FR2783698A1 - SPINAL OSTEOSYNTHESIS DEVICE WITH MEDIAN ANCHOR HOOK ON THE POSTERIOR VERTEBRAL ARCH - Google Patents

Abstract

This device comprises two longitudinal rods (7) adapted to be fixed on the spine and to extend respectively on each side of a section of the latter and, for a given vertebra (3), a hook (12) and two vertebral bearing means associated with said hook, which is adapted to bear against the median part of the vertebral posterior arch (20) between two longitudinal rods, the hook is provided with transverse rods (27, 28) for connection to the longitudinal rods and is made in two parts (13, 14) capable of being assembled to constitute the hook, namely a first part (13) comprising a body extended by a blade (16) which extends with a lateral off set relative to the body and is so profiled and adapted to be capable of bearing against a central region of the vertebral posterior arch (20), and a second part (14) forming a connector for connection with the first part, comprising a body integral with a transverse stem (21) insertable in a transverse bore in the body of the first part (13), means (41) being provided for fixing this rod in a detachable manner to the body of said first part (13). The invention avoids cutting the ligaments between the spinous processes to allow mounting hooks.

Description

The present invention relates to an osteosynthesis device

  spine with median hook and vertebral anchoring supports, of the type described in French patent n ° 95 00 732 (N0 2 729 556) of January 23, 1995, which

  is incorporated by reference into the present description.

  Such an osteosynthesis device comprises two longitudinal rods adapted to be able to be fixed on the spine and to extend respectively on either side of a section of the latter; for the same vertebra, it comprises a hook and two vertebral support means associated with said hook, which is adapted to be able to bear support on the median part of the posterior vertebral arch between two longitudinal rods, this hook being equipped with transverse means link

  between said hook and the longitudinal rods.

  If such a median hook is satisfactory, it obliges the surgeon, to allow it to be put in place, either in the supra-lamar position or in the sub-lamar position relative to the thorny bone and to the vertebral arch, to first sever the supraspinatus and interspinous ligaments as well as one of the contiguous spines to accommodate the body of the hook (the ligaments being the longitudinal fibrous mass which connects the spinous processes). At the end of the intervention, the surgeon must replace the ligaments and the severed part of the thorny, then suture the whole. However, the section of the supraspinous and interspinous ligaments has the consequence of destabilizing the spine overlying the instrumented segment, and in addition increases the invasive nature of the intervention. The invention aims to allow the establishment of the hook without proceeding to a prior cutting of the thorny and the above and interspinous ligaments. For this purpose in accordance with the invention the hook is formed in at least two parts which can be assembled to constitute the hook, namely: 3 () - a first part comprising a body in which a transverse bore is formed, - a second part forming a connector with the first part, comprising a body integral with a transverse rod adapted to be able to be introduced into the transverse bore of the body of the first part, means being provided for fixing this rod to the body of said first part, - and a blade secured to one of the aforementioned bodies, profiled and adapted to be able to bear on a central area of the posterior vertebral arch. As in the one-piece hook of the aforementioned patent, housings are arranged in the bodies of the two parts of the hook to each receive a bent tab or bar for connection with the longitudinal rod, each body being able to additionally receive a screw.

blocking of its connection tab.

  The blade extends with a lateral offset relative to the body.

  I () W According to a feature of the invention, in the end of the connector rod is provided a bearing surface of a transverse connecting tab between the hook and the associated longitudinal rod, and the receiving bore from the end of said connector rod opens into a housing of said tab produced in said body; a second housing for the 1. second connecting tab is produced in the body of the second part of the hook. The end of the connecting lug of the first part of the hook bearing on the bearing surface of the terminal end piece of the connector rod constituting the second part, the blocking element (screw) introduced into the) body of the first part allows when tightening, to fix the connector to the first part of the hook as well as the connection tab, constituting

  thus the complete hook, but the two parts of which remain separable.

  Thanks to this arrangement of the hook in two parts, it is enough for the surgeon to release in the above and interspinous ligaments, a small passage for the connecting rod between the two bodies of the hook without damaging the rest of the ligaments or a thorny . So during placement, the damage to the supraspinatus and interspinous ligaments is minimized and at the end of the intervention the surgeon is no longer required

to suture these ligaments.

  Other features and advantages of the invention will become apparent

  during the description which follows, with reference to the drawings

  attached which illustrate an embodiment by way of nonlimiting example. Figure 1 is a schematic elevational view of a spinal osteosynthesis instrumentation placed on a segment of the spine, one end of this instrumentation being equipped with the system

  vertebral anchoring and transverse connection according to the invention.

  Figure 2 is a partial perspective view on an enlarged scale of the anchoring and transverse connection system of Figure 1 provided with the hook constituting the invention, as well as the vertebra

  on which the hook of this system must be anchored.

