FR2870108A1 - Rachidian osteosynthesis device for rachidian arthrodesis, has pedicle screw and push rod joining unit with main sleeve in which traversing bore, having transversal section, is formed along axis, where rod is mounted slidably in bore - Google Patents

Abstract

The device has a unit (10) to join integrally a pedicle screw (2) with a push rod (1), and having a main sleeve defined along an axis (12). A traversing bore formed in the sleeve along the axis has a transversal section perpendicular to the axis and equal to width BA. The rod is mounted slidably in the bore. A traversing orifice (16) is formed in a screw plate (14) defined in a plane (15), along an axis (17) perpendicular to the plane. The screw plate is mounted in cooperation with a portion of a screw rod (4) such that the portion is plugged in the orifice. A unit integrates the sleeve and the plate such that the axis (12) makes with the plane an angle alpha comprised between a null angle and a right angle.

Description

SPINAL OSTEOSYNTHESIS DEVICE FOR MAINTAINING AT LEAST TWO

  VERTEBRATES ONE TO THE OTHER

  The present invention relates to spinal osteosynthesis devices 5 for maintaining at least two vertebrae relative to one another.

  Osteosynthesis devices find a particularly advantageous application for the maintenance of two vertebrae consecutive or not with respect to each other for the realization of a spinal arthrodesis, for example in a human being for the purpose of suppressing for example the cause of pain caused by a vertebral fracture, a defective intervertebral disc, etc. or to avoid the risk of paralytic complications related to these traumas.

  Practitioners in the field of spinal surgery use to secure two or more consecutive vertebrae to one another, in particular devices essentially comprising a connecting bar, a plurality of pedicle screws each comprising two first and second coaxial rod portions along a first axis. the first and second stem portions being joined by a shoulder spacer, the first rod portion being generally bone threaded and the second metal threaded portion, and a nut adapted to be screwed onto the second rod portion, and means for integrally binding the pedicle screw with the bar.

  Currently known devices of this type all have relatively complicated structures and are generally difficult to implant in the human body.

  Thus, it is an object of the present invention to provide a spinal osteosynthesis device for maintaining at least two vertebrae relative to one another which overcomes the aforementioned drawbacks.

  More specifically, the subject of the present invention is a spinal osteosynthesis device for maintaining at least two vertebrae relative to one another, comprising at least: E a cross-sectional connecting bar equal to BA, a screw pedicle comprising: two first and second coaxial rod portions along a first axis, the two first and second rod portions being joined by a shoulder spacer having a cross section perpendicular to said first axis equal to AND, the first rod portion; carrying a bone thread and the second rod portion carrying a metal thread, said second rod portion having a cross section perpendicular to said first axis equal to T1, and a nut adapted to be screwed onto the second rod portion, said nut having a cross section perpendicular to said first axis when it is screwed on the second rod portion, equal to EC, and E means for integrally connecting the pedicle screw with said bar, lo characterized in that the means for integrally binding the pedicle screw to said bar comprise: E a main sleeve defined along a second axis, É a through-hole made in said main sleeve according to said second axis, said through-hole having a cross section perpendicular to said second axis at least equal to BA, said bar being able to be slidably mounted in the through-hole, É a screw plate defined substantially in a general plane, É a through-hole made in said screw plate along a third axis substantially perpendicular to said general plane, said through orifice having a section greater than T1 but smaller than the smaller of the ET and EC values, said screw plate being mounted in cooperation with the second rod portion; so that this second portion of rod is plugged into the orif ice passing through, and E means for securing said main sleeve and said screw plate so that the second axis makes with the general plane of said screw plate an angle between a zero angle and a right angle.

  Other features and advantages of the invention will become apparent from the following description given with reference to the accompanying drawings, by way of illustration but in no way limiting, in which: FIGS. 1 and 2 show a first embodiment of the spinal osteosynthesis device according to the invention to maintain at least two vertebrae with respect to each other, FIG. 1 being a sectional view indicated by two arrows in FIG. 2 and further showing a nut which is not represented on the FIG. 2 being a view from above and without the nut, FIGS. 3 and 4 show two orthogonal views of a second embodiment of the spinal osteosynthesis device according to the invention; FIG. of the embodiment according to FIGS. 3 and 4, and FIGS. 6 and 7 show a third embodiment of the spinal osteosynthesis device according to the invention, FIG. re 6 being a view from above and FIG. 7 being a sectional view indicated by two arrows in FIG. 6.

  It is first of all specified that, in the figures, the same references designate the same elements, whatever the figure on which they appear and whatever the form of representation of these elements. Similarly, if elements are not specifically referenced in one of the figures, their references can be easily found by referring to another figure.

  It is also stated that the figures essentially represent three embodiments of the object according to the invention, but that there may be other embodiments that meet the definition of this invention.

