FR2840798A1 - Bar type spinal osteosynthesis device for maintaining two consecutive spinal vertebrae w.r.t each other has two convex hemispherical parts enclosed by corresponding hemispherical cavities in legs through which threaded bone screw passes - Google Patents

Abstract

The device includes a threaded bone (24) screw (22), a retaining head (25), a threaded rod (27) fixed to the head, and a screw (29) adapted to be screwed on the rod. Two main legs (30,31) each include an orifice (34,35), while the second ends (36,37) of each leg include a hemispherical cavity (38,39) situated on the same sphere. Two secondary legs (40,41) each include a convex hemispherical part (44,45) complementary to the hemispherical cavities (38,39), and a cylindrical cavity (48,49) complentary to a part of an external wall of the bar (21). The two secondary legs (40,41) are realised so that the two convex hemispherical parts are part of the same sphere, and the two cylindrical cavities are situated on the same cylindrical surface.

Description

different thicknesses.

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  7 SPINDLE BAR OSTEOSYNTHESIS DEVICE

  The present invention relates to spinal bar osteosynthesis devices which find a particularly advantageous application for the maintenance of two vertebras, consecutive or not, one relative to the other in order to carry out a spinal arthrodesis, by example in a human being in order to remove for example the cause of the pains generated by a vertebral fracture, a defective intervertebral disc, etc. or for

  Avoid the risk of paralytic complications linked to these traumas.

  77 es practitioners in the field of spinal surgery use in particular systems essentially comprising a plate in which wind practices an orifice and a lumen, and screws each comprising a rod with a bone thread ending in a shoulder head, these screws being steep to cooperate with the plate so that the plate bearing against the vertebrae is

  trapped between these vertebrae and the shoulder of the screws.

  These spinal osteosynthesis systems have drawbacks because, in particular, the epiphyses of the vertebrae make it difficult to place screws with bone threads in the orifices of the plates for their screwing in the vertebral bodies, and do not allow the practitioner to adjust easily the distance separating the two segments of vertebrae to eliminate the focus of the

  pain and restore normal height to the spine segment.

  In an attempt to overcome these drawbacks, systems have been developed comprising pedicle screws, steps, first means for fixing a first end of the steps on the holidays of the pedicle screws, at least one plate and second means for fixing the plate on the second end of the pastes. These systems are, however, still relatively co m pl exes a ussi bie n

  for their installation only for the optimal adjustment of the different distances.

  The aim of the present invention is therefore to provide a spinal osteosynthesis system which makes it possible to largely overcome the drawbacks of the prior art systems mentioned above. More precisely, the present invention relates to a spinal osteosynthesis device. bar, characterized in that it comprises: - a screw comprising a first rod comprising a bone thread7 a shoulder head integral with one end of said first rod, a second

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  threaded rod mounted integrally projecting on said shoulder head, the two rods being located substantially on the same axis, and a shoulder nut capable of being screwed on said second rod, - two main pastes, each main paste comprising an orifice made substantially at a first of its ends, the two orifices having a section greater than that of the second rod and less than those of the shoulder head and of the shoulder nut, the second end of each main paste comprising a hemispherical cavity , the two hemispherical cavities being made in correspondence of each other in such a way that when the two main pastes are located one above the other and the second rod passes through the two orifices, they are substantially located on the same sphere, and - two secondary pastes each comprising a convex hemispherical part substantially at a first of its ends, each hemispherical part conve xed being complementary to one of the hemispherical cavities cited, and a cylindrical cavity substantially at its second end, each cylindrical cavity being complementary to a part of the external wall of the bar, the two secondary pastes being made so, that, when the two convex hemispherical parts wind on the same sphere, the cylindrical cavities are substantially located on the same cylindrical surface. Other features and advantages of the invention will become apparent during

  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 represent two views of an embodiment of the spinal bar osteosynthesis device according to the invention, FIG. 1 being a view in longitudinal section referenced II in FIG. 2 and Figure 2 being

  a top view of the device according to the hgure 1.

  It is very precise that, in the figures, the same references designate the same elements, tail whatever the figure on which they appear and tail 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 the other figure.

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  The Applicant also wishes to clarify that the figures represent only one embodiment of the object according to the invention, but that it may exist

  other embodiments which meet the definition of this invention.

  Wile further specifies that when, according to the definition of the invention, the object of the invention comprises at least one "element having a given function, the

  described mode of realization can co mport several of these elements.

  Wile also specifies that, if the embodiment of the object according to the invention as illustrated comprises several elements of identical function and that if, in

  the description, it is not specific that the object according to this invention must

  must include a particular number of these elements, the object of

  [The invention could be defined as comprising "at least one" of these elements.

  With reference to FIGS. 1 and 2, the bar spinal osteosynthesis device 21 comprises a screw 22 of the pedicle type comprising a first rod 23 comprising a bone thread 24, a shoulder head 25 integral with an end 26 of the first rod 23, a second threaded rod 27 mounted integrally projecting from the shoulder head 25, the two rods 23, 27 being located substantially on the same axis 28, and a shoulder nut 29 capable of being screwed

on this second rod 27.