  Figure 3 is a front elevational view on an enlarged scale, of an embodiment of the median hook of the osteosynthesis device

  Figures 1 and 2 before assembly of its two constituent parts.

  Figure 4 is a side elevational view of the first

  part of the hook according to arrow K in FIG. 3.

  1 () FIG. 5 is a diagrammatic elevation view on an enlarged scale of the vertebra of FIG. 2 as well as of the part of the hook comprising the attachment blade, represented in the above-mentioned position in the

  central part of the posterior vertebral arch.

  Figure 6 is a posterior elevation view of a 1-5 spinal segment consisting of two vertebrae at the start of surgery

  for installing the vertebral anchoring device according to the invention.

  Figure 7 is an elevational view in a sagittal plane

corresponding to figure 6.

  Figure 8 is an elevational view in the frontal plane illustrating) the installation of the hook according to the invention between the spines of two vertebrae

  consecutive in the lamellar position.

  Figure 9 is a view similar to Figure 8 illustrating the next step of inserting a rod or connecting bar with a vertebral rod. Figure 5 is an elevational view in a sagittal plane

corresponding to figure 9.

  Figure 11 is a view of a lumbar spinal segment, on a reduced scale, equipped with an osteosynthesis device with two longitudinal rods joined by a pair of hook anchoring systems

  3) medians constituting the invention.

  The osteosynthesis instrumentation schematically represented in FIG. 1 has a general structure similar to that described in the aforementioned French patent. This instrumentation extends over a vertebral segment made up of three vertebrae 1, 2, 3 connected by vertebral discs 4, 5, 6, and comprises two longitudinal rods 7 anchored in the vertebral bodies at regular intervals, in a manner known per se, by means of

  pedicle screws 8 schematically shown.

  The instrumentation can be supplemented by one or more transverse connection devices (DLT) of a type known per se, such as the device 9 connecting the rods 7. These DLTs can, for example, be of the type described by French patents 2,645. 427 of April 11, 1989 and 2. 659.225 of March 8, 1990. The instrumentation is also equipped with a vertebral anchoring system 11 and transverse connection between the rods 7, mounted on one of the end vertebrae of the segment instrumented spinal column, for example the vertebra 3. This anchoring system will be described below in detail in

  l / referring more particularly to FIGS. 2 to 5.

  It comprises a median hook 12 and two vertebral support means associated with the hook 12 for the same vertebra such as 3, with

  know pedicle screws 8 in the example described.

  The hook 12 is formed in two parts 13 and 14 which can be assembled to reconstitute a one-piece hook, namely: - a first part 13 comprising a body 15 extended by a blade 16 ending in a curved beak 17 for bone anchoring, this blade 16, 17 extending with a lateral offset relative to the body 15; the blade 16 is profiled and adapted so that its anchoring beak 17 can come to bear on a central area 20 of the posterior vertebral arch of the vertebra 3, to come to be inserted in the widest part of the medullary canal spine (as shown in Figure 3 of the aforementioned French patent) and the

Figure 5 attached.

  a second part 14 forming a connector with the first part 13, comprising a body 19 integral with a transverse rod 21 adapted to be able to be introduced into a transverse bore 22 formed in the

body 15 of the first part 13.

  The bore 22 passes through the body 15 right through and the rod 21 is introduced into the bore 22 on the side of the profiled blade 16, so that when two parts 13, 14 are assembled as shown in phantom 14a (Figure 3 ) the anchoring spout 17 is located substantially in the central zone between the bodies 15, 19. In the latter are provided respective housings 23, 24 passing right through the bodies in a direction perpendicular to the longitudinal axis of the rod 21 (the first part 1 being assembled with the second part 14) and approximately parallel to the longitudinal rods 7 when the instrumentation is put in place. These housings 23, 24 have a cross section adapted to receive the corresponding ends 25, 26 of two bent rods or bars 27, 28 of

  connection of the hook 12 with the longitudinal rods 7.

  The bent rods 27, 28 are similar to those described in the aforementioned French patent and therefore comprise, in the example shown, cylindrical ends 25, 26 connected substantially at right angles to a respective bar 29, 31 of substantially rectangular section suitable for come into an inner channel of a respective hook 32, 33 for fixing to the rods 7. It can be seen in FIG. 2 that the ends such as 28a of the bars 27, 28 can protrude outside the hooks 32, 33 which

  W) are fitted with screws 34, 35 for locking the bars 29, 31 on the rods 7.

