JP6038718B2 - Tibial component and artificial knee joint including the tibial component - Google Patents

Description

  The present invention relates to a tibial component and an artificial knee joint including the tibial component.

  The present applicant has previously developed an artificial knee joint described in Patent Document 1. This knee prosthesis is connected to the tibial component and the femoral component by a hinge structure, and in addition to bending and stretching movements, it can also be rotated by the rotator included in the tibial component, making it suitable for cases such as femoral tumors ing.

  In such an artificial knee joint, it is necessary to set the rotation angle of the rotator to an optimum value according to the amount of remaining soft tissue such as muscle tissue. For example, when a lot of soft tissue is excised and the amount of remaining soft tissue is small, if the rotation angle of the rotator is not set to the optimal value, artificial walking or walking The sliding surface of the knee joint is not fixed, and the patient feels unstable.

By the way, since the amount of soft tissue excision is known only after an actual operation, the optimum rotation angle of the rotator needs to be set during the operation.
However, since the rotation angle of the rotator is constant in the knee prosthesis described in Patent Document 1, the rotation angle of the rotator could not be set to an optimal value according to the amount of soft tissue excision during the operation. .

JP-A-8-173464

  An object of the present invention is to provide a tibial component capable of setting an optimum rotation angle during an operation and an artificial knee joint including the tibial component.

As a result of intensive studies to solve the above problems, the present inventor has found a solution means having the following configuration, and has completed the present invention.
(1) A tray having a rotation shaft portion insertion hole that opens at a substantially central portion of the upper surface is opposed to each other and the inner wall portions that extend along the front-rear direction, and the rotation shaft portion insertion hole is formed between the trays. The first plate and the second plate attached to the tray so as to be exposed, the convolution shaft portion inserted in the convolution shaft insertion hole, and the outer peripheral portion along the longitudinal direction are opposed to the inner wall portion. A rotator having a substantially rectangular shoulder located between the first plate and the second plate, and a head portion having a hinge shaft insertion hole in order, the first plate and the first plate When the distance between the two plates is L and the width of the shoulder is W, L and W have a relationship of L ≧ W, and the shoulder is located at a substantially central portion. Has a through hole, and And the head part is detachably connected to each other in a state where at least a part of the head part is inserted into the through hole, and the shoulder part is fitted to the rotating shaft part or the head part, Tibial component.
(2) The convoluted shaft portion has a screw hole opened at an upper end portion thereof, the head portion extends downward from a lower portion thereof, and is connected to the connection shaft portion inserted into the through hole, and the connection The tibial component according to (1), further including a screw portion that is positioned at a lower portion of the outer peripheral portion of the shaft portion and can be screwed into the screw hole.
(3) The shoulder portion has at least one first convex portion or first concave portion located on an upper surface thereof, and the head portion is located at a lower portion thereof and the at least one first convex portion. Or the tibial component as described in said (1) or (2) which has at least 1 2nd recessed part or 2nd convex part which can be unevenly fitted in a 1st recessed part.
(4) The shoulder portion includes the two first concave portions that are located apart from each other through the through hole and are located on a straight line perpendicular to the rotation axis, and the head portion includes the two The tibial component according to (3), including a second convex portion.
(5) The tibial component according to (4), wherein each of the two first recesses extends from the inner peripheral surface of the through hole to the outer peripheral portion.
(6) The shoulder portion has a first tapered surface located on the inner peripheral surface of the through hole, and the head portion extends downward from a lower portion thereof, and is a connecting shaft that is inserted into the through hole. The tibial component according to (1) or (2), further including a second portion and a second tapered surface that is located on an outer peripheral portion of the connection shaft portion and can be taper-fitted to the first tapered surface.
(7) A knee prosthesis comprising: the tibial component according to any one of (1) to (6); and a femoral component coupled to the tibial component by a hinge structure through the hinge shaft insertion hole. .

  According to the present invention, there is an effect that the rotation angle of the rotator can be set to an optimal value in accordance with the amount of soft tissue excised during surgery.

1 is an exploded perspective view showing a tibial component according to an embodiment of the present invention. FIG. It is a figure which expands and shows the 1st plate and 2nd plate with which the tibial component shown in FIG. 1 is equipped, (a) is a perspective view, (b) is a top view (top view), (c) is (b). It is an A arrow side view. It is a disassembled perspective view which expands and shows the rotator with which the tibial component shown in FIG. 1 is provided. It is a disassembled side view which expands and shows the rotator with which the tibial component shown in FIG. 1 is provided. It is a figure which shows the tibial component shown in FIG. 1, (a) is a side view, (b) is the BB line expanded sectional view of (a). (A) And (b) is a schematic explanatory drawing which shows the shoulder part of the rotator with which the tibial component shown in FIG. 1 is provided. (A)-(c) is a schematic explanatory drawing which shows the modification of the shoulder part of the rotator with which the tibial component shown in FIG. 1 is provided.

  Hereinafter, a tibial component according to an embodiment of the present invention will be described in detail with reference to FIGS. In the figure, an arrow X indicates the front-rear direction of the tibial component, X1 indicates the front, and X2 indicates the rear.

<Tibial component>
As shown in FIG. 1, the tibial component 1 of the present embodiment can be used for both the right and left knee joints, and includes a tray 2, a first plate 3 </ b> A and a second plate 3 </ b> B, and a rotator 4. And.

(tray)
The tray 2 of the present embodiment includes an upper surface 21 and a rotation shaft portion insertion hole 22 that is open at a substantially central portion of the upper surface 21. The tray 2 of the present embodiment includes a lower surface 23 and a substantially rod-shaped stem 24 that extends downward from a substantially central portion of the lower surface 23. Examples of the material constituting the tray 2 include a titanium alloy. In addition, the tibial component 1 of this embodiment is installed in a tibia by embedding the stem 24 mentioned above in a tibia bone marrow cavity.

