ES2367014T3 - VERTEBRAL OSTEOSYNTHESIS TEAM. - Google Patents

Abstract

Vertebral osteosynthesis equipment, including bone restraint elements, such as pedicle screws (1) and / or hooks, one or two connection bars (2), intended to be connected to these fasteners, and parts (3 ) for connection of this bar (s) (2) to these fasteners; at least one of the fasteners is of the "polyaxial" type, that is, it comprises a proximal block (5) articulated with respect to a base part (6) allowing the fastening of bones; the clamp means (4) allows the assembly of the connection part (3) on the clamping element; equipment characterized by the fact that the proximal block (5) comprises a surface (12, 32) that forms an axial stop, against which the connecting part (3) for being installed in the polyaxial clamping element is intended for the rest, and by which said clamp means (4) allows this connection part (3) to be hugged against this surface (12, 32), said surface (12, 32) being positioned so that the connection part (3), when it is hugged against this surface (12, 32), it is not hugged against the base part (6) so that there remains, after hugging, a possibility of articulated play of the proximal block (5) with respect to said base part (6).

Description

[0001] The application from which this patent is derived claimed the following priorities:

-FR 03 07776, filed on June 27, 2003;

-Provisional Application US No. 60 / 490,519, filed on July 29, 2003;

-

FR 04 00747, filed on January 27, 2004;

-

FR 04 03413, presented on April 1st, 2004.

[0002] The present invention relates to a vertebral osteosynthesis equipment.

[0003] A vertebral osteosynthesis equipment generally includes bone restraint elements, such as pedicle screws and / or hooks, one or two connecting rods, intended to be connected to these fasteners and to be attached to the vertebrae by denting the same, and parts for connection of this joint bar (s) to these fasteners. The equipment can also comprise length-adjustable crossbars, which transversely join two parallel connecting bars to hold said bars relative to each other.

[0004] In an existing type of equipment, at least one clamping element is "polyaxial", that is, it comprises a base fraction that allows the bony clamping thereof and a proximal threaded stud, articulated with respect to that base fraction , where a nut can be screwed. Each connecting part may comprise a rounded section intended to be used to surround a connecting rod and two perforated parallel wings, these being intended to be engaged in said threaded proximal plug and to be embraced by that nut against a bearing surface provided in the fraction base, allowing said operation to embrace said rounded section around the joint bar and thus ensuring longitudinal immobilization of this bar with respect to the clamping element.

[0005] The vertebral osteosynthesis team is designed to immobilize two vertebrae with respect to each other, to eliminate any relative movement of these vertebrae, which is prone to be painful, or to return the proper position of a vertebra with respect to the other. To provide such immobilization, such equipment is designed to ensure the perfectly rigid assembly of the connecting rods with the fasteners.

[0006] Such a rigid assembly may, however, not be desirable in all cases. It leads in particular to significant loads being exerted in bone restraint areas of said fasteners, as well as to increased loads in the vertebral joints located on both sides of the treated vertebral segment (s), It can lead to early degenerations of these joints.

[0007] It is known from US 5,735,851 to provide a polyaxial clamping element from which the threaded proximal block can accommodate one or more concave spacers screwed thereon, these spacers being intended to rest against the convex head of the base fraction of the clamping element. The function of these spacers, in addition to adjusting the height of the connecting part, is to generate an additional grip load on the head of the base fraction to improve the immobilization of the block with respect to which base fraction later of grip

[0008] The clamping element according to this previous document, therefore, accounts for a rigid assembly of the block with respect to the fraction of the base, which does not allow the aforementioned defects to be remedied.

[0009] Document FR 2 697 742 describes a monoaxial clamping element that includes a washer made of impact absorption material placed between a support surface formed by the base fraction and the connecting part. The clamping nut, however, immobilizes this connecting part by connecting disposed with respect to the threaded proximal plug of the fastening element, and said washer only allows very limited movements of the connecting part with respect to the fastening element. WO 9855038 discloses equipment according to the preamble of claim 1.

