Bone fixation plate system

Abstract

To provide a plate system for bone fixation, capable of performing restoration of a meniscus in a short time and capable of keeping a restored state of the meniscus for a comparatively long period.SOLUTION: A plate system for bone fixation comprises: a plate member 1 to be brought into contact with a shinbone K; and screws 2 that are to be screwed into the shinbone K via the plate member 1 to fix the plate member 1 on the shinbone K. The plate member 1 comprises a protrusion part 4 that protrudes toward a meniscus H's lower part to push a tissue ranging from the meniscus H to the shinbone K.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a bone fixation plate system for regulating the movement of the meniscus.

Background Art

[0002] The meniscus is sandwiched between the joint surfaces of the femur and tibia in the knee joint and serves as a cushion to relieve various stresses applied to the knee joint, such as body weight and shear force. The meniscus does not contain cells and is composed of fibrous structures. Therefore, the meniscus may rupture due to deterioration associated with aging, etc., and once ruptured, self-repair is extremely difficult.

[0003] Therefore, as a method for repairing the meniscus, for example, a method of suturing a ruptured portion with a suture is known (see, for example, Patent Document 1).

[0004] Examples of methods for repairing the meniscus other than the above include posterior root repair of the meniscus and meniscus centralization.

[0005] Posterior root repair of the meniscus is a method of forming a hole near the original position of the posterior root of the ruptured meniscus, sewing an artificial ligament into the stump of the meniscus, and pulling it into the hole for fixation.

[0006] Meniscus centralization is an attempt to restore the cushioning role by driving a plurality of anchors (made of special threads) into the inner or outer edge of the tibia at a predetermined interval and pulling back the damaged meniscus that has shifted inward or outward to the central part of the knee.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, according to the above conventional methods, since all of them are performed in a narrow space using an arthroscope (endoscope), there is a disadvantage in that the operation takes a long time. In addition, there is a disadvantage in that the repaired state of the meniscus cannot be maintained due to elongation occurring in the suture thread or the like.

[0009] In view of the above conventional disadvantages, an object of the present invention is to provide a bone fixation plate system capable of repairing the meniscus in a short time and maintaining the repaired state of the meniscus for a relatively long period.

Means for Solving the Problems

[0010] In order to achieve such an object, the present invention provides a bone fixation plate system including a plate member that abuts against the tibia and a screw that fixes the plate member to the tibia by screwing into the tibia through the plate member, wherein the plate member is provided with a protruding portion that protrudes toward the lower part of the meniscus and presses the tissue from the meniscus to the tibia.

[0011] According to the present invention, by simply fixing the plate member to the tibia with a screw, the protruding portion provided on the plate member can press the tissue from the meniscus to the tibia to fix the meniscus in its original position. Thereby, the meniscus can be repaired in a short time, and moreover, the fixed state of the meniscus can be maintained for a relatively long period.

[0012] Further, in the present invention, as one aspect of the protruding portion, it is characterized in that the tip is formed to be sharp so as to penetrate the tissue from the meniscus to the tibia.

[0013] According to this, since the tip of the protruding portion penetrates the tissue from the meniscus to the tibia and the displacement between the protruding portion and the meniscus is surely prevented, the meniscus can be surely fixed.

[0014] In addition, in the present invention, as another aspect of the protruding portion, it is characterized in that the tip is formed to be non-sharp so as to contact the tissue extending from the meniscus to the tibia.

[0015] According to this, when the tip of the protruding portion starts to contact the tissue extending from the meniscus to the tibia, the movement of the meniscus is allowed, and the meniscus can be set in the most preferable posture. When the degree of press contact of the tip of the protruding portion with the meniscus becomes maximum, the meniscus can be surely fixed.

[0016] In addition, in the present invention, when the plate member is brought into contact with the tibia straddling a cut formed by a proximal tibial osteotomy or the like, the screw screwed into the tibia through the plate member is screwed into the tibia intersecting the surface of the cut, and the tip portion of the plate member is press-fixed.

[0017] According to this, the cut portion of the tibia can be firmly fixed in the most preferable state.

[0018] In addition, in the present invention, the plate member includes a screw hole portion through which the screw is inserted and screwed, the screw includes a first screw portion screwed into the bone and a second screw portion screwed into the screw hole portion of the plate member, and the screw pitch of the first screw portion is larger than the screw pitch of the second screw portion.

[0019] According to this, even if the rotation angle of the screw when screwing the screw into the plate member is relatively small, the screwing amount of the screw into the bone can be increased, and the plate member and the bone can be sufficiently press-contacted.

