JP3385018B2 - Flexible intervertebral stabilizer and method and apparatus for determining its tension before being attached to the spine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intervertebral disc stabilizer mounted between at least two spinal bones to correct defects in the spinal column.

The intervertebral disc stabilizers currently used to mitigate the often painful effects of spinal disorders such as scoliosis, nucleus pulposus, hernias, and lumbar instability are fixed to the vertebrae or spine along the affected area of the spine. It consists of a metal plate or rod. However, such disc stabilizers have the drawback of completely immobilizing the vertebrae and thus limiting or completely preventing flexion or torsion of the patient's torso.

The present invention seeks to overcome such shortcomings and, in order to achieve this end, provides a novel type of disc stabilizer. An intervertebral disc stabilizer according to the present invention comprises one or more flexible bands having flexibility in all directions, each flexible band including two flexible bands.
Means for securing to one vertebra are provided and / or associated with two retaining elements each implantable in a corresponding vertebra.

The at least one flexible band is generally closed loop or has a ring or closed loop at each end thereof. In this way, the ends of each flexible band constitute said fixing means which allow said flexible band to be tethered and fixed to the spinal column or other projection of the corresponding vertebra. If retaining elements are provided, each said retaining element is preferably a screw, advantageously with a free head for fixing one end of the corresponding flexible band.

Thus, depending on the mode of implantation, i.e., only one or both sides of the spine of the vertebra in question, whether anterior or posterior of the vertebra, a single flexible band is provided. Between the vertebrae to prevent the patient from bending or twisting the torso, depending on whether it is used or several flexible bands tied or crossed. Providing sufficient clearance makes it possible to compensate for all types of spinal defects or deformities.

In addition to these major advantages, the disc stabilizer according to the present invention has the advantage of simple installation.
Thus, for example, it is sufficient to engage the ends of each flexible band around the two vertebrae or the two screws implanted in the vertebrae.

When retaining elements such as screws are used, each said retaining element is provided with a removable cap that is of a larger radial size than the head of said retaining element to prevent slippage of the flexible band after attachment. It is effective to fit them. A similar effect is achieved by providing the head of each holding element with lateral projections for holding the flexible band.

Precisely determine the tension of the disc stabilizer, i.e., the resting length of each flexible band, according to the degree of the defect to be corrected, before mounting the disc stabilizer in place on the spinal column. Is required. To this end, the present invention is a method practiced after implanting a corresponding rigid rod at each of the vertebrae where a flexible band is to be attached so as to project from the patient's body. For each pair of two, the two rods are fixed at a predetermined distance from each other, and after a certain period of time, when the pain for removing the cause by the intervertebral disc stabilizer continues, the distance between the rods is Correct only a certain distance,
The rod is fixed in each new relative position, the pain test is performed again, and if necessary, the operation cycle is repeated until the pain disappears.

This method can also be used to identify and correct tension in one or more flexible bands already attached to the spinal column if the patient is in pain after a relatively long use. To be done.

Another object of this invention is a device for determining tension in a disc stabilizer before it is attached to the spinal column, each device having an end implanted in a corresponding vertebra. A rod set of two rods, the rods being associated with at least one rigid link having an adjustable length for connecting the rods at a position spaced from each implanted end; Is to provide a device characterized by.

According to a preferred embodiment, the implanted end of each rod is constituted by an element having a head on which an extension piece forming the rest of the rod is removably fitted,
The head is adapted to accommodate the length adjustable rigid link.

Once the task of determining the tension of the disc stabilizer is completed, the end elements of the rod, which are preferably screws, are attachable to the vertebrae and made to a length calculated using the method of the invention. The flexible strip is slid along the extension piece before the extension piece is removed,
It can be engaged around the screw.

The length-adjustable rigid link can be of various configurations, the simplest of which is a thin bar,
Two collars that can be fitted to each of the two rods and that are provided with means for slidably supporting the bar, each bar being provided with a bar locking member.

Furthermore, the device according to the invention comprises a device for determining the resting length of a flexible band constituted by two legs which are cross-coupled to each other in each middle part,
Each of the ends of the legs located on the same side of the cross connection part has a substantially semicircular contact piece, and the contact piece is applied to the corresponding holding element. In this way, between the other ends of the two legs of the device, a graduated ruler can be used to measure the length required for the flexible band to be implanted.

Embodiments of a disc stabilizer and methods and apparatus for determining tension of the disc stabilizer according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiment.