[0010] The equipment according to these previous documents also accounts accordingly for a rigid or semi-rigid assembly that does not allow the aforementioned defects to be remedied.

[0011] The purpose of the present invention is precisely to remedy these defects.

[0012] The affected equipment comprises, in itself, bone restraint elements, such as pedicle screws and / or hooks, one or two connecting rods, intended to be connected to these fasteners, and parts for connection thereof ( s) bar (s) to these fasteners; at least one of the fasteners is of the "polyaxial" type, that is, it comprises an articulated proximal block with respect to a fraction of the base that allows bone restraint; the clamp means allow the assembly of the connection part in the clamping element.

[0013] According to the invention, the proximal block comprises a surface that forms an axial stop, against which the connecting part to be installed in the polyaxial clamping element is intended for rest, and said fixing means allow to embrace this part of connection against this surface, said surface being positioned so that the connection part, when hugging against this surface, is not hugged against the fraction of the base so that there is, after the grip, a possibility of articulated block play proximal with respect to said part of the base.

[0014] Thus, in the equipment according to the invention, said connecting part is not immobilized with respect to the clamping element but can be moved slightly, with respect thereto, to allow limited movements of the vertebrae. The stresses exerted in the bone restraint areas of the restraint element are therefore markedly reduced, as are the risks of overloading of the vertebral joints located on both sides of the treated vertebral segment.

[0015] Preferably, at least one polyaxial fastener comprises at least one part or fragment of a part with an elastically deformable structure, interposed, after assembly, between said connection part and a support surface.

[0016] This part or fragment of a part with an elastically deformable structure makes it possible to dampen the movement of the connection part, and therefore of the connection bar, with respect to said base part. Thanks to the axial stopping surface shown by the block, the grip of the connecting part is made independent of any grip of said part or fragment of a part, which is elastically deformable, and therefore does not interfere with it.

[0017] Said part or fragment of a part with an elastically deformable structure can be formed to dampen the movement of the proximal block over the entire set of this block, especially if it is composed of a compressible material, or it can be formed to provide this effect. Shock absorber only in the extreme positions of this game.

[0018] According to a possible embodiment of the invention in the latter case, said part or fragment of a part with an elastically deformable structure is composed of a circular wall fixed to the connecting part, this wall including at least one transverse groove which extends therethrough, provided on one side of this wall in a direction substantially perpendicular to that occupied by a connecting rod when this rod is engaged in the connecting part, allowing this slot to reduce the thickness of this circular wall when a load it is applied on this wall in the axial direction, on the side where the groove is

[0019] The proximal block and said surface forming an axial stop can be formed to allow adjustment of the axial position of this surface with respect to the proximal block, and this surface can be formed to embrace said part or fragment of a part of elastically deformable structure between said surface and said support surface against which this part or part fragment rests.

[0020] Said surface forming an axial stop then allows, according to the grip made, to adjust the damping effect produced by said part or fragment of an elastically deformable structure part.

[0021] According to an embodiment of the invention in such a case, the proximal block is screwed and said surface forming an axial stop is in the form of a part with a narrowed hole that can be screwed into this block.

[0022] Said support surface against which the part or fragment of a part with an elastically deformable structure rests can be a surface provided in said base part or the vertebral bone itself.

[0023] The walls of the proximal block and the clamping element that slide against each other during the play of this block can include a smooth and resistant coating layer, capable of withstanding a very large number of sliding movements of these walls a against the other, such as a ceramic or titanium nitride coating layer.

[0024] When the articulation of this proximal block consists of faces in the form of a sphere or fragments of a sphere that slide against each other, advantageously, these faces show a diameter that is significantly larger than that of the proximal block, over all at least twice the diameter of this block, to increase the contact surface of their faces with each other.

[0025] Frictions are thus exerted on enlarged surfaces, thus reducing the risk of wear of said faces.

[0026] In addition, at least one connection bar of the equipment may comprise:

-a fragment of a bar that includes a part with an elastically deformable structure and an articulated block,

- another fragment of a bar that includes a support area against this part of an elastically deformable structure, and

-clamp means to hug this support area against this part of elastically deformable structure.

