IE74188B1 - Multifunctional spinal osteosynthesis device - Google Patents

Abstract

The object of the invention is a rachis ostheosynthesis device with pedicular screws of the type comprising a pin (1) having a threaded ogival shape and a threaded head (3) which are separated by a hexagonal body (2), said screws being connected by a linking element (5, 6), characterized in that it is comprised, additionally, of an unique fixing part (7, 8) provided with a hole (9) for the passage of said threaded head to which is screwed a nut (4, 4') for locking the assembly consisting of the fixing part (7. 8) and of the linking element (5, 6) on the head (3), one of the two members, that is to say either the fixing part or the linking element, being conformed on its lower face so as to form a groove (17, 21) for receiving and rotationally locking said hexagonal body (2). Application to osteosynthesis.

Description

The present invention relates to a device permitting spinal osteosynthesis with implants via the posterior route, one part thereof being intended for osseous anchoring in the vertebral pedicles, and the other part being able to receive either a plate or a rod for connecting the various screws to one another.

Normally, pedicle screws are implanted which are connected solely either by plates or by rods.

FR-A-2 615 095 has already disclosed a spinal osteosynthesis device according to the preamble of Claim 1, in which the connection element is a rod.

The object of the invention is to propose instrumentation which is of a simpler design than this known device, permitting particularly precise and reliable positioning and locking, and permitting the use both of a plate and of a rod, with a view to facilitating the spinal osteosynthesis irrespective of the anatomical conditions and irrespective of whether the deformation involves kyphosis, scoliosis or scoliokyphosis.

To this end, the subject of the invention is a spinal osteosynthesis device with pedicle screws of the type comprising a threaded point of ogival shape and a threaded head which are separated by a hexagonal body, the said screws being connected by a joining element, characterized in that it additionally comprises a single fixation piece equipped with a hole for passage of the said threaded head on which a nut is screwed for locking the fixation piece/joining element assembly on the said head, one of the two members - fixation piece or joining element - being designed on its lower surface in such a way as to constitute a groove for receiving the said hexagonal body and locking it in terms of rotation, the said stirrup-shaped piece likewise being equipped with striations on its face directed towards the plate.

According to one application, the joining element consists of a rod, and the device is characterized in that the said fixation piece comprises, on its upper surface, a groove in the bottom of which the said hole is formed, one of the flanks thereof forming a shoulder and the other flank delimiting a concave surface for receiving the said rod, the said locking nut being equipped on its lower surface with a frustoconical portion capable of bearing, on the one hand, against the said shoulder, and, on the other hand, against the said rod, and in that the lower face of the said fixation piece comprises the said groove for receiving and locking the hexagonal body.

According to one application, the joining element consists of a plate, and the device is characterized in that the said fixation piece is a stirrup-shaped piece which straddles the upper face of the said plate, is equipped with the said passage hole and is flanked by two parallel lateral projections, and in that the said plate comprises oblong holes and is equipped, on its upper face, with transverse striations, and, on its lower face, with the said groove for receiving and locking the hexagonal body.

Figure 1 in the attached drawing is an exploded view of an embodiment of the device of the invention for fixation of a rod.

Figure 2 is a cross-section of the device in Figure 1 when assembled.

Figure 3 is an exploded view of an embodiment of the device for fixation of a plate.

The device of the invention comprises pedicle screws, of a generally known type, made up of three parts: a point 1, a body 2 and a head 3.

The screw is made of materials approved for surgery in order to be biocompatible and to prevent equipment breaking at the point where it penetrates the vertebral body.

The screw point 1 is of threaded ogival shape and advantageously comprises a different conicity between the root of the threads and their crest.

The screw head 3 has a cylindrical shape with a threading permitting the reception of a nut (4, 4') for locking a rod 5 (Figure 1) or a plate 6 (Figure 3) by way of a single auxiliary piece (7 or 8) which is equipped in its central part with a smooth hole 9 and is threaded onto the head 3.

The nuts (4, 4') are continued in their upper part by a cylindrical tubular portion 10 with slots 11 permitting· a braking of the nuts by bringing the mutually facing portions 10 together slightly with the aid of a clip before threading the screw head 3 into the auxiliary piece 7, 8.

In addition, means are provided on one of the two following members: the single auxiliary piece or the element joining the pedicle screws, in order to form a seat for receiving the body 2 of the screws and locking it in terms of rotation in relation to the said joining element.

