FR2636227A1 - Inter-spinal-body device for holding a normal spacing between two vertebrae - Google Patents

Abstract

This device, intended for holding a normal spacing between two vertebrae separated by a gap coming from at least partial extraction of one vertebra, comprises two end parts 1, 2 provided with spikes 7 for anchoring in the vertebral bodies, a central rod 5 received in notches 8, 9 in the pieces 1, 2 and fixed to the latter by radial screws 11, and a central sleeve 6 which is freely passed through by the rod 5 and is placed in abutment between the two pieces 1 and 2. This compact device can be fitted relatively easily by the surgeon and ensures good stability by axial mounting in the direction of the mechanical stresses.

Description

 The present invention relates to a spinal intercorporeal device, intended to maintain a normal spacing between two vertebrae separated by a recess from an at least partial extraction of a vertebra.

 As is known, it is necessary in certain cases to carry out an at least partial ablation of a vertebra, in particular following a burst fracture of a vertebra, in particular in the dorso-lumbar region, and for the treatment of a vertebral tumor.

 European patent 188 954 of December 19, 1985 describes a shoring device adapted to this function. This device comprises two bases each provided with means for anchoring in one of the vertebrae, screws fitted with studs which can fit into the bases, and a threaded sleeve for connection between the screws.

This device consists of a high number of parts, so that its manufacture is complex and expensive, and that its installation by the surgeon is relatively long and delicate. In addition, its size is high and its stability is not satisfactory
However, the increasingly wide excision of the vertebral bodies requires the development of more and more efficient osteosynthesis equipment.

 The object of the invention is therefore to produce an intercorporeal spinal detractor which satisfies this requirement and does not have the above drawbacks.

 According to the invention, the device comprises two end pieces provided with anchoring means in the vertebral bodies, and a central rod connecting the end pieces as well as means for securing the latter with the rod.

 According to a possible embodiment, the device also comprises a central sleeve freely traversed by the rod and placed in abutment between the two end pieces.

 The rod and the sleeve have a variable length in order to be able to adapt to each case and to allow restoration of the normal height of the cavity between the two vertebral bodies.

 The sleeve ensures better stability of the device thanks to its contact with the base of the end pieces.

 Other features and advantages of the invention will become apparent during the description which follows, given with reference to the appended drawing which illustrates, by way of non-limiting examples, two embodiments.

 Figure 1 is an exploded perspective view of an embodiment of the spinal intercorporeal device according to the invention.

 Figure 2 is an end view of one of the end pieces, its side directed towards the central rod and the opposite end piece.

 Figure 3 is a perspective view of the device of Fig.1 and 2 placed between the vertebral bodies.

 Figure 4 is a perspective view of an alternative embodiment of the central rod.

 The intercorporeal device shown in the drawing comprises two identical end pieces 1 and 2 provided with means for anchoring in the vertebral bodies 3, 4, a central rod 5 connecting the pieces 1 and 2, as well as means for securing the latter with the rod 5. In addition, the dispOSitif is completed by a central sleeve 6 freely traversed by the rod 5 and placed in abutment between the end pieces 1,2 (Fig.3) when the device is put in place.

 In the embodiment described, each end piece 1, 2 has a substantially cylindrical shape and its anchoring means are constituted by longitudinal points 7 extending from one of the faces of the cylindrical body. These points 7 are for example three in number, and adapted to be able to be inserted in the vertebral body 3,4 sus and underlying the bone resection. In each end piece 1.2 is provided a respective notch 8.9 open laterally and longitudinally on the side opposite the points 7, so as to be able to receive the central rod 5.

 The parts 1, 2 are also equipped with elements for fixing the rod 5, constituted in the example described by two radial screws there for each part 1, 2, passing through a tapped hole which opens into the notch 8 or 9. Each screw It is provided with a profiled head 11a to receive a tightening tool, for example a hexagon profile. The screws 11 therefore have the function of locking the rod 5 in place according to the same principle as that used in the Cotrel and Dubousset equipment.

 The rod 5 has a surface provided with roughness, for example diamond points, as in the instrumentation of Cotrel-Dubousset.

