WO2015025108A1

WO2015025108A1 - Osteosynthesis plate provided with a positioning assistance element

Info

Publication number: WO2015025108A1
Application number: PCT/FR2014/052102
Authority: WO
Inventors: Pierre Dominique RICHERME; Lionel CALAMEL; Christophe TAMBURINI
Original assignee: Yellowsteps
Priority date: 2013-08-19
Filing date: 2014-08-19
Publication date: 2015-02-26
Also published as: FR3009678B1; FR3009678A1

Abstract

The invention relates to an osteosynthesis plate (1) designed to be fastened on the bone mass of a patient's vertebral column (2), and comprising at least one pair of wells (9) each having a geometric centre, and each being associated with at least one fastening screw (10) in order to fasten said plate (1), said plate (1) comprising at least one positioning assistance element (4) to guide the movement of said plate (1) along at least one distraction rod (8) fastened on the bone mass in order to fasten said plate (1), said plate (1) being characterised in that it comprises at least one retaining blade (11) mounted on said plate (1) around an axis of rotation substantially aligned with each of the geometric centres of the wells (9), the retaining blade (11) being designed to move between a position partially obstructing the two wells (9), and a position releasing said fastening screws (10). Orthopaedic implant.

Description

DOSSEOSYNTHESIS PLATE WITH AN ASSISTANCE ELEMENT

POSITIONING

TECHNICAL AREA

The present invention relates to the general field of surgical devices for osteosynthesis of the spine, and concerns in particular the osteosynthesis plates.

The present invention relates more particularly to an osteosynthesis plate intended to be fixed on the spine of a patient by means of fixation on the bone mass of said spine, and comprising at least one pair of wells each having a geometric center, each well being associated with at least one fixing screw for forming said fastening means, said plate comprising at least one positioning aid element arranged through said plate, and comprising guide means designed to guide the movement of said plate to the bone mass and along at least one distraction rod fixed on the bone mass of said patient's spine, to help positioning said plate for attachment to said spine via the fixing means.

The present invention also relates to a medical kit formed by an osteosynthesis plate and at least one distraction rod intended to contribute to the positioning of the plate for attachment to the spine of a patient.

PRIOR ART It is known to use implants of the osteosynthesis plate type to treat different paihologies of the spine of a patient such as, for example, vertebral collapse, scoliosis, lordosis, kyphosis or vertebral instability. In particular, osteosynthesis plates are used in the treatment of cervical pathologies, for example to stabilize and reconstruct the cervical spine of a patient. These pathologies are cited of course by way of illustration and not limitation. It is known to implant osteosynthesis plates anteriorly, laterally or posteriorly, sometimes in combination with other implants such as an intersomatic cage, or a corporectomy cage.

The osteosynthesis plates are provided with spinal fixation means for attaching said plates to the patient's spine. Such fastening means generally consist of the combination of wells formed through the plate, through which are threaded fastening screws designed to be screwed into the bone mass of the spine to secure the plate with the patient's spine.

They thus make it possible, for example, to strengthen a bone of the rachis, or to immobilize two bones of the rachis with respect to one another.

The proper functioning of the osteosynthesis plate thus lies in its safe positioning and its connection with the patient's spine, which must be carried out very precisely in order to effectively treat the pathology while minimizing the trauma generated by the operation. . When placing the plate, generally performed by screwing into the bone mass of the spine, it may be difficult to insert all the screws at a satisfactory location of the bone mass of the spine so that the plate is placed in a correct and sustainable way. Indeed, maintaining in position both the bone and the plate before attachment thereof to the spine is a delicate operation and can, therefore, lead to imprecise positioning of the plate or its attachment means. A bad positioning of the plate is obviously not desirable, for example in the case where said plate must be fixed on two different bones movable relative to each other, the establishment of the plate defining the relative position subsequent and definitive of the two bones relative to each other, such a position being difficult to modify thereafter. Furthermore, improper placement of the fastening means, in particular resulting from misplacement of the plate, may result in improper attachment of the bone plate, which may for example result in a subsequent migration or separation of the plate. plaque and have particularly harmful consequences for the patient. The known osteosynthesis plates are generally flat, which allows them to adapt to most geometric configurations of the bones. On the other hand, it may be difficult to set up accurately and durably, the flat surface of the plate in contact with the bones of the spine whose shape is irregular, and unsuitable for stabilizing the position of said plate. It is then possible to use custom shaped plates depending on the location situation, which has the disadvantage of increasing the cost of the plate. In practice, such a plate is often used to maintain two bones of the spine in a precise relative angular orientation of several degrees, for example to apply lordosis to the spine. In particular, when the orientation between two bones has a high angle and the surgeon has only a flat plate, it may be caused to bend or slightly twist the latter prior to its introduction, such an operation being particularly imprecise. The surgeon may alternatively use a specialized shaped plate, which in turn incurs an additional cost. In addition, such an operation is often consistent and frequently performed under general anesthesia of the patient. It therefore requires to be performed in a limited time, so that the surgeon must be able to set up the plate so both accurate and fast, which can be difficult in practice, especially because of the lack of means to ensure and / or verify that the plate has been put in place adequately.

