FR2719759A1 - Intervertebral osteosynthesis screw system - Google Patents

Abstract

The system consists of a pedicular screw or hook with a recess (3) to receive a reinforcing rod (6), and a locking nut (8-10) to hold the rod in place by means of its curved under-surface (10) which is shaped to fit against the rod. The screw or hook has four sections, including two upright branches (1,4), one with a threaded end for the nut and the other with a tongue to guide the rod, the recess and a horizontal section (2). The screw can be machined in one piece.The recess is slightly smaller than the rod to ensure a locking fit, and is offset relative to the axis of the screw. The locking nut is in three parts, with an upper hexagonal section (8), and middle and lower sections (9,10) to lock the rod from the top and side.

Description

- 1 The present invention relates to a material intended to be implanted in

  level of the vertebrae to treat the various lesions of the spine. It relates more particularly to improvements to this type of material. There are already different types of intervertebral osteosurgical equipment, and with little successive improvements developed by the manufacturers, no current system is completely satisfactory. Conventional problems lie in the difficulty of aligning the pedicle screws during implantation. causing an incorrect adaptation between these screws and the consolidation rods. This results in either a rupture of the screw itself, or a rupture of the fixing system between the screw and the rod, or simply a loosening of the assembly which can cause the rod to slip. Another problem is the complication of the

  fixing system between screw and rod and the difficulty of its installation.

  The equipment according to the invention seeks to resolve the drawbacks of current equipment. The invention therefore provides new material consisting of laminar hooks, pedicle screws. and round stems of

  consolidation, as well as a transverse reinforcement device.

  It consists of installing laminar hooks. or pedicle screws, and connect them on each side, with a properly bent consolidation rod, to adapt to the screw or hook fixing system. A nut of specific shape comes to apply the rod in a housing specially arranged for this purpose, and ensures the rigidity of the

mounting.

  Note that the laminar hook and the pedicle screw are provided with the

  same rod fixing system.

  According to an advantageous arrangement, the fixing system is machined in the extra-vertebral part in one piece with the hook or the screw; and outside the clamping nut. does not include any additional parts to

  add which could reduce the precision and intensity of the fixation.

  According to a characteristic of the invention, a housing is provided in the hook and screw fixing system for housing the consolidation rod. This housing is located between two rising branches, one threaded to receive the tightening nut and the other in tongue to allow the establishment of the rod and guide it to the housing; this tab being slightly flared up! to offer a wider

rod entry surface.

  According to an advantageous arrangement, the housing is eccentric with respect to the axis of the screw, and a rotat on of 180 'of this e screw makes it possible to offset the location of the housing and to catch up with the alignment due to a

incorrect screw placement.

  According to another advantageous arrangement. the diameter of the housing is slightly less than the diameter of the rod, to allow optimal tightening and to guarantee two diametrically opposed tightening lines. unlike a single line in traditional assemblies. This device makes it possible to limit the overload applied to the nut during the movements of the spine and to reduce the risk of its loosening; it also makes it possible to play on the elasticity of the material, which has the effect of absorbing the stresses undergone by the assembly during the various movements. According to another characteristic, the locking nut has a high hexagon part for tightening. a movable part in tray to be applied on the top of the rod and a low part in radius of curvature which comes laterally to match the shape of the rod. According to an aagerageu conception. e, the locking system according to the invention is based on the special shape of the nut which. screws onto the fastening system, allows mixed tightening from the top and side of the rod. what

  increases the contact surface with the rod and therefore the fixation.

  Note that with a traditional nut, a point or a tightening line is obtained, while in the case of the invention there are two T-tightening lines. According to an additional characteristic, lateral tightening allows good control of the positioning. of the rod and check its application and

  its correct adaptation in the housing of the screw or hook.

  According to another advantageous design, the pedicle screw according to the invention has in its intra-vertebral part a spongy thread well pronounced in the distal part. which comes to fade away as one approaches the pedicle part, and this to reinforce the bottom of the net and increase the resistance of the VIs against a possible rupture -3 - The transverse device, according to the invention, is consisting of a rectangular bar with two oblong slots. To this bar are added two hooks, each fixing through a slot on one of the

  two mounting rods to form a frame mounting.

