KR100881436B1 - Implant comprising a two-piece joint - Google Patents

Abstract

In the intervertebral implant, (A) the central axes (1) and (26) of each are provided, respectively, and the curved sliding surfaces (6) and (7) are traversed through the central axes (1) and (26), respectively. Two joints (4) (5) having outermost ends (14) (15) connectable to bones;

(B) the sliding surfaces 6 and 7 form a curved surface and are movable with each other,

(D) The second joint part 5 is an intervertebral implant consisting of two connecting pieces, characterized in that the rotation around the mutually asymmetric rotation axis (10) (11) of the first joint part.

Implant, Femur, Saddle, Rotation axis, Circular arc, Sprocket, Shear

Description

IMPLANT COMPRISING A TWO-PIECE JOINT}

The present invention relates to implants and in particular to intervertebral implants as defined in the preamble of claim 1.

When looking at human joints, such as between the femur end and the patella, or between the knuckle and the phalanx end, one or several joint axes may already be articulated, while connecting or rotating about all other spatially possible axes. Are joints that limit or entirely exclude. On the other hand, an implant having a number of rotational joints is used as an intervertebral implant or an internal prosthesis between the spinal discs.

In general, one or several injured natural human scoliosis will be removed along with the damaged scoliosis nucleus. In addition, the intervertebral disc and the intervertebral disc nucleus will be replaced by sandwiching an implant or artificial organ between two adjacent vertebrae. The purpose of this procedure is to restore the damaged spine to its most natural state. In other words, it restores the original intervertebral disc height and the space between two adjacent vertebrae. Perhaps in the future, within the natural range of motion, spinal substitutes without implant or artificial organ degeneration will emerge. This requirement is possible within the natural limits of the tilt back and forth. That is, there is a problem that the movement ability must be achieved in bending or stretching the spine as well as bending to the side of the spine. In addition, changes in the specific positions of adjacent vertebrae relative to one another should fit within the range of physiological displacements.

U.S. Patent 6,368,350 (Erickson) discloses an implant that replaces the spinal plate. The known implant basically comprises two joints at the distal end of each of the implants. According to one embodiment of the prior art, the joint consists of a concave joint comprising a convex joint and a special joint surface complementary thereto. As a result, the joints can be rotated about different rotation axes. The axis of rotation is then located in one plane and is not limited to the axis of rotation of the lateral spine bending or to another axis of rotation for the bending or stretching of the spine. Moreover, unlimited longitudinal rotation of adjacent vertebrae is allowed. According to another embodiment of the prior art, the joint surface is elliptical. As a result, the axis of rotation does not impose any limitation on the axis of rotation of the lateral spine bending or on another axis of rotation for the bending or stretching of the spine.

An object of the present invention is to solve the above problems of the prior art. The object is to make an implant comprising two joints, the implant comprising two axes of rotation which are asymmetrical to each other and spaced apart by a defined distance. As a result, the replacement of the adjacent vertebrae can be reproduced by excision of the intervertebral disc.

The present invention solves the above problems by means of implants, and preferably solves the above problems by using an intravertebral implant as shown in claim 1.

In particular, the implant of the present invention comprises two joints having sliding surfaces which interview each other, and the sliding surfaces move relative to each other as the joints rotate. Each articulation includes a central axis that is substantially parallel or coaxial to the axis of axis of two adjacent bones. The longitudinal central axes coincide with each other in a state in which the human body is established, that is, when the joints are not oblique to each other. The articulations further comprise an outermost end that can engage the bone, respectively, in the axial direction. When the implant is configured in the form of an intravertebral implant, the distal end may be connected to an adjacent vertebra. The sliding surface will traverse the central axis of the joint and will move relative to each other as the joint rotates, while the second joint moves relative to the first joint to enable rotation about two mutually asymmetric axes of rotation.

Hereinafter, it is assumed that the first joint portion is fixed and the second joint portion is movable. As a result, the other axes of rotation move relative to the first joint and settle relative to the second joint.

In essence, the following advantages are provided by the implant, in particular the intervertebral implant of the invention:

The position of the center of rotation is well coordinated with physiology during flexion or tension of the spine and / or flexion to the side.

-The sliding surface can move relatively and move relatively without substantial friction, and the forces and torques are minimized as much as possible by making the corresponding levers.

Torsional movement of the spine's spasm can be hindered by bracing.

In a preferred embodiment of the implant according to the invention the sliding surface is in the form of a saddle and each comprises a saddle center. The saddle surface is composed as follows. Two surface points can be found in the vicinity of the surface point P bounded by the size of the joint so that the surface points are located on different sides of the interface passing through the surface point P.