Also, access to the spine, particularly anteriorly, is often made difficult by the presence of fragile vital organs, or major arteries, so that the implantation of the fixation means in the bone, if it fails , can lead the surgeon to commit decisive body damage affecting the well-being, health, or even survival of the patient. The space available for the passage of tools is mostly very small, leaving little freedom of movement to make a precise placement without reaching nearby body parts. The spine itself presents a certain fragility, an undesirable lesion being likely to cause irremediable consequences for the health of the patient, so that any positioning error or failure to set up the attachment means is to be avoided rigorously. Thus, the osteosynthesis plates known in the art do not not seem able to guarantee the surgeon the absence of health risks for the patient when positioning them.

STATEMENT OF THE INVENTION

The objects assigned to the invention therefore aim at remedying the various aforementioned drawbacks and at proposing a new bone plate and a new medical kit allowing a correct and particularly easy placement of said plate to treat a pathology in a satisfactory manner. minimizing the traumatic consequences of the intervention.

Another object assigned to the invention is to propose a new osteosynthesis plate and a new medical kit whose installation is facilitated, whatever the means of attachment.

Another object assigned to the invention is to propose a new osteosynthesis plate and a new medical kit allowing easily and precisely maintain two bones of the spine of a patient in a precise relative position, for example in lordosis.

Another object assigned to the invention is to propose a new osteosynthesis plate and a new medical kit of moderate cost compared to the plates of the prior art, and adapting to many configurations.

Another object assigned to the invention is to propose a new osteosynthesis plate and a new medical kit to improve and facilitate the establishment of fastening means to reliably secure the plate while minimizing the risks. related to this implementation.

Another object assigned to the invention is to propose a new osteosynthesis plate and a new medical kit enabling the surgeon to verify precisely and quickly whether said plate is positioned adequately.

The objects assigned to the invention are achieved with the aid of an osteosynthesis plate intended to be fixed on the spine of a patient by means of attachment to the mass. bone of said spine, and comprising at least one pair of wells each having a geometric center, each well being associated with at least one fastening screw to form said fastening means, said plate comprising at least one positioning aid element arranged at through said plate, and comprising guide means adapted to guide the movement of said plate to the bone mass and along at least one distraction rod attached to the bone mass of said patient's spine, to assist positioning of said plate for attachment to said rachis via the fixing means, said plate being characterized in that it also comprises at least one rotatable retention blade rotatably mounted on an accessible face of said plate around an axis of rotation substantially aligned with each of the geometric centers of the pair of wells, the retention blade being adapted to rotate in rotation between a posit partially obstruction ion of the two wells to retain the two fixing screws in said two respective wells, and a release position in which it does not retain said fixing screws in said wells.

The objects assigned to the invention are also achieved by means of a medical kit formed by an osteosynthesis plate according to the invention and at least one distraction rod intended to contribute to the positioning of the plate with a view to its fixation. at the spine of a patient. SUMMARY DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the invention will appear in more detail on reading the description which follows, and with the aid of the accompanying drawings, provided for purely illustrative and non-limiting purposes, among which:

- Figure 1 illustrates in perspective view an osteosynthesis plate according to the invention, associated with two distraction rods.

- Figure 2 shows in perspective view the osteosynthesis plate of Figure 1 before its introduction on the two distraction rods. FIG. 3 illustrates in a perspective view the osteosynthesis plate of FIG. 1 placed along the distraction rods on the spine of a patient.

- Figure 4 illustrates in perspective view the osteosynthesis plate implemented in the manner of Figure 3, further comprising the fixing means. - Figure 5 illustrates in perspective view the osteosynthesis plate set up in the manner of Figure 4, and for which we removed the distraction rods and locked the fastening means.

BEST MODE OF REALIZING THE INVENTION

The invention relates in a first aspect to an osteosynthesis plate 1. The osteosynthesis plate 1, as represented in the figures according to a nonlimiting preferred embodiment, is of generally flat and rectangular shape, and comprises an accessible face 20 opposite to a bearing surface 21, intended to bear against the bones 3 of the patient. The term "accessible face 20" means the face that is visible by the surgeon when the plate 1 is in place and fixed on the bones 3 of the patient. The accessible face 20 is advantageously opposite to the bearing face 21, which forms the second face of the plate 1, and which is preferably intended to be hidden from the view of the surgeon when the plate 1 is in place on the bones 3 of the patient, the plate 1 resting on said bones 3 via the bearing surface 21. The outer edge 25 of the plate 1, as well as the angles and the edges of said plate 1 are preferably chamfered or rounded, so as to be soft and not sharp so as not to damage the patient's tissues. The plate 1 is preferably substantially symmetrical with respect to at least a first axis XX 'defined by the major axis of the generally rectangular shape of the plate 1, and preferably with respect to a second axis YY' perpendicular to the axis XX , corresponding to the minor axis of the generally rectangular shape of the plate 1. The osteosynthesis plate 1 according to the invention makes it possible to treat various pathologies of the spine 2 of a patient, such as, for example, vertebral collapse, scoliosis, lordosis, kyphosis or vertebral instability. The osteosynthesis plate 1 is preferably used in the treatment of cervical pathologies, for example to stabilize and reconstruct the cervical spine 2 of a patient. These pathologies are cited of course by way of illustration and not limitation.

