JPH08509645A - Vertebral body implant - Google Patents

Abstract

(57) [Summary] An upper cover plate (11), a lower cover plate (12), and an elastic intermediate member (13) arranged between the both cover plates, which are inserted between adjacent vertebral bodies. A vertebral body implant comprising a spacer member (10) that can be applied. Anchor members (14, 15, 16) are provided on the outer surfaces of both cover plates (11, 12). The elastic intermediate member (13) is made of a plate (17) made of a biocompatible material, in particular titanium, and bent into a substantially U-shape, S-shape or W-shape. .

Description

DETAILED DESCRIPTION OF THE INVENTION vertebral body UmaSo member present invention relates to vertebral bodies UmaSo member (vertebral body imp lant) by Te write portion at claim 1. Vertebral body implants of this kind are well known. Reprinted on this [Vertebral Column Surgcry II-Surgical treatment of chronic sacral pain], Symposium Augsburg 1991, editor Klaus A. Matzen, publishcd by Georgt hieme-Vcrlag Stuttgart, New York, 1992 ”. This reprint describes the development and current state of artificial intervertebral discs, where the current state of the art is. , Two metal cover plates made of chrome-cobalt alloy and having a trough-shaped recess, and a lens-shaped central sliding core made of polyethylene (Chirulen) provided between the plates, three, A prosthcsis (prosthcsis: prosthetic device) is presented, which is divided into two parts. Anchor-fixed to the end plate The sliding core has an annular ring wall and is formed in a biconvex shape so as to allow the segment to move in the extending and bending plane and to tilt and rotate laterally. However, at the same time, this structure prevents movement from 10 ° to more than 15 ° and dislocation of the polyethylene lens in extreme positions. One of these is the European patent document EP-O 176 728-B1.A well-known problem with this structure is the limit of elasticity of the polyethylene core, that is, this elasticity causes cold flow and weakening. As a practical matter, the polyethylene core, especially its edges, becomes unusable relatively quickly due to damage, which is why additional surgery that you might want to avoid should be avoided. The object of the present invention is to have a structure that is substantially simpler than the state of the art, and to be as close as possible to the function of the original (genuine) disc, and The object of the present invention is to provide a vertebral body implant having a complete wear resistance and a long service life by using the vertebral body implant according to the present invention. No surgery is required The above-mentioned object is achieved by the features stated in claim 1. As claimed, the vertebral body implant according to the invention is essentially a single essential component, namely a special component. In the extreme case, ie according to claim 2, it is assumed that the vertebral body implant member consists almost exclusively of the spring member according to the invention. No wear can occur in, it is composed of only a single material that is homogeneous and biocompatiblc. The construction according to the invention is therefore characterized by an extremely low number of components, a very simple construction and manufacturability, and a very easy implantation procedure. Manipulation of this implant during a surgical procedure is further facilitated by the means described in claims 8-10. Surprisingly, it has been experimentally confirmed that the vertebral body implant member according to the present invention has elastic characteristics similar to the original intervertebral disc. This is true both for the movement in the extension bending plane and the lateral inclination. On the other hand, the arrangement according to the invention does not allow rotation. However, such a slight defect does not actually become a defect. This is because the rotational excursion that is acceptable even for a perfect disc is so small that the limitation introduced by this implant according to the invention is not a problem. Further advantageous structural details of the vertebral body implant according to the invention are set out in the dependent claims. It should be emphasized among them that the structural solution with clay 6 is encapsulation on all sides of the spring element according to the invention. Therefore, the implantable member provides a closed system that is shielded from the outside world. Further, this embedding member according to the present invention is dimensionally set so that each segment having a disk with a thickness of about 12 mm can be displaced within a range of about 5 °. With thicker discs, the displacement of this segment can be larger. Hereinafter, a preferred embodiment of a vertebral body implant member according to the present invention will be described in detail with reference to the accompanying drawings. 