  The rod 21 of the connector 14 is advantageously made up of two sections of different cross sections, namely in the example shown a first section 21a adjoining the body 19 and a second end section 21b forming a nozzle. The cross section of the first section 21a is greater than the cross section of the end piece 21b in order to limit a shoulder 36 therebetween. The section 21a can be cylindrical while the end section 21b can advantageously be of non-circular section, for example elliptical , and can be introduced into the bore 22 whose contour is complementary, for example elliptical (Figures 4 and 5). In addition, the length I of the terminal section 21b is adjusted to be practically equal to the width I

  of the body 15, that is to say the length of its through bore 22.

  Furthermore, in the end section of the rod 21 is provided a bearing surface 37 for supporting an end 25 (26) of a tab 28 (27), cylindrical in the example shown. The bearing surface 37 is thus constituted by a cylindrical surface complementary to that of the end 25 (26) which comes to take there

  support during assembly of the anchoring system 11.

  The transverse bore 22 extends on either side of the housing 23 of the body 15 into which it opens. In each body 15, 19 is further drilled a tapped hole 38, 39 opening into the respective housing 23, 3 (24 and adapted to receive a locking plug 41, 42 (Figure 2) for locking

  connecting rods 27, 28 on the assembled hook 12.

  The blade 16 and its end beak 17 are profiled so as to be able to adapt to the anatomy of the central zone of the vertebral arch 20, either in the supra-lamar position, shown in solid line in FIG. 5, or in the under position lamina or infra-lamina, shown in phantom 16a, 17a in Figure 5. The connecting bars 27, 28 are of course oriented accordingly to adapt to one or the other of the two positions. If the blade 16 must be placed in the sub-lamar position, its geometry is appreciably modified compared to that which it presents for a supra-lamar support, (FIG. 5) in order to adapt to the anatomy of the part under - arc bow

posterior vertebral.

  ) The surgical method of placing a median hook 12 in spinal osteosynthesis instrumentation, for example on the

  lumbar spine (figure 11), is illustrated in figures 6 to 11.

  - Figures 6 and 7: The surgeon cuts in the ligaments and interspinous 43, between the spinous 44, 45, a small window 46 whose In section is reduced to that necessary for the introduction of the connecting rod 21. - Figure 8: Using appropriate pliers 47, 48 known per se, the surgeon positions the two parts 13, 14 on either side of the window 46, by introducing the rod 21, the end piece 21b of which comes I. insert inside the bore 22 of the body 15, until the annular shoulder 36 abuts against the latter. The bearing 37 is then placed exactly in the extension of the cylindrical inner surface of the housing 23, in order to allow the insertion of the end 25 of the transverse connecting bar 28. The second bent bar 27 is also) introduced by its end 26 in the housing 24, and the position

  longitudinal and angular of the rods 27, 28 is correctly adjusted.

  After which the surgeon locks together the two parts 13, 14 of the middle hook 12 and the rods 27, 28 thereon by tightening the screws 41 and 42, these different operations being illustrated in FIGS. 9 and 10. The transverse connecting rods 27, 28 are finally locked on the rods

  longitudinal 7 by means of hooks 32, 33.

  The instrumentation illustrated in FIG. 11 by way of example extends over the first four lumbar vertebrae, L5 to L2 and it is equipped with two vertebral anchoring systems comprising a respective median hook 12 3 (). A first hook 12a is mounted on the upper vertebra L2 in position. above-lamar, and a second median hook 12b is mounted on the vertebra L4 in the sub-lamar position, these two hooks being connected to the rods

  7 by the corresponding transverse rods 27, 28.

  The realization of the hook 12 in two parts 13, 14 which can be l) locked one on the other has the advantage of avoiding causing significant damage to the supraspinatus and interspinous ligaments 43 during implantation of the middle hook. Indeed, the cutting of these ligaments previously necessary had the consequence of destabilizing the spine overlying the instrumented segment. Only the small window 46 having to be cut in the ligament 43 with the hook and the surgical method according to the invention, this surgery therefore becomes clearly less invasive and does not

  no longer destabilizes the overlying segment.

  The hook according to the invention also has the following advantages: Because the hook 12 is "trapped" in its window

  ligament 46, it is much more stable than the anterior hook.

  I (- As the surgical technique is simplified, the exposure time is

  reduced compared to the previous hooks.

  The invention is not limited to the embodiments described and may include variant embodiments. Thus the cross section of the bore 22 and the end piece 21b can be generally non-circular, therefore other than elliptical. The advantage of this arrangement is to prevent any untimely rotation of the connector 14 relative to the first part 13 of the

  hook after insertion of the end piece 21b into the bore 22.

  Similarly, the blade 16 with its anchoring spout 17 may be integral with the body 19 of the second part 14 of the hook. In this case the 2 () first part 13 is reduced to the body 15 pierced with the bore 22 and the housing 23. The rod 21 for connecting the two parts 13, 14 can be either in one piece with the body 19, or made of separately and then fixed to the body 19 by any suitable means known per se. In this case the hook is actually

made up of three parts.