  It is furthermore specified that, when, according to the definition of the invention, the object of the invention comprises "at least one" element having a given function, the embodiment described may comprise several of these elements. Conversely, if the embodiments of the object according to the invention as illustrated comprise several elements of identical function and if, in the description, it is not specified that the object according to this invention must obligatorily comprise a number particular of these elements, the object of the invention may be defined as comprising "at least one" of these elements.

  Lastly, it is specified that when, in the present description, an expression alone defines, without specific specific mention concerning it, a set of structural characteristics, [for example E = E (p, T, s, ...)] these characteristics can be taken, for the definition of the object of the protection requested, when technically possible, either separately, [for example s, and / or z, and / or p,

  .], either in total and / or partial combination, [eg E (s, -c, p), and / or E (s, z), and / or E (t, p), and / or E (s, p)] ... DTD: Figures 1 and 2 show a first embodiment of the spinal osteosynthesis device according to the invention to maintain at least two vertebrae relative to each other, which has all the characteristics of the invention.

  This device comprises at least one connecting bar 1 of cross section equal to BA and at least one pedicle screw 2 which comprises two first and second coaxial portions of rod 3, 4 along a first axis 5, the first and second second portions of rod being joined by a shoulder spacer 6 having a cross section perpendicular to the first axis 5 equal to ET, the first rod portion 3 bearing a bone thread and the second rod portion 4 carrying a metal thread, said second rod portion having a cross section io perpendicular to the first axis 5 equal to TI.

  It is also provided a nut 7 or the like adapted to be screwed on the second rod portion 4, the nut 7 having a cross section perpendicular to the first axis 5 when it is screwed on the second rod portion, equal to EC.

  The device further comprises means 10 for integrally linking the pedicle screw 2 with the connecting bar 1.

  According to the invention and as illustrated in both Figures 1 and 2, these means 10 comprise a main sleeve 11 defined along a second axis 12, a through-hole 13 formed in the main sleeve 11 along the second axis 12, the through-hole 13 having a cross section perpendicular to this second axis at least equal to BA, so that the connecting bar 1 can slide in this through-hole 13.

  There is also provided a screw plate 14 defined substantially in a general plane 15 adapted to cooperate with the pedicle screw as explained below and a through hole 16 made in this screw plate 14 along a third axis 17 substantially perpendicular to the general plane 15. The through hole 16 has a section greater than T1 but smaller than the smallest of the ET and EC values, and the screw plate is mounted in cooperation with the second stem portion 4 of the pedicle screw 2 so that this second portion of rod passes through the through hole.

  It should be noted that the section of the through orifice 16 is defined above so that, when the screw plate 14 is plugged onto the second rod portion 4, there is a large clearance between the wall of the through orifice and this portion of rod, but this game does not allow in any way, nor the nut or the spacer, to go through this through hole.

  It is obvious that the embodiment illustrated in the figures is that which is preferential. However, an embodiment comprising a screw plate 14 and a through hole 16 of section greater than that of the nut, but with a washer between the nut and the screw plate to achieve the purpose defined above, enters into the definition of the invention, the nut and the washer then to be considered as constituting a composite nut. It would be the same with the shoulder spacer 6.

  The device further comprises means 18 for securing the sleeve 11 and the screw plate 14 so that the second axis 12 makes with the general plane 15 of the latter an angle a, Figure 1, between a zero angle and an angle right, for example of the order of ten to twenty degrees.

  As more particularly visible in certain figures, the means 18 for securing the main sleeve 11 and the screw plate 14 are constituted by at least one lug 20 or the like whose two ends 21, 22 are respectively integral with an edge of the plate screw and the outer surface of the main sleeve.

  The shape of this tab 20 can be of any type: flat, round, square, U-shaped, T-shaped, etc., but especially of a shape such that, when a pair of forces is applied respectively to the sleeve and on the screw plate, the leg does not tend to deform significantly.

  The fastening of the lug with the screw plate and the sleeve can be carried out in any possible way, in particular by welding, forging, machining for example in one piece of the screw plate, the lug and the sleeve, etc.

  According to a preferred embodiment, as more particularly visible in Figure 2, the cross section of the through-hole 13 has a value greater than BA, albeit relatively weakly, but sufficiently so that the sleeve 11 and the connecting bar 1 can have relative non-zero rotational movement relative to each other about an axis substantially perpendicular to the second axis 12.

  According to a second possible embodiment shown in FIGS. 3 and 4, the main sleeve 11 consists of at least two first and second secondary sleeves 111, 112 coaxial along the second axis 12, the tab 20 then being constituted by two first and second secondary lugs 28, 29 secured to the screw plate 14 and respectively to the first and second secondary sleeves 111, 112.