According to the invention, the osteosynthesis plate 1 is intended to be fixed on the spine 2 of a patient.

Thus, the plate 1 is designed to be placed on the spine of a patient, preferably anterior, lateral or posterior. The plate 1 is intended to be brought into contact with the bones 3 of the spine 2 via the bearing face 21, whose shape is adapted to such contact, preferably being substantially flat to be adaptable to several geometrical configurations of bone, on the contrary of a personalized form corresponding to the irregular shape of the bones 3 against which it will be put in contact.

Preferably, the plate 1 is designed to be attached to two, three or more bones 3 of the spine 2, preferably cervical vertebrae 18 (as shown in the figures) in order, for example, to stabilize or immobilize the mutual position. said bones 3 when they are movable relative to each other. The establishment of the plate 1 according to the invention allows to position and maintain several bones 3 in a fixed and permanent relative position. In particular, the plate 1 can be used to maintain two bones 3 of the spine 2 in a precise relative angular orientation, preferably of several degrees, for example to apply a lordosis to said rachis 2.

Without departing from the scope of the invention, it is possible to envisage a plate 1 intended to be attached to a single bone 3 of the spine 2 in order to strengthen the structure of the bone, to help treat for example cracked bones 3 or weakened.

Furthermore, the plate 1 can be used in combination with other osteosynthesis implants, preferably spinal, such as an interbody cage, or a corporectomy cage. The plate 1 is preferably rigid and resistant to the forces generated by the bones 3 to which it is intended to be attached, for example tensile forces, compression or bending, especially when attached to several bones or fragments of 3 For this purpose, the plate 1 may preferably be made of a rigid and biocompatible material such as PEEK, titanium or stainless steel. Preferably, the plate 1 is made by molding and then by machining.

According to the invention, the plate 1 is intended to be fixed on the spine 2 by fixing means 19 on the bone mass of said spine 2.

The plate 1 can thus be fixed firmly and durably to the bone mass of the spine 2 by means of the fixing means 19. The fastening means 9 make it possible to fix the plate 1 by screwing, anchoring, gluing, impaction, or any other known means of the technique adapted to the fixation of the plate 1 on the bone mass of the spine 2. A preferred variant of the fastening means 19 will be described in more detail below. Preferably, the plate 1 is intended to be attached in particular to the vertebral body of one or more vertebrae 18 of the spine 2 by means of the fastening means 19, in order to be mounted along the spine 2, for example vertically . The plate 1 can be attached to cervical, thoracic or lumbar vertebrae 18 of the spine 2, preferentially to cervical vertebrae 18. According to the invention, the osteosynthesis plate 1 is intended to be fixed on the spine 2 of a patient by means of attachment 19 to the bone mass of said spine 2, and is characterized in that said plate 1 comprises at least a positioning aid element 4 arranged through said plate 1, and comprising guide means 5 designed to guide the movement of said plate 1 towards the bone mass and along at least one distraction rod 8 fixed on bone mass of said spine 2 of the patient, to assist in the positioning of said plate 1 for attachment to said spine 2 via the attachment means 19.

Furthermore, according to an important characteristic of the invention, the plate 1 comprises at least one positioning aid element 4 formed through said plate 1, which advantageously allows the surgeon to position the plate 1 on the spine 2 during the operation of the patient. In particular, according to the invention, the positioning aid element 4 makes it possible to assist the positioning of said plate 1 with a view to its attachment to said rachis 2 via the fastening means 19. Thus, the element of assistance at the position 4 makes it possible to accurately and quickly position the plate 1, before or during its attachment to the bones 3, by means of the fixing means 19. The plate 1 is therefore placed in a stable and safe position before and / or during attachment to bones 3 of the spine 2.

The positioning aid element 4 thus makes it possible to guarantee, or to help guarantee, that the fastening means 19 will be put in place on the spine 2 in an appropriate, precise and controlled manner, in order to reduce the risk of poor attachment of the plate 1 to the bones 3 and the risk of subsequent disconnection of said plate 1.

Preferably, the positioning aid element 4 advantageously allows positioning a plate 1 whose bearing face 21 is flat, or not in accordance with the shape of the bones 3 of the spine 2 on which it is preferably in contact. Of course, the positioning aid element 4 can also make it possible to position the plate 1 in the case where the bearing surface 21 substantially conforms to the shape of the bones 3 of the spine 2.

