ^" the invention, the elastic return means are associated with the anchoring elements of the vertebrae with a shape distinct from their shape at rest, that is to say from their shape before their installation, so as to exert forces when the vertebrae are in the corrected position and to maintain this position According to the invention, the holding means comprise at least one flexible and elastic curved holding rod in flexion associated with anchoring elements of at least two distinct vertebrae and able, after installation, to exert elastic forces to maintain the vertebrae in the corrected position while allowing physiological movements from the corrected position of the vertebrae, and the means for coupling this rod to the anchoring elements of at least one vertebra has a cylindrical bore through which the rod passes and in which it can slide in translation.

According to the invention, this bore is formed in a member rotatably mounted relative to the anchoring elements around an axis perpendicular to the frontal plane and / or around an axis perpendicular to the sagittal plane of the corresponding vertebra. This member may be a sphere pierced with the cylindrical bore, and this sphere is enclosed in a spherical housing integral with the anchoring elements allowing it complete freedom of rotation around all the axes located in the horizontal plane. Furthermore, according to the invention, the means for coupling the rod ¹ to the anchoring elements of at least one vertebra allow a proper rotation of the rod around its axis relative to the anchoring elements.

According to the invention, each rod is placed in a lateral position relative to the spinous processes in the paravertebral gutters.

The orthosis according to the invention can comprise a single rod on one side of the spinous processes or two rods, one on each side. Each of the rods is bent at the time of manufacture, so that its shape at rest is curved. During its installation and its association with the anchoring elements, the curvature of each of the rods is modified so that it exerts elastic bending stresses on the anchoring elements. The material and dimensions of each rod are determined so that subsequent voluntary elastic flexions of the spine are possible, after placement and from the corrected position of the vertebrae.

Advantageously and according to the invention, the holding means comprise at least one spring acting on the anchoring elements of at least one vertebra. Such a spring may be a spring with contiguous or non-contiguous turns, one end of which is associated with the anchoring elements of one vertebra and the other end of which is associated with the anchoring elements of another vertebra. Such a coil spring can be a compression or tension spring surrounding a retaining rod connecting the anchoring elements of the various instrumented vertebrae. The rod then acts as a guide for the spring. Thus, according to the invention, the holding means comprise on the concave side of a deformation to be corrected and / or on the side convex of a deformation to be corrected, a rod and at least one compression spring, and / or respectively, of traction surrounding the rod. According to the invention, the two ends of a spring can be locked in rotation relative to the anchoring elements of two vertebrae so as to impart a torque to these vertebrae. To do this, the coils of the spring are wound or unwound relative to their shape at rest after the association and before the fixing of the ends of this spring to the anchoring elements. Such a torsional torque imparted by a spring surrounding a rod makes it possible to exert a rotational torque of the vertebrae with respect to one another - and in particular with respect to the central vertebra. The same spring is then a compression or tension spring and a torsion spring.

An orthosis according to the invention further comprises means for adjusting the value of the elastic restoring forces exerted at least by part of the elastic restoring means. According to the invention, adjustment means make it possible to vary, in the corrected position of the vertebrae, the elastic elongation (that is to say the elastic variation in length or in shape) of the elastic return means with respect to their rest form. These adjustment means may comprise at least one electronic micromotor and / or at least one position of the manual adjusting device of a support abutment of the elastic return means by ^'relative to anchoring elements of a vertebra. According to the invention, the adjustment means comprise transcutaneous or percutaneous control means after implantation of the orthosis, for example in the form of an electromagnetic control.

According to the invention, the adjustment means comprise at least part of the holding means and / or elastic return means which is formed from a metal alloy with shape memory. Therefore, the adjustment can be made by heating this part so as to restore all or part of its shape to use its elasticity as needed. Thus, the rods and / or the springs can be made wholly or partly of a metal alloy with shape memory.

The invention also relates to an implanted vertebral orthosis comprising in combination all or part of the characteristics mentioned above or below.

Other characteristics, aims and advantages of the invention will appear on reading the following description of its preferred embodiments which refers to the appended drawings, in which:

FIG. 1 is a diagrammatic rear view of a first embodiment of an orthosis according to the invention, more particularly intended for the treatment of scoliosis,

FIG. 2 is a schematic profile view of a second embodiment of an orthosis according to the invention, more particularly intended for the treatment of scoliosis,

FIG. 3 is a schematic view in vertical section of detail of the means for locking in rotation of a spring end of an orthosis according to the invention,

FIG. 4 is a schematic sectional view along the line IV-IV of FIG. 3,

- Figure 5 is a schematic view in vertical section of detail of a manual adjustment device of the elastic return means of an orthosis according to the invention, - Figure 6 is a schematic sectional view along line VI- VI of Figure 5,

- Figure 7 is a schematic view in vertical section of detail of a micromotor for adjusting the elastic return means of an orthosis according to the invention, - Figure 8 is a schematic posterior view of a third embodiment of '' an orthosis according to the invention, more particularly intended for the treatment of degenerative lumbar instability, FIG. 9 is a schematic view in section of detail along the line IX-IX of FIG. 8,

FIG. 10 is a schematic posterior view of a fourth embodiment of an orthosis according to the invention, more particularly intended for the treatment of degenerative lumbar instability,

FIG. 11 is a schematic posterior view illustrating a first step of fitting the orthosis of FIG. 1, FIG. 12 is a schematic posterior view illustrating a second step of fitting the orthosis of FIG. 1,

FIG. 13 is a diagrammatic rear view illustrating a third step of laying the orthosis of FIG. 1,

FIG. 14 is a diagrammatic rear view illustrating a fourth step of fitting the orthosis of FIG. 1,

FIG. 15 is a schematic sectional view through a horizontal plane of the anchoring elements of a vertebra of an orthosis according to a fifth embodiment of the invention,

FIG. 16 is a diagrammatic rear view of a clamp of ancillary equipment for fitting an orthosis according to the invention,

FIG. 17 is a schematic view in section along the line XVII-XVII of FIG. 16,

FIG. 18 is a theoretical diagram in section in a horizontal plane making it possible to determine the characteristics of a support and elastic return rod of an orthosis according to the invention,

- Figure 19 is a theoretical diagram in section in a sagittal plane for determining the characteristics of a support rod and elastic return of an orthosis according to the invention.