1 is a partial sectional side view of an intervertebral disc stabilizer according to a first embodiment of the present invention, FIG. 2 is a front view of an intervertebral disc stabilizer according to a second embodiment of the present invention, and FIGS. 2a and 2b are 2 shows a modification of the disc stabilizer of FIG. 2, FIGS. 3a, 3b and 3c show one of the flexible band retention elements of the disc stabilizer of FIG. 1, FIGS. 2 is a longitudinal and front view of one of the flexible band retention elements of the intervertebral disc stabilizer of FIG. 2, FIG. 5 showing a device according to the present invention being used on two adjacent vertebrae. FIG. 6 is a cross-sectional side view, FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5, and FIG. FIG. 8 shows the condition at one time, FIG. 8 shows the device of FIG. 5 being used to insert a flexible band around the holding element. , It is.

FIG. 1 shows two adjacent vertebrae V1, V2 in a patient's spinal column connected by a disc stabilizer according to the present invention. The disc stabilizer comprises a flexible loop 1 in the form of a closed loop and two screws 2, 3 implanted in the corresponding vertebra for supporting the flexible strip 1 between the vertebrae V1, V2, respectively. And the flexible band 1 is simply wrapped around the wide cylindrical head 4 of the screws 2, 3 and is exposed from the vertebrae. The flexible band 1 is an artificial ligament made of "Dacron" (registered trademark) or other flexible plastic material having flexibility in all directions.

The head 4 of each said screw 2, 3 is shown more clearly in the longitudinal section and front view of Figures 3b and 3c.
Comprises an axial blind hole 5 of hexagonal cross section for engaging a hexagonal key for implanting said screw in the corresponding vertebra.

After the flexible band 1 is attached around the screws implanted in the vertebra, the holes 5 of each screw are made with a flat circular cap or plug 6 which is only shown in Figure 3a, To be closed. The cap having a diameter greater than 4 of the screw head is screwed into a screw hole 8 opening at the bottom of the hole 5 via a central pin 7 having a threaded end. Is. In order to perform such screwing work, two holes 9 formed around each cap 6,
A special key is used that works with 9a. Alternatively, each said cap is provided with a hexagonal central hole and is screwed onto the head 4 of the corresponding screw 2, 3 by using a hexagonal key which engages the central hole. Good. As shown in FIG. 1, by projecting radially around the head 4 of the corresponding screws 2, 3, the two caps 6 prevent the flexible band 1 from slipping off the head 4. To prevent.

The cap 6 corresponds to the intervertebral disc stabilizer of the present invention shown in FIG.
It is particularly useful when using several auxiliary flexible bands, such as those designated by the numerals 1a and 1b in. The auxiliary flexible bands 1a and 1b are connected to the first flexible band 1 on the vertebrae before and after the two vertebrae V1 and V2 via the same number of auxiliary holding screws.

In the example shown in FIG. 2, the flexible band 1 having a closed loop shape.
However, only one is arranged between two consecutive vertebrae V1, V2, and as shown in the sectional and front views of FIGS. 4a and 4b, the head 4 of each screw 2, 3 is It has lateral projections 10 of suitable height. In the case of this example, first, the flexible strip 1
Implanting the two screws 2, 3 with their protrusions 10 facing each other so that they can be wound around the head 4 of the screws 2, 3 without any interference. It is necessary to do. The two screws 2, 3
After implantation, the screws 2, 3 will be rotated half a turn to orient each protrusion 10 to the flexible band holding position as shown in FIG.

The disc stabilizer according to the invention makes it possible to overcome a number of painful illnesses affecting the spinal column, depending on their mounting position. The intervertebral disc stabilizer shown in FIGS. 1 and 2 is the posterior surface of the vertebrae V1 and V2, and each vertebra A
It can be installed only on one side of 1, A2. However, depending on the type of disease to be treated, two intervertebral disc stabilizers according to the present invention may be attached to both sides of the vertebrae A1 and A2, or the two vertebrae V1 may be attached to the front or back of the two vertebrae V1 and V2. , V2 can also be installed by crossing. However, in each case, the tension of the disc stabilizer, ie the resting length of the flexible band 1, is determined as a function of the degree of the defect to be corrected before the flexible band is attached. There is a need.

To this end, the invention proposes a method and a device for making said length determination, which will be described below with reference to FIGS.

