MXPA06006559A - Instrument for the insertion of an intervertebral articular prosthesis - Google Patents

Abstract

The invention relates to an instrument for the insertion of an intervertebral articular prosthesis in an intervertebral space between two vertebral bodies. Said inventive instrument comprises;a) an adjusting device which is provided with an intervertebral plate (11) and an adjusting bar (31) which protrudes therefrom, b) a guiding device (34) which is supported, in a detachable manner, by the adjusting device (31), said guiding device forming two guiding axes (37, 38) for a treatment instrument in the vertebral bodies, said guiding axes being arranged above and below the adjusting bar (31) on the median plane, c) two fixing means which can be introduced into the vertebral bodies (2) in the direction of the guiding axes (37, 38) by means of the treatment instrument and d) a distraction instrument which maintains the fixing means in a fixed direction.

Description

MEMBRANE FILTER SYSTEM COMPRISING FILTRATION MODULES BY WHICH A MEDIUM CAN FLOW IN PARALLEL DESCRIPTION OF THE INVENTION When inserting an intervertebral joint prosthesis as a substitute for an intervertebral disc, the operating surgeon works in a very difficult operating site of the patient. see and that is in immediate proximity to nerve pathways and important blood vessels. This applies in particular to the area of the cervical spine, because there the dimensions of the vertebrae are very small and there is in particular little distance to the adjacent sensitive areas. Therefore, in the case of instruments that constitute a particular risk of injury or that must be inserted with particular precision, the aim is to restrict their freedom of movement to the necessary interval by means of suitable instruments. However, in doing so, visual supervision must remain unaffected as much as possible. Instruments for inserting intervertebral prostheses into the lumbar spine are known (DE-U-299 16 078, EP-A-0 333 990, FR-A-2737656) in which the cover plates of a prosthesis are first inserted and separated in the intervertebral space, and then the core of the prosthesis is pushed between them. In this case it is usually possible to do without the preparation on the vertebral surfaces. The insertion instruments are relatively large, but this can be tolerated in the area of the lumbar spine. The intervertebral spaces in the area of the cervical spine are so narrow that it is necessary to create space to receive the prosthesis by preparing the adjacent vertebral bodies. By doing this, the access space is so narrow and, due to the proximity of vital organs so sensitive that it is not possible to use large instruments. The object of the invention is to provide a set of instruments for preparing and / or distracting the cervical spine for. insertion of an intervertebral joint prosthesis, being that this instrument allows a high degree of precision and the best possible visual supervision. The solution according to the invention, as set forth in claim 1, proposes a set of instruments comprising the following component parts: a) an adjustment device consisting of an intervertebral plate and an adjustment rod protruding from the same, b) a guide device that is detachably supported on the adjustment rod and that forms two guide shafts for a preparation instrument, the guide shafts are located medially below and above the adjustment rod, c) two clamping means that can be inserted in the direction of the guide shafts into the vertebral bodies by means of the preparation instrument, and d) a distraction instrument that holds the clamping means in a fixed direction. When the set of instruments is used, the intervertebral plate is first inserted after the intervertebral disc and, if appropriate, the ventral protrusions of the upper vertebral body were removed; After having placed it it provides an accurate indication of the position of the vertebral body surfaces between which the prosthesis should be placed. It also ensures that the vertebral bodies are spaced from one another in the predetermined way. Conveniently it is chosen so that it has approximately the same shape and size as the natural intervertebral space, or such that its extension is only slightly smaller than that of the intervertebral space. This makes it easier to place in position since, due to its contour, it automatically adopts a centered position with respect to the intervertebral space, and in the same orientation. It may also be provided with X-ray control markings for more accurate placement. It remains in the position that is required by the tension generated by the natural ligaments between the vertebral bodies. This tension depends on the thickness of the intervertebral plate. Sufficient tension will be present in each case if this thickness is approximately equal to the thickness of the required prosthesis. To ensure that your position can still be corrected later, its surface is essentially smooth, that is to say, without elevations that, when penetrating the bone surface or the cartilaginous surface, impede the relative movement parallel to the direction of the surface. The guide device is supported by an adjustment rod protruding from the intervertebral plate. By virtue of the fact that the position of the adjustment rod is predetermined by the intervertebral plate, a measure is also obtained for the position of the guide device. Therefore, the latter can be placed exactly with the aid of the adjustment instrument, that is, with the same precision as the adjustment instrument itself. The mutual position of the vertebral bodies is then ensured by the intervertebral plate, in the same way as the position of the preparation tools is ensured by the guiding device. The preparation of the vertebral bodies then takes place with the assistance of the guide device during the time that the latter remains connected to the adjustment instrument and is maintained by the latter in the exact position. Preferably the guide device can be pushed with a hub over the adjustment rod from the free end thereof. This allows the operating surgeon to assemble the interactive adjustment surfaces of the rod and guide device in a clearly visible front area of the operation site, rather than doing so in a location deep between the vertebrae and difficult to observe. Then the guide device is guided along the adjustment rod to the depth of the operation site. The rod of. Adjustment and the device. The guide rail conveniently has interactive surfaces whose contour complements each other and provides a non-rotational adjustment, so that the guide device can not rotate relatively to the adjustment rod.