Throughout the text, and unless otherwise indicated, the term "vertical" designates the axial direction of the spine which does not correspond to the absolute vertical direction since the spine has a curvature (kyphosis and lordosis). Likewise, the term "horizontal" designates any direction contained in the plane perpendicular to the vertical direction, the term "sagittal" designates any plane containing the vertical and horizontal anteroposterior directions, and the term "frontal" designates any plane containing the vertical directions and horizontal lateral. These farms are therefore used with reference to each vertebra. FIG. 1 represents a first embodiment of a vertebral orthosis implanted according to the invention which makes it possible to carry out and maintain a correction of the relative position of five dorsal vertebrae for the treatment of a deformation of scoliotic type. Before the installation of 1 Orthosis, the vertebrae have a lateral deviation such as a curvature with convexity oriented to the right (Figure 11). The orthosis according to the invention comprises an anchoring element 1 fixed on the extreme upper vertebra, an anchoring element 2 fixed on the lower extreme vertebra, and an anchoring element 3 fixed on the median vertebra located in the center of the original natural curvature of scoliosis.

LOrthesis further comprises two holding rods 4a, 4b extending laterally on each side of the spinous processes, namely a left rod 4a placed on the side of the concavity of the deformation to be corrected, and a right rod 4b placed on the side of the convexity of the deformation to be corrected. Each rod 4a, 4b is a curved rod, flexible and elastic in bending made of biocompatible material such as a metal alloy (stainless steel or titanium) and / or of composite material. Each rod 4a, 4b is associated with the anchoring elements 1, 2, 3 of the vertebrae by coupling means 5a, 5b, 6a, 6b, 7a, 7b. Each rod 4a, 4b is originally curved during manufacture and is associated with the anchoring elements by extending in a sagittal plane with its convexity oriented towards the posterior direction. This original bending of the rods 4a, 4b is not modified before their installation. The stems 4a, 4b are made of a material of high tensile strength and having a high modulus of elasticity. Their dimensional and mechanical characteristics are determined so that these rods 4a, 4b are capable, after their installation, of exerting elastic forces intended to maintain the vertebrae in the corrected position represented in FIG. 1, while allowing physiological movements from of this corrected position of the vertebrae. To exert elastic restoring forces, the rods 4a, 4b have, once associated with the anchoring elements 1, 2, 3 and in the corrected position of the vertebrae, a shape distinct from their shape at rest. In particular, in the case of correction of a dorsal scoliosis, the curvature at rest of the rods 4a, 4b is greater than that which they present when associated with the anchoring elements 1, 2, 3. From the so, the rods 4a, 4b exert, in the corrected position of the vertebrae, elastic stresses in bending. These elastic flexural stresses thus maintain the corrected position. They tend to suppress scoliosis in the frontal plane, to create physiological kyphordordosis in the sagittal plane, and to suppress vertebral rotation in the horizontal plane. The rods 4a, 4b therefore constitute in themselves elastic return means exerting elastic return forces which are determined to maintain the vertebrae in the corrected position against the natural forces of deformation. In addition, the dimensional and mechanical characteristics of the rods 4a, 4b are determined in such a way that these rods 4a, 4b have a residual elasticity from the corrected position of the vertebrae. In this way, the rods 4a, 4b do not oppose the natural physiological movements of the vertebrae with respect to each other from the corrected position. These physiological movements are also made possible by the coupling means 5a, 5b, 6a, 6b, 7a, 7b which are designed for this purpose.

The means 5a for coupling the left rod 4a to the upper anchoring element 1 of the upper instrumented vertebra comprise a sphere 8 freely rotatably mounted and enclosed in a spherical housing 9 of a cylinder 10 integral with the anchoring element 1 so as to form a ball joint liaison. The sphere 8 is pierced with a cylindrical bore 11 through which the rod 4a passes, and in which this rod 4a can slide in longitudinal axial translation in the vertical direction. The width of the bore 11 corresponds to the width of the rod 4a and the sphere 8 is engaged in the housing 9 without the possibility of relative movements in horizontal translation, and in particular in the lateral and anteroposterior directions of the vertebra. In this way, the coupling means 5a thus produced, prohibit, after the installation of the rod 4a, any relative movement in horizontal translation of the rod 4a relative to the anchoring elements 1 and to the corresponding vertebra. On the other hand, these coupling means 5a allow, after the installation of the rod, a relative movement according to four other degrees of freedom: a slide ent in relative longitudinal translation along a vertical axis of the rod 4a and three degrees of freedom of rotation of the sphere 8 relative to the cylinder 10, namely a relative rotation around an axis perpendicular to a frontal plane, a relative rotation around an axis perpendicular to a sagittal plane, and a relative rotation around a vertical axis . The bore 11 is cylindrical of revolution and the rod 4a is provided with ribs 12 regularly distributed around its axis and extending along the rod 4a projecting from its outer face to come into contact along the face inner 13 of the bore 11. In the example shown, there are provided three ribs 12 of triangular cross section. In this way the contact friction is reduced. The constituent materials of the sphere 8 and of the cylinder 10 are chosen to allow the rotations of this sphere 8 in the housing 9 as indicated above. For example, the sphere 8 is made of high-quality surface metal alloy or ceramic and the cylinder 10 consists of a block of synthetic material such as polyethylene or the like. The sphere 8 and / or the cylinder 10 can be made of a self-lubricating material or include a coating of this material. The cylinder 10 has upper 14 and lower 15 openings allowing the passage of the rod 4a and whose width dimensions are greater than those of the rod 4a to allow tilting movements of the rod 4a relative to the axis of the cylinder under the effect of the aforementioned rotational movements. Preferably, the dimensions of the openings 14 and 15 are such that they allow an amplitude of inclination of at least 45 degrees of the rod 4a relative to the vertical axis of the cylinder 10. The sphere 8 is engaged in the housing spherical 9 during the fitting of the rod 4a. To do this, a threaded crown 16 is mounted at the upper end of the cylinder 10 which comprises a housing for receiving this crown 16 provided with a corresponding thread. The crown 16 has an axial bore which determines the upper opening 14 of the cylinder 10 opening into the spherical housing 9. The dimensions of the reception housing of the crown 16 are defined to allow the insertion of the sphere 8 from above into the spherical housing 9. The underside of the crown 16 has a concave shape as a portion of a sphere so that it comes as an extension of the spherical internal face of the housing 9 by enclosing the sphere 8 in this housing 9 (FIG. 3) without the block. As a variant (FIG. 1), the cylinder is formed from a block of synthetic material and the upper opening 14 has a diameter slightly smaller than that of the sphere 8 which can be forcefully engaged in the housing 9 through this opening 14 which then retains the sphere 8 in the housing 9. Before introducing the sphere 8 in the housing 9, the rod 4a is introduced inside the cylinder 10. To do this, this cylinder 10 is provided over its entire height d '' a slot 17 communicating with the

