FR2744011A1 - Spinal osteosynthesis device - Google Patents

Abstract

The device consists of a plate (1) with a series of elongated apertures (2) which have chamfered edges and are designed to receive intermediate elements (21, 26) which match the shape of the apertures and have their edge chamfers in the opposite direction. Each of the intermediate elements has a slot in one side to engage with a screw, the base of each slot being in the shape of a semi-cylindrical recess. Each intermediate element can be replaced by two halves, fitted on either side of the screw, and the screws can have annular grooves (9) to receive locking plates (27).

Description

 The present invention provides a device for osteosynthesis of the spine.

 Vertebral synthesis devices are already known using perforated metal plates fixed by screws in the pedicles of the vertebrae (the merit of the first description of which belongs to Professor ROY CAMILLE) and aiming to stiffen part of the spine while keeping it in place stably vertebrae relative to each other.

 These plates are generally used in pairs and are each placed in a vertebral groove.

 Their length depends on the number of vertebrae to be joined.

 They can be straight or belted to match the shape of the area of the spine to be treated.

 The perforations are often circular to allow them to be opposite the pedicle or the articular process of the vertebrae where the screws are implanted. The perforations are sometimes oblong accepting an intermediate stud between the perforated plate and a screw which is then special and requires a locking nut.

 These known devices have certain drawbacks.

 The fixed center lines make it difficult for the surgeon to set up the plate, each perforation of which must coincide with the location of a possibility of screwing.

 Simple screw systems make it difficult to locate the hole in the bone through the hole in the plate at the bottom of an operative field where there is necessarily bleeding.

 Systems using a lock nut are bulky under muscle mass.

 Finally, in all these systems, there is sometimes a gradual loosening of one or more screws.

 The object of the present invention is to remedy these drawbacks.

 The originality of the system lies first in the realization of a chamfered removable part whose central bore along the longitudinal axis is extended laterally by a notch allowing the body of a screw to pass but not that of its head.

 The plate then has elongated lights each allowing to receive a removable part and a reverse chamfer from that of the intermediate part (21,22,23).

 There is another variety of intermediate pieces, each consisting of 2 half-pieces that can be opposed to each other and whose juxtaposition occupies the entire lumen of the plate and has a hole centered or eccentric along the longitudinal axis, for the passage of the pedicle screw- (24,25,26).

 Optionally, the system can be locked: - Either by using a thin clip, cap the screw head bypassing the lateral faces of the plate and taking support under it, - Or by using a thin notched plate, slipping in a groove of the screw, just under the underside of the plate and the shim; the screw in the latter situation and only in this latter, requires the machining of a circumferential groove. Apart from this last situation, the screws used can be the usual screws for surgical screws.

The present invention is now described more precisely using the attached figures.

Figure 1 shows the plate seen from above before bending.

FIG. 2 represents the plate seen from the side before bending and FIG. 3 is a section along the line AA before bending.

Figure 4 is a section along line BB.

Figures 5,6,7,8 and 9 show an intermediate piece of the "centered" type respectively seen from below, seen from the side. according to section BB seen opposite the notch then seen towards the notch finally according to section AA.

Figures 10 and 11 show an intermediate piece of the "eccentric" type, seen from below and from the side (22).

Figures 12 and 13 show an intermediate piece of type "S1", seen from below and from the side (23).

your Figures 14 and 15 show an opposable half-piece "centered" seen from below and seen from A (24).

Figures 16 and 17 show an opposable half-piece "offset" seen from below and seen from A (25).

Figures 18 and 19 show an opposable intermediate half-piece type "S1" seen from below and seen from A.

FIG. 20 represents a special screw admitting a locking plate, or a locking clip.

Figures 21 and 22 show a locking plate seen from above and side view.

Figures 23 and 24 show a locking clip viewed from the side and from above.

The plates (1) according to the invention are made of a biocompatible material, sufficiently resistant, for example metal and have a width of about fifteen millimeters with possibly narrowing in the parts uniting the lights (fig 1 ). The length of each plate depends on the number of lights it contains. They are arched to adapt to the usual curvatures of the parts to be fixed in the spine.