 The establishment of the intercorporeal device which has just been described requires specific instrumentation, namely: a tripod pusher for driving the end pieces 1 and 2 into the vertebral bodies 3 and 4, and a key for tightening the screws 11.

The assembly of the device according to the invention is carried out as follows
1. On the cervical floor, the unilateral or bilateral anterolateral approach allows the excision of one or more vertebral bodies 3,4. In this way, the intercorporeal system is put in place. The parts 1,2 forming tripods are inserted into the vertebral bodies above and underlying the bone resection. The central rod 5 provided with its sleeve 6 is introduced into the lateral notches 8 and 9 of the parts 1 and 2. The screws 11 are tightened on 3a rough surface of the rod 5, joining the various parts of the device. The assembly is then completed by placing, in a manner known per se, bone grafts or acrylic cement.

 2. On the dorso-lumbar stage, the first way is a bilateral posterolateral way by transverso-arthropediculectomy, which allows the complete excision of one or more vertebrae by controlling the radiculomedullary axis in first intention . By this way, the device is put in place. The two end pieces 1 and 2 are inserted by their points 7 in the bodies 3,4 sus and underlying. The central rod 5 provided with its sleeve 6 is introduced into the notches 8, 9 of the parts 1.2, the screws 11 of which are then tightened, in order to secure the mounting elements. The operative gesture is then completed by the placement of bone grafts or acrylic cement and a posterior osteosynthesis.

The advantages of the device according to the invention are as follows:
- It consists of a reduced number of parts compared to the previous device mentioned above, so that its manufacture is more easy and less expensive, and that its implementation by the surgeon is less delicate and difficult.

 - its size is reduced, which facilitates the placement of bone grafts or acrylic cement.

 - it makes it possible to restore the anterior part of the vertebral tripod 1,2 to the cervical stage by anterolateral approach, and to the dorso-lumbar stage by posterolateral approach, therefore at the same time and by the same approach as radiculo-medullary decompression.

 - It ensures maximum stability by axial mounting in the direction of mechanical stresses, and therefore allows the widest possible excision of the vertebral body or bodies.

The indications for this device are as follows
primary or secondary spinal tumors which require the widest possible excision to be carcinological. The device enables a complete vertebrectomy to be performed on both the cervical and dorso-lumbar levels, by the stability it provides once the bone resection has been performed.

 - traumatic spinal lesions with significant bone decay of one or more vertebral bodies.

 In the second embodiment illustrated in FIG. 4, the rod 5 and its sleeve 6 are replaced by a block, constituted by a smooth rod 12 provided with a cylindrical central projection 13 produced in one piece with the rod 12 and coaxial with it.

Of course, the dimensions of the rod 12 and of the projection 13 are adapted to each particular case, so that the parts 1 and 2 bear on the projection 13.

 Various variant embodiments can be made to the device which has just been described without departing from the scope of the invention. Thus the shape of the end pieces 1 and 2 can vary, as can the number of their anchor points 7, which could moreover be replaced by any other equivalent anchoring means.

Claims (6)

 1. Spinal intercorporeal device, intended to maintain a normal spacing between two vertebrae (3,4) separated by a recess from an at least partial extraction of a vertebra, characterized in that it comprises  - two end pieces (1,2) provided with means for anchoring in the vertebral bodies,  - And a central rod (5) connecting the end pieces (1,2) as well as means for securing the latter to the rod.  2. Device according to claim 1, ca acterized in that it comprises a central sleeve (6) freely traversed by the rod (5) and placed in abutment between the two end pieces (1,2).  3. Device according to claim 1, ca acterized in that the rod (t2) is provided with a cylindrical central projection (13) made in one piece with the rod and coaxial therewith.  4. Device according to one of claims 1 to 3, characterized in that in each end piece (1,2), preferably cylindrical, is provided a notch (8,9) open laterally and longitudinally on the side opposite to anchoring means (7), in order to be able to receive the central rod (5), and said parts are provided with elements for fixing the rod to the parts, for example radial screws (11) opening into the notch (8 , 9).  5. Device according to one of claims 1 to 4, characterized in that the rod (5) has a surface provided with roughness, for example diamond points.  6. Device according to one of claims 1 to 5, characterized in that the means for anchoring the end pieces are points (7), for example three in number.