Conveniently the guide device has a guide for two guide axes arranged in the medial parallel to the adjustment rod, above and below the latter. It is possible, for example, to arrange a drill gauge below and above the hub of the guide device surrounding the adjustment rod. An embodiment provides an additional advantage in that the hub surrounding the adjustment rod has only one guide, and the interacting surfaces of the hub and the adjustment rod can be assembled in two positions displaced by 180 ° relative to one another. In this way the instrument becomes smaller and the view of the operation site is improved accordingly. In one of these two positions, the guide device is used to prepare a first of two vertebral bodies and, if appropriate, to anchor in it a means of restraint. (preferably a spike). Then the guide device is retracted along the adjustment rod to its round cross-sectional part, rotated by 180 ° and pushed forward again to allow the same preparation in the other vertebral body. Then a distraction tool can be applied to the fastening means and keeps them in a fixed direction during distraction, ie, the fastening means are connected to the distraction tool so that the fastening means, and with them the vertebral bodies maintain their mutual orientation. The guide shafts of the guides and the fastening means or pins which are applied accordingly are preferably parallel to one another. Accordingly, the seats provided to receive the fastening means or pins in the distraction instrument are then also arranged parallel to each other.

In many cases the natural kyphosis is reduced (curvature of the cervical spine with the axis of curvature located dorsally). In these cases it is convenient not only to distract the vertebral bodies before inserting the intervertebral prosthesis, but also to restore the natural kyphosis. According to the invention this is achieved by the fact that the intervertebral plate is wedge-shaped, that is, its thickness decreases from its ventral margin towards its dorsal margin. The set of instruments may include, intervertebral plates with different wedge angles. The invention allows a method of inserting intervertebral prostheses in the intervertebral space between two vertebral bodies in which in a first stage the intervertebral disc is removed; in a second stage the intervertebral plate of an adjustment instrument is placed in the intervertebral space, and is imprisoned in it; in a third step a hub of a guide device is pushed on an adjusting rod protruding from the intervertebral plate so as to define two guide axes in the medial above and below the adjustment rod; in a fourth stage the pins are introduced into the vertebrae in the direction of the guide axes; in a fifth stage a distraction forceps is connected to the pins so that they remain parallel to one another; and in subsequent stages the mutual space of the vertebral bodies is adjusted, the guide device and the adjustment instrument are removed, the intervertebral space is prepared, if desired, and the intervertebral prosthesis is inserted. The precision with which the set of instruments according to the invention can be used depends on the precise placement of the intervertebral plate in the intervertebral space. Therefore it is important that the intervertebral space has a shape that matches the intervertebral plate. This is usually also the way that the prosthesis matches that. it should be inserted next. To ensure that this condition is satisfied, the set of instruments according to the invention is complemented by a collection of rasps, the largest of which has substantially the shape of the intervertebral plate or prosthesis., while at least one additional scrape that is used for the preparatory preparation is slightly smaller. If several smaller rasps are provided, their sizes are relatively relative to each other. The invention is explained below in more detail with reference to the drawing, in which: Figure 1 shows the fitting instrument fitted in an intervertebral space, Figure 2 shows a corresponding view with a guide de pushed on the adjusting rod, Figures 3 and 4 show a cross-sectional view and a front view, respectively, of the guide device, Figure 5 shows a partial side elevation view of the adjusting instrument, Figure 6 shows a drill bit to be used with the guide device, Figure 7 shows a screwdriver and a threaded pin to be used with the guide device, Figure.8 shows one. view corresponding to figure 1, with threaded pins inserted. in the vertebrae, and Figure 9 shows a view corresponding to Figure 8 with an applied distraction instrument. and Figures 10-18 illustrate scraping tools intended for a specific prosthesis, namely: Figures 10-15 a set of three different raspas, Figure 16 the outline of the raspas for comparison, and Figures 17 and 18 the prosthesis for which they are destined the raspas. The set of instruments shown in Figures 1-9 comprises an adjustment instrument 30 with an intervertebral plate 11. This has a surface area only slightly smaller than the surface area of the intervertebral space, so that it is placed within it automatically between the raised lateral protuberances. It has approximately the size of the prosthesis that should be inserted later. Its dimensions in the AP direction and in the LM direction (LM = lateral-medial, that is, perpendicular to the medial plane) are not significantly smaller than those in the intervertebral space. Its dimension in the LM direction should be at least 70% of the effective distance between the lateral protuberances of the lower vertebral body, preferable at least 80%. Therefore, when inserted in its place, the intervertebral plate adopts a more or less central position. It is possible to use an X-ray apparatus with at least one beam AP trajectory to verify the central position of the intervertebral plate and its orientation relative to the medial plane, being that at this moment the position and direction of the external surfaces of the beam are critical. the adjustment rod 32. They form the reference marks of the instrument for X-rays for this verification. For this purpose, the adjustment rod becomes opaque to radiation, for example, of metal. It is also possible to use a lateral beam path to verify if the intervertebral plate has the correct depth placement in the AP direction. In this case, the reference marks for the X-rays are formed by those edges of the intervertebral plate that extend