According to the invention, the positioning aid element 4 comprises guiding means 5 designed to guide the movement of said plate 1 towards the bone mass and along at least one distraction rod 8 fixed on the bone mass said spine 2 of the patient, as shown in Figures 1, 2 and 3.

The guide means 5 are adapted to interact with the distraction rod 8, with or without contact with the latter, in order to drive the movement of the plate 1 towards its final position on the spine 2, and then to ensure that it is in an appropriate position before it is fixed on the bone mass of the spine 2. The distraction rod 8 has a lateral surface 24 capable of interacting with the guiding means 5, and is therefore generally elongated, cylindrical or prismatic, lateral surface 24 being preferably smooth. Preferably, the distraction rod 8 is rigid, for example made of metal material. The distraction rod 8 comprises at one of its ends an implantation element 22, such as a self-tapping thread, particularly adapted to allow to firmly implant said distraction rod 8 in the bone mass of the spine 2, preferably in the body of one of the vertebrae 18 of the spine, preferably one of the cervical vertebrae 18.

Moreover, the distraction rod 8 preferably comprises an interaction element 23 with a tool, for example hexagonal panels distributed around its circumference, making it possible to implant said distraction rod 8 in the bone mass, for example by rotating the bone. said distraction rod 8 about its longitudinal axis. Of course another type of implantation element 22 and interaction element 23 may be envisaged without departing from the scope of the invention, since they allow to connect the distraction rod 8 to the bone 3 of the spine 2.

Preferably, the distraction rod 8 is implanted in bone mass of the spine 2 temporarily, and is intended to be removed once the plate 1 is positioned and fixed on said bone mass of said spine 2.

Preferably, the plate 1 comprises two positioning aid elements 4 each distributed at an opposite end of said plate 1, and allowing the sliding of said plate 1 along two distraction rods 8. In this way, the plate 1 can be guided along two axes at a time, so that the distraction rods 8 define the final position of said plate 1 more completely, in particular by suppressing a degree of freedom in rotation of said plate 1 of the made of the presence of two rods of distractions 8.

Preferably, according to a variant of the invention, said at least one positioning aid element 4 is in the form of an opening 6 passing through said plate 1, and whose walls 7 form the guide means 5 (such as as shown in the figures). Thus, the positioning aid and the guide of the plate 1 are made by threading the plate 1 on the distraction rod 8, and translation of said plate 1 along said distraction rod 8 until reaching the bone mass spine 2 (such as illustrated in Figures 2, 3 and 4). Preferably the opening 6 is wider than the distraction rod 8, so that the interaction between said opening 6 and said distraction rod 8 is loose or present play. It is possible, however, to consider that the size and the shape of said opening 6 is, on the contrary, adjusted to the lateral surface 24 of the distraction rod 8, in order to obtain a more precise guidance, by sliding.

According to another variant of the invention, said at least one positioning aid element 4 is in the form of a recess, or notch, formed on the outer edge 25 of the plate 1 (not shown in FIGS. figures). The wall of the recess then forms the guiding means 5, and is intended to come into contact with the lateral surface 24 of the distraction rod 8 in order to guide the plate 1 by sliding the recess, or to the notch, along said distraction rod 8.

Preferably, the opening 6 is in the form of an oblong hole whose length is aligned in the direction D-D 'from the outer edge 25 of said plate 1 towards the center of said plate 1.

Thus, the opening 6 is of elongated shape, for example oval or rectangular, so as to allow a game or a beat of the distraction rod 8 in one direction, and to restrict the play, or the beat, of the rod of distraction 8 in another direction. The opening 6 of obiongue form, then extends along the direction D-D ', which is preferably aligned with, or parallel to _3rd first axis XX' or to the second axis Y-Y '. Such an arrangement allows in particular the mounting of the plate 1 along the distraction rod 8 in a configuration where said plate 1 is not orthogonal to said distraction rod 8, for example when the plate 1 has been bent. Preferably, in the case where the plate 1 comprises two positioning aid elements 4, the latter are in the form of two openings 6 forming oblong holes arranged opposite one another on the plate 1, said oblong holes each having a large diameter and a small diameter, so that their large diameter is carried by the same axis. The oblong holes are thus advantageously aligned in the direction of their length. Preferably, in the case where the plate 1 comprises two positioning aid elements 4, these are in the form of two openings 6 which are preferably oblong holes aligned along the direction DD 'in the direction of their length.

Such an arrangement advantageously allows the plate 1 to be guided along the two distraction rods 8, even in the situation where the spacing of the latter does not correspond perfectly to the spacing of the openings 6. In a particularly advantageous manner, when the plate 1 is placed against the bones 3 of the spine 2 and the distraction rods 8 are implanted in two bones 3 movable relative to each other, the oblong shape of the openings 6 gives the surgeon the possibility of direct the bones 3 relative to each other via the distraction rods 8, to bend the spine 2 and cause for example a lordosis. Indeed, the oblong shape allows inclination of the distraction rods 8 relative to the plate 1, preferably several degrees. The distraction rods 8 are fixed sufficiently securely to the bones 3 to allow them to rotate. Preferably, a distraction distractor distraction tool 8 can precisely adjust the inclination of said distraction rods 8 to allow to bend the spine 2 easily and accurately. The subsequent fixation of the plate 1 to the spine 2 makes it possible to freeze the curvature of the spine 2 obtained thanks to the inclination of the distraction rods 8. According to the invention, the fastening means 19 are in the form of at least one well 9, for example circular or cylindrical, passing through the plate 1, which is designed to receive a fixation screw 10 intended to be screwed into the bone mass of the spine 2 in order to fix said plate 1 to said bone mass of said spine 2 .

