Bone repair device

Translation of description of equivalent WO 02058529 A2

BONE REPAIR DEVICE.

The present invention relates to a device for bone repair by arthrodesis, intended for the reconstruction of a traumatic bone, especially for the cervical vertebrae.

In the context of operations performed to treat bone diseases of the spine, the surgeon proceeds to the total or partial removal of one or more vertebral bodies. No mechanical support is then provided by the extracted bones. To overcome this drawback, it is known to use rods, generally of titanium, and to fill the spaces left empty by the ablations with an inert and biocompatible filling material.

A rod is inserted between two healthy vertebrae to ensure a first shoring that allows to wait for hardening of the pasted material injected. It is also possible to use an autologous monoblock graft or a bank bone or a bone substitute.

Another technique is to replace the stem and biocompatible pasty material with a rigid mesh structure called vertebral body, or "vertebral body", into which bone graft is inserted to fill the void left by the ablation and form a support bony. But the establishment of the rigid cage requires distracting adjacent vertebrae resulting in operative complications. The cage is also opaque to X-rays.

A first object of the invention is to overcome this disadvantage.

According to the invention, the graft repair device of a traumatized bone is characterized in that it comprises a biocompatible fabric tube with large mesh, coated with a bioabsorbable material, into which the graft is introduced.

By fabric, we will hear both knits as woven or non-woven fabrics. It can be bioabsorbable or not. The tube is introduced into a bone cavity to fill it. But, preferably, the tube is held by means of a screw-fixed plate on healthy bone parts and, in the case of vertebrae, the tube is held in position by the vertebral endplates of the upper and lower vertebrae.

The tube is constituted by a biocompatible textile envelope, resorbable or not, wide mesh. The coating material may be a poly-L-lactide, polyglycolic acid compound or copolymers thereof. Poly-L-Lactide resolves over time, allowing growth of the graft through the meshes to the healthy bone areas cleared by ablation. The tissue tube alone would be too soft to ensure good implant contact with the healthy bone walls of the cut portion.

The deposition of bioabsorbable material, such as PLLA, makes it possible: to stiffen the tube for a certain time;

- to give it an adapted anatomical shape;

- First, make the tube tight passage grafts to prevent their dispersion.

According to another characteristic of the invention, in the case of vertebrae, the plate also serves to hold the implant in position by means of at least one screw whose end is embedded in the bone graft.

In the case of the vertebrae, it is known to proceed to the total or partial removal of the vertebral body anteriorly, which releases the necessary space for the introduction of the tube filled with grafts or compressed bone fragments. The purpose of the plate is to maintain good mechanical strength of the framework and to maintain the tube including a filling product in a precisely defined area between the bones, pending bone consolidation. Because of its composition, the tube is transparent to X-rays, which makes it possible to see the development of the bone graft by radiography and to monitor the development of engraftment. The tissue tube can be adapted to the intervertebral space available by simply cutting with scissors. When the PLLA is resorbed,

Other features and advantages of the invention will become apparent from the following description of a particular embodiment, given solely by way of non-limiting example, with reference to the drawings which represent:

- Figure 1 is a side view, in partial vertical section of the implant in position in the cavity of a vertebra having undergone a corpectomy, between two healthy vertebrae; - Figure 2, seen from above, in horizontal section of a vertebra having undergone partial corporectomy.

In the figures, the same references designate the same elements. In Figure 1, we see that the implant is constituted by a substantially cylindrical tube 1 containing bone grafts 2, which is included between two healthy vertebrae V. A plate 3 is applied along the tube 1, the plate 3. screwed into the vertebrae respectively superior and inferior to the vertebra which has undergone partial removal of the body. The plate 3 is held in position by holding screws 4 at its two ends, the screws 4 being fixed in the two healthy vertebrae V. The implant is connected to the plate 3 by at least one screw 5, which in the The example shown is central. According to the invention, the wide meshes 6 emerge after a certain time to allow the growth of the grafts.

We also distinguish in this figure transverse and spinous processes (not referenced) vertebrae. Figure 2 shows a view over the implant in position within a cut vertebra VI body.

In this figure, we have schematized the medullary canal

(not referenced). In the center of the plate 3, there is the screw 5 which penetrates through the tube 1 is fixed in the mass of bone grafts to provide safety in the maintenance of the tube 1.

Although the foregoing description relates to vertebrae, the invention can be applied in all cases where it is a matter of filling cavities between two bones, especially in the case of ablation.

It goes without saying that many variants can be made, in particular by substituting equivalent technical means, without departing from the scope of the invention.