  The device further comprises two main pastes 30, 31 each comprising an orifice 34, 35 produced substantially at a first 32, 33 at its ends, the two orifices having a section greater than that of the second rod 27 and less than those of the shoulder head 25 and shoulder nut 29, the second end 36, 37 of each main paste comprising a hemispherical cavity 38, 39, the two hemispherical cavities 38, 39 being produced in correspondence one of the other in such a way that when the two main pastes 31 are located one above the other and the second rod 27 passes through

  the two orifices 34, 35, they are located substantially on the same sphere.

  It is specified that, within the framework of the present description, by "cavity

  hemispherical "means a cavity in the form of a spherical sector whose ['angle

  in the center is less than 180 degrees, as in Figure 1.

  The device also comprises two secondary pastes 40, 41 each comprising a convex hemispherical part 44, 45 substantially at a first 42, 43 at its ends, each convex hemispherical part being complementary to a hemispherical cavity 38, 39, and a cylindrical cavity 48 ,

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  49 substantially at its second end 46, 47, each cylindrical cavity being complementary to a part of the external parol of the bar 21, the two secondary pastes 40, 41 being made so that when the two hemispherical convex parts 44 , 45 wind on the same sphere, the two cylindrical cavities 48, 49 are substantially located on the same surface

  cylindrical, which is substantially that which envelops the lateral wall of the bar.

  The value of the angle at the center of each cylindrical cavity 48, 49 is at most equal to 180 degree, and the sum of these two angles at the center is less than 360 degree, so that these two cylindrical cavities, by approaching the one of

  The other, can perfectly trap the bar.

  According to an advantageous embodiment, the advantage of which will appear below, the two orifices 34, 35 have oblong orifices with axes substantially parallel to the length of the main pastes 30, 31, the length of these orifices being

  greater than the cross section of the second rod 27.

  In a preferential embodiment, such as that which is illustrated in the figures, the device comprises first means 50 for securing the first ends 32, 33 of the two main pastes 30, 31 so that, with these first securing means 50, they form a first piece

  substantially "U" shaped 51 having substantially the shape of a tuning fork or the like.

  These first means of attachment 50 wind for example constituted by a wall integrally connecting the two first ends 32, 33 of the two pastes

main 30, 31.

  In a con, advantageous, this first piece in "U" 51 is made, as in the illustrated embodiment, in one piece, for example by

machining, titanium or the like.

  Similarly, this device comprises second means 60 for securing the second ends 46, 47 of the two secondary pastes 40, 41 so that, with these second securing means 60, they form a second piece

  substantially "U" shaped 61 having substantially the shape of a tuning fork or the like.

  These second securing means 60 wind for example constituted by a wall integrally connecting the two second ends 46, 47 of the two pastes

secondary 40, 41.

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  In a fa, con advantageous, this second piece in "U" 61 is made, like the iliustree, in one piece, for example by machining, titanium or the like. In a way, very advantageously, the first and second pieces substantially in a "U" 51, 61 are arranged and produced in a material given in a way, which have a certain elasticity of deformation, that is to say that their two branches can be moved angularly relative to their base and automatically return to their rest position when efforts for

  remove or bring them closer to each other removed wind.

  In the illustrated embodiment, the device further comprises locking means 70 of at least one first 44 of the two convex hemispherical parts 44, 45 with a first 30 of the two main pastes 30, 31, to freeze the position of the two "U" pieces 51, 61 one by

compared to the other.

  In an advantageous embodiment, these blocking means 70 wind constituted, as illustrated in the figures, by a needle screw 71 screwed in a tapped hole 72 made in the first main paste 30, the tapped hole 72 opening into the hemispherical cavity 38 made in this

first main paste 30.

  It is quite clear that other embodiments than that illustrated wind

  possible. The device may for example comprise, with the same pedicle screw 22, several pairs of first and second "U" pieces 51, 61, the first ends 32, 33 of the first "U" pieces overlapping the

  one on the other by snapping on the second rod 27.

  To implant a spinal bar osteosynthesis device such as that described above and illustrated in FIGS. 1 and 2, the practitioner begins by screwing several pedicle screws 22 into the pedicures of the vertebras. Given the difficulty in implanting such screws, it is impossible to obtain that they are perfectly parallel to each other and that their parties are all perfectly aligned on the same straight line. Under these conditions, it is practically impossible to position the bar 21, directly on the parties.

these screws.

  With the spinal osteosynthesis device according to the invention, after having fully screwed on the pedicle screws in the pedicures of the vertebras, the practitioner

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  composed of at least as many pairs of first and second "U" pieces 51, 61 as implanted pedicle screws, positioning the hemispherical parts

  44, 45 respectively in the hemispherical cavities 38, 39.

