FR2709245A1 - Internal dynamic vertebral orthesis - Google Patents

Abstract

The invention relates to a device for correcting vertebral deformations while at the same time preserving the movements of the vertebral column. This device consists of a hook plate (1) which is fixed on the vertebra at 3 points (transverse apophysis, pedicle, and spinous apophysis). Each hook plate comprises a cylinder (15) which contains either a second cylinder (17) for fixing the rod (24), or a ball (18) which permits the sliding of this rod (24) whose curvature (in terms of its rotation) ensures correction both of kyphosis/lordosis and vertebral derotation. Springs (27) around the rods (24) bear on the cylinders (15) so as to effect compression of the convexity of the column by means of tensioning or to effect detraction of the concavity of the column by means of compression.

Description

L) ESCRlPTION
The present invention relates to a device for correcting vertebral ueformations while retaining movements in the spine which will be as physiological as possible.

TITLE
Dynamic Internal Vertebral Orthosis AND PREVIOUS TECHNIQUE: It performs
- either a rigid intervertebral osteosynthesis allowing the deformations to be corrected and the vertebrae to be immobilized until the arthrodesis obtained by a graft
- or a "flexible" stiffening of the spine so as to reduce movement and therefore the arthritis pain associated therewith.

LONG wERTERRAL ORTHESIS
It is used for the correction of vertebral derormations such as scoliosis and / or kyphosis and is based on at least 3 vertebrae with 2 intermediate vertebrae which allows the correction of 5 vertebrae
It consists of 4 main elements
- the Hook Plate:
The plate (1) of hemispherical section rests forward on the posterior vertebral arch and therefore follows the contours of the spinous process, the blade and the transverse process by being unilateral or bilateral with respect to the spinous process, It involves
+ a bone face (2) made of porous metal of the diamond tip type and which can be covered with hydroxyapatite in order to allow better bone-material cohesion.

+ one end (3) fixed on the spinous process
the flat (or curved) face rests on the bone
the hemispherical rear face has a terminal bulge (7) which ensures better stability of the fixing means which can be
- either a metal banding or a self-locking synthetic material around the spinous process,
- or a double metal hook (4) vertically gripping the spinous process whose contours it closes closing with a vertical self-locking screw and 5) which can be located at the top or bottom relative to the spinous process. It also has a horizontal clamp (6) which encloses and secures the whole plate-spinous process = adapted to the hemispherical shape of the plate on both sides if the plate is bilateral or on one side to the spinous process and the 'other to the plate if the latter is unilateral.

 This double hook is located in front of the terminal bulge (7) of the plate which therefore serves to stabilize it by blocking its sliding towards the point of the spinous process.

 The plate is perforated horizontally (8) opposite the pedicle to allow the passage of an intrapedicular screw (9) which will fix it to the latter.

+ the transverse end (10) which has 2 parts:
a fixation on the transverse process which is done by a vertical clamp formed by 2 hooks (ll) which are supported respectively on the upper and lower edge of the transverse; they are tightened by a vertical screw (12) which separates their posterior ends, thus making them pivot on their horizontal axis (13) and therefore brings their hooked ends (14) which enclose the transverse process.
the cylinder (15): it is a postero-external reinforcement of the plate perforated vertically to allow the passage of the rod It is of 2 types
- simple cylinder comprising a transverse screw (16) used to block the rod therein. Its internal diameter is fixed by about 10mm allowing it to receive a second cylinder (l7) split over half its length for the passage of the screw: this 2nd cylinder has its fixed external diameter (adapted to that of the internal cylinder) and its variable internal diameter as adapted to the diameter of the rod chosen This 2nd cylinder therefore serves as a wedge for fixing the rod to the hook plate
- cylinder containing a movable sphere (18) relative to it and also perforated from top to bottom for the passage of the rod which centers it - This sphere allows the rod to move.
free longitudinal sliding,
of rotation (along the axis of the rod and therefore theoretically 360)
free vertical angle of at least 45 "in relation to the plate
This sphere has a fixed outer diameter which is adapted to the cylinder but its central perforation (19) will vary to adapt to the diameter of the rod chosen according to the dynamometric data obtained during the installation of the system.
After its insertion in the cylinder the sphere will be locked there without being blocked to allow it to rotate
This blocking is done:
either by a self-locking system of a block of polyethylene (20) contained in the cylinder and whose "entry" diameter and slightly less than the largest diameter of the sphere so as to prevent its exit after it has been there inserted in force,
either by a screw (21) closing the cylinder above or below, itself perforated to allow passage of the rod.