SUBSTITUTE SHEET {RULE26) housing 9 and whose width corresponds to the largest diameter envisaged for the rod 4a. This slot 17 can be placed on the inside of the cylinder 10 opposite the spinous processes, as shown in FIG. 15, or on the opposite side, or even on the posterior side. Preferably, this slot 17 is nevertheless formed in a portion of the cylinder 10 which undergoes the least stresses in the horizontal radial direction. For the assembly of the assembly, the sphere 8 is engaged around the rod 4a by introducing this rod 4a through the bore 11, the rod 4a is introduced into the housing 9 through the slot 17 while maintaining the sphere 8 at above the cylinder 10, then the sphere 8 is engaged in the housing 9. In the embodiment shown in FIG. 3, the crown 16 is then screwed into the corresponding housing of the cylinder 10. If applicable, this crown 16 will have been previously engaged around the rod 4a above the sphere 8. The diameter of the rods 4a, 4b adaptable to the same anchoring elements can thus vary, the adaptation being carried out using spheres 8 whose bore 11 corresponds the diameter of the rods 4a, 4b. In a variant not shown, the sphere 8 can also be engaged in the housing 9 from below. The crown 16 is then disposed at the lower end of the cylinder 10. The means 6a for coupling the rod 4a relative to the lower anchoring element 2 of the lower extreme vertebra are identical to the means 5a for coupling this rod 4a to the upper anchoring element 1 of the upper extreme vertebra previously described. On the other hand, the means 7a for coupling the rod 4a to the median anchoring element 3 of the median vertebra are rigid association means preventing any relative movement of the rod 4a relative to the anchoring element 3 To do this, these coupling means 7a consist of a cylinder 18 mounted integral with the anchoring element 3 and provided with a cylindrical bore 19 over its entire height traversed by the rod 4a. This bore 19 is similar to the bore 11 of the coupling means 5a beforehand. described, and therefore has shapes and dimensions corresponding to those of the rod 4a. In a variant not shown, the bore 19 can be provided in an adaptation cylinder whose internal diameter can vary and which is mounted concentrically in the cylinder 18. In addition, the cylinder 18 carries one or more screws 20 for transversely locking the rod 4a. The screw 20 is engaged in a corresponding tapping of the cylinder 18 which opens out into the bore 19. By tightening the screw 20, the latter presses on the rod 4a and blocks it in translation relative to the bore 19. To favor this blocking, the rod 4a can be provided with one or more horizontal peripheral grooves. Also, the cylinder 18 is provided with a slot over its entire height for mounting the rod 4a in the bore 19.

Thus, the rod 4a is blocked by the coupling means 7a relative to the anchoring element of the median vertebra according to each degree of freedom for which the rod 4a is associated movable relative to the anchoring elements 1, 2 of other vertebrae. It is important indeed that the rod 4a is blocked by coupling means with respect to the anchoring elements of at least one vertebra according to at least one - notably each - degree of freedom for which this rod 4a is associated S- _ movable by coupling means relative to the anchoring elements of at least one other vertebra. However, the blockages of the rod 4a, according to the different degrees of freedom, may not be gathered on the same vertebra. In certain cases also, the rod 4a can be blocked according to one or more degrees of freedom with respect to several distinct vertebrae. In most cases, however, it is advantageous to provide that the rod 4a is blocked according to all the degrees of freedom relative to the anchoring elements 3 of a single vertebra and associated movable according to the different degrees of freedom provided by relative to all the anchoring elements 1, 2 of the other vertebrae. Thus, the rod 4a is blocked by coupling means relative to the anchoring elements 3 one of the vertebrae and associated movable by coupling means to all the anchoring elements 1, 2 of the other vertebrae which allow. after installation, a relative movement according to at least one degree of freedom. The rod 4b placed to the right of the spinous processes (Figure 1) is associated with the anchoring elements 1, 2, 3 by coupling means 5b, 6b, 7b similar to the coupling means 5a, 6a, 7a, previously described for the left stem 4a. In particular, the right rod 4b is rigidly fixed to the same vertebra as the left rod 4a, that is to say to the median vertebra.

Each rod 4a, 4b thus mounted on the anchoring elements 1, 2, 3 of the vertebrae provides a means for front and sagittal support of the vertebrae with respect to each other. It also achieves, to a certain extent, a means for holding the vertebrae in the vertical direction. Once laid, these rods 4a, 4b exert elastic restoring forces on the anchoring elements against the natural forces of deformation. The corrected position corresponds in fact to the equilibrium position between the natural forces of deformation of the spine and the elastic restoring forces exerted by the orthosis according to the invention. Taking into account ₍ the flexibility of the rods 4a, 4b and the degrees of freedom authorized by the various coupling means, natural physiological movements are possible at least to a certain extent with respect to the corrected position.

In most cases, the only bending elasticity of the rods 4a, 4b will be considered as insufficient to carry out and maintain the correction of deformation, taking into account the forces at play, the space constraints and the flexibility that these rods must have for authorize movements. According to the invention, the elastic return means of the orthosis comprise at least one spring 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b acting on the anchoring elements of at least one vertebra. In the embodiment of the Figure 1, 1 Orthosis includes for each rod 4a, 4b, a coil spring 21a, 21b interposed between the anchoring elements 1, 3 of the upper vertebra and the median vertebra, a coil spring 22a, 22b interposed between the anchoring elements 2, 3 of the lower vertebra and the median vertebra, a coil spring 23a, 23b interposed between the anchoring element 1 of the upper vertebra and a free end 25a, 25b of the upper rod 4a, 4b, and a coil spring 24a, 24b interspersed between the anchoring element 2 of the lower vertebra and the free end 26a, 26b of the lower rod 4a, 4b. Each coil spring 21a, 21b, 22a, 22b is interposed between the anchoring elements 1, 3 and 3, 2 of two distinct vertebrae and has one end associated with the anchoring element 1 or 3 of a vertebra and the other end associated with the anchoring element 3 or 2 of another vertebra. The springs 21a, 22a, 23a, 24a surround the rod 4a placed on the concave side of the deformation to be corrected and are compression springs. The springs 21b, 22b, 23b, 24b surround the rod 4b placed on the convex side of the deformation to be corrected and are tension springs.