According to another embodiment of the invention, the rotation axes preferably cross each other at an angle between 80 ° and 100 °. For example, this form has the following advantages: The intervertebral implant may be implanted in a situation where one of the axes of rotation runs parallel or coaxially with the axial direction of the lateral bending of the spine and the other axis of rotation is parallel or coaxial with the axis of bending or tension of the spine.

According to another embodiment of the implant according to the invention, the axis of rotation is at least a distance A apart from A between 0.1 and 20 mm and preferably between 2 and 20 mm. The distance A depends on the location of the implant in the spine and the segmental height of the lumbar spine, so the distance A decreases toward the thoracic spine.

Preferably the sliding surface is designed in such a way that the second saddle center point moves along an arc concentric with the axis of rotation in accordance with the rotation of the second joint with respect to each axis of rotation. The saddle-like configuration of the sliding surface provides the advantage that the joint can be rotated about the central axis of these parts. However, when the joints rotate relative to each other on the axis, the two preceding joints move away from each other on the axis, so that axial rotation is only possible if it involves a continuous change in the implant height. Because of the constant compressive force in the ligaments, muscles and tendons of the spine, the joint can only rotate to a limited degree (angle). This feature is similarly applied physiologically to the lumbar spine because of the rotation of the back element, such as a small joint, and only allows rotation about an axis in a limited range.

The rest position of the joint should preferably coincide with the sliding surfaces as described above. By constituting the sliding surface of the implant according to the present invention, the present invention prevents twisting in the longitudinal direction of the spine if there is no change in the height of the intravertebral implant. As the height of the intravertebral implant changes between movements of the intravertebral implant, the ligaments will be stretched, thereby preventing twisting of the spine.

In another embodiment according to the present invention, the outermost end of each joint portion includes a connecting device that can be connected adjacent to the bone or spine. When the implant according to the invention is an intravertebral implant, the connecting device is preferably each cover plate comprising an outermost section on an axis transverse to the central axis. At this time, the surface is provided with a three-dimensional shape such as a sawtooth or fin shape.

Furthermore, in the above configuration, one of the cover plates is integrally formed with the adjacent joint portion.

In an embodiment according to the invention in the form of an intravertebral implant, one of the cover plates comprises a guide or a groove. It is insertable into the back end of the adjacent joint portion perpendicular to the central axis of the adjacent joint portion and complementary to the guide. The advantage of this structure is that, firstly, two cover plates placed on the first joint can move between the adjacent vertebral bones, and the upper plate can be pressurized against the surface ends of the adjacent vertebrae, so that the second only at the ends An articulation may be inserted between the first articulation and the second cover plate. As a result, the vertebrae experience minimal friction during implantation. Secondly, after insertion the articulation is attached to the second cover plate as a result of the insertion.

Depending on the application, the joint may be a pair of metals / metals. Moreover, ceramics can also be used as appropriate, and the impact is minimized due to the large compressive forces in the spine between the vertebrae.

As a more specific embodiment of the implant according to the present invention, when one joint is made of plastic, look at the results:

Highly crosslinked polyethylene (macromolecular weight polyethylene) and cobalt / chromium alloys can be used as a combination of joint substitutes with known performance results.

-The sliding surfaces move relative to each other, so the friction is small.

Rotation of the joint about the central axis can be reduced.

In another embodiment of the implant of the present invention, one of the joints is housed in a suitable connecting device (ie, cover plate) to allow rotation about the central axis. As described, the outermost end of the joint is fixed in a complementary groove coaxial with the central axis and located in a suitable connecting device (ie, cover plate). On the contrary, the connecting device may have an upper end coaxial with the central axis, and the joint part may include a groove. In this way the invention has the advantage that the torsional movement of two adjacent vertebrae is not disturbed by the implant.

In another embodiment of the implant of the invention, one joint is received in a manner movable in parallel with respect to the axis of movement parallel to the central axis with respect to the associated connecting device (ie cover plate). Preferably, the associated connecting device (ie, cover plate) surrounds the complementary groove of the outermost end of the joint, while the outermost end of the joint end is provided with an extension end configured coaxially with the central axis. And the associated connecting device (ie cover plate) is fitted into the groove for receiving the extension. This configuration of the implant according to the invention allows for a uniaxial shear motion between the implant and two adjacent vertebrae, which is not constrained. Shear motion on the spine can be limited by adjusting the length of the grooves.