 This sphere, rotating in the cylinder and allowing the sliding of the rod, will therefore be of the same metal as that composing the entire assembly. It can also be made of ceramic or polyethylene in order to promote different movements while reducing friction forces as much as possible.

 The springs surrounding the rods will come to bear on the upper and lower parts of the cylinders when they have to work in compression. If they have to work in tension, they will always be centered by the rod and will be fixed to the surface of the cylinder on a lug (22) located laterally.

In the case of using a bilateral hook plate, the latter is symmetrical with respect to the spinous process on which it is fixed as described above. If the mounting action needs to be bilateral, the hook plate has a cylinder on each side. If one wishes to act only unilaterally on the vertebrae, the hook plate can however be bilateral: its role and then to ensure better fixation (in 5 points: 2 on the transverse, 2 on the pedicles and 1 on the thorny) of the assembly on the vertebra and it does not include a cylinder (23) unlike the "corrector" side
- the Intrapediculary Screw -
Passed from back to front in the orifice of the plate first, then in the axis of the pedicle, it ends in the spongy vertebral body.

 It has a countersunk head which allows it to adapt to the corresponding orifice of the plate which it presses tightly against the posterior arch.

 Cortico-cancellous threading is carried out over the entire length of the screw to the base of the head.

 The diameter and the length are variable according to the vertebral level instrumented and are therefore respectively from 3 to 7mm for the diameter and from 25 to 55mm for the length.

 It is made of stainless steel or a titanium type alloy to be compatible with the other elements.

- the Rod (24):
Metallic (stainless steel or titanium type alloy), it is of smooth circular section whose diameter, from 2 to 8mm, varies according to the mechanical characteristics which are required of the rod after having been determined intraoperatively by the dynamometric clamp.

 It has at its periphery 3 longitudinal rails (25) projecting, of triangular section with base supported on the rod, and each achieving a prominence of lmm to the surface of the rod positioned at L20 "from each other.

 Its length varies from 5 to 30cm depending on the number of vertebrae that one wants to instrument. It forms a variable curvature which is pre-established during manufacture and will therefore be used either to create the kyphosis or the desired lordosis in an isolated manner or to obtain at the same time the desired correction of a scoliotic vertebral curvature by flexibility and the elasticity of the rod according to the position of rotation given to the latter during fixing in the cylinder.

It is slid into the cylinders of the transverse ends of the hook plates and is fixed at a single point (preferably on the hook plate located in the center of the assembly) by the screw (16) of the transverse end on the central cylindrical bulge that it contains
At the level of the other hook plates, it slides freely in the spheres included in the transverse ends. The rod is in contact with these spheres only by the projection of the 3 longitudinal rails which aim to facilitate sliding while reducing the friction forces.

The ends of the rod are
+ be free and therefore 1 to 3cm beyond the end of the hook plate in which it slides
+ either threaded and then receiving a nut (26) which will block the spring (27) which is inserted around the end of the rod and which also rests on the hook plate. The rod then exceeds the hook plate by 2 to 5 cm depending on the length of the spring that we want to use, which is determined by the correction forces measured with the torque clamp.

 + is also threaded but without interposition of spring, the nut only serving to block the possible "disassembly" of the rod-plate-hook assembly during untimely movements.

 + the nut is perforated at its periphery with 6 holes allowing the hooked end of the spring which works in tension to be fixed.

- the Springs (27):
They surround the rods and work either in compression or in tension on the transverse ends of two consecutive hook plates or on the end of the rod and the adjacent hook plate.