in the LM direction, or by a special mark. The thickness of the intervertebral plate 11 corresponds approximately to that of the intervertebral prosthesis to be inserted. If a selection of prostheses of different sizes is available, then different intervertebral plates of conformity are also provided in the instrument set. In any case, it is large enough to ensure that it can be pushed into the intervertebral space - after removing the intervertebral disc, and it is safely retained within this space by the natural attention of the ligaments. In side elevation view it can have a wedge shape, as shown in figure 5. When it reaches the site intended for it, it has an exactly defined position with respect to the surfaces of the vertebral bodies that enclose it. This ensures that the adjustment rod 32 protruding at the front from the vertebral bone plate 11 also has an exactly defined position relative to the vertebral bodies. It has a square cross section, at least in its area 31 next to the intervertebral plate 11, while the portion 33 furthest from it is shown with a circular cross section. The adjustment rod 32 is designed as a tube so that it can serve as an X-ray reference mark for an X-ray beam extending in the AP direction. However, the tube shape is not necessary, in view of the fact that the external contour of the adjusting rod can also serve as a reference mark for X-rays. The adjustment rod 32 is used to adjust (locate) the guide device 34. In Figures 3 and 4 it can be seen that the latter has a perforation 35 with a cross section that coincides with the portion 31 of the adjustment rod 32. This part of the guide device forms a hub by means of which it is retained on the adjusting rod. It also comprises a perforation 36 of circular cross section, parallel to the perforation 35. This perforation 36 serves as a drill gauge or, more generally, for guiding preparation tools. When the guide device 34 is pushed onto the portion 31 on the adjustment rod it can adopt the position shown in Figure 2, in which the guide axis 37 defined by the perforation 36 points to the center of the upper vertebral body 2. It can also adopt a rotated position, by 180 ° relative to the previous one, in which the guide axis 38 defined by the perforation 36 points to the center of the lower vertebral body. The axes 37 and 38 are in the same medial plane as that of the adjustment rod 32. Instead of the square cross section of the portion 31 it is also possible to choose another non-circular contour which allows the possibility of interaction in two positions of the guide device 34 displaced by 180 ° relative to one another. The guide device 34 is first used to prepare a vertebra, and, after it is retracted to the portion 33 of circular cross section of the adjustment rod 32 is then rotated by 180 ° in order to prepare the other vertebra. The preparation involves first doing, by means of a drill 39 whose rod is designed to coincide with the perforation 36, a hole in a vertebra in which then a threaded pin 41 is introduced by the screwdriver 40, whose rod also coincides with the perforation 36. The pin 41 fits exactly in a bore provided in the screwdriver 40, and this ensures that it is screwed in alignment with the screwdriver 40 and, therefore also aligned with the shafts 37, 38, and parallel to the adjusting rod 32. After this has been done on both vertebrae, the image shown in FIG. 8 is reached. By virtue of the guide device and its adjustment by the adjustment instrument, the threaded pins 41 protrude ventrally from both vertebrae 2 exactly in the medial plane and parallel to each other. Now a distraction instrument can be applied to spikes 41, an instrument that has two arms 42, each with a receiving portion 43 for the pins 41, and the arms 42 can be placed on an instrument body 44 and be distracted parallel to each other , another in the direction of arrow 45. Distraction instruments of this type are known, and therefore it is not necessary to describe them here. With the aid of this instrument it is possible, if necessary, to further distract the vertebrae 2 so that it is possible to remove the intervertebral plate 11. If desired, it is possible to prepare the intervertebral space in the state in which the vertebrae are held by the instrument 42 to 44 and the spikes 41, in order to prepare it upon receiving the intervertebral prosthesis. Finally the prosthesis is inserted into the intervertebral space and obtained its final position by distracting the vertebrae 2 with the reversion of the instrument 42 to 44. The instrument set also comprises a collection of rasps that prepare the contour of the surface of the vertebrae to receive the prosthesis. It is shown in Figures 10 to 16. The examples shown are suitable for the illustrative embodiment of the prosthesis shown in Figures 17 and 18. It has an oval to rectangular outline designed to extensively utilize the area of the intervertebral space. It is so flat that it can be adjusted without a deep scraping of the cover plates of the vertebral bodies. It has external surfaces that face the cover plates of the vertebral bodies and that are approximately horizontal and serrated along their greater part 50. Their dorsolateral corners 51 are bevelled, so that the surface in these areas are retracted from the plane of the 50 lot of surface. A complementary contour of the intervertebral space is prepared using a collection of rasps 52, 53 and 54 shown in Figures 10 to 15. Figure 16 shows the graduated siof the raspas. The smaller scraper 52 is first pushed into the intervertebral space using a handle (not shown in detail), - in order to open the access. This is followed by trapezoidal rasp 53, which corresponds approximately to the trapezoidal contour of the horizontal surface portion of the prosthesis surface. Finally, the rasp 54 provides the intervertebral space substantially the contour of the prosthesis to be adjusted. The height of all the raspas is the same that the one of the prosthesis. All the raspas are designed without teeth in those surfaces that correspond to the horizontal part 50 of the prosthesis. This means that they abrade the cartilage and cut the bone mainly with its front edge without removing an appreciable amount of material from the extreme face of the vertebral bodies. In all the rasps a stop piece 56 is provided which ensures that they can only penetrate the intervertebral space to the established depth.