In another embodiment of the implant according to the invention, one of the joints is housed in an associated connecting device (ie cover plate), in order to be movable in a plane perpendicular to the central axis. Preferably, the outermost end of the joint portion has a diameter smaller than the diameter of the groove provided in the corresponding connecting device. This type has the advantage of allowing relative movement of the implant and the adjacent spine in relation to several axes.

Further advantageous embodiments of the invention are defined in the dependent claims.

Another embodiment according to the invention in the above invention is described below in connection with the partial schematics of some described embodiments.

1A is a front view showing the form of an embodiment according to the present invention, which is a second joint portion rotating about a first axis of rotation;

FIG. 1B is a side view of the implant shown in FIG. 1; FIG.

FIG. 1C is a front view of an embodiment of the implant shown in FIGS. 1A and 1B showing a second joint that rotates about a second axis of rotation;

1D is a side view of an embodiment of the implant shown in FIG. 1C;

2 is a perspective view of a joint of an embodiment of the implant;

3 is a perspective view showing one embodiment of the intervertebral implant form according to the present invention;

4A is an internal perspective view showing one embodiment of an implant according to the present invention;

4b is a side view of one embodiment of an implant according to the invention shown in FIG. 4a;

Fig. 5 is a longitudinal sectional view showing the form of another embodiment of the implant according to the present invention having a joint fixed to the cover plate and rotatable about a central axis.

FIG. 6A is a longitudinal cross-sectional view of another embodiment of an implant in the present invention having a replaceable joint in a plane perpendicular to the central axis; FIG.

FIG. 6B is a cross-sectional view showing the form of an embodiment of an implant according to the present invention shown in FIG. 6A;

7A is a longitudinal sectional view showing the form of another embodiment of an implant according to the present invention having a joint that is displaceable perpendicularly to a central axis;

FIG. 7B is a cross-sectional view showing the form of an embodiment of the implant according to the present invention shown in FIG. 7A.

1a to 1d show an embodiment of an implant according to the invention comprising a joint of a first joint part and a second joint part, and FIG. 1b shows the first and second joint parts 4 and 5 as A The side view seen from the direction is shown. The first joint part 4 includes a first central axis 1 and a first sliding surface 6 that crosses the first central axis 1. The first sliding surface 6 is in the form of a saddle and has a first saddle point 8. Similar to the first joint 4, the second joint 5 has a second central axis 26 and the second sliding surface 7 crosses the second central axis 26. The second sliding surface 7 is also saddle shaped and includes a saddle center point 9. Furthermore, the joints 4, 5 comprise the outermost ends 14, 15 for securing stability to the distal face of the bone. The distal face of the bone here refers in particular to the adjacent vertebrae. The protrusions of the rotary shafts 10 and 11 intersect at 90 ° on a plane perpendicular to the central axis 1. In the structure of the sliding surfaces 6 and 7 as described above, the shortest distance of the distance A is the vertical distance of the two rotation shafts 10 and 11. In FIGS. 1A and 1B, the second joint portion 5 is rotated about the first rotation shaft 10 (FIG. 1B). The second saddle center point 9 is moved while the second joint part 5 is rotated at β ° along an arc concentric with the first axis of rotation 10 with a radius R ₁ .

1C and 1D show the joints 4 and 5 of the embodiment shown in FIGS. 1A and 1B, the second joint 5 being at α ° about the second axis of rotation 11 (FIG. 1C). It is rotated. While the articulation part 5 rotates about the second axis of rotation 11, the second saddle center point 9 is moved along an arc concentric with the second axis of rotation 11 and having a radius of R ₂ .

2 shows a first joint 4 with a sliding surface 6 in the form of a saddle. The two rotary shafts 10 and 11 represent a case in which the implant according to the present invention is in a rest position corresponding to the upright of the body. That is, the central axis 1 of the first joint part 4 coincides with the central axis 26 of the second joint part 5 (FIG. 1). In the rest position the axis of rotation 10, 11 is perpendicular to the central axis 1 and lies in the planes 23, 22. The first axis of rotation 10 vertically crosses a first plane defined by the intersection of the central axis 1 and the second axis of rotation 11. The second axis of rotation 11 is perpendicular to the first plane and perpendicularly crosses the second plane 23 defined by the intersection of the central axis 1 and the first axis of rotation 10. In the rest position, the first saddle center point 8 of the first sliding surface 6 is located at the intersection of the central axis 1 and the two arcs 24 and 25. At this time, the center of the joint part 4, 5 in the rest position is the point where the central axis 1 and each of the rotating shafts 10, 11 intersect. The first sliding surface 6, on the one hand, moves tightly along the first arc 24, which is coaxial with the first axis of rotation 10, and on the other hand, the second axis of rotation 11. It moves along the second circular arc 25 which is coaxial with. If the sliding surfaces 7 and 8 are congruent and the distance to the sliding surface is equal to half of the distance A between the two rotational axes 10 and 11, then the radius of the first circular arc 24 is R ₁ and R _{2, which} is the radius of the second arc 25, are the same.