  It plugs the first "U" pieces respectively onto the second rods 27 of the pedicle screws, and screws a shoulder nut 29 on each

  second rod, without screwing it fully.

  It should be noted that the bar 21 can be pre-positioned in the two cylindrical cavities 48, 49 of each second "U" piece 61 or positioned after the pairs of first and second "U" pieces 51, 61 have been

  associated with pedicle screws 22.

  As the shoulder nuts 29 do not wind fully, the first "U" pieces 51 can pivot around the second rods 27 and are

  translate with respect to them, due to the oblong shape of the orifices 34, 35.

  The second "U" pieces 61 can, for their part, pivot relative to the first "U" pieces 51 around the center of the hemispherical cavities 38, 39, in a solid angle which is illustrated in dots in the two figures 1 and 2,

reference As and As2 respectively.

  With an ancillary well known in itself, the practitioner distracts the vertebrae so that they assume their desired relative position. In this movement of the vertebrae relative to each other, the "U" pieces 51, 61 move relative to each other and always find their position

  optimal desired while restart linked to the same bar 21.

  The practitioner then screws the shoulder nuts 29 fully onto the second rods 27. In their translational movement on the second rods 27, the nuts bring the branches of the first "U" pieces 51 which are brought closer to one another. pinch the branches of the second "U" pieces 61 which, in turn, approach each other in pine, firmly cant the bar 21 and hold it

  perfectly attached to the second "U" pieces.

  After the final assembly (bar 21, pedicle screws 22 and pairs of first and second pieces 51, 61) has been positioned, for safety, the practitioner screws the needle screws 71 into the holes 72, until their ends come '' inserts, in sinking, cant at least partially, in the convex hemispherical parts 44, to avoid that the second pieces 61 do not

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  can, however, move relative to the first pieces 51 and for

  keep this set perfectly rigid.

  In the description above, the main advantages of the

  spinal osteosynthesis system according to the invention, namely: the pedicle screws-22 can be implanted relatively independently of one another, the bar can always be connected to the pedicle screws tail whatever the relative position of these hindquarters and, being positioned laterally relative to the pedicle screws, its installation is not hampered

by thorny epiphyses.

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Claims (7)

  1. Spinal bar osteosynthesis device (21), characterized in that it comprises: - a screw (22) comprising a first rod (23) comprising a bone thread (24), a shoulder head (25 ) integral with one end (26) of said first rod (23), a second threaded rod (27) mounted integrally projecting on said shoulder head (25), the two rods (23, 27) being located substantially on the same axis (28), and a shoulder nut (2g) capable of being screwed onto said second rod, two main pastes (30, 31) each comprising an orifice (34, 35) produced substantially at a first (32, 33) from its ends, the two orifices having a section greater than that of the second rod (27) and less than that of the shoulder head (25) and the shoulder nut (29), the second extremitb (36, 37) of each main paste comprising a hemispherical cavity (38, 39), the two hemispherical cavities (38, 39) being produced in correspondence one of the other re fa, con that, when the two main pastes (30, 31) are located one above the other and that the second rod (27) passes through the two orifices (34, 35), they are substantially located on the same sphere, - two secondary pastes (40, 41) each comprising a convex hemispherical part (44, 45) substantially at a first of its ends (42, 43), each convex hemispherical part being complementary to a cavity hemispherical (38, 39), and a cylindrical cavity (48, 49) substantially at its second end (46, 47), each cylindrical cavity being complementary to a part of the external wall of the bar (21), the two pastes secondary (40, 41) being reacted in such a way that when the two hemispherical convex parts (44, 45) wind on the same sphere, the two cylindrical cavities (48,   49) are substantially located on the same cylindrical surface.   2. Device according to claim 1, characterized in that the two orifices (34, 35) wind oblong orifices whose wind axes substantially parallel to the length of the main pastes (30, 31), the length of the orifices   being greater than the cross section of the second rod (27). 9 2840798   3. Device according to one of claims 1 and 2, characterized in that   that it comprises first means (50) for securing the first ends (32, 33) of the two main pastes (30, 31) in such a way that, with these first securing means (50), they form a first part substantially in "U" ()   4. Device according to one of claims 1 to 3, characterized in that qutil   comprises second means (60) for securing the second ends (46, 47) of the two secondary steps (40, 41) in such a way that, with these second securing means (60), they form a second piece substantially in "U" (61)   5. Device according to one of claims 1 to 4, characterized in that qutil   comprises locking means (70) of at least one first (44) of the two convex hemispherical parts (44, 45) with a first (30) of the two main steps (30, 31).   6. Device according to claim 5, characterized in that said biocage means (70) wind constituted by a needle screw (71) screwed in a tapped hole (72) made in the first main paste (30), said tapped hole (72) opening into the hemispherical cavity (38) produced in   this first main paste (30).   7. Device according to claims 3 and 4, characterized in that the   first and second pieces substantially in a "U" shape (51, 61) are arranged and produced in a given material so that the two branches of each   "U" shaped pieces have a certain elasticity of deformation.