 Their own diameter varies from 1 to 4mm depending on the force which will be required of them (determined by the torque clamp). The diameter of the spiral which they produce has an internal diameter greater than 0.5 to 1 mm than that of the rod (taking account of the longitudinal rails) which they surround.

 Their length depends on the space existing between two consecutive hook plates or the hook plate and the nut of the end of the rod and also varies with the force which one wants to apply between these points (in compression or in tension) which is determined by the torque clamp.

Their ends are =
either flat (28) to bear directly on the transverse ends of the hook plates and the terminal nuts of the rods when they are working in compression;
either, when it is desired that they work in tension, ending with an eccentric ring (29) at each end to be fixed on the lug (22) provided for this purpose on the transverse end of the hook plate; they end with a hook (30) which is fixed on the terminal nut (26) of the rod when they are placed at the end of this rod.

 In the case of insertion of the material on a growing spine, the forces determined at the time of instrumentation will be modified by this growth.

The increase in the length of the spine but also in the weight of the body and the strength of the muscles can make the material placed insufficient and therefore see the recurrence of the deformation
If the modification of these factors is major a reintervention is necessary with change of the rods and springs, the hook plates fixed to the bone remaining unchanged.

 In the case of a moderate variation of the forces, it is possible to obtain compensation for these new forces by acting on the springs by means of electronic micro-motors or mechanical tensors.

Placed during the 1st intervention around the rods, they will allow:
- either to "recompress" the springs which work in compression by reducing their length,
- or to "tighten" the springs which work in tension by increasing their length.

Electonic Micro-Motor (31):
+ Cylindrical shape 1 to 2 cm high,
Its outside diameter is variable depending on the components necessary to obtain the desired force but from 20 to 30mm approximately.

Hollow in its center, its internal diameter is 1 to 2mm greater than that of the rod it surrounds (and therefore which serves for its stability) in order to allow the latter the necessary free movements
+ Its supports: it is positioned between the cylinder of the hook plate and the spring on which it will act. It is absolutely not fixed and is therefore supported, up or down either =
on the one hand on the cylinder of the hook plate,
on the other hand on the spring which works in compression and whose length it will reduce.

If it has to act on a spring which works in tension, it will position itself on the other side (32) of the hook plate relative to the spring which it has to extend. The spring will therefore be fixed
on one side on the lug (22) of the cylinder
- on the other side on the distal end of the engine by its hook (30) which will pass in bridge next to the 2nd cylinder on which it will act.

 + Its power supply: by lithium micro-batteries activating the electronic or ultrasonic micro-motor.

 + Its order = it must be done cross-skinned by an electromagnetic or other remote control without requiring a skin incision.

 + Its function = it must thus be lengthened according to the needs of the correction from 1 to 20mm approximately to reduce or increase the corresponding spring accordingly.

The Tensor (33):
+ Its cylindrical shape, its supports, its position and its function are completely comparable to those of the electronic micro-motor
+ It is mobilized by a central (34) and lateral screw whose rotation drives a toothed wheel located at the end of the axis of the screw. This gear causes by its rotation the sliding in opposite direction of 2 corresponding notched rods and each secured to one of the 2 upper or lower plates of this tensor. I1 will therefore realize, like the micro-motor, a variation in length from 1 to 20mm of the spring on which it must act.
+ Its control is done by rotation of the screw by a percutaneous screwdriver and under local anesthesia. The precise location of the screw is done under image intensifier control.

SHORT VERTEBRAL ORTHESIS
It is used in cases where one wants to reduce the efforts required of the spine without reducing mobility; therefore most often in the case of chronic painful instability associating more or less anterior disc disease and posterior apophyseal arthritis.

 It instruments from 2 to 4 consecutive vertebrae, each of which receives the hook plate system.

- The Hook Plate (35) r
it is an element quite comparable to that described for the long system, the only variant residing in the sphere contained in the transverse end (36) - this spnere includes a peripheral ring37) (Saturn ring type) located in the frontal plane and which therefore blocks the flexion-extension movements of the rod which always slides freely in this sphere. These latter movements are however possible in relation to the flexibility of the rod itself and the elasticity of which brings the vertebrae back to the desired kyphosis or especially lordosis position. The sphere therefore allows lateral movements of the rod in the frontal plane of about 45 to admit free vertebral inclinations.