1 is a perspective view of a vertebral body implant according to a first preferred embodiment of the present invention; FIG. 2 is a front view of the implant shown in FIG. 1 as viewed in the direction of arrow II in FIG. 1; 3 is a side view of the embedding member shown in FIG. 1 as seen from the direction of arrow III in FIG. 1; FIG. 4 is a side view of an embedding member according to another embodiment of the present invention; FIG. 6 is a side view of the implantation member shown in FIGS. 1 to 3 in a compressed state before being mounted between two adjacent vertebral bodies; FIG. 6 is a diagram showing the implantation member shown in FIGS. FIG. 7 is a perspective view showing a compressed state before being mounted between two adjacent vertebral bodies; FIG. 7 is an elastic intermediate member showing a vertebral body implant member according to a third embodiment of the present invention in a dotted line. And FIG. 8 is a schematic view in longitudinal section; FIG. 8 shows the capsule for the implantable member shown in FIG. It is a greatly enlarged with shows to indicate the relative mobility of the part shell. The vertebral body implanting member shown in FIGS. 1 to 3 includes a spacer unit 10 mounted between adjacent vertebral bodies (not shown). The spacer unit includes an upper cover plate 11, a lower cover plate 12, and a pair of them. And an intermediate elastic member 13 provided between two cover plates. Spike-shaped anchor members 14, 15, 16 are provided on the outer surface of the cover plates 11, 12, that is, the surface facing the vertebral body. These members penetrate the bones of the vertebral bodies after the vertebral body implants have been mounted between two adjacent vertebral bodies and secure the implant between the adjacent vertebral bodies. The intermediate elastic member 13 is made of a biocompatible material such as titanium, titanium-coated cobalt-chromium-molybdenum, cobalt-chrome, or stainless spring steel, and is bent into an S shape to form a spring. There is. The thickness of this plate is about 0.2-0.6 mm, especially about 0.35 mm. The upper and lower plates and the intermediate spring member 13 are substantially elliptical in plan view. It may have a broad bean (kidncy-shapcd) outer shape. In the embodiment shown in FIGS. 1 to 3 and in the embodiment shown in FIGS. 4 to 6, which will be described in more detail below, the upper and lower covers 11, 12 are part of an S-shaped plate 17. They are connected by the intermediate elastic member 13. That is, the upper and lower cover plates 11 and 12 are formed by two outer rims (branch-shaped protrusions) of the S shape formed by bending the plate 17. Alternatively, as shown in FIG. 4, the intermediate elastic member 13 may be formed by bending the plate 17 into a W shape. The simplest embodiment is a U-bent spring plate. As shown in FIGS. 2 and 3, the outer surface of each of the cover plates 11 and 12 is convexly curved in both the longitudinal direction and the direction orthogonal thereto. As a result, the two plates are better implanted or secured to the corresponding vertebral bodies. When tension is not applied to the intermediate elastic member 13 as shown in FIGS. 3 and 4, the two cover plates 11 and 12 are about 3 to 25 °, and particularly about 8 in a plane orthogonal to their longitudinal ranges. It encloses an angle α of °. The embedding member is mounted between two adjacent vertebral bodies with the upper side of the body facing forward. In this way, the desired elasticity and cushioning properties are assured against both deflection and lateral inclination of the extensional flexion surface. As shown in FIGS. 7 and 8, in another embodiment, an intermediate elastic member may be formed, for example, by the upper shell 18 and the lower shell 19 and the upper and lower cover plates according to FIGS. It can be placed or contained within a capsule 20 that is part of the upper shell 18 and the lower shell 19. In this case, the spikes 14, 15 and 16 described above are provided on the outer surface of the soil portion and the lower shell. The upper shell 18 and the lower shell 19 are formed of a sheet of biocompatible material, especially titanium. Both of them are connected to each other, and in particular, as shown in FIGS. 7 and 8, their ends are hooked so that they can follow the movement of the intermediate elastic member 13 without play. FIG. 8 schematically shows the possible relative deviation between the upper shell and the lower shell. Here, the mobility of the segment is set to about 5 ° corresponding to the embedding member having a height of about 12 mm. As shown in FIG. 7, the upper and lower shells 18 and 19 are each formed in a convex shape. This convex surface additionally imparts an intrinsic stability to each shell 18, 19 so that said shell can be made from a thin metal sheet without the risk of breaking. After all, in the present embodiment, the central portion of each shell can be made extremely thin, while the wall thickness (wall thickness) of the peripheral edge of each shell can be increased. With titanium sheets, the wall thickness in the middle of the upper and lower shells is up to about 0.05-0.25 mm, in particular about 0.10 mm. The wall thickness preferably increases continuously about 25-30% towards the periphery. In the embodiment shown in FIG. 8, the wall thickness of the upper and lower shells 18, 19 is about 0.10-0.30 mm, in