The sliding surface is configured in such a way that the surface of the donut pieces form complementary to each other.

Figure 3 shows an embodiment of the implant according to the present invention in the form of intervertebral implants. At the outermost ends 14, 15 of the implant, the two joint connections 4, 5 are axially outermost in the direction of the central axis 1, 26, and the central axis 1, 26. Connecting portions 2, 3 for connecting to each cover plate 12, 13 having surfaces 16, 17 formed across the surface, the surfaces 16, 17 being the end of the spine. It is provided to be movable to ensure stability with respect to the cross-sections. The cover plates 12 and 13 each comprise two side cross-sections 27, one front end 28 and one end face 29, and the side cross-sections 27 are basically It is provided in parallel with respect to the first rotating shaft (10). Both the front end face 28 and the end face 29 are basically provided parallel to the second axis of rotation 11. The joints 4 and 5 that rotate about the second axis of rotation 11 are capable of bending and respective tension of the vertebrae connected to the implant, while the joints 4 that rotate about the first axis of rotation 10. (5) is capable of lateral bending of the vertebrae connected to the implant, in which state the implant is provided between the damaged and removed vertebrae and adjacent vertebrae. As described, in the embodiment of the implant according to the present invention, the second cover plate 13 has a guide 20 formed in the form of a tube which traverses the central axis vertically, is parallel to the side cross-section 27 and whose bottom is open. On the other hand, the first cover plate is fixedly coupled to the first joint portion (4). As a result, the second articulation part 5 is provided to be fitted to the guide 20 together with the outermost end 15 complementary to the guide 20. Furthermore, for the stability of basic implants in adjacent vertebrae, a tooth or fin 19-shaped portion is provided on the outermost surfaces 16 and 17 of the cover plates 12 and 13.

The embodiment of the implant according to the invention shown in FIGS. 4a and 4b excludes the embodiment of the implant according to the invention shown in FIG. 3 and only the serrated or fin-shaped part, with the joints 4 and 5 being about the axis of rotation. It differs only in that the rotation angle is limited to α ° to β °. 4A shows the implant in an internal perspective view. That is, it is shown in a direction parallel to the rotary shaft 10. 4b shows the implant in a side view. That is, it is shown in a direction parallel to the parallel axis (11). The limitations of the angles of rotation α ° and β ° are determined by determining the sizes of H _L , H _A , H _P , R ₁ , R ₂ , h ₁ and h ₂ in the joints 4, 5. Here, when the rotation angles α ° and β ° reach their maximum values, the distal ends 32, 33, 34 facing the other joint portions 4, 5 of the joint portions 4, 5 are the joint portions. (4) (5) will be mounted on the inner surface of the cover plate (12) (13) opposite.

At this time, H _L represents the height between the first saddle center point 8 and the inner end of the first joint portion (joint) portion facing the second joint portion (5),

H _A represents the height between the second saddle center point 9 and the front end of the second articulation part 5 facing the first articulation part 4,

H _P represents the height between the second saddle center point 9 and the rear end of the second articulation part 5 facing the first articulation part 4,

R ₁ is the radius of the first sliding surface 6 in the first plate 22 (FIG. 2) perpendicular to the first axis of rotation 10 and comprising a first saddle center point 8,

R ₂ is the radius of the second sliding surface 7 in the second plate 23 (FIG. 2) perpendicular to the second axis of rotation 11 and comprising a second saddle center point 9,

h ₁ is the distance between the first saddle center point 8 and the inner surface 31 of the first cover plate 12,

h ₂ is the distance between the second saddle center point 9 and the inner surface 30 of the second cover plate 13.

5 shows an embodiment of an implant according to the invention. Here, the implant shown in FIG. 5 is formed in the groove 37 provided in the cover plate 12 whose outermost end 14 of the first joint portion 4 is coaxial with the central axis, unlike the embodiment shown in FIGS. 1 to 4. It is different in that it is complementary. As a result, the first joint part 4 is rotatable about the central axis 1 to be assembled to the cover plate 12.

6a to 6b show an embodiment of an implant according to the invention. 6A to 6B differ from the embodiment shown in FIG. 5 only in that the groove 37 is provided with a larger diameter than the outermost end 14 of the first joint with respect to the central axis. . As a result, the first joint portion 4 can be moved relative to the cover plate 12 on a plane perpendicular to the central axis.