 - The Intrapediculary Screw and 9) - identical to that used for the long system.

- The Rod (38)
Comparable in all points to that described for the long system, its particularities are:
+ its length: from 5 to ZOcm depending on the number of instrumented vertebrae
+ Its attachment to the hook plate is located at the end of the rod in the case where the assembly is carried out on two vertebrae and can be central or terminal if the assembly involves three or more vertebrae. The terminal fixation is done on the upper or lower vertebra; it is reinforced by a nut (39) (fixed on the threaded end of the rod) which comes to rest on the hook plate to secure it with the rod. It is mainly fixed in lordosis so as to reduce the loads on the discs; this lordosis is in fact maintained by the spheres whose "central frontal crown blocks any movement of anterior flexion of the hook plates relative to the rods. Only the flexibility of the rods can allow the anteflexion of the spine.

 - The Springs (40): remain identical to those described for the long orthosis system. They work mainly in compression to "unload the posterior vertebral joints. Since this material is mainly intended for adults no growth is to be expected at the vertebral level: the micro-motor or the tensor are therefore only to be expected in the case where we want to achieve a variation of the forces exerted by the springs if the latter cannot be determined with sufficient precision during instrumentation.

NNCILLIRE EQUIPMENT: DYNAMOMETRIC PLIERS (41) (Fig. 6 and 7)
It is used on the one hand for the intraoperative correction of the vertebral deformation in 3 dimensions and on the other hand it makes it possible to evaluate the forces and displacements necessary for the conservation of this correction. It acts on 3 consecutive hook plates and homolateral. It will therefore provide us with decisive data in the choice of rods and springs which will carry out the correction expected by this Dynamic Internal Vertebral Orthosis.

 It is formed by two main branches (42) and an intermediate branch (43), all three resting on the same transverse axis (44).

The two main branches are articulated in their center by a vertical axis (45) but do not intersect which allows reverse movements of their ends:
- The vertebral ends (46) are fixed by lugs (47) which penetrate into the corresponding orifices provided (48) in the transverse ends of the hook plates. These vertebral ends of the clamp can be rotated by L80 according to a pivot (49) so as to achieve either the approximation (compression) or the distance (detraction) of the vertebrae concerned, These two main branches will therefore rely on the vertebra extremes of mounting above and below.

The pins are mounted on spheres (50) included in the end of the rod and which will allow their orientation as a function of that of the hook plate fixed on the vertebra
- The dynamic ends are articulated (51) to the transverse axis (44) which secures them; they will be brought closer or further apart by the rotation of the handle (52) located in the extension of the axis on which they move, The rotation of this axis (44) causes the displacement of the most distal branch by a step of screws (53).

 Their displacements generate at the other end vertebral compression or detraction by compressing 2 transverse springs (54) (one for each of the respective actions).

 The compressive forces of these springs are measured by dynamometric sensors (55) located on the main axis of the clamp. The values are recorded instantaneously on a cathode screen and make it possible to determine the choice of rods and springs adapted to the desired correction.

 Given that the vertical axis (45) of rotation of the clamp is located at equal distance from the vertebral and dynamic ends we also have, in direct reading on a graduated scale (56) on the axis of the clamp, the displacement between the 2 extreme vertebrae. These instantaneous data will be modified by the action of the third branch of the forceps on the vertebral deformation.

The intermediate branch, 43) (the 3rd) of this clamp is secured to the other two by relying movably on the transverse axis of movement of the dynamic ends of the two main branches; it attaches to the other vertebral end in the same way as the two main branches at the transverse end of the hook plate by a fixed lug (57) not mounted on a ball joint. In the center, it solidifies with the other 2 branches at their vertical axis of rotation (45) which it surrounds since a central recess (58) allows it to move longitudinally. It performs a double displacement of the central vertebra of the assembly
- a longitudinal displacement in the axis of the forceps (transverse to the axis of the spine) in order to reduce the curvature in the frontal plane: it is provided by the handle (59) whose axis of rotation is placed in the extension of this intermediate branch. The displacement is evaluated by direct reading on a scale (60) located on the rod of this branch (60). The correction force applied to the central vertebra performs the compression of a longitudinal spring (61>: a dynamometer (62) measures this force and transmits the information to the cathode ray tube for instant reading.