The basic components of this device are, in the preferred embodiment shown in FIG.
At the ends formed by each vertebra V1, V2
Fixed to. Two rigid linear rods 11 and 12
Is. On the patient's back to expose the vertebrae,
After performing a local incision on the anterior side of the vertebra, each of the screws is implanted as described above. Cap 6
After the rods are removed, the rods 11 and 12 are screwed into the screw holes 8 of the corresponding screws 2 and 3, respectively.
It comprises a cylindrical extension piece 13 having a threaded end 14 which is fitted on the head 4. For this purpose, the free end of each extension piece 13 is suitable for accommodating a key for tightening.
A prismatic head 23 is provided. In addition, each extension piece 13 is a leg
13a, the leg 13a having, in its diameter, the leg 13a.
It gradually expands outward until it becomes approximately the same diameter as the head 4 of the screw to which it is fitted.

The two rods 11, 12 are thus implanted so as to project from the patient's back D and are connected by a length-adjustable rigid link 15 near each free end. The distance between the rods 11, 12 is adjusted to a predetermined value as a function of the previously diagnosed nature and extent of the spinal column defect to be corrected.

In this way, after the two rods 11, 12 are fixed in this initial position, the incision in the patient's back is closed,
The patient will then undergo a test after a period of time, for example one or two days, to see if the affected area of the spine is still in pain. If the patient is still in pain, the spacing between the rods 11, 12 is slightly modified. This modification is generally done by changing the length of the links 15 to reduce (compress) the spacing. Thus, the above test is repeated as before after the same period.

Such a double test is repeated until the patient feels no pain in his back, optionally varying the spacing between the rods 11, 12 at a constant pitch. When the patient no longer feels pain in the back, the required length of the flexible band 1 to be implanted between the vertebrae at rest is determined or calculated with the highest accuracy.

In fact, the maximum number of consecutive cycles of the work leading to pain relief is three, and if the pain persists after the three cycles of work, the paining defect is tested. Therefore, the method according to the present invention must be applied to the next pair of vertebrae, and further to the next pair of vertebrae, until the pain disappears.

Of course, if one wishes to connect several flexible bands, such as 1, 1a, 1b in FIG. 1 over a long region of the spinal column, the method described above applies to all successive vertebrae to be treated. Will be applied simultaneously. That is, in this case, the same number of rods 11 and 12 as the vertebrae are used, and the rods are connected two by two by using a link whose length is adjustable as indicated by reference numeral 15.

The link, shown more clearly in FIG. 6, is
A thin cylindrical bar 16 held by two collars 17,18
The collars 17 and 18 are fixed to the corresponding rods 11 and 12 by fixing screws 19. The bar 16 is the head of the fixing screw 19 of the corresponding collar 17, 18.
After the distance between the rods 11 and 12 is adjusted by the rod 21, the collars 17 and 18 are slidably accommodated and fixed in the grooves 20 of the collars 17 and 18 more accurately. Alternatively, the link 15 may have a threaded rod of a particular pitch, which is also compatible with a system for directly measuring the distance between the rods 11,12.

The length assigned to the flexible strip 1 is, for example, the link 15
It can be obtained by trigonometric calculation from the distance d between the rods 11 and 12 fixed at appropriate positions measured in the vicinity of. However, according to an additional feature of the invention, by using the instrument described below with reference to FIG.
The length assigned to the flexible band 1 in between can be measured directly.

As can be seen, the device 24 for measuring the length of the flexible band 1 is generally one scissor-like configuration, and more specifically the same, intersecting each other in its middle part. It is constituted by two legs 25, 26 of length. These legs 25 and 26 are connected to each other by fixing screws 30 at intersections. On the same side of the fixing screw 30, at the ends of the two legs 25 and 26, contact pieces 28 and 29 which are substantially semicircular and have an inner diameter slightly larger than the diameter of the head 4 of the holding screws 2 and 3. Is supported. These contact pieces 28, 29 face each other, and each contact piece 28, 29
The arcuate inner surface of 29 is flush with the inside of the corresponding leg 25, 26. On the other side of the fixing screw 30, each leg 25,
Rings 31 and 32 for inserting fingers are provided on 26.

When measuring the length of the flexible band using the device 24, first, the back of the patient is incised until the vertebrae V1 and V2 are exposed. Then, by loosening the screw 30 and holding the device 24 with one hand through the rings 31, 32, each contact piece 28, 29 is placed on each rod 11, 12 and the contact piece
The device 24 is slid along the rods 11 and 12 until 28 and 29 are supported on the ends of the head 4 of the screws 2 and 3. The screw 30 is then tightened and the distance between the free ends 25a, 26a of the legs 25, 26 is measured using a graduated ruler 33. In this way, the required length of the flexible band to be implanted between the holding screws 2, 3 is directly determined.

