WO1997046165A1

WO1997046165A1 - Surgical instrument for the fusion of vertebrae

Info

Publication number: WO1997046165A1
Application number: PCT/TR1997/000007
Authority: WO
Inventors: Cengiz Türkmen
Original assignee: Tuerkmen Cengiz
Priority date: 1996-06-04
Filing date: 1997-06-04
Publication date: 1997-12-11
Also published as: EP0909142A1; AU2989997A

Abstract

The present invention is related to a medical instrument which provides spinal stabilization during the fusion of the substitute bone fitted in the place of the removed vertebra that is damaged as a result of fracture, displacement, infection etc. in human body in order to prevent the bruising of the medulla (spinal cord). The instrument is characterized in that it consists of at least two basic screws (1), two locking pieces (2) preventing the rotation of the vertebra and a connecting piece (3, 4, 5).

Description

SURGICAL INSTRUMENT FOR THE FUSION OF VERTEBRAE

FIELD OF THE INVENTION

The present invention is related to a surgical instrument which provides spinal immobility (stabilization) during the fusion of the substitute bone placed after the removal of the damaged vertebra in order to prevent the medulla (spinal cord) from being bruised, as the result of a damaqe occurred in the vertebral column of a human body due to such reasons as fracture, dislocation, infection and the like.

In such cases when the vertebral column is bruised, the damaged vertebra is removed and replaced by a piece of bone taken from another part of the body. However the vertebral column must remain immobile during the fusion of this new bone with the undamaged vertebrae. PRIOR ART

The instruments used currently in order to provide this, may be classified in two groups, namely anterior and posterior instruments.

Anleπoi devices, that is to say the devices that are applied from the fore-part, are related to inserting screws into the vertebral column corpus through the lateral wall of the corpus and providing communication between the rods and these screws.

Whereas, the posterior devices, i.e. those applied from the back-side, are applied by inserting screws from the peduncle region of the vertebral column and connecting these screws with rods.

Here the object is helping the process of fusion by providing immobility during the fusion of the newly aced bone with the undamaged vertebrae, as mentioned above.

However, the disadvantage of the said systems is that it is easily subject to bending or fracturing as the result of being left outside the axis where the loads on the vertebral column a re maximum . Furthermore , the insert ion of the screws into critical anatomical regions may lead to injuries during the implementation of these devices.

The object of this application is to eliminate these disadvantages and this object is realized with the device as defined herebelow with two preferred embodiments.

DETAILED DESCRIPTION OF DRAWINGS

The present invention is explained in detail by making reference to the attached drawings and two embodiments of the device.

In the drawings;

Fiqure 1 shows the anterior and posterior systems;

Figure 2 i s the v i ew of the basic principle of the device according to one embodiment of the present invention;

Fiqure 3 is the view shown after the insertion of screws into the upper and lower undamaged vertebrae according to tne first embodiment;

figure 4 is the view formed by the addition of extension pieces according to the first embodiment;

Fiqure 5 is the view after securing the pieces which prevent rotation according to the first embodiment;

Figure 6 is the view after attaching the connector according to the first embodiment;

Figure 7 is the view after the placement of the bones that will provide the fusion according to the first embodiment.

Figure 8 is the view of the device after the insertion of the screws (1) into the upper and lower undamaged vertebrae, upon the removal of the damaged vertebra according to the second embodiment.

Figure 9 is the view of the anti-rotation locking pieces (2) shown after their insertion into the parts of screws (1) that are left outside the vertebrae according to the second embodiment.

Figure 10 is the view of the connector (3,4) after it is placed onto the lower screw (1) according to the second embodiment.

Figure 11 is the view of the bones intended to provide fusion with the undamaged vertebrae after the insertion of the fixing screws (5) upon the completion of distraction following the opening of the connector

(3,4 ) by turning it according to the second embodiment.

Fig ure 12 is the overal l view of the device according to tne second embodiment .

DETAILED DESCRIPTION OF THE INVENTION

The present invention solves the above mentioned problems and disadvantages by using the instrument of the invention applied from the anterior in order to fasten with screws from the bottom or the top of the corpus instead of screwing up from the lateral wall of the same and to connect them with an intermediary piece (connector) . By reducing the size of the screw, for example up to 26 mm and by providing the appropriate width e.g. 2.8 m and pitch e.g. nine threads for the threads of the screw, as well as by employing the improved supplementary instruments, it has been possible to fit the screws (1) from the small gap created by the removal of the damaged (broken, with tumor, infected) bone. It is also possible to attach the extension pieces on back aftei inserting the said screws (1) into the upper and lower undamaged vertebra. However, as the instrument is strong enough even without the extension piece (4), the said piece (4) is not required in cases when the fracture does not adversely effect more than one vertebrae. As shown in Fiq. 5, following the affixation of the screws (1) on both vertebrae, the connector piece (2) is connected to the screws. Then the pieces (5) that prevent rotation in this region are driven into the bone after passing through the connectors (2).

Following these operations, four nuts (3) are attached to the connector (4) and the connector, thus prepared, is mounted on the joining piece (2) placed in the upper and lower vertebrae; the connection is finalized by sliding the nuts (3) towards the joining piece (2) and by coupling them. First nuts are tightened by an appropriate spanner to counteract with second nuts (3).

Installation of the instrument is thus completed.

The instrument is made of stainless steel and titanium.

In addition to its advantage of being applied very easily and rapidly as compared to those instruments employed in the prior art, there are no breaking nor bending problems as the resul t of compression and rotation forces.