The well 9 is thus formed through the plate, the fixing screw 10 being threaded through said well 9. The fixing screw 10 is also screwed into the bone mass of the spine 2, so that the head 27 of said fixing screw 10 retains the plate 1 by the accessible face 20 so that said plate 1 is leaned against the bone mass of the spine 2. Preferably, the head 27 is embedded in the thickness of the plate 1 through in the presence of a countersink 26 of the well 9, said countersink 26 being located on the side of the accessible face 20. Preferably, the fixing screw 10 is preferably screwed on the vertebral wall, or in the vertebral body of a vertebra 18 of the spine 2. The fixing screw 10 can be screwed to one of the thoracic vertebrae 18, lumbar, or cervical, preferably to one of the cervical vertebrae. The plate 1 of the invention preferably comprises several wells 9, each well 9 passing through the pia 1 having a geometric center, corresponding to an axis of rotation, in this case a screw axis, of the associated fixing screw 10. For example, in the case where the wells 9 have a section of revolution, circular, cylindrical or conical, the geometric center will be formed by the center of the form of revolution, or at least carried by its axis of revolution.

According to the invention, the plate 1 comprises at least one pair of wells 9 associated with at least one pair of fastening screws 10, each well 9 being associated with at least one fastening screw 0 to form said fastening means 19.

The plate 1 of the invention also comprises at least one rotatable retention blade 11, which is preferably flexible, and is rotatably mounted on the accessible face 20 of said plate 1 to rotate between a position of partial obstruction of the two well 9 at a time (as shown in FIG. 5), in order to retain the two fastening screws 10 in said two respective wells 9, and a release position in which it does not retain said fastening screws 10 in said well 9 (as shown in Figure 4).

Thus, the retention blade 11 is preferably mounted to rotate substantially parallel to the accessible face 20, its axis of rotation then being orthogonal to said accessible face 20. The retention blade 11, when in the release position allows the fastening screws 10 to be freely screwed or unscrewed, threaded or withdrawn from their respective wells 9. The retention blade 11, when it is in position of obstruction, allows on the contrary to retain the fixing screws 10 in their housing, so that they do not unscrew, which prevents any subsequent risk of disconnection of the plate 1 by progressive unscrewing. The preferred characteristic of flexibility of said at least one retention blade 11 allows it to retain the fixing screws 10, even in the case where the heads 27 of the screws of said fixing screws 10 are placed at different heights, for example Bending or twisting of the plate 1. It may be possible, on the contrary, without departing from the scope of the invention, that the retention blade 11 is rigid.

Preferably, said at least one retention blade 1 comprises at least one drive orifice 12, and preferably two drive orifices 12, designed to receive a complementary tool, said tool being intended to drive in rotation said The drive holes 12 are, for example, off-axis with respect to the axis of rotation of the retention blade 11, so that it is possible to communicate a rotational drive torque. the retention blade 11 by means of a suitable tool, designed to be housed both in the two drive holes 12. Such a tool thus allows, via the drive port 12 , to move the retention blade 11 from its obstruction position to its release position and vice versa.

According to the invention, said at least one rotating retention blade 11 is rotatably mounted about an axis of rotation substantially aligned with each of the geometric centers of the pair of wells 9. The wells 9 of the pair of wells 9 are thus aligned side by side, in the substantially plane body of the plate 1, with the rotation axis of the retention blade 11, so as to be distributed for example symmetrically on either side of the axis of rotation of said blade; retention 11. Preferably, the axis of rotation of the retention blade is substantially parallel to the axis of rotation of the fixing screws 10, and is advantageously placed medially between the geometric centers of the wells 9. Such a geometric arrangement advantageously allows the system comprising the pair of wells 9 and the retention blade 11 to have a particularly small footprint, which allows for example to free space on the accessible face 20 of the plate. Such a design makes it possible for example to place an observation window 17 of relatively large size, as described below. Such a design can also make it possible to produce a particularly compact plate 1. Preferably, said at least one retention blade 11 is a double cam 13, having two opposite endings 14 designed to each retain a fixing screw 10, said at least one double cam 13 being designed to move from its release position to its position of obstruction by a rotation of an angle less than 90 °.