  According to an advantageous characteristic, the bar is formed of a smooth part, and another striated which is applied against the rod and ensures

  two clamping lines instead of a single one thanks to the striped shape.

  According to another advantageous arrangement, the hook. composed of a flat rectangular upper part. engages through the slot of the bar by its curved lower part and comes to hang the rod. The tightening of the screw incorporated in the upper part of the hook against the bar, presses this last clnie the rod to form a single

united together.

  Other characteristics and advantages of the invention will emerge

  of the description which will follow with regard to the annexed drawings which are not

  given only by way of nonlimiting examples.

  Figures 1 to 10 show the different parts of the intervertebral system according to the invention, separated and in assembly: Figure la- is a front view of the laminar hook and its

fastening system.

  Figure lb- is a side view of the laminar hook and its

fastening system.

  Figure 2a- is a front view of the pedicle screw and its

fastening system.

  Figure 2b- is a side view of the pedicle screw and its

fastening system.

  Figure 2c- is a top view of the pedicle screw and its

fastening system.

  Figure 3- is a view of the consolidation rod.

  Figure 4- is a view of the lock nut with specific shape.

  Figure 5- is a front view of the rod mounted on the screw

  pedicle and fixed with the locking nut.

  Figure 6- is a top view of the rod mounted on the screw

  pedicle and fixed with the locking nut.

-4-

  Figure 7a- is a front view of the cross bar.

  Figure 7b- is a front view of the hooks for transverse device.

  Figure 8a is a top view of the cross bar.

  Figure 8b- is a top view of the hooks for transverse device. Figure 8c- is a rear view of the hooks for the transverse device. Figure 9- is a race view of the transverse reinforcement device

mounts on the rod.

  Figure 10- is a top view of a complete frame assembly

  formed of four screws and a transverse reinforcement device.

  The accompanying drawings illustrate the invention. A description will be given below, with reference to FIGS. 1 to 10. the mechanism for mounting a rod on a hook or a screw, knowing that an assembly can be composed, depending on the case and the number of vertebrae to be consolidated, of a different number of screws and hooks, but it is usually always symmetrical

  on either side of the center line.

  The material according to the invention consists of laminar hooks (fig. 1) and pedicle screws (fig. 2) which feel connected together according to the

  same fixing system by consolidation rods (fig. 3).

  A locking nut a plate (fig.4) will strongly apply the rod in its housing (fig.5) and ensure the stability of the assembly. A transverse reinforcement device (fig. 7) will come, tightening the rod (6) between a hook (fig. 7b) and a transverse bar (-20), forming a frame with

  the entire assembly (fig. 10) to eliminate any possible mobility.

  This material can be made both in titanium alloy and

  stainless steel alloy or any other material supporting the constraints of the spine.

  and this to specifically meet the different requirements

functional.

  The laminar hook according to the invention (fig. 1) can have different shapes and sizes to adapt to different types of vertebrae. The variations can relate to its branch of attachment to the vertebra (5) or to its fixing system (1,2,3,4) modifying separately or simultaneously the size and the height, of the tongue (4), of the housing (3), the threaded branch (1), the horizontal branch 2) and the nut (fig. 4), to

  adapt to different anatomical and functional situations.

  The pedicle screw (fig. 2) can also undergo variations in diameter and length in its threaded distal part (11.12) to respect the diameter of the pedicle and the length of the vertebral body, as well as variations in its fixing system modifying separately or simultaneously the size and the height, of the tongue (4),. housing (3), threaded branch (1), horizontal branch (2) and nut (fig. 4), to meet all the functional and anatomical requirements of the

mounting.

  Let us cite by way of nonlimiting example an advantageous arrangement consisting in increasing the height of the threaded branch (1) to catch up with the sliding at the front of a vertebra (spondylolysthesis) and bring it back to the

mounting level.

  The consolidation rod (fig. 3) can be of different diameters

  to adapt to the requirements of resistance required.

  The transverse bar (20) can also have several sizes, as well as the hooks (fig.7b) which will have different sizes for

  adapt correctly to different types and diameters of rods.