 - a posterior or anterior displacement of this intermediate vertebra: the point of application of the force being unilateral, the latter will cause vertebral de rotation in the horizontal plane and a kyphosis or lordosis by moving, in the sagittal plane, posteriorly or anteriorly , this vertebra compared to the other two instrumented.

 A thread (63) ensures the vertical displacement of this axis (45) which is mobilized by a vertical handle (64) located at the end of this axis. Depending on the direction of rotation chosen, a posterior displacement in kyphosis or an anterior displacement in lordosis is obtained. There are 2 vertical springs (65) and two dynamometric sensors (66) which allow the displacement and the forces necessary for this reduction to be evaluated as before. .

 For educational and clarity purposes, the action of each of the branches of this clamp has been described successively but it is obvious that the effect of each (both in displacement and in force) is closely related to the effect produced and obtained by the other two branches.

 The system will be considered in equilibrium "when the correction has been obtained in all planes and confirmed by two front and side views of the spine in this state under the action of the torque clip.

The data collected by the sensors will then allow the choices:
- on the one hand of the rods: diameter and curvatures
- on the other hand springs: length and force.

 The mounting of the rods, springs and electronic or mechanical spacers on the hook plates is carried out while the torque clamp maintains the correction position. This clamp is removed after stabilization of all the elements as described above.

In the case of bilateral instrumentation, it is obvious that two dynamometric clamps will be necessary to achieve their effects simultaneously = one in compression on the convex side of scoliosis, 15 the other in detraction on the concave side
If a large vertebral curvature in C justifies the instrumentation of 5 vertebrae (9 levels since the hook plates are positioned every 2 vertebrae), a 2nd dynamometric clamp is used: it only includes the 2 main branches which are supported on the upper and lower end vertebrae The intermediate branch (43) is removable after dismantling at the level of the two transverse (44) and vertical (45) axes.

Claims (1)