The double cam 13 is then mounted substantially median between the pair of wells 9 so that its two opposite ends 14 reach in a substantially equitable manner each of the two heads 27 of the fixing screws 10 (as shown in Figure 5). The double cam 13 preferably has a shape of I, or a disc shape truncated by two curved notches 28 arranged in an opposite manner on the circumference of said disc (as shown in the figures), the two opposite endings 14 being formed by the part not truncated edge of said disk. The curved notches 28 are then intended, once aligned with the heads 27, to allow the passage of said heads 27. The opposite endings 14 allow on the contrary to block the passage of said heads 27 when they partially obstruct the wells 9. Each opposed terminations 14 of the double cam 13 is preferably formed by an ear, or a wing, disposed opposite the other end, so as preferably to form a substantially symmetrical part vis-à-vis the axis of rotation of said double cam 13. Preferably, the plate 1 extending between two opposite ends, the pair of wells 9 and the retention blade 11 is placed on an intermediate portion of the surface of the plate 1 between said ends , for example midway between said ends, so that the free space of the plate 1 located between the ends of said plate 1 and the pair of wells 9 is optimized. The plate 1 may also include one or more pairs of wells 9 each associated with a retention blade 11 so that the geometric centers of said wells 9 are aligned with the rotational axis of said retention blade 11, said pairs of wells 9 being placed at one or both end (s) of the plate 1. In this preferred case, the retention blades 11 are for example formed by double cams 13 as described above. Advantageously, the plate 1 comprises at least one pair of additional wells 9, for example placed at one end of said plate 1, and associated with an additional retention blade 11. The plate 1 thus advantageously comprises several pairs of wells 9 each associated with a retention blade 11, at least one of said retention blades 11 being advantageously formed by a wing blade 15 having two wings 16 arranged in a V and designed to retain each a fixing screw 10, said wing blade 15 being adapted to move from its disengaged position to its obstruction position by a rotation greater than 90 °. The wing blade 15 is then mounted so that its axis of rotation and the centers of the wells 9 with which it is associated form a substantially isosceles triangle in said axis of rotation (as shown in the figures). The wings being arranged in V, the top of the V then corresponds to the axis of rotation of the winged blade 15. In this way, in the position of obstruction, the wings 16 cover a portion of the wells 9 and heads 27 of the fixing screw 10 in order to block the latter (see Figure 5).

In this preferred case, which is illustrated for example in FIG. 1, the positioning aid element 4 (for example formed by the opening 6) can advantageously be positioned between the wells 9 of the well pair 9 which is associated with the winged blade 15.

In this configuration, the opening 6 is thus for example aligned with the geometric centers of the wells 9 of the pair of wells 9. The axis of rotation of the winged blade 16 is for example arranged so that the opening 6 is placed between the wings of the wing blade 16, in the hollow of its V shape. The shape of the wing blade 16 thus advantageously allows to provide a passage for the distraction rod 8 between the two wings for example when said winged blade 16 is in the position of obstruction of the wells 9. Because of such an arrangement, the bulk of the positioning aid element 4, the wells 9 and the winged blade 16 thus described is thus particularly reduced.

Preferably, the plate 1 comprises at least one observation window 17 formed in said plate 1 and allowing a user to see through said plate, for example from the accessible face 20. The observation window 17 allows also to ensure the lightness of the plate 1 and save material for the manufacture thereof. Preferably, two observation windows 17 are formed in the plate 1 and are of substantially rectangular shape, or square. The observation windows 17 are preferably arranged along the first axis XX. Preferably, the plate 1 comprises at least six wells 9, or more preferably, arranged in pairs along two parallel rows of three wells 9. in order to fix said plate 1 with six associated fixing screws 10 (as shown in the figures). The two parallel rows of wells 9 are then preferably arranged in the direction of the length of the plate 1, parallel to the first axis XX. The pairs of wells 9 are then arranged so as to be parallel to each other and parallel to the second axis YY '.

Preferably, the plate 1 also comprises a retention plate 11 per pair of wells 9, that is to say for example three retention blades 11 for three pairs of wells 9, the axes of rotation of which are substantially aligned with the first axis XX, said retention blades 11 being separated in pairs by one of the observation windows 17, so that the two observation windows 17 are also arranged along the first axis XX.

Each observation window 17 is advantageously formed in the plate 1 between two pairs of wells 9. The alignment of the wells 9 with the axis of rotation of the retention blade 11 preferably makes it possible to optimize the space available on the surface of the plate for household observation windows 17 of substantial size, and in particular of sufficient size to provide good visibility through the plate 1.

Preferably, the three retention blades 11 comprise at least one double cam 13 and at least one wing blade 15, each retention plate 11 being respectively associated with a pair of wells 9. Preferably, two of the pairs of wells 9 are disposed at the ends of the plate 1 and are associated with winged blades 15 forming two of the retention blades 11 of the plate 1, which advantageously allows to free space for the circulation of the distraction rods within the openings 6 , while the pair of central wells 9 is associated with a double cam 13 (as shown in the figures), which notably makes it possible to reduce the space requirement of the system including said double cam 13 and the pair of central wells 9, insofar as their axis of rotation is preferably aligned with the geometric centers of said pair of central wells 9.