particular about 0.15 mm. The embodiments shown in Figures 7 and 8 provide a closed system. The capsule 20 may include a spring member other than the spring members shown in FIGS. 1 to 3 and 4. In theory, it is possible to use a coil spring package. In particular, the conical compression spring is advantageous in terms of spring characteristics. In addition, in all the embodiments, the length of the spike is such that the length of the spikes 14 and 15 arranged near the edge that is the front when the embedding member is mounted is located rearward. Note that it is larger than spike 16 that does. Such features are related to the spatial relationship between two adjacent vertebrae. The vertebral body implant described herein is provided with a compression band 21, a compression wire, a compression clamp, and the like before the implant is mounted between two adjacent vertebral bodies so that a complicated attachment device is not required. It is preferable that the intermediate elastic member is compressed in the operating direction by a means that can be removed after mounting. This is shown in FIGS. 5 and 6. The embedding member added the height of the anchor member (spikes 14, 15, 16) to about 1/4 of the maximum height by the compression band before being mounted between two adjacent vertebral bodies. Compressed to height. Thus, the implantable member can be mounted between two adjacent vertebral bodies without the use of dilators or forceps. The compression band can be opened and removed when the embedding member is in place. Then, the embedding member expands in the axial direction of the spinal column by the spring tension of the intermediate elastic member. This causes the spikes 14, 15, 16 to enter the bone of the corresponding vertebral body. Thus, the embedded member fixes itself. Preferably, the compression band 21 is provided in a groove 22 formed around the embedding member 10, particularly on the outer surface of the upper and lower cover plates 11, 12 as shown in FIG. There is. The depth and width of the groove 22 substantially correspond to the thickness and width of the compression band 21. It is also possible to use a compression wire or the like instead of the compression band. In the case of this embodiment, the two ends of the compression band 21 are attached to each other in front of the embedding member 10 (soldering or the like). This joint is opened and broken by, for example, a side cutter after mounting the embedding member. When a compression wire is used, it can be twisted in front of the embedding member 10. After mounting the embedding member, the wire is removed by pulling it forward along the periphery of the embedding member. The rationale is to position the tip of the forceps on the soil and lower surface of the implant member in order to keep the implant member compressed during installation between two adjacent vertebral bodies. It is also possible to form a plurality of recesses or openings. However, the above method using a compression band or the like is superior in that a relatively high compression force can be applied in advance in the manufacturing process of the embedding member. Further, this compression force may be released only by opening the compression band or the like after mounting the embedding member. Needless to say, this compression band is also made of a biocompatible material. Instead of providing the convexly curved upper and lower cover plates 11, 12 as shown in the embodiment according to FIGS. 1 to 3, the outer rim of the spring member 13 is provided with a convex spike-holding cover plate, for example. It can also be attached by screwing or the like. According to this embodiment, there is an advantage that the curvatures of the cover plates 11 and 12 can be changed so as to suit each patient. In the embodiment described here, the lateral flexibility of the embedding member is somewhat lower than in the plane orthogonal to the longitudinal direction of the embedding member. Therefore, the embedding member is mounted so that the surface orthogonal to the longitudinal direction extends parallel to the extension and bending surface of the patient. In this plane, the embedding member exhibits the desired high flexibility. Due to the lateral inclination, the implant exhibits a higher resistance to bending in the lateral direction. In this regard, this implant mimics the operation of a natural interbody disc. That is, even if the lateral mobility is large, it is estimated to be about half of the longitudinal mobility. The embedding member here fulfills such a requirement. The deflection of the segments for rotation of the individual vertebral bodies with respect to each other is between 2 ° and 4 °. Therefore, these movements are generally negligible in constructing the implantable member. Therefore, according to the embodiments described herein, a non-rotating embedding member is provided. As a result, the construction of the embedding member is greatly simplified. The features described in this specification are all claimed as the essence of the present invention, to the extent they are novel in view of the state of the art, either alone or in combination.