RESEND1CTIONS 1) Device. to correct vertebral deformations and stabilize degenerative lesions of the spine while retaining its movements in the spine, characterized in that it consists of the combination of anchoring elements and at least 1 of the 2 connecting elements after: a) anchoring elements on the vertebrae preferably produced by hook plates (1 or 35), formed from biocompatible metal alloys, intended to come to bear on the posterior vertebral arch where the fixation can be done by 2 to 5 points by possibly associating the grip on the process (es) epineuseis) by in particular a double hook (4) and fou on the (the) pedicle (s) by a screw (9) stfou on the (the) transverse process (es) by hooks (11}, interconnected by b) one or more elements) for guidance and / or elastic return which are preferably at least 1 or 2 flexible rods (24 or 38 ), made of biocompatible metal alloys, arranged) lon gitudinally on or on each side of the vertebral spinous processes, which can be rigidly associated with an anchoring element and movably with the other anchoring elements with at least one degree of freedom in translation longitudinal but possibly degrees of axial rotation and / or angulation in the frontal and sagittal planes, and whose mechanical characteristics as elastic return means by effect of recovery of its initial curvature, are determined to obtain either the realization and the maintenance desired correction positions, namely the reduction of the forces supported by the degenerative vertebral discoarticular structures,  c) compression or traction elements, in particular helical springs (27 or 40), elastic means capable of surrounding the guide elements, formed of biocompatible metal alloy, interposed between the anchoring elements on which they are fixed, intended to work on the vertebrae either alone or in addition to the guide elements in order to ensure the same correction and / or the same vertebral support 2) Device according to claim 1) characterized in that the bone face (2) of the plate- hooks (l or 35), intended to follow the contours of the posterior vertebral arch, can optionally be made of porous metal of the "diamond point" type and / or covered with a material facilitating bone integration + hydroxyapatite or other.  3) Device according to claim 1 or 2 characterized in that the hook plate (l or 35) may optionally include a terminal bulge (7) which ensures better stability of the fixing of this hook plate (l or 35) on the spinous process. 4) Device according to claim 1 or 3 characterized in that the hook-plate or 35), single or double, can be fixed to the spinous process optionally by a rim either metallic or self-locking synthetic material. 5) Device according to claim 1 or 3 characterized in that the hook-plate 1 or 35), single or double, can be fixed to the spinous process optionally by a double metal hook (4) intended to ensure, on the one hand a vertical stabilizing clip directly supported on the bone by a preferably self-locking screw (5) located at the top or bottom of this process, and / or on the other hand a horizontal clip (6}, adapted to the external hemispherical shape of the hook plate (1 or 35) uni- or bilateral, and aiming to secure the assembly against the bone 6) Device according to claim 1 or 2 characterized in that the hook plate (l or 35) intended to adapt against the posterior arch of the vertebra will be fixed there optionally by an intra-pedicular screw (9) which passes through 150rifice (8) formed in this hook plate opposite the corresponding pedicle 7) Device according to claim 1 or 2 characterized in that the hook plate s (l or 35) intended to adapt against the posterior arch of the vertebra possibly includes a fixation on the transverse process which is done by 2 hooks which enclose it, by resting respectively on its upper and lower edges , under the action of a vertical screw (12) which rotates them about their horizontal axis (13} so as to bring them closer to this transverse process 8) Device according to claim 1 characterized in that the hook plate ( l or 35) has or does not have (23) near its transverse end a reinforcement which may be of the cylindrical type (15) perforated vertically to allow the passage of a rod (24) and therefore providing the connection between the anchoring elements and the guide element (s) either by fixing the rod (24) possibly with a transverse screw (16) and a second cylinder (17) acting as a wedge between the variable diameter of the rod and the cylinder ( 15), either by allowing sliding and / or the angulations and / or rotations of this rod (24) in particular by a sphere (l8) mobile in rotation and contained in the cylinder (15) itself which has on its lateral surface a lug (22) for fixing the rings eccentric (29) springs (27) which work in tension. 9) Device according to claim 8 characterized in that the sphere (18), intended to adapt to the variable diameter of the rod (24), is enclosed secondarily in the cylinder (lS) or by a self-locking block (20) peripheral (possibly polyethylene) whose entry diameter is slightly smaller than that of the sphere (18), either by a screw (21) closing the cylinder (15) above or below but perforated, as the polyethylene block, to keep the free movement of the rod (24). 