The ends of the springs 21a, 23a acting on the anchoring element 1 and placed around the left rod 4a, bear on the cylinder 10. The ends of the springs are mounted relative to the anchoring element 1 so to print a torque on the corresponding vertebra. To do this, the free end 27 of the spring which is folded to extend radially is introduced into a radial bore 28 of a ring 29. As a variant, the last turn of the spring is welded to the ring 29. This ring 29 has an external circumferential groove 30. The cylinders 10 have an external flange 31 surrounding the crown 29. This flange 31 carries screws 32 for radial locking engaged in threads of the flange 31 and the ends of which penetrate into the groove 30 of the crown 29 to block it axially with respect to the cylinder 10 then, after twisting the spring, in 21 rotation with respect to the cylinder 10. The crown 29 has blind holes 33 allowing it to rotate around the axis of the spring. When the desired twist is obtained, the screws 32 are finally tightened to block the crown 29 relative to the flange 31 of the cylinder 10. Such a crown 29 blocked by screws 32 can be provided not only at each end of a spring taking support on anchoring elements comprising a cylinder 10 or 18, but also at the end of a spring bearing on a nut 34 fixed at the end 25a, 25b, 26a, 26b of a rod 4a, 4b.

According to the invention, the orthosis also comprises means 29, 35, 36 for adjusting the value of the elastic return forces exerted by at least part of the elastic return means, namely the rods 4a, 4b and / or the springs. These means 29, 35, 36 are means making it possible to vary, in the corrected position of the vertebrae, the initial elastic elongation (that is to say the initial elastic variation in compression or traction of length or shape) elastic return relative to their shape at rest. In fact, both the rods 4a, 4b and the springs are placed and associated with the anchoring elements 1, 2, 3 with a shape which is distinct from their shape at rest so as to exert elastic forces against it. 'natural forces of deformation, and to maintain the vertebrae in the corrected relative position with respect to each other. However, the restoring forces exerted by the elastic return means vary with said elastic elongation of these elastic return means relative to their shape at rest. Consequently, by modifying this elastic elongation, the value of the elastic restoring forces exerted is modified. In particular, the length of the compression and tension springs is varied by decreasing or increasing it. To do this, said adjustment means may consist of a shim of variable height interposed between one end of the spring which it is desired to be able to adjust, and the corresponding support element, to namely a cylinder 10 or 18 or a rod end nut 34. Such a shim 35, 36 of variable height may consist of an electronic micromotor 35 (FIG. 7) of one to two centimeters in height having a rotor 38 pierced axially.

The rotor 38 is provided with a thread 42 which cooperates with an external thread 43 of an internal cylinder 44 carrying a movable plate 40. The plate 40 is locked in rotation relative to the stator 39 of the micromotor by vertical rails 140 integral with the plate 40 sliding in external vertical slides 141 secured to the stator 39.

When the micromotor 35 is activated, the plate 40 which bears on the end of the spring slides in axial translation relative to the stator 39 of the micromotor which bears on the cylinder 10 or 18 or on the corresponding nut 34. The stator 39 of the micromotor 35 can be mounted on the cylinder 10 or 18 or the corresponding nut 34 in the same way as the crown 29 previously described for adjusting the torsion of the springs. To this end, the stator of the micromotor 35 has a circular peripheral groove in which screws such as 32 for radial locking are tightened. Also, the end of the spring bearing on the plate 40 of the micromotor 35 can be fixed to this plate 40 by means of torsional adjustment as described above, namely a ring 29 on which the end of the spring is mounted, which is itself mounted on a flange 31 of the plate 40 of the micromotor 35 by means of locking screws 32. The micromotor can be supplied with electrical energy by micropiles 41, and its operation can be controlled through the skin by an electromagnetic or other remote control.

As a variant or in combination, an adjustment shim may consist of a manual adjustment device 36 (FIGS. 5 and 6) comprising two concentric cylinders 142, 143, one of which 143 is movable in vertical axial translation relative to the other 142 which is fixed, and this under the effect of a control screw 37 which extends radially and which carries, at its internal end, a pinion 144 cooperating with a rack 1 5 secured to the movable cylinder 143 to actuate it in relative axial translation in a one way or the other. The cylinders 142, 143 are locked in rotation relative to each other. The manual adjustment device 36 also comprises an axial central bore 146 for the passage of the rod 4a or 4b through the movable cylinder 143. It is interposed between a spring end and a cylinder 10, 18 or an end nut 34 rod. The manual adjustment device 36 can be fixed to the end of the spring and to the cylinder 10 or 18 or to the nut 34 in the same way as the micromotor 35, in particular by means of means for adjusting the torsion of the spring. By turning the screw 37, for example percutaneously, the movable cylinder 143 is made to slide axially relative to the fixed cylinder 142.

In the embodiment of FIG. 1, all the springs 21a, 22a, 23a, 24a surrounding the left rod 4a are provided with means for adjusting and locking in torsion (crown 29 and screw 32 for locking). The two compression springs 21a, 22a bearing on each side on the cylinder 18 of the means 7a for coupling the rod 4a to the middle anchoring element 3, are provided with adjustment means 35, 36. An electronic micromotor 35 is shown above the cylinder 18 to 21a the upper spring adjuster, and a manual tensioning device 36 with its screw 37 is shown in the cylinder 18 ^* for adjusting the length of the lower spring 22a. The tension springs 21b, 22b interposed between the anchoring elements around the straight rod 4b are also provided with adjustment and torsional locking means 29, 32. Adjustment micromotors 35 are provided between the cylinders 10 of the means 5b, 6b for coupling the rod 4b to the upper and lower anchoring elements 1, 2, and the corresponding ends of the end springs 23b, 24b.

Adjustment of the restoring forces by the springs which can be carried out by means of the crowns 29, micromotors 35 and manual tensioning devices 36 makes it possible to easily adapt the characteristics of the orthosis according to the natural physiological modifications of the patient (increase in length of the column vertebral, body weight, muscle strength ...). However, if these physiological changes are too great, the adjustment may prove to be insufficient. In this case, it will still be possible to easily change the rods 4a, 4b and / or the springs. The anchoring elements 1, 2, 3 do not generally have to be modified taking into account that the coupling means 5a, 5b, 6a, 6b, 7a, 7b authorize the intraoperative assembly and disassembly of the rods and springs relative to these anchoring elements.