[0027] The connection part preferably comprises a rounded section intended to surround a connection bar and two perforated parallel wings, intended to engage in said proximal block and to be hugged together to provide the grip of said rounded section around a bar of connection.

[0028] The invention will be better understood, and other features and advantages thereof will be presented, with reference to the schematic annexed drawing, which represents, for non-limiting exemplification purposes, two embodiments of parts included in the affected equipment.

Figure 1 is one of these parts, before assembly, according to an embodiment;

Figure 2 is a view of these parts similar to Figure 1, after assembly;

Figure 3 is a view of these parts similar to Figure 2, in a direction perpendicular to that according to Figure 2, in a first position;

Figure 4 is a view of these parts similar to Figure 3, in a second position;

Figure 5 is a view of these parts similar to Figure 3, in a third position;

Figure 6 is a perspective view of the same parts, after the screw is placed in a vertebra and before the final grip;

Figure 7 is a view of these parts similar to Figure 6, after the final grip;

Figure 8 is a view of said parts, before assembly, according to the second embodiment;

Figure 9 is a view of said parts similar to Figure 8, after assembly;

Figure 10 is a partial cross-sectional view of a connecting rod, before assembly, and

Figure 11 is a view similar to Figure 10, after assembly.

[0029] Figure 1 represents a pedicular polyaxial screw 1, a bar 2 connecting different of these screws 1, a part 3 that connects this bar 2 to one of these screws 1 and a nut 4 that allows to assemble the connection bar 2 a this screw 1.

[0030] The screw 1 comprises a threaded proximal plug 5 and a screwed base fragment 6. The plug 5 is intended for receiving the part 3 hooked on it and the nut 4 screwed on it while the body 6 is intended to the insertion in pedicle 100 of a vertebra, as shown in Figures 6 and 7.

[0031] The block 5 shows a screwed cylindrical fragment 10, an enlarged distal head 11 and a collar 12 forming a stop surface.

[0032] Part 10 shows an area 15 of reduced diameter, which allows to break its proximal fragment after placement and grip of nut 4, as it appears by comparison of Figures 2 and 3.

[0033] Head 11 shows a diameter that is twice the diameter of fragment 10 and looks like a spherical plug. This head 11 is intended to engage in a proximal cavity 16 delineated by the proximal area of the body 6 and to the retention in this cavity 16 by bending a proximal wall 17 exposed by this body 6. After bending, the wall 17 is formed to show a hemispherical proximal shape. As shown in Figure 1, the dimensions of the cavity 16 and the opening delineated by the wall 17 after bending to leave the block 5 therethrough are such that a multidirectional play of this block 5 with respect to the body 6 is possible. .

[0034] The body 6 also comprises a proximal collar 18, intended to collide with the pedicle 100. This collar 18 shows different radial notches 19, especially four notches at 90 ° to each other, for retention of the body 6 in rotation when hug the nut 4.

[0035] The connecting rod 2 is cylindrical and shows such rigidity as to support different vertebrae with respect to each other. This bar 2 is nevertheless deformable to be formed in relation to the correction of the spine to be performed.

[0036] The connection part 3 comprises a rounded section 20 intended to surround the connection bar 2 and two parallel side wings 21 perforated with holes for engaging the part 3 in the block 5. These wings 21 are mutually distant so that , in a distant position, the bar 2 can be inserted and can slide in the fragment 20, and so that in a close position provided by the grip of the nut 4, they embrace the fragment 20 around the bar 2, immobilizing it with respect to part 3.

[0037] As shown in Figures 1 and 2, the proximal wing 21 shows a proximal layer 25, where the shape is suitable for the nut 4 to rest to rest, while the distal wing 21 comprises a circular cavity 26 allowing the hook this wing on collar 12.

[0038] This distal wing 21 further comprises a circular wall 27 integral with it. The height of this wall 27 is smaller than that of the wall 17, and delineates a spherical concave inner face 28 of larger diameter than that of the wall 17.