7a to 7b show an embodiment of an implant according to the invention. 7A to 7B, the embodiment of the present invention is different from the embodiment shown in FIG. 5 in the following points. The groove 37 is provided in an elliptical shape parallel to the displacement axis 40 perpendicular to the central axis 1, and the groove 37 is provided including an empty space 39. Correspondingly, the outermost end 14 of the first joint portion differs in that it includes an extension 38 which will be located in the empty space 39 coaxial with the central axis 1. As a result, the first joint part 4 is movable in parallel with the displacement axis 40 on the one hand, and on the other hand the empty space 39 at the position where the first joint part 4 is relative to the central axis 1. Stability is secured in the axial direction by the expansion part including the ().

Claims (18)

Each of the central shafts (1) and (26) is provided, respectively, the first sliding surface (6) and the second sliding surface (7) across the central axis (1, 26) are provided, respectively, which can be connected to the bone A first joint part 4 and a second joint part 5 provided with outermost ends 14 and 15; The two slip surfaces (6) (7) are curved; The two slip surfaces (6) (7) are mutually movable; The second sliding surface (7) is rotatable about an asymmetric rotation axis (10) (11) with respect to the first joint portion (4); Connection devices (2) (3) are respectively provided at the outermost ends (14) (15) of the two joint parts (4) (5); The connecting device (2) (3) is characterized in that it is provided with an elliptical groove (37) for accommodating the outermost end of each of the adjacent joint portion (4) (5) coaxial with the central axis (1) (26) and, The groove 37 comprises an empty space 39 at the axis ends 14, 15, ie the outermost end of the adjacent joints 4, 5 is coaxial with the central axes 1, 26. (38), wherein the extension can be inserted into the empty space (39); Implant consisting of two connecting pieces, characterized in that the two sliding surfaces (6) (7) are in the form of a saddle. The method of claim 1,  Implant consisting of two connecting pieces, characterized in that the two slip surfaces (6) (7) each comprises a saddle center point. The method according to claim 1 or 2,  The rotation shaft (10) (11) is an implant consisting of two connecting pieces, characterized in that intersecting at an angle between 80 ° and 100 ° each other. The method according to claim 1 or 2,  The rotary shaft (10) (11) is separated from the shortest distance A, the shortest distance A is an implant consisting of two connecting pieces, characterized in that 0.1 to 20mm. The method of claim 4, wherein The distance A is an implant consisting of two connecting pieces, characterized in that 2mm to 20mm. The method of claim 1, The two slip surfaces 6 and 7 each include a first saddle center point 8 and a second saddle center point 9, When the second joint part 5 rotates about each rotation axis 10, 11, the second saddle center point 9 moves along an arc 12, 14 coaxial with the rotation axis. An implant consisting of two connecting pieces. The method of claim 1, The two sliding surfaces (6) (7) is an implant consisting of two connecting pieces, characterized in that the interview in the starting point of the same axis and the central axis (1) (26) of the two joints (4) (5). The method of claim 1, The connecting device (2) (3) consists of a cover plate and each cover plate (12) (13) comprises an outermost end face (16) (17) on an axis traversing the central axis (1) (26). Implant consisting of two connecting pieces, characterized in that configured by. The method of claim 8,  Implant consisting of two connecting pieces, characterized in that one of the cover plate (12) (13) is integral with the adjacent second joint (5). The method of claim 8, One of the cover plates 12 is provided with a guide 20 perpendicular to the central axis 1, and the adjacent first joint portion 4 has a rear end portion 14 into which the guide 20 can be inserted. Implant consisting of two connecting pieces, characterized in that configured to include. The method of claim 1, One of the two joints (4) (5) is connected to the two connecting pieces, characterized in that it is possible to rotate about the central axis (1) (26) of the joint to be assembled to the associated connecting device (2) (3) Consisting of implants. The method of claim 1, One of the two joints 4, 5 can be moved in a plane perpendicular to the central axis 1, 26 of the joint for assembly to the associated connecting device 2, 3. An implant consisting of two connecting pieces. The method of claim 1, One of the two joints (4) (5) is characterized in that it is movable in a plane perpendicular to the central axis (1) (26) of the joint for assembly to the associated connecting device (2) (3) Implant consisting of two connecting pieces. The method of claim 1, Implant consisting of two connecting pieces, characterized in that one of the two joints (4) (5) is made of plastic. The method of claim 1, Implant consisting of two connecting pieces, characterized in that at least one of the two joints (4) (5) is made of ceramic. delete delete delete

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