  If necessary also, the transverse rod 21 could be formed in two distinct parts (21a, 21b) fixed together and to the body 19. Finally the connection lugs 27, 28 can be fixed to the body 15, 19 by means other than the screws 34, 35. For example the ends 25 of the tabs can be threaded rods, and fitted with locking nuts coming to bear

  _ <) on the respective bodies 15, 19.

Claims (12)

  1. Spinal osteosynthesis device, comprising two longitudinal rods (7) adapted to be able to be fixed on the spine and, for the same vertebra (3), a hook (12) and two means (8) of vertebral support associated with said hook, which is adapted to be able to bear on the middle part of the posterior vertebral arch (20) between two longitudinal rods, this hook being equipped with transverse means (27, 28) for connection between said hook and the longitudinal rods, characterized in that the hook (12) is formed in at least two parts (13, 14) which can be I () assembled to constitute the hook, namely: - a first part (13) comprising a body (15) in which is formed a transverse bore (22), - a second part (14) forming a connector with the first part, comprising a body (19) integral with a transverse rod (21) adapted to be able to be introduced into the transverse bore (22) of the body (15) of the first 1st part (13), means (37, 41) being provided for fixing this rod to the body of said first part (13), - and a blade (16) integral with one of the abovementioned bodies (15, 19), contoured and adapted to be able to lean on a central area of the arch 2 () posterior vertebral (20).   2. Device according to claim 1, characterized in that in the end (21b) of the rod (21) is provided a bearing surface (37) for supporting a transverse tab (28) connecting the hook (12 ) and the associated longitudinal rod (7), a housing (23) for receiving one end (25) of said tab being arranged in the body (15) of the first part (13) and opening into said transverse bore (22 ), and in that a second housing for the second tab (27) is produced in the body (19) of the   second part (14) of the hook (12).   3. Device according to claim 2, characterized in that 3 () said end (25) of the connecting lug (28) is cylindrical and the scope   associated support (37) forms a semi-cylindrical notch.   4. Device according to claim 2, characterized in that the transverse bore (22) of the body (15) of the first part (13) extends on either side of the housing (23) of the tab (28 ) into which it opens, and it 3.5 has a non-circular section (22), combined with a corresponding profile   from the end (21b) of said transverse rod (21).   5. Device according to claim 4, characterized in that said non-circular section (22) and the profile (21b) of the rod (21) are elliptical. 6. Device according to claim 2, characterized in that the rod (21) consists of a first section (21a) adjoining the body (18) and a second end section (21b) forming a nozzle, and the first section has a cross section greater than that of the second section in order to delimit a shoulder (36) which can abut against the body (15) of the first part (13) of the hook (12), and the length (1) of the second section I ((21b) is correlatively adjusted to be substantially equal to the length of the transverse bore (22).   7. Device according to claim 2, characterized in that the blade (16) of the hook (12) is profiled to adapt to the anatomy of the area   central vertebral posterior arch (20) in supra-lamar support.   8. Device according to claim 2, characterized in that the blade (16a) of the hook is profiled to adapt to the anatomy of the area   central of the posterior vertebral arch (20) in sub-lamar support.   9. Device according to claim 2, characterized in that in each body (15, 19) are arranged holes (38, 39) opening into the 2 () housings (23, 24) of the tabs (27, 28) of connection and into which can be screwed threaded plugs (41, 42) for blocking said tabs and the rod (21) of the connector (14) in the body (15) of the first part (13) of the hook (12).   10. Device according to claim 1, characterized in that the blade (16) integral with one of the bodies (15, 19) extends with a lateral offset relative to the body.   11. Median hook (12) associated with means (8) of vertebral support and with means (27, 28) for connection between said hook and said vertebral support means, this hook and the support means being intended 1 () the same vertebra and spinal osteosynthesis instrumentation comprising two longitudinal rods (7) adapted to be able to be fixed on the spine, characterized in that said hook (12) is formed in two parts (13, 14) can be assembled to form the hook, namely: - a first part (13) comprising a body (15) in which a transverse bore (22) is formed, - a second part (14) forming a connector with the first part, comprising a body (19) integral with a transverse rod (21) adapted to be able to be introduced into the transverse bore (22) of the body (15) of the first part (13), means (37, 41) being provided for fix this rod to the body of said first part (13), - and a l core (16) integral with one of the aforementioned bodies (15,19), profiled and adapted to be able to bear on a central area of the arc posterior vertebral (20).   12. Hook according to claim 11, characterized in that the   blade (16) extends with a lateral offset relative to the body (15, 19).