[0039] On the other hand, two transverse grooves 29 are provided in this wall 27, on two opposite sides of the wall 27, and in a direction substantially perpendicular to that occupied by the connecting rod 2 when this bar is engaged in the section rounded 20. Each slot 29 extends angularly over approximately 120 ° of the wall 27 and terminated by a widened area 30 in the form of a circle.

[0040] As can be understood with reference to Figure 5, the distal fragments of the wall 27 delineated by the grooves 29 have, in these rounded areas 30, reduced height, so that these fragments can flex in these zones 30, allowing thus reducing the height of the wall 27.

[0041] In practice, the number of screws 1 necessary for the treatment to be performed are placed in the pedicles 100 of the affected vertebrae, then the connecting parts 3, with the bar 2 engaged in the fragments 20, are placed in the studs 5, until the collars 12 are engaged in the cavities 26. The nuts 4 are then embraced to immobilize the bar 2 with respect to the parts 3 and the proximal fragments of the studs 5 are cut.

[0042] In this grip position of each part 3 against the corresponding collar 12, the wall 27 rests only against the wall 17 by a very small surface, as shown in Figure 2. This grip preserves the possibility of articulated play of the block proximal 5 with respect to the screw body 6, this play being free as long as the wall 27 has not collided with the body 6 (cf. Figure 4), then being possible with a deformation of the wall 27 beyond, thus damping the movement of the block 5 at the maximum game angles of this block (cf. Figure 5). The possible limit of play of the latter corresponds to the contact of the edges of the wall 27 that delineates the slots 29.

[0043] Thanks to the diameter of its face 28, larger than the diameter of the wall 17, the wall 27 does not oppose the play of the block 5.

[0044] The sliding areas of the head 11 against the wall 17 and of the face 28 against the wall 17 can include a smooth and resistant coating layer, capable of resisting a very large number of sliding movements of these walls between Yes, such as a ceramic or titanium nitride coating layer.

[0045] Figures 8 and 9 represent parts 2 to 4 identical or similar to those described with reference to Figures 1 and 2, the parts being identical or similar with the same numerical references being designated.

[0046] In this case, the part 3 is deprived of the wall 27, and the equipment comprises, for at least one fastener 1, a part 31 in the form of a washer made of material with elastically deformable structure, especially silicone or PMMA, and a washer 32, especially metal, with a narrowed hole for being screwed into the block 5 until part 31 is caught between said spindle and part 6 of the screw.

[0047] Part 31 delineates a cavity as a part of a sphere, of dimensions adjusted to the outer face of the wall 17.

[0048] The washer 32 comprises an upper fitted to the cavity 26 and a lower widened fragment, which includes a peripheral edge that can be engaged in the upper part of the washer 31, as shown in Figure 9.

[0049] This washer 32 can be screwed into the block 5 until the part 31 is grasped in relation to a given damping effect required for the play of the block 5. Once such a grip has been provided, part 3, with the bar 2 hooked on it, is placed in block 5, then nut 4 is gripped to immobilize bar 2 with respect to part 3.

[0050] Figures 10 and 11 show a connection bar 2 of the equipment comprising:

- a fragment of bar 2a that includes a part 41 with elastically deformable structure and a threaded articulated block 50, this joint being identical to that previously described,

- another fragment of bar 2b, which includes a support area 42 against this part 41 and a narrowed hole 43 to screw this fragment 2b into the block 5 in order to embrace the support area 42 against the part 41.

[0051] The connection bar 2 can thus also have a certain degree of elastic flexibility.

[0052] As shown above, the invention provides vertebral osteosynthesis equipment that allows a certain space of the connection part 3, and therefore of the connection bar 2, with respect to the base holding fragment 6 to the vertebra, to allow limited movements of the treated vertebrae. The stresses exerted in the bone restraint anchoring areas of the restraint element are thus significantly reduced, as are the risks of overloading in vertebral joints located on both sides of the treated vertebral segment.

[0053] It is obvious that the invention is not limited to the embodiment described above for exemplary purposes but extends to all embodiments covered by the appended claims. Consequently, one would not leave the framework of the invention by replacing the wall 27 with a washer of elastic material or with an elastic structure, for example, in the form of a spring.