  According to one possible variant, each secondary sleeve 111, 112 is constituted by an open chute 21, 22, FIG. 5, the two open channels 21, 22 being mounted substantially head to tail with respect to a plane passing through the second axis 12 that their concavity is turned towards this second axis.

  The opening angle of the chutes may be greater than or equal to one hundred and eighty degrees, and even slightly less than this value, in order to obtain, by receiving the connecting bar 1 as shown in dashed lines in this FIG. clipping or retention.

  It is also possible to produce the osteosynthesis device according to the invention as more particularly illustrated in FIGS. 6 and 7.

  According to this third embodiment, the main sleeve 11 consists of three third, fourth and fifth secondary sleeves 113, 114, 115 coaxial along the second axis 12 and the tab 20 consists of three third, fourth and fifth secondary tabs 201, 202, 203 secured to the screw plate 14 and respectively the third, fourth and fifth secondary sleeves 113, 114, 115.

  It is then advantageous that at least one of the third, fourth and fifth secondary tabs 201, 202, 203 comprises at least one portion 40 having a thickness in a direction substantially perpendicular to the second axis 12 which is greater than the thickness of the two other secondary tabs, this thicker portion 40 being made so that it is adapted to be clamped between the nut 7 and the spacer 6 when the screw plate surrounds the second rod portion 4, for the purpose that will be described below.

  It is furthermore preferable that, as illustrated in FIG. 6, the secondary leg having the thicker portion 40, or the secondary leg 202 which is situated between the two other secondary legs 201, 203.

  In addition, in order to further ensure the connection between the sleeve 11 and the bar 1, as will be explained below in the explanation of the use of the device according to the invention, it is advantageous that the wall the through-hole 13 comprises, as illustrated in FIG. 7, at least one crown portion 30 projecting towards the second axis 12, the section defined by the free edge 31 of this projecting crown portion 30 being at least equal to BA, and even preferably, that the free edge 31 of the projecting crown portion 30 is bevelled.

  In an advantageous embodiment, the ring is complete by making all the way around the wall of the through-hole 13.

  Of course, such a projecting ring can be used, both in the case of a main unitary sleeve (Figures 1 and 2) than in the case of several secondary sleeves (Figures 3 to 7).

  Fixing washers may also be provided between the screw plate 14 and the nut 7, of the same type or the like as the washers which are used to prevent a nut from unscrewing.

  It is also possible to make a slot or the like, as shown in dashed lines in FIG. 5, in the screw plate 14 between the through orifice 16 and the space defined between the two secondary lugs 28, 29, for the purpose in particular to promote deformation of the assembly "screw plate 14, lug 18 and sleeve 11" during a force applied on the connecting bar 1 by the sleeve 11 when the bar can no longer be deformed, so that, at the end of screwing of the nut, the screw plate 14 is perfectly and completely sandwiched while laying flat on the nut 7 and the base 6, respectively.

  The osteosynthesis device according to the invention is used and operates as follows: First, the Practitioner implants, in the vertebral bodies of the vertebrae to be connected to each other, the number of pedicle screws 2 necessary for a such a connection, for example three pedicle screws, by screwing the first portion 3 of each rod into the vertebral bone and leaving the second rod portion 4 free, without nut 7.

  On a connecting bar 1, he places three sleeves 11 each associated with a screw plate 14 and passes the connecting bar in their through-hole 13.

  He then threads the screw plates onto the second rod portions 4, which can be placed there irrespective of their position relative to the connecting rod 1, since the through orifice 16 has a much larger cross-section than that of the second rod portion 4.

  As illustrated in Figure 1, it is likely that each screw plate 14 will be positioned at an angle relative to the second rod portion 4 on which it is plugged.

  He can then fully screw a nut 7 on the second rod portion 4 of one of the pedicle screws. During this screwing of the nut, the screw plate 14 associated with this pedicle screw tends to undergo, with reference to FIG. 1, a dextral rotation substantially around the axis Ax (FIG. 2) perpendicular to the axis 17 and passing through the center 41 of the orifice 16, that is to say to straighten in the plane of the faces of the nut and the spacer which are opposite this screw plate. By being straightened, it prints a rotation to the sleeve around the axis Ax, which is transmitted to the connecting bar 1. The connecting bar 1 is maintained at the other pedicle screws, it will deform at least on the surface .

  During this deformation, if the section of the through-hole 13 is greater than that of the bar, it is even possible for one point of each end of the through-hole 13 to become anchored in the bar.

  It will be the same with the other sleeves, when the Practitioner screws thoroughly the nuts on the other pedicle screws.

  The bar thus deformed is perfectly maintained and can no longer slide in translation in the sleeves. It defines constant distances between the vertebrae to obtain the osteosynthesis as with the devices of the prior art.