FIG. 2 represents a profile view of an alternative embodiment of the previously described orthosis. As can be seen, the curvature of the rod 4a makes it possible to restore and maintain the kyphosis. In this alternative embodiment, the cylinder 18 of the median coupling means 7a is provided with an electronic micromotor 35 for adjustment on each side. The two springs 21a, 22a interposed between the anchoring elements on either side of the central cylinder 18 are provided with a crown 29 of end ^* for adjusting and locking in torsion. In this way, this torsion of the springs participates in the derotation of the vertebrae. It should be noted that this derotation is also obtained by the elastic curvature of the rod 4a itself and pr the fact that it is placed with its plane of curvature at rest inclined relative to a sagittal plane.

FIG. 8 represents an embodiment of an orthosis according to the invention more particularly intended for the treatment of lumbar degenerative instability. Unlike the previously described orthosis which allows you to instrument a length of spine corresponding to five vertebrae, this short lumbar orthosis extends over a more limited number of vertebrae including three vertebrae 25 in the example shown.

This short orthosis also includes anchoring elements 1, 2, 3 on three vertebrae, one or two posterior lateral rods 4a, 4b, springs 21a, 22a, 21b, 22b, each of them being interposed between the elements d anchorage 1, 3 or 3, 2 of two distinct vertebrae. The main function of such a lumbar orthosis is not to correct a deformation, but to correct the value of the forces exerted between vertebrae by reducing the forces undergone by the vertebrae due to degenerative instability. After the placement of the orthosis, that is to say in the so-called corrected position of the vertebrae, the springs and the elasticity of the rods make it possible to modify these forces exerted between vertebrae by reducing the stresses required on the spine without eliminating physiological mobility natural. Consequently, the springs 21a, 21b, 22a, 22b are all compression springs acting in the direction of the spacing of the vertebrae with respect to each other in order to discharge the posterior vertebral joints. The rods 4a, 4b are curved in the direction of the lordosis and make it possible to maintain the relative position of the vertebrae, and in particular the spacing of the vertebral bodies, which reduces the forces applied to the anterior disco-ligament apparatus. The springs bear directly on the anchoring elements since there is generally no correction to be made in the direction of rotation around the vertical axis.

The orthosis represented in FIG. 8 also differs from the orthoses represented in FIGS. 1 and 2 by the means 45a, 45b, 46a, 46b, 47a, 47b for coupling the rods 4a, 4b to the anchoring elements 1, 2, 3 ( figure 9). Indeed, these coupling means do not have the same degrees of freedom. More precisely, to maintain the spacing between the vertebral bodies more effectively, the degree of freedom in rotation about an axis perpendicular to the sagittal plane is eliminated at the level of all the vertebrae. Thus, the means 45a, 45b, 47a, 47b for coupling the rods 4a, 4b to the anchoring elements 1 upper and 3 median allow relative movements of the rods 4a, 4b relative to these elements 1, 3 for anchoring in longitudinal translation along a vertical axis, in relative rotation about an axis perpendicular to a frontal plane, and in proper rotation of the rod around a vertical axis, but prohibit any relative rotation around an axis perpendicular to a sagittal plane. To do this, the sphere 8 of the previously described orthosis is replaced by a sphere 48 provided with an annular circumferential projection 52 and the housing 49 for receiving the sphere 48 is provided with an annular groove 53 in which the projection 52 of the sphere is engaged. The projection 52 and the groove 53 extend in a frontal plane so as to allow rotation about an axis perpendicular to the frontal plane by preventing rotations around an axis perpendicular to the sagittal plane. As a variant, these coupling means could also be produced in the form of a cylinder with a horizontal axis provided with a radial bore for the passage of the rod engaged in a cylindrical housing with a horizontal anteroposterior axis of the cylinder 50. The member 48 rotatably mounted with respect to the cylinder 50 (that is to say the sphere 48 or the cylinder with a horizontal axis) has a bore 51 with a vertical axis for the passage of the rod 4a, 4b. Rotations around an axis perpendicular to the sagittal plane are not possible at the coupling elements but are made possible at the elastic retaining and return elements by the flexibility of the rods and springs, so as to allow the spine the physiological movements of flexion and extension in the sagittal plane.

The means 46a, 46b for coupling the rods 4a, 4b to the lower anchoring elements 2 are rigid association means blocking the rod in all directions, that is to say are identical to the coupling means 7a, 7b rods to the median anchoring elements described with reference to Figures 1 and 2. These coupling means 46a, 46b therefore comprise a cylinder 18 provided with a bore 19 and at least one transverse locking screw 20. A nut 34 is fixed to the lower end 26a, 26b of each rod 4a, 4b. On the contrary, the upper free ends 25a, 25b of the rods 4a, 4b are left free without nut or spring.

Figure 10 shows an alternative embodiment of the short lumbar orthosis according to the invention. In this variant, all the coupling means have the same degrees of freedom and are identical to the coupling means 45a, 45b, 47a, 47b of the embodiment shown in FIGS. 8 and 9. The rods 4a, 4b are held in position by relative to the means 45a, 45b, 46a, 46b, 47a, 47b for coupling and facing the corresponding vertebrae by a weld 54a, 54b rigidly associating a turn of the springs 22a, 22b with the outer surface of the rods 4a, 4b. In this embodiment, the springs 22a, 22b are also provided at each of their ends with a crown 29 locked by screws 32 relative to the cylinders 50 of the means 46a, 46b, 47a, 47b of corresponding coupling making it possible to block these springs 22a, 22b rotating around the vertical axis. The rod 4a, 4b is therefore kept in rotation about the vertical axis by the springs 22a, 22b, in the desired lordosis position. The embodiments shown in Figures 8 and 10 may also include, if necessary, means for adjusting - in particular micromotors 35 and / or manual tensioning devices 36 - of the elastic restoring force exerted by the springs 21a, 21b , 22a, 22b.

In addition, and in all of the embodiments of the invention, the orthosis may include means for adjusting the elastic return forces exerted by the elastic return means produced in the form of at least part of the holding means. and / or elastic return means consisting of a metal alloy with shape memory. For example, all or part of the rods 4a, 4b and / or all or part of the springs can be made of metal alloy with shape memory. Consequently, after implantation, it will be possible to modify the elastic restoring forces exerted by proceeding with transcutaneous heating of this part made of shape memory alloy, and this for example by microwave.