For instance, while the strength of the system being the subject of this invention is 19000 Newtons under compression, it is approximately 7000 Newtons in other systems.

Another advantage of the present invention is that it can be elongated as much as required in case more than one vertebrae are broken. Due to the power provided by the instrument, rib and/or bone chips are sufficient for fusion. However, as the instruments of the other devices are weaker, strong bones must be used. For this reason pieces from the femur or fibula of the patient are required to be utilized as substitute piece.

Ready-packed bones (ALLOGRAFT) may also be used instead o f vertebra but these bones are weaker, more expensive and more difficult to fuse in structure.

Besides, there is a danger of rejection by the body as they are provided outside the body.

Whereas due to the stiffness and ability to provide spinal stabilization of the instrument provided by the present invention, the chance of fusion being the aim of the operation is much higher than that of the other systems. According to the second embodiment of the invention, as in the previous system, after the screws are inserted into the upper and lower vertebrae, the anti-rotation lockinq pieces (2) are directly pushed into the screws (1) without lequiring the attachment of the connector.

Then the connector II (3,4,5) is applied instead of the connector equipped with nuts. The said connector II (3,4,5) consists of two pieces (3,5) and fixing screws

(5). The thickness of the external part is variable according to the type of vertebrae to be placed in (e.g.12 mm at thoracolumbar region) and its exterior surface is rough in order to prevent its slipping from the instruments whereas its inner surface is grooved.

There are also grooved recesses on it for the passage of the fixing screw (5) in order to fix the screw (1) and to f ix the pieces (3,4) to each other. The length of the piece (3) varies according to the damaged vertebrae region. There is a hexagonal recess at its lowest section which opens to the inner grooved space. It fits on the hexagonal end of the screw (1) and the screw is locked by fixing screw (5) and the piece (3) through the hole on the said piece. At the upper section of this piece (3) there is a threaded opening (3) through which the piece (4) can be screwed.

The inner part (4) consists of two sections. The head section is hexagonal or octagonal and allows the use of a spanner and thus the pieces (3,4) slide over each other as they are threaded. The section below the head is completel y threaded and the piece (4) also varies in length and width, depending on the location and damage of the vertebra. There are two holes on the head section.

One of them that can be seen from the top, is the hole in which the hexagonal part of the screw (1) is fitted and it must be larger than the diameter of the hexagonal part.

Thus, this screw is not drawn tight in the said hole and allows the rotation while the pieces (3,4) are rotated due to their grooves and slided over each other. By this system, distraction which is very important for the comfort ana safety of the medulla, is provided.

The hole that can be seen from the lateral sides are threaded holes opened according to the fixing screws (5) that are also provided for the piece (3), in order to tighten the hexagonal section of the screw (1) .

The fixing screws (5) are inserted into these holes in order to lock the pieces (1) and (4).

As a result of removing the previous connector joining pi ece and thus eliminating the thin connection points of the instruments, the system has become stronger and more durable and the installation period has been signiticantly shortened. As this device is very strong, it is possible to use small bone pieces for fusion. The system has become stronger by this connector (3,4,5) and its supporting capacity has increased five times as compared to the first embodiment. Again, the most important advantage of this system is that there is almost no risk of injuring the peripheral tissues during the fitting of the instrument. However in otner systems, this risk may be very high in a manner inversely proportional to the experience of the surgeon.

Claims

CLAIMS 1. An instrument for providing immobility (spinal stabilization) during the fusion of the substitute bone fitted in the place of the damaged vertebra that has been removed, characterized in that it eonsists of a basic screw (1), more than one, preferably two or more connecting pieces ( 2 ) , more than one and preferably two or more pieces (5) preventing rotation and more than one and preferably four connectors (3,4).

2. Instrument as defined in claim 1, characterized in that it is installed by inserting the screw through the connecting piece, the piece preventing rotation and the connector, followed by fixing the said screw.

3. Instrument as defined in claim 1, characterized in that the screw is a piece providing the fixation of the instrument along the long vertebrae the tip of which is pointed to facilitate its insertion.

4. lnstrument as defined in claim 1, wherein the connecting piece provides the connection with the screws pushed forward.

5. Instrument characterized in that the piece preventing rotation as defined in claim 1, prevents the substitute piece fitted in for fusion, from being effected by rotation towards left or right.

6. Instrument characterized in that the connector completes the system by connecting the screw system inserted in the upper and lower vertebrae as defined in claim 1.

7. An instrument for providing immobility (spinal stability) during the fusion of the substitute bone fitted in the place of the damaged vertebra that has been removed characterized in that it consists of at least two basic screws (1), two locking pieces preventing the rotation of the vertebra (2) and a connecting (3,4,5) piece.

8. Instrument as claimed in Claim 7, characterized in that the screw (11) is installed in such a manner that it prevents rotation and fixes the connector.

9. Instrument as defined in Claim 7, characterized in that the said screw provides the fixation and rigid placement of the device along the long vertebrae, having its tip tapered in the form of a triangle and provided by a groove along its longitudinal axis for facilitating sliding into the bone, also with a conic shaft and wide and closely placed wings.

10. lnstrument as defined in Claim 7, characterized in that the anti-rotation piece prevents the substitute pieces placed for fusion from being effected by the rotational movement to left or right.

11. Instrument as defined in Claim 7, characterized in that the connector completes the system by connecting the screw system inserted in the upper and lower vertebrae.