After this measurement, the flexible strip 1 or 1,1 to be implanted
a, 1b are made from a flattened, folded and sewn tubular artificial flexible band. After the link 15 is removed, the flexible band formed into a loop as described above is wound around the two extension pieces 13 and then the heads of the screws 2 and 3 are wound along the extension pieces 13. It is slid to the part 4. Said flexible band is engaged around the head 4 if necessary using a special semi-cylindrical tool such as the one shown in FIG. Then, the extension piece 13 is removed and the cap 6 is screwed onto the heads of the screws 2 and 3 (FIG. 1), or the screws 2 and 3 are oriented so that the projection 10 is in the flexible band holding position. 2), and the incision in the patient's back is completely closed.

For example, according to another embodiment of the disc stabilizer of FIG. 2 shown in FIG. 2a, the flexible band 1c has a metal ring 41,
It is composed of a single member to which 42 is attached, and is fixed by being connected to the heads of the respective holding screws 2 and 3 via the rings 41 and 42.

According to another embodiment shown in FIG. 2b, the closed loop flexible band 1d of the intervertebral disc stabilizer is associated with the vertebrae of the corresponding vertebra V1.
Tie to form a first end loop 43 that engages around A1. At its second end, the flexible band 1d is
The inferior vertebra V2 is wrapped around the spine A2 and the fixation pin 44
After being inserted, it is tied to form the second end loop 45. Here, the vertebrae A1 and A2 are holding screws 2, 3
2d, but also in the flexible band 1d of FIG. 2d.
It goes without saying that the holding screw may be used in the same manner as the flexible bands 1 and 1c of 2a. Conversely, Figures 2 and 2a
The flexible bands 1, 1c of Fig. 2b may be fixed by being directly connected to the vertebrae A1, A2 of the vertebrae V1, V2 without using a retaining screw like the flexible band 1d of Fig. 2b. Good. Of course, the configuration of connecting multiple flexible bands, such as that shown in FIG. 1, is to secure the flexible bands either via pre-implanted retention screws or on the spine of the vertebra. Can also be realized in the embodiment of FIGS. 2a and 2b.

The retaining screws 2, 3 may be constituted by other retaining elements which are implantable in the vertebrae and which have a free head for fixing the flexible band.

Furthermore, although the rods 11, 12 of the device of the present invention may be made of a single member, if a flexible band retaining element such as a screw is used, it will be made up of two members, as in the previous embodiments. Is preferred. This is because in this case it is not necessary to re-implant the holding element after preliminary work for determining the tension of the disc stabilizer.

Furthermore, the screws or other retaining elements 2,3 their cap 6 and the rods 11,12 are preferably made of a biocompatible alloy.

Continued front page    (72) Inventors Blial, Francis, Henri               France, 75014 Paris, Lufria               13 (72) Inventor Graph, Henry               69002, Lyon, Quig, France               Ukulekulman 12                (56) References JP-A-60-111651 (JP, A)                 US Patent 4743260 (US, A)                 British Patent 1519139 (GB, A)

Claims (5)

(57) [Claims] 1. A disc stabilizer mounted between at least two continuous vertebrae, comprising one or more flexible bands (1,1a, 1b, 1c) having flexibility in all directions. , 1d), each said flexible band for fixing said flexible band to two corresponding vertebrae (V1, V2) and / or each corresponding flexible band Means for securing to two retaining elements (2,3) implantable in the vertebra (V1, V2), wherein at least one said flexible band (1,1a, 1d) is in a closed loop And the end of the closed loop constitutes the fixing means. 2. A disc stabilizer mounted between at least two continuous vertebrae, comprising one or more flexible bands (1,1a, 1b, 1c) having flexibility in all directions. , 1d), each said flexible band for fixing said flexible band to two corresponding vertebrae (V1, V2) and / or each corresponding flexible band Means for securing to two retaining elements (2,3) implantable in the vertebra (V1, V2) are provided, at least one said flexible band (1c, 1d) being provided at each end An intervertebral disc stabilizer comprising a ring (41, 42) or a closed loop (43, 45) constituting the fixing means. 3. Each said flexible band has said two holding elements (2,
3) is provided with means for fixing it at its end, each holding element (2, 3) having a free head (4) for fixing the end of the corresponding flexible band. 3. The intervertebral disc stabilizer according to claim 1 or 2, further comprising: 4. Each of said retaining elements (2, 3) comprises a removable cap (6) having a larger radial size compared to the head (4) of said retaining element, said cap (6) )
The intervertebral disc stabilizer according to claim 3, wherein the intervertebral disc stabilizer can be fitted on the head. 5. The head (4) of each holding element (2, 3)
The intervertebral disc stabilizer of claim 3, wherein the intervertebral disc stabilizer comprises a lateral projection (10) for retaining the flexible band.