Claims (11)

1. Vertebral osteosynthesis equipment, including bone restraint elements, such as pedicle screws (1) and / or hooks, one or two connection bars (2), intended to be connected to these fasteners, and parts (3) for connection of this bar (s) (2) to these fasteners; at least one of the fasteners is of the "polyaxial" type, that is, it comprises a proximal block (5) articulated with respect to a base part (6) allowing the fastening of bones; the clamp means (4) allows the assembly of the connection part (3) on the clamping element; equipment characterized by the fact that the proximal block (5) comprises a surface (12, 32) that forms an axial stop, against which the connecting part (3) for being installed in the polyaxial clamping element is intended for the rest, and why said clamp means (4) allows to embrace this connecting part (3) against this surface (12, 32), said surface (12, 32) being positioned so that the connecting part (3), when hugging against this surface (12, 32), is not hugging against the part base (6) so that there remains, after hugging, a possibility of articulated play of the proximal block (5) with respect to said base part (6).

2.

Vertebral osteosynthesis equipment according to claim 1, characterized in that at least one polyaxial anchoring element comprises at least a part or fragment of a part (31) with elastically deformable structure, interposed, after assembly, between said part of connection (3) and a support surface (17, 18).

3.

Vertebral osteosynthesis equipment according to claim 2, characterized in that said part or fragment of a part (31) with elastically deformable structure is formed to dampen the movement of the proximal block (5) over the entire set of this block, and It is mostly composed of a compressible material.

Four.

Vertebral osteosynthesis equipment according to claim 2, characterized in that said part or fragment of a part (31) with elastically deformable structure is formed to provide this damping effect only in extreme positions of the proximal block play (5).

5.

Vertebral osteosynthesis equipment according to any of claims 2 to 4, characterized in that the proximal block (5) and said surface (12, 32) forming an axial stop are formed to allow adjustment of the axial position of this surface (12, 32) with respect to the proximal block (5), and because this surface (12, 32) is shaped to embrace said part or fragment of a part (31) with elastically deformable structure between said surface (12, 32) and said support surface (17, 18) against which this part or fragment of a resting part.

6.

Vertebral osteosynthesis equipment according to claim 5, characterized in that the proximal block (5) is screwed and said surface (32) forming an axial stop is in the form of a part with a narrowed hole that can be screwed into this block (5).

7.

Vertebral osteosynthesis equipment according to any of claims 2 to 6, characterized in that said support surface (17, 18) against which the part or fragment of a part (31) with elastically deformable structure rests, can be a surface (17, 18) provided in said base fragment (6) or the vertebral bone itself.

8.

Vertebral osteosynthesis equipment according to any one of claims 1 to 7, characterized in that the walls (11, 17) of the proximal block (5) and the fragment of the base (6) that slide against each other during the This block set (5) includes a smooth and resistant coating layer, capable of withstanding a large number of sliding movements of these walls with each other, such as a ceramic or titanium nitride coating layer.

9.

Vertebral osteosynthesis equipment according to any one of claims 1 to 8, characterized in that the articulation of the proximal block (5) consists of faces (11, 17) in the form of a sphere or fractions of a sphere that slide a against the other, and because these faces (11, 17) show a diameter that is significantly larger than that of the proximal block (5), in particular at least twice the diameter of this block.

10.

Vertebral osteosynthesis equipment according to any one of claims 1 to 9, characterized in that at least one connection bar (2) of the equipment comprises:

-a part (2a) of bar that includes a part (41) with elastically deformable structure and an articulated block (50), - another fraction (2b) of bar that includes a support area (42) against this part (41) with elastically deformable structure, and - clamp means (43) to hug this support area (42) against this part (41) with elastically deformable structure. 11. Vertebral osteosynthesis equipment according to any one of claims 1 to 10, characterized in that the connecting part (3) comprises a rounded section (20) intended to surround a connecting rod (2) and two perforated parallel wings (21), intended to embrace said proximal block (5) and to be hugged with one another to provide the grip of said rounded section (20) around a connecting rod (2).