Finally, of course, the plate 1 according to the invention can also be used specifically on one or more bones 3 that are not part of the spine 2, in particular for the treatment of pathologies related to bone fractures, or to participate in the reconstruction of bone. a bone following a bone graft. These bones 3 can be short or long, such as for example a tibia, a patella, or a humerus. Therefore, the whole of the foregoing description applies mutatis mutandis to these other types of bone 3 and pathologies.

The invention relates, according to a second aspect, to a medical kit formed by an osteosynthesis plate 1 according to the foregoing description and at least one distraction rod 8 intended to contribute to the positioning of the plate 1 with a view to its attachment to the spine 2 of a patient. The invention finally relates to a method of placing an osteosynthesis plate 1 on the spine 2 of a patient, the plate 1 being fixed by fixing means 19 to the bone mass of said spine 2, the method being characterized in that it comprises the following steps:

at least one distraction rod 8 (preferably two distraction rods 8) is fixed on the bone mass of said spine 2 of the patient,

the displacement of the plate 1 towards the bone mass of the spine 2 is accompanied, said plate 1 being guided along said distraction rod 8 by means of at least one positioning aid element 4 arranged through said plate 1, said positioning aid element 4 comprising means 5 for guiding said plate,

the plate is fixed to the spine 2 via the fastening means 19 when it is positioned by means of the distraction rod 8 and the means of the positioning aid element 4.

said distraction rod 8 is removed from the bone mass of said spine 2. Preferably, the plate 1 is prepared, by orienting the retention blades 11 in the release position. Optionally, the plate 1 is flexed in the direction of the length.

Preferably, two distraction rods 8 are screwed onto the bone mass of the spine 2, exerting a screwing force on the interaction element 23 of each distraction rod, the implantation element 22, namely the threading, allowing the implantation of each distraction rod 8 by self-perforation and self-tapping of the bone mass of said spine 2. Preferably, it uses for this a tool adapted to the screwing of the distraction rods 8. Preferably, it fixes the two distraction rods 8 with two bones 3 of the spine 2, placing said distraction rods 8 in the same plane, preferably along the spinal axis, and substantially parallel. Preferably, the two distraction rods 8 are placed at a distance from each other corresponding to the spacing of the guide means 5 of the plate 1. Preferably, the plate 1 is threaded onto the two distraction rods. 8 through the positioning aid elements 4, which comprise the guide means 5 adapted to guide the movement of the plate 1 along the two distraction rods 8, said guide means 5 being formed by the walls 7 of the openings 6. The plate 1 is thus presented so that the two openings 6 are aligned respectively opposite the ends of the two distraction rods 8, then said plate 1 is led so that the distraction rods 8 pass through said plate 1. Thus, the plate 1 slides along the distraction rods 8 to the bone mass of the spine 2, the wall 7 of each opening 6 being for example in line contact with the outer wall of the that distraction rod 8.

Preferably, the displacement of the plate 1 along the distraction rods 8 is accompanied so as to advance said plate 1 towards the bone mass of the spine 2, until said plate 1 reaches its abutment, its face support 21 coming into contact with the bone mass of the spine 2. The distraction rods 8 impose, or help to impose, a spatial orientation on the plate 1 at As the plate 1 is approached to the bone mass of the spine 2. When the plate 1 reaches the end of the race at the base of the distraction rods 8, its spatial orientation is close to the desired final orientation for the fixation. from said plate 1 to the spine. Preferably, it is therefore possible to adjust the positioning and orientation of said plate 1 through the existence of a clearance between the guide means 5 and the distraction rods 8. In particular, this game is obtained thanks to the shape of the openings 6, whose walls 7 form said guide means 5, said openings 6 being wider than the distraction rods 8 which pass through them, and preferably of oblong shape.

Preferably, when the plate 1 is placed in abutment against the spine 2, the orientation of the bones 3 in which the distraction rods 8 are implanted is adjusted, by modifying the mutual orientation of said distraction rods 8 so that they are no longer parallel. It is thus possible to apply a distraction to the spine 2, preferably a lordosis, particularly when the distraction rods 8 have been implanted along the spinal axis of said spine 2. It is possible to modify the orientation precisely using a suitable distraction tool, allowing the grasping and the orientation of the distraction rods 8.

At any moment, the two observation windows 17 of the plate 1 make it possible to observe the spine 2 through said plate 1, in order to check, for example, whether said plate 1 is correctly placed on the spine 2, or if the desired distraction has been applied.

Preferably, the plate 1 is screwed onto the bone mass of the spine 2 by means of the fixing screws 10 through the wells 9, in order to fix the said plate 1 to the spine 2, and to retain the distraction adjustment performed at the spine 2 through the distraction rods 8. The screwing is carried out using a tool suitable for the screwing of self-piercing and self-tapping fixing screws. Preferably, furthermore, after fixing the plate 1 to the spine 2, the distraction rods 8 are removed by unscrewing them from the bone mass of said spine 2, and releasing them through the openings 6.