Claims (1)

[Claims]   1. It can be installed between the adjacent vertebral bodies, and the upper cover plate (11) and lower cover Bar plate (12) and intermediate elasticity arranged between these two cover plates A spacer member (10) with a member (13), Anchor members (14, 15, 16) provided on the outer surface, that is, the surface facing the vertebral body In a vertebral body implant member having   Said intermediate elastic member (13) is coated with a biologically suitable base material, especially titanium, titanium Cobalt-chromium-molybdenum alloy, copalto-chromium alloy, or stainless steel It is composed of a plate (17) made of steel or the like, and the plate is substantially U-shaped, S-shaped, Alternatively, the vertebral body implant member is characterized by being bent into a W shape.   2. The embedded member according to claim 1, wherein the upper and lower cover plates (1 1, 12) is one of the U-shaped, S-shaped, or W-shaped spring plate (17) Body member, or the upper and lower cover plates are U-shaped, S-shaped, Or formed by two outer rims of a W-shaped spring plate (17) Embedded member characterized by being.   3. The embedding member according to claim 1 or 2, wherein the upper and lower cover plates To (11, 12) each have an oval shape or broad bean shape in a plan view. An embedding member characterized by the above.   4. The embedded member according to claim 1, wherein the two covers are provided. The plates (11, 12) are each formed in a convex shape, or their outer surfaces are curved. An embedding member formed on the surface.   5. The embedded member according to claim 1, wherein the two covers are provided. The plates (11, 12) are tensioned to the intermediate elastic member (13). Surface, that is, the plane perpendicular to the longitudinal direction of these cover plates Characterized by enclosing an angle (α) of about 3-25 °, especially about 8 ° in a curved surface Embedded member.   6. The embedding member according to claim 1, wherein the intermediate elasticity is provided. The member is a capsule formed by an upper shell (18) and a lower shell (19) ( 20) and the upper and lower cover plates are housed in the upper shell. (18) and a part of the lower shell (19), characterized in that Mounting member.   7. The embedding member according to claim 6, wherein the earth shell (18) and the lower shell. (19) consists of a biocompatible material, in particular sheet titanium, and both Are joined to each other, in particular, the edges of the intermediate elastic member (13) move relative to each other. An embedded part characterized by being hooked so that it can follow without play. Material.   8. The embedding member according to any one of claims 1 to 7, wherein the embedding member is adjacent to the embedding member. Before fitting between the two vertebral bodies in contact, the compression band (21), compression wire, compression The intermediate elastic member (13) can be removed by means such as a lamp that can be removed after mounting. ) The embedding member characterized in that it is compressed in the operating direction.   9. The implantable member according to claim 8, wherein the implantable member is between two adjacent vertebral bodies. Before mounting on the anchor member (14, 15, 16) to about 1/4 of the maximum height An embedding member, which is capable of being compressed to a height including the height of the embedding member.   10. The embedding member according to claim 8 or 9, wherein the compression band (21) and the like are Around the embedding member (10), in particular at least said upper and lower cover plates It is provided in a groove (22) formed on the outer surface of (11, 12), and the depth of the groove is increased. The width and the width of the compression band (21) substantially correspond to those of the compression band (21). Embedded member to be.   11. The embedding member according to claim 6, wherein the upper shell (18) and the lower shell (18). The wall thickness of the shell (19) is about 0.10 to 0.30 mm, especially about 0.15 mm. An embedding member characterized by:   12. Embedding member according to claim 6 or 11, wherein the upper shell (18) and the lower shell The wall thickness of the shell in the peripheral region of the partial shell (19) is larger than that in the central region, The maximum thickness of the central area is about 0.05 to 0.25 mm, especially 0.10 mm. Characterized embedded member.