  In the case of the embodiment according to FIGS. 3 and 4, the two secondary sleeves make it possible to maintain the bar even better, since at least two deformations and / or four anchorings of the edges of the through-through breakthrough 13 then occur. the wall of the bar 1, two by secondary sleeve 112, 113.

  It is the same with the embodiment according to Figures 6 and 7. But in addition, in this embodiment, if one of the legs has a thicker portion as described above, for example the central secondary leg 202, the bar tends to be deformed into a "U" shape, as schematically illustrated in an exaggerated manner in FIG. 7.

  The ring 30 on the wall of the through hole 13 with a free edge 31 shaped bevel significantly improves the anchoring of the sleeve or sleeves in the bar.

Claims (10)

  Spinal osteosynthesis device for holding at least two vertebrae relative to each other, comprising at least: E a crossbar (1) of cross section equal to BA, a pedicle screw (2) comprising two coaxial first and second portions of rods (3, 4) along a first axis (5), the two first and second rod portions being joined by a shoulder spacer (6) having a cross section perpendicular to said first o axis (5) equal to AND, the first rod portion (3) bearing a bone thread and the second rod portion (4) bearing a metal thread, the second rod portion having a cross section perpendicular to said first axis (5) equal to TI, and * a nut (7) adapted to be screwed on the second rod portion (4), said nut (7) having a cross section perpendicular to said first axis (5) when it is screwed on the second portion of stem, equal to EC, and E means (1 0) for integrally binding the pedicle screw with said bar, characterized in that the means (10) for integrally connecting the pedicle screw with said bar comprise: E a main sleeve (11) defined along a second axis (12), a through-hole (13) formed in said main sleeve (11) along said second axis (12), said through-hole (13) having a cross section perpendicular to said second axis (12) at least equal to BA, said bar (1) being able to be slidably mounted in the through-hole (13), É a screw plate (14) defined substantially in a general plane (15), É a through-orifice (16) formed in said screw plate (14) in accordance with a third axis (17) substantially perpendicular to said general plane (15), said through orifice (16) having a section greater than TI but smaller than the smallest of the ET and EC values, said screw plate being mounted in cooperation with the second rod portion (4) so that said second rod portion is plugged into the through hole (16), and E means (18) for securing said main sleeve (11) and said screw plate (14) so as to that the second axis (12) makes with the general plane (15) of said screw plate (14) an angle between a zero angle and a right angle.   2. spinal osteosynthesis system according to claim 1, characterized in that the means (18) for securing said main sleeve (11) and said screw plate (14) are constituted by at least one lug (20) whose two ends (21, 22) are respectively integral with an edge of said screw plate (14) and the outer surface of said main sleeve (11). io   3. spinal osteosynthesis system according to one of claims 1 and 2, characterized in that the cross section of the through hole (13) has a value greater than BA.   4. spinal osteosynthesis system according to one of claims 2 and 3, characterized in that said main sleeve (11) consists of at least two first and second secondary sleeves (111, 112) coaxial along said second axis (12), said lug (20) being constituted by two first and second secondary lugs (28, 29) integral with the screw plate (14) and respectively of the first and second secondary sleeves (111, 112).   5. spinal osteosynthesis system according to claim 4, characterized in that each secondary sleeve (111, 112) is constituted by an open channel (21, 22), the two open channels (21, 22) being mounted substantially head -bêche relative to a plane passing through said second axis (12) so that their concavity is turned towards said second axis (12).   6. spinal osteosynthesis system according to one of claims 2 and 3, characterized in that said main sleeve (11) consists of at least three third, fourth and fifth coaxial secondary sleeves (113, 114, 115). along said second axis (12) and said tab (20) consists of three third, fourth and fifth secondary tabs (201, 202, 203) integral with said screw plate (14) and third, fourth and fifth sleeves respectively; secondary (113, 114, 115).   7. spinal osteosynthesis system according to claim 6, characterized in that at least one (202) of the third, fourth and fifth secondary tabs (201, 202, 203) comprises at least a portion (40) having a thickness in a direction substantially perpendicular to said second axis (12) greater than the thickness of the two other secondary tabs, this thicker portion (40) being made so that it is able to be clamped between the nut (7) and the spacer (6) when the screw plate surrounds the second rod portion (4).   8. Spinal osteosynthesis system according to claim 7, characterized in that the secondary leg having the thicker portion (40) is the secondary lug (202) which is located between the two other secondary lugs (201, 203).   9. spinal osteosynthesis system according to one of claims 1 to 8, characterized in that the wall of said through hole (13) comprises at least one crown portion (30) projecting towards said second axis (12). the section defined by the free edge (31) of said projecting crown portion (30) being at least equal to BA.   10. spinal osteosynthesis system according to claim 9, characterized in that the free edge (31) of the projecting crown portion (30) is bevelled.