  With reference to the accompanying drawings, a laminar hook (fig. 1) consists of a fixing system (1.2.3.4). and an attachment branch (5) which can take different forms and angulations depending on the anatomy of the vertebra. A pedicle screw (fig. Is made up of a fixation system (1,2,3,4), and a threaded distal part (12) intended to be housed in the pedicle and the vertebral body. This distal thread. well pronounced at the end of the screw, comes to die in the pedicular part (11) to ensure optimal resistance to the screw and to prevent any breakage. The bottom of the thread, cylindrical at the distal end (12) , becomes confined in the pedicle part (11) to abut against the coaTical bone and provide resistance and

screw stability.

  A hook (fig. 1) or a pedicle screw (fig. 2) have the same

  fixing system (1,2,3,4) factory in nonoblock with the hook or the screw.

  This fastening system consists of four parts: 1- A rising branch in the form of a tongue (4) which serves to guide the rod (6) during its introduction. This tab (4), the same width as that of the screw or hook. is more flared up to offer

  a larger entry surface to the rod.

  6 - 2- The second component of the fastening system is the housing

  (3) of semi-circular shape intended to receive the consolidation rod (6).

  This housing is cut over the entire width of the screw or hook with a

  diameter slightly undersized compared to that of the rod (6).

  According to an advantageous arrangement, this housing (3) is eccentric relative to the axis of the screw (AA). and pnnert. by rotating the screw, to catch up with the alignment of the housings (3) of the different

  screw due to incorrect installation.

  3- A second branching threadec (1) serves as a support for

the locking nut (fig. 4).

  4- Finally a flat horizontal branch (2 which will be used for the various maneuvers to activate the implant and will especially facilitate the

  compaction of the bone graft against its flat part.

  Once the hooks (fig. 1) or the screws (fig. 2) are put back in place, their connection is ensured with a round rod (fig. 3), correctly bent, to penetrate between the tongue (4) and the threaded branch (1), and come and stay in the housing (3) provided for this purpose. The rod (fig. 3) is provided, at each end, with a hexagon (7 allowing, using a suitable key, to rotate to better position the rod t3) in the housing According to an arrangement advantageous, nonlimiting, the housing (3) is made with a diameter slightly internal to that of the rod (6), which leads to an entry of this rod 6) in high friction in the housing (3). We are therefore sure to have two diametrically opposite clamping lines, more favorable than a single line at the bottom. thus limiting everything

  rotation and sliding movement of the rod (6).

  This device also plays on the elasticity of the material by slightly spreading the tongue (4) during insertion, thus helping with the elastic absorption of stresses, and limiting the forces applied to the nut (fig. 4) for prevent any possible loosening [The locking nut (fig. 4) has a fairly specific workpiece. It is provided in its upper part with a hexagon (8) for tightening, and has in its middle part a plate (9) which will be applied to the upper part of the consolidation rod (FIG. 6) . Its lower part is formed by a radius of curvature peripheral (10) which marries the shape of the rod and appi: that has it laterally (fig. 5) for

ensure effective clamping.

  -7 Once the rod (6 well bent ei positioned in its housing (3), the locking nut (fig.4) will press it strongly from above (fig.6) using its plate (9 ), and laterally (fig.5) the radius of curvature (10) will be applied against the rod (6) to ensure optimal fixing preventing any movement of rotation or sliding thereof. The same assembly is carried out svyéetriquemient, on each side of the midline. We will therefore have two lightS for implantation of screws or

  hooks with two consolidation rods fig.3) parallel.

  Once the assembly is in place and tight, it can be reinforced by transforming it into a frame using the bar (fig.7a) and the two hooks (fig.7b). The bar (20) is provided with two oblong slots (19) with flat walls. It is applied against the two rods (6) by its striated face (14) while the hook is introduced through: .ers the slot (19) by the smooth face

opposite (13).