 Each lumen (2) is elongated along the longitudinal axis and has a rounded shape at each end; all lights are the same size. They are delimited by a flared chamfer (3), made over the entire thickness of the plate and wider at the upper face than at the lower face of the plate.

 The lower part of each outer edge of the plate opposite the lights is marked with an imprint (4) making it possible to receive the end of the legs curved with a staple.

 The intermediate parts intended according to the invention to cooperate with the openings (2) of the plate (1) are shown in FIGS. 5 to 19.

 Each intermediate piece cooperates exactly with a light (2) of the plate (1). It thus has a peripheral chamfer (5) made in the thickness of the part, the upper face of which is thus wider and longer than the lower face; this chamfer (5) is opposed to the chamfer (3) of the plate.

 The part is notched (6) on one side along the transverse axis BB with a width identical to the diameter of the body of a screw; the bottom of the notch (6) is rounded according to a half-cylinder whose axis is perpendicular to each of the faces of the intermediate piece and whose diameter is the smallest diameter allowing the wise pitch of the body of a screw.

 The upper face of each intermediate piece is marked by the imprint (7) of a screw head centered on the cylinder axis described above and identical to the axis of the screw implanted dae the vertebral pedicle.

 The intermediate piece shown in Figures 5 to 9 is used when the screw implanted in the vertebral pedicle and incompletely screwed, is placed substantially in the center of the lumen (2) of the plate (1). Thus the axis of the bottom of the notch (6), perpendicular to the upper and lower faces of the part, passes through the geometric center of each of these two faces; the intermediate piece is said to be "centered" (21).

 An alternative solution to this situation is possible by using two half-pieces opposing one another as shown in FIGS. 14 and 15 at the lateral edge presenting the chamfer (5); the upper face of each half-piece is marked with the impression (7) of a screw head and each half-piece is hollowed out over its entire thickness in the middle of its mesial edge of the half-cylinder (6). The opposition of the two half-cylinder recesses allows passage to the body of a screw. The two half-pieces are said to be "centered" (24).

 The intermediate piece shown in FIGS. 10 and 11 is used when the screw implanted in the vertebral pedicle and incompletely screwed is not placed substantially in the center of the lumen (2) of the plate (1) but is shifted upwards. or down from this light. The axis of the bottom of the notch is then offset on the longitudinal axis AA of the part and is no longer on the transverse axis BB of this part. The intermediate piece is said to be "eccentric" (22).

 An alternative solution to this situation is also possible here by using two half-pieces opposing "in mirror" by their mesial edge whose opposite recesses in half-cylinder are offset with respect to the transverse axis BB of the two half-pieces . These two half-pieces are said to be "offset" (Figures 16 and 17).

he intermediate piece shown in FIGS. 12 and 13 is used for the particular case of a screw implanted in the pedicles of the first sacral vertebra; the peculiarity of this wedge called "S1" compared to the other intermediate parts described, is that the bottom of the notch (8) is no longer a portion of cylinder, but a portion of truncated cone, flaring towards the face bottom of the intermediate piece thus allowing a movement of the screw relative to a perpendicular to the plate
An alternative solution to this situation S1 (fig 18 and l9) is here also possible by using two half-pieces opposing "in mirror" by the mesial edge whose opposite recesses are in truncated half-cone at the lower base (26 ).

 The screws used can be conventional surgical screws, but a special screw can be used, which, as shown in FIG. 20, has a circular groove (9) located so that it is located just below the lower edge of the plate when the screw is completely screwed. This groove accepts a clip or a plate (FIGS. 21 and 22), thus making it possible to lock the system.

 This plate (fig 21 and 22) makes a square whose part -; vertical tie (11) comes to rest on a lateral edge of the plate. On the horizontal part (10) there is a notch (12) which narrows from its free edge towards the vertical part; the bottom of the notch is a semicircle (13) which corresponds to the bottom of the groove (9) of the screw in FIG. 20. This flaring guides the plate on the body of the screw.