Preferably, after having fixed the plate 1 to the spine 2, and preferably after removing the distraction rods 8, the retention blades 11 are tilted from their release position to their obstruction position, in order to prevent any subsequent unscrewing of the fixing screws 10, the tilting being effected by a rotation of said retention blades 11, preferably by means of a tool interacting with the drive orifices 12 of said retention blades 11. POSSIBILITY OF APPLICATION INDUSTRIAL

The invention finds its industrial application in the design, manufacture and implementation of osteosynthesis plates whose guidance is carried out via distraction rods.

Claims

Plate (1) of osteosynthesis intended to be fixed on the spine (2) of a patient by fixing means (19) on the bone mass of said spine (2), and comprising at least one pair of wells (9) passing through the plate (1) each having a geometric center, each well (9) being associated with at least one fixing screw (10) to form said fixing means (19), each fixing screw being intended to be screwed into! a bone mass for fixing said plate (1) to said bone mass via the wells (9), said plate (1) having at least one positioning aid element (4) formed through said plate ( 1), and comprising guide means (5) adapted to guide the movement of said plate (1) towards the bone mass and along at least one distraction rod (8) fixed to the bone mass of said spine (2). ) of the patient, to assist in positioning said plate (1) for attachment to said spine ( 2) via the fastening means (19), said plate (1) being characterized in that it also comprises at least one rotatable retention blade (11) rotatably mounted on an accessible face (20) of said plate (1). ) around an axis of rotation substantially aligned with each of the geometric centers of the pair of wells (9), the retention blade (11) being designed to evolve in rotation between a position of partial obstruction of the two wells (9) in order to retain the two fastening screws (10) in said two respective wells (9), and a release position in which it does not retain said fastening screws (10) in said wells (9),

Plate (1) of osteosynthesis according to the preceding claim, characterized in that said at least one retention blade (11) is a double cam (13), having two opposite endings (14) designed to each retain a fixing screw ( 10), said at least one double cam (13) being adapted to move from its disengaged position to its obstructed position by rotation of an angle less than 90 °.

Plate (1) for osteosynthesis according to any one of the preceding claims, characterized in that, the plate (1) extending between two opposite ends, the pair of wells (9) and the retention blade (11) is placed on an intermediate portion of the surface of the plate (1) between said ends, for example halfway between said ends.

4 - plate (1) of osteosynthesis according to any one of the preceding claims, characterized in that said at least one positioning aid element (4) is in the form of an opening (6) passing through said plate (1), and whose walls (7) form the guide means (5).

5 - plate (1) of osteosynthesis according to the preceding claim, characterized in that said opening (6) is in the form of an oblong hole whose length is aligned in the direction from the outer edge (25) of said plate

(1) towards the center of said plate (1).

6 - plate (1) of osteosynthesis according to any one of the preceding claims, characterized in that it comprises two positioning aid elements (4) each distributed at an opposite end of said plate (1), and allowing sliding said plate (1) along two distraction rods (8).

7 - Plate (1) of osteosynthesis according to any one of the preceding claims, characterized in that said at least one retention blade (11) is flexible. 8 - Plate (1) of osteosynthesis according to any one of the preceding claims, characterized in that said at least one retention blade (11) comprises at least one drive orifice (12) designed to accommodate a complementary tool, said tool being adapted to rotate said at least one retention blade (1). 9 - Plate (1) of osteosynthesis according to any one of the preceding claims, characterized in that the plate (1) comprises several pairs of wells (9) each associated with a retention blade (11), one at at least one of said retention blades (11) being formed by a wing blade (15) having two wings (16) arranged in a V-shape and adapted to each retain a fixing screw (10), said wing blade (15) being adapted to move from its disengaged position to its obstruction position by a rotation of a greater angle at 90 °.

10 - Plate (1) of osteosynthesis according to the preceding claim, characterized in that the positioning aid element (4) is positioned between the wells (9) of the pair of wells (9) which is associated with the blade wing (15), the latter allowing to provide a passage for the distraction rod (8) between the two wings, for example when said wing blade (16) is in the position of obstruction of the wells (9).

11 - plate (1) of osteosynthesis according to claims 2 and 9 or 10, characterized in that it comprises six wells (9) arranged in pairs along two parallel rows of three wells (9), in order to fix said plate (1) with six fixing screws (10), two of the three pairs of wells (9) being arranged at the ends of the plate (1) and being associated with wing blades forming two retention (11) of the plate (1), the pair of wells (9) central being associated with a double cam (13).

12 - Plate (1) osteosynthesis according to any one of the preceding claims, characterized in that it comprises at least one observation window (17) formed in said plate (1) and allowing a user to see at through said plate (1). 13 - Medical kit formed by an osteosynthesis plate (1) according to one of the preceding claims and at least one distraction rod (8) intended to contribute to the positioning of the plate (1) for attachment to the spine (2) a patient.