The anchoring elements 1, 2, 3 comprise (FIG. 15) at least one plate 55 having an anterior convex face 56 bearing in contact with at least one portion of the concave surface of the posterior arch, in particular in contact of the vertebral blade 57 and / or at least on one side of the spinous process 58. The cylinders 10, 18, 50 of the coupling means are carried by a plate 55 facing the transverse end of the blade 57 at neighborhood of the transverse process 59. Each plate 55 is fixed on a vertebra in at least two distinct portions. For example, each plate 55 is fixed to the corresponding vertebra by an intrapedicular screw 61 and / or hooks 71 for clamping on the transverse process 59 and / or a clamping flange 65 on the spinous process 58. The elements of Anchoring may include two plates 55a, 55b, one on each side of the spinous process, even when the orthosis has only one rod, on one side of the spinous process (Figure 15). Alternatively, a single plate 55 can be provided. In all cases, the anchoring elements according to the invention respect the disco-ligament and articular structures of the vertebrae, the integrity of which will allow the conservation of the vertebral physiological movements. In particular, the anchoring elements according to the invention make it possible to conserve the movements authorized by the dynamic orthosis. In addition, if this orthosis is then removed, for example at the end of the patient's growth, natural physiological movements are possible.

The orthosis according to the invention can be produced at least in part from a metal alloy (stainless steel, titanium, etc.) and / or from a composite material.

Figures 16 and 17 show a clamp of ancillary correction material for the installation of a vertebral orthosis implanted according to the invention. This clamp has three action ends 81, 82, 83 intended to cooperate respectively with the anchoring elements 1, 2, 3 of the vertebrae. Each of the action ends 81, 82, 83 of the clamp is formed of a stud intended to be engaged in a bore 78 with a vertical axis formed in the vicinity of the coupling means of the anchoring elements 1, 2, 3. Each nipple 81, 82, 83 which can be oriented towards, the bottom or up (FIG. 16) can act in compression or in detraction as required. Thus, each plate 55 of the anchoring elements comprises a bore 78 formed through a horizontal extension of the plate 55 which supports a cylinder 10, 18 or 50 for coupling a rod 4a, 4b. The bore 78 is preferably formed on the front and lateral side of the cylinder 10, 18, 50.

According to the invention, the clamp also comprises dynamometric means 93, 94, 95 for measuring the forces imparted on the end pins 81, 82, 83 to maintain their relative positions. Also, the clamp comprises means 112, 117, 127 for measuring the displacements of the end studs 81, 82, 83 during modifications of their relative positions.

Each clamp is composed of three articulated branches 90, 91, 92 carrying the pins 81, 82, 83 at their free end. More specifically, the clamp comprises an upper branch 90 carrying the upper end stud 81, a lower branch 91 carrying the lower end stud 82, and a middle branch 92 carrying the middle end stud 83. The two upper and lower branches 90, 91 are articulated to each other about a horizontal axis 99 orthogonal to the direction passing through the two pins 81, 82. The branches 90, 91, 92 are articulated by relative to the others and controlled in their relative movements by three control rods 104, 114, 124 provided with handles 113, 123, 135. A vertical control rod 104 has a thread 105 cooperating with a thread 106 at one end 103 of the lower branch 91 opposite the nipple 82. The end 102 of the upper branch 90 opposite the stud 81 is in the form of a sliding sleeve around a cylinder 109 integral with the vertical control rod 104 but whose position in translation relative to the rod 104 can be adjusted . This sleeve 102 is trapped between two compression springs 107, 108 surrounding the rod 104 and bearing at their opposite ends on dynamometric sensors 93. The sleeve 102 also includes a light 111 allowing the reading of a graduated scale 112 on the rod 104. When the handle 113 is turned, the end studs 81, 82 are separated or brought closer to one another. If the pins 81, 82 do not support forces in the vertical direction, the upper sleeve 102 remains midway between the two sensors 93, the springs 107, 108 not being activated. If on the contrary a force is necessary to move the pins 81, 82, one of the springs 107, 108 is activated in compression to balance this force and allow the position to be modified. The load cells 93 then deliver an electrical signal proportional to this force.

The middle branch 92 is articulated on the assembly thus formed by the upper 90 and lower branches, 91. A sagittal control rod 114 extends along the axis 99 of articulation of the two upper and lower branches 90, 91 ^*** : in the sagittal direction. This rod 114 is provided, at its end, with a thread 115 engaged in a tapping 116 of one of the branches 90, 91. The rod 114 also carries a graduated scale 117 making it possible to identify its position relative to the branches 90, 91. The middle branch 92 has an oblong slot 118 crossed by the control rod 114. This oblong slot 118 extends in a direction orthogonal to the vertical direction passing through the end studs 81, 82 upper and lower, and at the horizontal axis 99 of articulation of the two upper and lower branches 90, 91. Thus, a displacement of the middle branch 92 relative to the axis 99 of articulation and according to this direction is possible. The oblong opening 118 of the middle branch 92 is engaged around the control rod 114 trapped between two springs 119, 120 whose opposite ends press on load cells 94. These load cells 94 provide a measurement of the forces imparted to the stud 83 in the horizontal sagittal direction. By turning the handle 123, the position of the stud 83 in the horizontal sagittal direction relative to the frontal plane containing the studs 81, 82 upper and lower is therefore modified.

The end 129 of the middle branch 92 opposite the end stud 83 is associated with a front control rod 124 which makes it possible to control the movements of this middle branch in the horizontal frontal direction perpendicular to the vertical direction passing through the studs d ends 81, 82 upper and lower and to the axis 99 of articulation of the two branches 90, 91 upper and lower. This front control rod 124 has a threaded end 125 engaged in a thread 126 formed in a bearing 110 comprising a cylinder 121 surrounding the vertical control rod 104. The cylinder 121 carries a graduated scale 127 visible through a light 128 of the branch middle 92. The end 129 of the middle branch 92 opposite the stud 83 slides around the front control rod 124 and is trapped between two springs 130, 131 whose opposite ends bear: on load cells 95. The displacement of the median branch 92 in the frontal direction is authorized by the oblong opening 118. By turning the handle 135, the position of the median stud 83 in the frontal direction is therefore modified relative to the sagittal plane containing the studs 81, 82 upper and lower. The sensors 95 provide a measure of the forces necessary for this displacement. In a variant not shown, the branches 90, 91, 92 and the control rods 104, 114, 124 can be articulated to a support or to a common frame.