 The distance B from the diameter of the semicircle to the vertical part of the plate is equal to the half-width of the plate in FIG. 1.

 The free edge of the horizontal part of the plate is bevelled (14) on its lower surface and marked on its upper face by a small elevation (15) whose distance A to the diameter of the semi-circle is equal to the half-width of the plaque.

 An alternative to the locking, moreover optional, of the system is shown in FIG. 23 and 24 in the form of a staple whose curved ends (16) of the side tabs, fit into the imprints 4 of the plague of FIG. 1.

 Its horizontal upper part, which covers the upper face of the plate, of the intermediate piece and of the screw head, may be pierced with a hole (17) admitting the screwdriver and thus making it possible to better center the staple.

 Also optionally, the underside of the plate 1 and / or intermediate wedges, may have reliefs in diamond points or notches to ensure a better seat on the vertebrae.

 With the system of the present invention, it is possible to start by placing the screws chosen in the pedicle aims of the vertebrae by screwing them only very incompletely. It is then easy to place the plate (1) in the gutter, the screw heads passing very widely through the slots (2).

 Under these conditions, for a given position of the screw in a slot (2) in the plate (1) and with the set of centered and eccentric intermediate pieces introduced in one direction or the other, it is possible to have a correct centering of the screw in the plate-intermediate piece assembly.

 The intermediate parts, thanks to their notch (6), are slid along the screws in the slots (2) of the plate (1).

 The chamfers of the intermediate pieces opposing those of the lights of the plate, block the intermediate pieces in the lights of the plate.

 The principle is obviously the same using intermediate half-pieces (24,25,26).

 The tightening of the screws, the heads of which rest on the impressions (7) of the upper face of the intermediate parts, stiffens the system and ensures vertebral synthesis.

Optionally, it is then possible to lock the system and prevent the unscrewing of the screws using: - Either a staple (Figure 23 and 24), - Or, if the implanted screw is a special screw, a clip or a
plate (fig 21 and 22) that its notch 12 will guide on the
screw under the plate until its bottom 13 enters the
groove (9) of the screw.

 Finally, one can provide on the intermediate parts, a flexible coating which would allow flexibility to the system.

Claims (9)

 1) Spine osteosynthesis device comprising a plate (1) and intermediate parts (21 to 26) integrating screws previously implanted in the vertebrae.  2) Device according to claim 1, characterized in that the plate (1) has slots (2) elongated, each chamfered can receive an intermediate piece (21 to 26) of corresponding shape but with the reverse chamfer.  3) Device according to claim 2, characterized in that the chamfered intermediate piece (21,22,23) has laterally a notch (6) allowing the passage of the body of a screw and the bottom of which is a cylindrical half-bore on the longitudinal axis of said intermediate piece and perpendicular to it.  4) Device according to claim 3, characterized in that the notch and the cylindrical bore are on the transverse axis or at another point of the longitudinal axis of the intermediate piece.  5) Device according to claim 2 characterized in that the bore may be conical (8) with upper apex and lower base allowing movement of the screw.  6) Device according to any one of the preceding claims, characterized in that each intermediate piece (21,22, 23) can be replaced by two intermediate half-pieces (24, 25,26) opposite by their longitudinal axis, including the notches are limited to centered or eccentric half-cylindrical or semi-conical bores and enclosing the screw bodies after fitting in the slots (2) of the plates.  7) Device according to any one of the preceding claims, characterized in that one can use a special screw (20) having a circumferential groove (9) admitting a clip or plate type locking device (27) and located at a distance of the screw head such that the plate and any intermediate piece are wedged between the head and said locking device.  8) Device according to claim 7, characterized by a plate quet (27) having a notch (12) whose bottom is semicircular (13) responding to the bottom of the groove (9) of the screw (20) and bearing under the plate (1).  9) Device according to any one of the preceding claims, characterized by a clip (19) totally or partially covering the screw head and bypassing the lateral faces of the plate 1 and the curved ends of which (16) hang notches 4 on said faces. from the plate to their lower part.