10) Device according to claim 1) characterized in that the rod (24) is preferably of smooth circular section and may comprise at its periphery at least 3 longitudinal rails (25) projecting, positioned at l20e from each other, of triangular section with base supported on the rod (24), so as to reduce as much as possible the frictional forces with the sphere (18) which allows this rod to be movable at one or both ends while it can be fixed at one end or in the center in a cylinder (15) and possibly end with threads intended to receive nuts (26), perforated with several holes at their periphery, which on the one hand prevent externalization of the rod (24) relative to the sphere (18) and on the other hand the support of the springs (27). ll) Device according to claim 1) characterized in that the springs (27) have either flat ends (28) for working in compression between 2 consecutive cylinders Il5) or between the nut (26) of the end of the rod and the neighboring cylinder (15), either ends preferably of the type of eccentric rings (29) or hooks (30) intended to be fixed respectively on the lug (22) of the cylinder (15) or on the terminal nut (26) of the rod (24) 12) Device according to claims 1) and 11) characterized in that an electronic micro-motor (31} ensures by its variation in length (or height) the possible voltage variation of the springs (27), also being inserted around the rod (24) between the cylinders (15) and the springs (27) of which it will increase compression or traction, while allowing in its hollow center the free movements of the stem (24) and the post-operative actuation of which is carried out transcutaneously under the eventual effect tuel of microwaves or electromagnetic waves 13) Device according to claims 1) and 11) characterized in that a tensor 33) ensures by its variation in length (or height) the possible variation in tension of the springs (27) , also being inserted around the rod (24) between the cylinders 15) and the springs (27), the compression or traction of which it will increase, while allowing the free movements of the rod (24) in its hollow center and whose the post-operative action is optionally done percutaneously, under ultrasonic or radiographic control, by rotation of a lateral screw which achieves the desired length variation for correction. 14) Device according to claim 1) characterized in that the hook plate35) of the short vertebral orthosis optionally comprises in the cylinder of its transverse end (36} a sphere (37) surrounded by a solid peripheral ring, ring type of Saturn, located in the frontal plane and aimed at blocking the movements of flexion-extension of the rod (24) while preserving its rotational movements on itself and lateral angulations. 15) Torque clamp (41) intended for the insertion of the correction device according to any one of claims 1) to 14) characterized in that it comprises  a) two main branches (42) moving along a transverse axis (44) and hinging in their center on a vertical axis C45) without intersecting so that their vertebral ends46) and their dynamic ends (51) perform reverse displacements ,  b) an intermediate branch 43) resting on the one hand on the transversalt axis 44) to effect transverse displacements, on the other hand on the vertical axis (45} to effect antero-posterior displacements. 16) Torque clamp (41) according to claim 15) characterized in that its vertebral ends (46) can be fixed on the hook plates (l) optionally by lugs (47) intended to penetrate into the corresponding orifices (48) of the transverse end (10) and can be mounted on spheres (50), included in the vertebral ends (46), to allow them to orient themselves precisely with respect to the position of the hook plate (1} fixed on the vertebra. 17) Torque clamp (41) according to claim 15) characterized in that its articulated dynamic ends (51) are brought closer or apart by the rotation of the transverse axis (44) effected by means of a handle (52) which acts on the most distal branch by a thread of screw (53). 18) Torque clamp (41) according to claim 15) characterized in that its vertebral ends (46) can be rotated 180 by a pivot (49) in order to achieve either the approximationtcompression) or the distance (detraction) of the plates crochetst1) on the instrumented vertebrae. 19) Torque clamp (41) according to claim 15) characterized in that the dynamic ends (51) on 1 transverse axis (44) include transverse springs (54} which are put in compression by their movements (in compression or in detraction). 20) Torque clamp (41) according to claim 15) characterized in that dynamometric sensors (55} located on the transverse axis (44) measure the compressive forces of the transverse springs (54}. 21) Torque clamp (41) according to claim 15) characterized in that a graduated scale (56) located on 1 transverse axis (44) makes it possible to directly measure the displacements of the vertebral ends (46), which can also be recorded from sensors (55). 22) Torque clamp (41) according to claim 15) characterized in that the intermediate branch (43) is secured to the other two main branches (42) by being movably movable longitudinally on their transverse axis (44). 23) Torque clamp (41) according to claim 15) characterized in that the intermediate branch (43) is secured to the center of the two main branches {42} on the vertical axis (45) which surrounds by a central recess (58) allowing it to carry out its longitudinal movements 24) Torque clamp (41) according to claim 15) characterized in that the rotation of a longitudinal handle (59) ensures the longitudinal displacements of the intermediate branch (59). 25) Torque clamp {41} according to claim 15) characterized in that the graduated scale (60) gives a direct reading of the displacements of the intermediate branch (43) while the dynamometric sensor62) evaluates the forces necessary for these displacements under the compressive effect of the spring (61).  26) Torque clamp (41) according to claim 15) characterized in that the handle (64) which generates the rotation of the vertical axis (45) on a thread (63) thus ensures the vertical displacements of the intermediate branch (43). 27) Torque clamp (41) according to claim 15) characterized in that the dynamometric sensors (66}, stimulated by the springs (65), make it possible to evaluate the forces necessary for the vertical displacements of the intermediate branch (43) which carry out displacements in kyphosis or lordosis of the vertebrae. 28) Dnamometric clamp (41) according to claim 15) characterized in that the intermediate branch (41) is removable from the transversalt44) axis and the vertical axis (45) allowing the clamp to be used with only its two branches main (42) "