To place an orthosis according to the invention, we discover the vertebrae intended to receive the anchoring elements 1, 2, 3, we place and fix the anchoring elements 1, 2, 3 on each vertebra concerned and bilaterally (Figure 11), we associate at least one clamp correction ancillary to the anchoring elements 1, 2, 3 of each vertebra to be moved for the desired correction, and in particular a clamp for each rod 4a or 4b which must be placed (FIG. 12), the handles 113, 123 are actuated, 135 of each clamp in order to place the vertebrae in the corrected position to reduce deformation and / or exert the desired static forces (Figure 13), the necessary holding forces are applied to the anchoring elements 1, 2, 3 of each vertebra thanks to the various dynamometric sensors 93, 94, 95 to maintain said corrected position, the characteristics of the holding means and elastic return means of the orthosis are determined to generate the elastic return forces similar to the holding forces measured, the elastic retaining and / or return means are put in place (FIG. 14), that is to say the rods 4a, 4b and the springs by associating them by the different coupling means with the anchoring elements 1, 2, 3, we remove the ancillary correction material (figure 1), and we end the implantation surgical operation. In Figures 12 to 14, the forceps placed on the right of the spinous processes are similar to that described and shown in Figures 16 and 17, and the forceps placed on the left are reversed, the upper branch

90 being associated with the lower anchoring elements 2 and the lower branch 91 being associated with the anchoring elements

1 superiors. The dimensions and the shape of the branches 90,

91 used are chosen according to the distance between the corresponding vertebrae.

According to the invention, therefore, corrects distortion and / or the effort with ancillary pliers fully before associating the holding means and / or elastic return (rods and springs), and unlike the known osteosynthesis devices ¹ with which the correction is carried out by or with the stiffening elements of the vertebrae.

The holding forces are measured by dynamometric sensors 93, 94, 95 integral with the ancillary equipment, that is to say along three orthogonal axes of translation of the end pins 81, 82, 83, namely a vertical axis ( vertical control rod 104), a sagittal axis (sagittal control rod 114), and a front axis (front control rod 124). The various characteristics and dimensions of the holding means and / or of elastic return means are determined, at least approximately, by calculation by an information processing device programmed for this purpose from the values of the holding forces measured by the various load cells. The desired effectiveness of the means of retaining and / or elastic return of the orthosis is checked before the ablation of the clamps by reading the cancellation of the static forces recorded by the dynamometers 93, 94, 95. The means of maintaining and of elastic recall are then and if necessary adjusted or changed in whole or in part.

Thanks to the means for adjusting the elastic return means of the orthosis, after removing the ancillary correction material, it is possible to check that the corrected position and / or the desired value of the static forces between the vertebrae are maintained, and then we proceed any necessary adjustments before completing the operation or after the operation and the patient's awakening.

Figures 18 and 19 illustrate a diagram for determining the main characteristics and orientation of each rod 4a, 4b of an orthosis according to one invention.

The rod 4a, 4b is placed by orienting its plane of curvature at an angle β (Figure 18) relative to the sagittal plane of the spine in the corrected position. This angle β makes it possible to impose the positioning of the median vertebra V2 in the sagittal plane of the upper and lower vertebrae VI and V3. If FI and F2 are the 34 measured values (given by sensors 95, 94) of the holding forces respectively in the frontal direction and in the sagittal direction, we have: tg β = F1 / F2 From this value of β obtained by calculation, we fix a clamp on the rod before its installation in the plane of its curvature, and this clamp is oriented relative to the sagittal plane after having engaged the rod in the coupling means of the orthosis, and this thanks to a protractor placed in the horizontal plane of the patient. The screws 20 for locking the rod are then tightened relative to the cylinder 18 to block it in rotation around the vertical direction relative to the anchoring elements 3 of the median vertebra. The sagittal displacement MV2 which must then be given to the median vertebra by the sagittal control rod 114 to restore the kyphosis is illustrated in FIG. 19. If α is the Cobb angle of the kyphosis which should be given between the extreme vertebrae VI and V3, we have:

MV2 = tg (α / 4) x ¥ 1 VÂ

where V1V3 is the vertical distance between the two upper and lower vertebrae. < _f The calculations are the same for concavity and convexity.

The initial curvature of each rod 4a, 4b corresponds to the desired final curvature given by the angle σ modified by the deformation of the rod due to the elastic holding forces which it must exert. The resulting elastic FR force that the rod must exert is:

FR = - F1 ² + F2 ² The length of the rod depends on the distance between the instrumented vertebrae, and its diameter is chosen according to the curvature and the material to obtain the force FR with sufficient residual flexibility to allow physiological movements vertebral.

Compression and traction springs are dimensioned in a conventional manner essentially from the value of the vertical holding forces provided by the sensors 93 of the vertical control rod 104. The coil springs working in torsion are tensioned in the opposite direction to the winding of the turns , i.e. by reducing the diameter of the spring. The upper springs 21a, 21b are both wound in the same direction, and in the opposite direction of the lower springs 22a, 22b. The coils of the springs are tensioned to derote the vertebrae in the desired direction.

The orthosis according to the invention may be the subject of numerous variants, in particular as a function of the deformation or the instability to be corrected, of the patient, and of the operating conditions encountered. In particular, the orthosis may include only retaining and elastic return rods, or only retaining and elastic return springs. The springs can also be leaf springs or other. Envelopes for protecting the springs against fibrotic invasion may be provided.

Furthermore, an orthosis according to the invention can be used to instrument any portion of the spine, and is not limited to the corrections of dorsal kypho-scoliosis and lumbar degenerative instabilities illustrated in the examples. In particular, the orthosis according to the invention is applicable with minor modifications to a portion of the cervical spine.

Claims

CLAIMS 1 / - Implanted vertebral orthosis preserving at least in part the natural physiological mobility of the vertebrae by allowing, without osteosynthesis, grafting or arthrodesis, to effect and maintain a correction of the relative position of the vertebrae and / or of the forces exerted on the vertebrae, for the treatment of a congenital or acquired spinal deformation, in particular

1 idiopathic or other. such as kyphoscoliosis, or post-traumatic, tumor, infectious, degenerative, or other instability of the spine, comprising anchoring elements (1, 2, 3) fixed on the vertebrae and means (4a , 4b, 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b) holding associated with the anchoring elements (1, 2, 3) for holding the vertebrae relative to each other in corrected position, characterized in what the means (4a, 4b, 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b) for holding include or consist of elastic return means exerting elastic return forces whose orientation and value are determined to maintain the vertebrae in a corrected position against natural deformation forces or to reduce the forces exerted on the vertebrae while retaining their mobility.