[0020] In addition, in the present invention, the plate member includes a communicating screw hole portion having two adjacent holes communicating with each other, and the communicating screw hole portion is formed so that the two holes guide the insertion of the screw in different directions.

[0021] According to this, either one of the two holes of the communication screw hole part through which the screw is inserted can be selected, and by this selection, the screw can be easily screwed in in a preferable direction.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0023] An embodiment of the present invention will be described with reference to the drawings. The bone fixation plate system according to this embodiment is composed of a plate member 1 and a plurality of screws 2 as shown in FIG. 1, and is used by being fixed to the upper side surface of the tibia K.

[0024] The plate member 1 is a plate-shaped member that is fixed to the upper medial surface of the tibia K after osteotomy in high tibial osteotomy for varus knee osteoarthritis, and is formed in a substantially T shape as a whole. In this embodiment, an example in which the plate member 1 is fixed to the upper medial surface of the tibia K is shown. However, high tibial osteotomy may be performed from the outside. In this case, the plate member 1 is fixed to the upper lateral surface of the tibia K.

[0025] As shown in FIG. 2, the plate member 1 is formed with a plurality of screw holes 3 through which the screws 2 can be inserted. Further, a protrusion 4 is provided at the upper end of the plate member 1.

[0026] As is well known, there are multiple types of screws 2, and they are appropriately selected and used according to the screwing position. For example, the first screw 2A shown in FIG. 3A or the second screw 2B shown in FIG. 3B can be used.

[0027] As shown in FIG. 3A, the first screw 2A includes a small-diameter main body portion 6 having a first thread portion 5 formed on its outer peripheral surface and a large-diameter head portion 8 having a second thread portion 7 formed on its outer peripheral surface. The thread pitch 5P of the first thread portion 5 and the thread pitch 7P of the second thread portion 7 are formed with the same dimensions.

[0028] As shown in FIG. 3B, the second screw 2B includes a small-diameter main body portion 10 having a first thread portion 9 formed on its outer peripheral surface and a large-diameter head portion 12 having a second thread portion 11 formed on its outer peripheral surface. The thread pitch 9P of the first thread portion 9 is formed with a dimension larger than the thread pitch 11P of the second thread portion 11.

[0029] In both the first screw 2A and the second screw 2B, the main body portions 6 and 10 are screwed into the bone, and the head portions 8 and 12 are screwed into the screw holes 3 of the plate member 1.

[0030] When the first screw 2A is used, according to the rotation angle of the first screw 2A, the screwing depth of the main body portion 6 with respect to the bone and the screwing depth of the head portion 8 with respect to the plate member 1 become the same degree.

[0031] On the other hand, when using the second screw 2B, when the second screw 2B is rotationally operated, the screwing depth of the main body portion 10 into the bone becomes deeper than the screwing depth of the head portion 12 into the plate member 1. Thereby, the number of rotations of the second screw 2B can be reduced and the screwing of the main body portion 10 into the bone can be performed quickly, and the degree of pressure contact of the plate member 1 against the bone can be increased.

[0032] Furthermore, by forming the screw pitch 7P of the second screw portion 7 of the first screw 2A and the screw pitch 9P of the first screw portion 9 of the second screw 2B to have the same dimension, the screw pitch of the screw hole portion 3 of the plate member 1 is made common, and the first screw 2A and the second screw 2B can be selected and exchanged freely.

[0033] In addition, in the present embodiment, as shown in FIGS. 3A and 3B, for both the first screw 2A and the second screw 2B, those in which the first screw portions 5 and 9 are formed over substantially the entire length of the main body portions 6 and 10 are used. However, the present invention is not limited to this. Although not shown, a type of screw called a half thread in which the first screw portion is provided on the tip side half portions of the main body portions 6 and 10 can be adopted as necessary.

[0034] As shown in FIG. 1, the protruding portion 4 of the plate member 1 is formed in a shape that protrudes toward the lower part of the meniscus H when the plate member 1 is fixed to the tibia K.

[0035] By providing the protruding portion 4 on the plate member 1, when the plate member 1 is fixed to the tibia K, at the same time, the protruding portion 4 can press the tissue from the meniscus H to the tibia K to fix the meniscus H in its original position. Thereby, the meniscus H can be repaired in a short time, and moreover, the fixed state of the meniscus H can be maintained for a relatively long period.