  A hook (fig.7b) is made up of an upper horizontal rectangular flat part (16) provided with an incorporated screw (15) with a flat lower end, of a movable part (71 vertical right of square or rectangular section and the length of a rib (the shortest in the case of a rectangular section) is equal to that of the width of the oblong slot (19), and of a lower part (18I horizontal with upper concavity intended for adapt to the rod (6) the hook (fig.7b) is introduced through the smooth face of the oblong slot (19), it is brought closer to the rod (6) until its middle part (17) The lower part (18 of the hook is then under the rod ready to hang it. The incorporated screw (15) in the upper part (16) is then tightened, and presses the bar (14) against the rod ( 6), making the system integral and very resistant. Note that the diameter of the incorporated screw (15) is greater than the width of the oblong slot (19), which forces it to tighten on the two smooth flat edges of this slot (19) and ensure optimum fixing. A second hook (fig.7b) is then placed on the opposite side. and the

  incorporated screw (15) is tight j'so'i ufine satisfactory fixing.

  According to an advantageous provision. the two hooks (fig.7b) can be placed in the contraction or distraction position by

  relation to the two consolidation rods (fig. 3).

  The installation of the complete transverse device, with two bars (fig.7a) and four hooks fig.7b. allows to end up with a!

  formation of an indefinable rigid frame fig. O).

-8-

Claims (6)

REVENDIC, A.TiONS   1- System of internal - ertebral osteosvnthesis, characterized in that it consists of an eccentric housing (3), located in a pedicle screw or a laminar hook, into which vienda is inserted the consolidation rod (6 ): and by a locking crank 8.9,! 0) which by fixing the rod (6) ensures a mixed tightening: - from above thanks to its nmoenie part (9), which is applied against the upper part of the rod (6).   - laterally by its lower part (i (0 which follows the shape of the rod.   2- inter-erttbral osteosynthesis system according to claim 1, characterized in that the fixing system (1,2,3.4) of the consolidation rod (6) to the pedicle screw or to the laminar hook is provided of four parts: - A rising branch in tongue 5 4 to guide the rod (6) - A housing (3) for the rod (6) - A second threaded rising branch (1) intended to receive the nut (8,9,10)   - A flat horizontal branch i 3- osteosvnthese system, nte.rcrbrarle according to claim 2. characterized in that the tixalion i 1.2.3.4 svstelme torme of four parts is machined in rnonobloc a- ec 'a, .is pediculair -e or the laminar hook. 4- Integrated osteosynthesis system according to the   claims 1,2 and 3. characterized in that! rod housing (3 ')   (6) of semi-circular shape is eccentric to the axis of the screw   pedicle (AA '), and with a large horizontal axis.   - Svsteème d'osteosvnthese intervertebraie seion ies   Claims 1 and 4, characterized in that the housing (3) is   slightly undersized with respect to the rod (6) ensuring during the   fixation. two diametrically opposite lateral clamping lines.   6- inter: ertbral osteosvniithesis system according to claim 1, characterized in that the nut blocking r8,9,1 8 consists of three parts: - upper (8) in hexagon serving to ease in place and tightening - movenne (9) in plate ensuring: n tightening from above   - lower (10) in ravon of curvature ensuring the lateral tightening.   7- System of internal osteostebral according to moon   any of the preceding claims, characterized in that it   further comprises a transverse reinforcing device composed of a strip (20) with double slots and two faces, one smooth. the other ribbed, and two hooks (15,16,17,18), ensuring the tightening of the rod (6) between   the laminated face. of the bar (20 and the lower valleys of the hook (18).   8- Ostosy-nthe.se intc system. eriébrale according to claim 7, characterized in that each quaver + and consists of three parts: upper (15,16) horizontal rectangular whose width is equal to that of the bar (20). This part has a built-in screw   (15) whose lower part is wider than the slot of the bar.   - medium (17) vertical with square or rectangular section and the width of one side (the shortest in the case of rectangular section) is equal to the width of the slot of the ba: 'rette (20) to prevent any rotation.   - lower (18) horizontal presented ani housing intended to receive the consolidation rod (6).   9- Inic-eretebrale osteosvnthese system according to   Claims 7 and 8, characterized in that the hook (15,16,17,18)   threaded through the slot of the e / 2 bar () hooks the rod (6) with its lower part (18). The tightening of the incorporated screw i (15) a at the upper part of the hook (16) presses the bar (20) against the rod of   consolidation (6) forming an integral unit.