Claims (10)

1. CLAIMS 1. Set of instruments for inserting an intervertebral prosthesis in an intervertebral space between two vertebral bodies, characterized in that it comprises: a) 5 an adjustment device consisting of an ihtervertebral plate and an adjustment rod protruding from the latter, b) a guide device that is removably supported on the adjustment rod and forms two guide shafts for a preparation instrument, the guide shafts are located medially below and above the adjustment rod, c) two holding means, which can be inserted in the direction of the. guide axes within the vertebral bodies by means of the preparation instrument, and, d) a distraction instrument that holds the clamping means in a fixed direction.
2. 2. Set of instruments according to claim 1, characterized in that a cube of the guide device can be pushed onto the adjustment rod from the free end thereof, and the adjustment rod and the hub have interactive surfaces formed to complement each other and provide a non-rotational adjustment.
3. Instrument set according to claim 2, characterized in that the guide device has a guide above the adjustment rod and a guide below the adjustment rod.
4. The instrument set according to claim 2, characterized in that the guide device has only one guide, and the complementary interactive surfaces of the adjusting rod and the hub can be assembled in positions displaced by 180 ° relative to one another. other.
5. 5. Set of instruments according to claim 2, characterized in that the guide axes extend parallel to the adjustment rod.
6. 6. Set of instruments according to claim 5, characterized in that the fastening means are spikes.
7. 7. An instrument set according to claim 1, characterized in that the surface area of the intervertebral plate is slightly smaller than the surface area of the intervertebral space.
8. Instrument set according to claim 1, characterized in that the surface of the intervertebral plate is designed so that it can be displaced in the transverse direction and placed in the intervertebral space controlled by X-rays.
9. 9. Set of compliance instruments with claim 1, characterized in that the intervertebral plate has the shape of. cradle.
10. 10. Set of instruments for inserting an intervertebral prosthesis in an intervertebral space between two vertebral bodies, characterized in that it comprises material removal tools to shape the intervertebral space so that it coincides with the contour of the prosthesis, in each case being assigned a set of tools to remove material to a I form of prosthesis, being that the greater of these tools substantially has the same form that the one of the prosthesis and the other tools are smaller in stepped form.