[0036] As shown in FIGS. 2 and 4, the protrusion 4 may be constituted by a plurality of sharp-tipped protrusions 13, or as shown in FIG. 5, it may be constituted by a plurality of non-sharp-tipped protrusions 14. Alternatively, as shown in FIG. 6, the protrusion 4 may be constituted by a continuous ridge 15.

[0037] Also, as shown in FIG. 7, the screw 2 may be screwed into the tibia K intersecting the cut surface Ka of the bone. The plate member 1 abuts against the upper medial surface (or lateral surface) of the tibia K so as to straddle the cut after bone cutting in proximal tibial osteotomy, but the plate member 1 can be firmly pressed and fixed to the tibia K by the screw 2 intersecting the cut surface Ka of the bone.

[0038] Thereby, the tibia K can be pressed against each other through the cut after bone cutting to increase the adhesion degree, and at the same time, a state in which the tissue from the meniscus H to the tibia K is strongly pressed can be formed.

[0039] Also, as shown in FIG. 8, a communicating screw hole portion 16 having two communicating holes may be provided in the plate member 1. The communicating screw hole portion 15 is formed such that the two holes 16a and 16b guide the insertion of the screw 2 in different directions respectively.

[0040] That is, as shown in FIG. 9a, when the screw 2 is inserted into and screwed into one hole 16a of the communicating screw hole portion 16, the screw 2 is screwed into the bone obliquely downward, and as shown in FIG. 9b, when the screw 2 is inserted into and screwed into the other hole 16b of the communicating screw hole portion 16, the screw 2 is screwed into the bone obliquely upward.

[0041] Note that, as shown in FIG. 8, female threads (not shown) are formed in both of the two holes 16a and 16b of the communicating screw hole portion 16, but the present invention is not limited thereto, and according to the screw to be used, neither one or both of the two holes 16a and 16b may be provided with threads.

[0042] As described above, according to the bone fixation plate system of the present embodiment, as is apparent with reference to FIG. 1, by providing the protruding portion 4 on the plate member 1, just by fixing the plate member 1 to the tibia K, the protruding portion 4 can press the tissue extending from the meniscus H to the tibia K to fix the meniscus H in its original position. Therefore, the meniscus H can be repaired in a short time, and moreover, the fixed state of the meniscus H can be maintained for a relatively long period. Furthermore, the movement of the meniscus H can be restricted to prevent the meniscus H from deviating.

[0043] In the present embodiment, the plate member 1 having a vertically long shape has been described as an example. However, in addition to this, as shown in FIG. 10, a short plate member 17 may be adopted, and for example, the plate member 17 may be fixed with one screw 2. Also by this, the tissue extending from the meniscus H to the tibia K can be pressed by the protruding portion 4 provided on the plate member 1B.

Explanation of Reference Numerals

[0044] K... Tibia, H... Meniscus, Ka... Surface of the cut, 1, 17... Plate members, 2... Screw, 2A... First screw (screw), 2B... Second screw (screw), 3... Threaded hole portion, 4... Protruding portion, 5... First threaded portion, 7... Second threaded portion, 16... Communicating threaded hole portion, 16a, 16b... Holes.

Claims

1. In a bone fixation plate system comprising a plate member adapted to abut against the tibia and a screw for fixing the plate member to the tibia by screwing into the tibia through the plate member, the plate member is characterized by comprising a protruding portion that protrudes toward the lower part of the meniscus and presses the tissue extending from the meniscus to the tibia.

2. The bone fixation plate system according to claim 1, wherein the protruding portion is formed with a sharp tip so as to penetrate into the tissue extending from the meniscus to the tibia.

3. The bone fixation plate system according to claim 1, wherein the protruding portion is formed with a non-sharp tip so as to abut against the tissue extending from the meniscus to the tibia.

4. When the plate member is abutted against the tibia across a cut formed by a proximal tibial osteotomy or the like, the screw screwed into the tibia through the plate member is screwed into the tibia intersecting the plane of the cut and presses and fixes the tip portion of the plate member. The bone fixation plate system according to any one of claims 1 to 3.

5. The plate member comprises a threaded hole portion through which the screw is inserted and screwed, the screw comprises a first threaded portion screwed into the bone and a second threaded portion screwed into the threaded hole portion of the plate member, The bone fixation plate system according to any one of claims 1 to 4, wherein the thread pitch of the first threaded portion is larger than the thread pitch of the second threaded portion.

6. The plate member comprises a communicating threaded hole portion having two adjacent holes communicating with each other, The bone fixation plate system according to any one of claims 1 to 5, wherein the communicating threaded hole portion is formed such that the two holes guide the insertion of the screw in different directions respectively.

Images