2 / - Orthosis according to claim 1, characterized in that it comprises at least one rod (4a, 4b) for holding which is movably associated with the anchoring elements (1, 2, 3) of at least one vertebra by coupling means (5a, 5b, 6a, 6b, 45a, 45b, 46a, 46b, 47a, 47b) which prohibit any relative movement in horizontal translation relative to the vertebra but allow, after fitting, a relative movement according to the minus another degree of freedom.

3 / - Orthosis according to claim 2, characterized in that each retaining rod (4a, 4b) is rigidly associated with the anchoring elements (3 or 2) of a vertebra by means (7a, 7b, or 46a, 46b) of coupling prohibiting any relative movement, and in that each holding rod (4a, 4b) is associated mobile with all the anchoring elements (1, 2 or 1, 3) of the other vertebrae by means (5a, 5b, 6a, 6b or 45a, 45b, 47a, 47b) of coupling which allow, after installation, a relative movement according to minus a degree of freedom. . 4 / - Orthosis according to one of claims

2 and 3, characterized in that each retaining rod (4a, 4b) is associated mobile: a) with the anchoring elements (1, 2, 3) of at least one vertebra by means (5a, 5b, 6a , 6b, 45a, 45b, 46a, 46b, 47a, 47b) coupling allowing, after installation, sliding in relative longitudinal translation along a vertical axis, b) to the anchoring elements (1, 2, 3) d ' at least one vertebra by means (5a, 5b, 6a, 6b, 45a, 45b, 46a, 46b, 47a, 47b) of coupling allowing, after installation, a relative rotation around an axis perpendicular to a frontal plane, c) the anchoring elements (1, 2, 3) of at least one vertebra by means (5a, 5b, 6a, 6b, 45a, 45b, 46a, 46b, 47a, 47b) allowing coupling, after the pose, a relative rotation around a vertical axis.

5 / - Orthosis according to one of claims 2 to 4, characterized in that each rod (4a, 4b) for holding is movably associated: - d) to the anchoring elements (1, 2) of at least one vertebra by coupling means (5a, 5b, 6a, 6b) allowing, after installation, a relative rotation about an axis perpendicular to a sagittal plane.

6 / - Orthosis according to one of claims 1 to 5, characterized in that the means (4a, 4b, 21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b) of elastic return are associated with the elements of anchoring (1, 2, 3) of the vertebrae with a shape distinct from their shape at rest, so as to exert elastic restoring forces when the vertebrae are in the corrected position.

7 / - Ortnese according to one of claims 1 to 6, characterized in that the holding means comprise at least one rod (4a, 4b) for curved holding flexible and elastic in flexion associated with anchoring elements (1, 2, 3) of at least two distinct vertebrae, and in that each rod (4a, 4b) is able, after its installation, to exert elastic forces maintaining the vertebrae in the corrected position while allowing physiological movements from the corrected position of the vertebrae.

8 / - Orthosis according to one of claims 1 to 7, characterized in that the holding means comprise at least one rod (4a, 4b) flexible and elastic curve associated with anchoring elements (1, 2, 3) at least two distinct vertebrae, and in that each rod (4a, 4b) is able, after its installation, to exert elastic forces to maintain the vertebrae in the corrected position while allowing physiological movements from the corrected position , and in that the means (5a, 5b, 6a, 6b) for coupling each rod (4a, 4b) to the anchoring elements (1, 2) of at least one vertebra have a bore (11, 51) cylindrical through which the rod (4a, 4b) and in which it can slide in translation.

9 / - Orthosis according to claim 8, characterized in that the bore (11, 51) is formed in a member (8, 48) rotatably mounted relative to the anchoring elements (1, 2) around an axis perpendicular to the frontal plane of the corresponding vertebra.

10 / - Orthosis according to claim 9, characterized in that the member (8) is rotatably mounted relative to the anchoring elements around an axis perpendicular to the sagittal plane of the corresponding vertebra.

11 / - Orthosis according to claim 9, characterized in that the member (8) is a sphere pierced with the cylindrical bore (11) and which is enclosed in a housing (9) spherical anchoring elements (1, 2 ). 12 / - Orthosis according to one of claims 8 to 11, characterized in that the means (5a, 5b, 6a, 6b, 45a, 45b, 46a, 46b, 47a, 47b) for coupling the rod (4a, 4b) the anchoring elements (1, 2, 3) of at least a vertebra allow a proper rotation of the rod around its axis relative to the anchoring elements (1, 2, 3).

13 / - Orthosis according to one of claims 1 to 12, characterized in that the elastic return means comprise at least one spring (21a, 21b,

22a, 22b, 23a, 23b, 24a, 24b) acting on the anchoring elements (1, 2, 3) of at least one vertebra.

14 / - Orthosis according to one of claims 1 to 13, characterized in that it comprises, on the concave side of a deformation to be corrected, a rod (4a) for holding and at least one spring (21a, 22a, 23a , 24a) of compression surrounding the holding rod (4a).

15 / - Orthosis according to one of claims 1 to 14, characterized in that it comprises, on the convex side of a deformation to be corrected, a rod (4b) for holding and at least one spring (21b, 22b, 23b , 24b) of traction surrounding the holding rod (4b).

16 / - Orthosis according to one of claims 1 to 15, characterized in that it comprises at least one rod (4a, 4b) for holding and at least one torsion spring (21a, 21b, 22a, 22b, 23a, 23b, 24a, 24b) with turns surrounding the rod (4a, 4b), the ends (27) of this spring being locked in rotation relative to the anchoring elements (1, 2, 3) of at least one vertebra of so as to print a torque.

17 / - Orthosis according to one of claims 1 to 16, characterized in that it comprises means (29, 35, 36) for adjusting the value of the elastic restoring forces exerted by elastic restoring means.

18 / - Orthosis according to claim 17, characterized in that the adjustment means (29, 35, 36) are means making it possible to vary the corrected vertebrae, the elastic elongation of the elastic return means relative to their rest form.

19 / - Orthosis according to one of claims 17 and 18, characterized in that the means O 95/05

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(29, 35, 36) for adjustment include at least one device (35, 36) for adjusting the position of a support stop for elastic return means with respect to anchoring elements of a vertebra. 20 / - Orthosis according to one of claims 17 to 19, characterized in that the adjustment means (29, 35, 36) comprise transcutaneous or percutaneous control means after implantation of the orthosis.

21 / - Orthosis according to one of claims 17 to 20, characterized in that the adjustment means comprise at least part of the holding means and / or elastic return means formed of metal alloy with shape memory.