In the embodiment illustrated by Figures 1 and 2, the single auxiliary or intermediate piece 7 is interposed between a rod 5 which is of cylindrical crosssection and which has a diameter sufficient to withstand the stresses and loads imposed on the spine, the smooth surface having the advantage of permitting bending in order to obtain a certain curvature adapting to the deformations or to the anatomy of the spine.

This piece 7 comprises, on its upper face, a central groove 13 in the bottom of which the hole 9 is drilled. One of the flanks of the groove 13 is straight and forms a shoulder 14, and the other flank of the groove delimits a concave surface 15 serving as a seat for the rod 5 alongside the hole 9.

In this embodiment, the nuts 4 are continued in their lower part by a frustoconical portion 16 capable of bearing (Figure 2), on the one hand, on the edge of the shoulder 14, and, on the other hand, on the rod 5 in place in its seat 15 upon fixation and locking of the assembly 7, 5 on a screw head 3.

The piece comprises, on its lower face, a groove 17 (Figure 2) corresponding to the body 2 and receiving the latter and locking it in terms of rotation.

In the embodiment in Figure 3, the single intermediate piece 8 has a general stirrup shape which is intended to straddle a lumbosacral plate 18 which is precurved and of rectangular cross-section, comprising here and there oblong holes 19 for receiving the screw heads 3 .

The plate 18 comprises, on its upper face, transverse striations 20 and, on its lower face, a groove 215 [sic] analogous to the groove 13 of the piece 7, and intended to receive and to lock the screw bodies 2.

The intermediate piece 8 comprises a central portion which is drilled with a hole 9, preferably oblong for ease of insertion of the screw head 3, and which is flanked by two lateral projections 22 for guiding and wedging the piece 8 along the upper striated face of the plate 18, that face of the piece 8 directed towards the striations 20 being likewise correspondingly striated.

The striations prevent displacement of the screw head 3 in the oblong hole 19 once the tightening of the nut 4' has been tightened.

The nut 4' is analogous to that in Figures 1 and 2, except that it does not comprise a f rustoconical portion at its base.

By modifying the size of the screws (1, 2, 3), the device according to the invention can be used, in whichever embodiment thereof, to perform vertebral fixation along the entire height of the dorsal, lumbar and sacral spine.

Claims (5)

1. Spinal osteosynthesis device with pedicle screws of the type comprising a threaded point (1) of ogival shape and a threaded head (3) which are separated by a hexagonal body (2), the said screws being connected by a joining element (5, 6), characterized in that it additionally comprises a single fixation piece (7, 8) equipped with a hole (9) for passage of the said threaded head on which a nut (4, 4') is screwed for locking the fixation piece (7, 8)/joining element (5, 6) assembly on the said head (3) , one of the two members - fixation piece or joining element - being designed on its lower surface in such a way as to constitute a groove (17, 21) for receiving the said hexagonal body (2) and locking it in terms of rotation.

2. Device according to Claim 1, in which the joining element consists of a rod (5), characterized in that the said fixation piece (7) comprises, on its upper surface, a groove (13) in the bottom of which the said hole (9) is formed, one of the flanks thereof forming a shoulder (14) and the other flank delimiting a concave surface (15) for receiving the said rod (5) , the said locking nut (4) being equipped on its lower surface with a frustoconical portion (IS) capable of bearing, on the one hand, against the said shoulder (14) and, on the other hand, against the said rod (5), and in that the lower face of the said fixation piece (7) comprises the said groove (17) for receiving and locking the hexagonal body (2).

3. Device according to Claim 1, in which the joining element is an elongate plate (6) which is open-worked in places for the passage of the pedicle screw heads (3), characterized in that the said fixation piece is a stirrup-shaped piece (8) which straddles the upper face of the said plate (6), is equipped with the said passage hole (9), which is preferably oblong, and is flanked by two parallel lateral projections (22), and in that the said plate (6) comprises oblong holes (19) and is equipped, on its upper face, with transverse striations (20) , and, on its lower face, with the said groove (21) for receiving and locking the hexagonal body (2), the said piece (8) likewise being equipped with striations on its face directed towards the said plate (6).

4. Device according to one of Claims 1 to 3, 5 characterized in that the said nut (4, 4') is continued on its upper face via a cylindrical tubular portion (10) which is slotted diametrally (11) for the purpose of braking the nut.

5. A spinal osteosynthesis device substantially as 10 hereinbefore described with reference to and as illustrated in the accompanying drawings.