(First plate and second plate)
As shown in FIG. 2, the first plate 3 </ b> A and the second plate 3 </ b> B of the present embodiment are connected to each other by a patella receiving portion 31 included in the tibial component 1. The first plate 3A of the present embodiment has an upper surface 3A1 and a recess 3A2 located on the upper surface 3A1. Similarly, the 2nd plate 3B of this embodiment has upper surface 3B1 and recessed part 3B2 located in upper surface 3B1. Each of the recesses 3A2 and 3B2 of the present embodiment is a part that houses a condyle portion of a femoral component (not shown) and functions as a sliding surface with respect to the femoral component.

  Further, the first plate 3A of the present embodiment has an inner wall portion 3A3 extending along the front-rear direction. Similarly, the 2nd plate 3B of this embodiment has the inner wall part 3B3 extended along the front-back direction. Then, the first plate 3A and the second plate 3B of the present embodiment are attached to the tray 2 so that the inner wall portions 3A3 and 3B3 face each other, and the above-described rotating shaft portion insertion hole 22 is exposed from between them.

  Examples of the constituent material of the first plate 3A and the second plate 3B include ultra high molecular weight polyethylene resin. The ultrahigh molecular weight polyethylene resin is a polyethylene resin having a weight average molecular weight of 1,000,000 or more, and can be produced, for example, by increasing the reaction time while reacting the ethylene monomer by a low-pressure suspension polymerization method. The weight average molecular weight of the ultrahigh molecular weight polyethylene resin is usually about 1 million to 7 million.

(Rotator)
As shown in FIGS. 3 and 4, the rotator 4 of the present embodiment includes a rotation shaft portion 41 that is inserted into the rotation shaft portion insertion hole 22 of the tray 2 described above, a substantially rectangular shoulder portion 42, and a hinge shaft. And a head portion 43 having an insertion hole 431 in order.

  Here, as shown in FIG. 5, the shoulder portion 42 of the present embodiment includes the first plate 3 </ b> A and the second plate so that the outer peripheral portions 421 and 421 along the longitudinal direction face the inner wall portions 3 </ b> A <b> 3 and 3 </ b> B <b> 3 described above. Located between 3B. 6A, the distance between the first plate 3A and the second plate 3B is L, the width of the shoulder portion 42, that is, the distance between the outer peripheral portions 421 and 421 along the longitudinal direction is W. , L and W have a relationship of L ≧ W. In the present embodiment, L and W have a relationship of L> W. According to these configurations, as shown in FIG. 6B, the rotator 4 can be rotated around the rotation axis S at the rotation angle θ. In other words, the rotator 4 of the present embodiment can be rotated within a range in which the vicinity of the corner portion 422 of the shoulder portion 42 abuts against the inner wall portions 3A3 and 3B3. As described above, the shoulder portion 42 of the present embodiment has a substantially rectangular shape. However, the substantially rectangular shape is not limited to a rectangular shape, and the vicinity of the corner portion 422 of the shoulder portion 42 is the inner wall portion 3A3. This is a concept including a rectangular shape or a substantially elliptical shape as long as the rotation angle θ can be controlled by coming into contact with 3B3.

  The rotation angle θ of the present embodiment is ± 5 °, but is not limited to this. That is, the rotation angle θ can be controlled to a desired value by adjusting the relationship between L and W described above. When adjusting the relationship between L and W, it is preferable to adjust W in terms of ease of adjustment and manufacturing cost. Specifically, when W is decreased, the rotation angle θ can be increased. Further, the rotation angle θ can also be controlled to a desired value by adjusting the curvature radius of the corner portion 422 of the shoulder portion 42. Specifically, when the radius of curvature of the corner portion 422 is increased, the rotation angle θ can be increased.

  As a modification of the shoulder part 42, the structure shown to Fig.7 (a)-(c) is mentioned, for example. When the shoulder 42a shown in FIG. 7A is employed, the rotation angle θ can be ± 6 °. Further, when the shoulder 42b shown in FIG. 7B is employed, the rotation angle θ can be ± 8 °. When the shoulder portion 42c shown in FIG. 7C is employed, the rotation angle θ can be ± 10 °. In addition, as for shoulder part 42a, 42b, W is the same as the shoulder part 42 of this embodiment, and the curvature radius differs. Specifically, the radius of curvature increases in the order of the shoulder 42, the shoulder 42a, and the shoulder 42b. The shoulder portion 42c has the same radius of curvature as the shoulder portion 42 of the present embodiment, and has a different W. Specifically, W of the shoulder part 42c is smaller than W of the shoulder part 42 of this embodiment.

  Further, the rotation angle θ can be set to 0 °. That is, the rotation angle θ can be set to 0 ° by setting the above-described L and W to the relationship L = W, and the rotator 4 can be fixed.

  On the other hand, as shown in FIG. 3, the shoulder portion 42 of the present embodiment has a through hole 423 located at a substantially central portion thereof. More specifically, the shoulder portion 42 of this embodiment has an upper surface 424 and a lower surface 425. The through hole 423 of the present embodiment penetrates between the upper surface 424 and the lower surface 425. Further, in the present embodiment, the rotating shaft portion 41 and the head portion 43 are detachably connected to each other in a state where a connecting shaft portion 433 (described later) that is a part of the head portion 43 is inserted into the through hole 423. And the shoulder part 42 of this embodiment is fitted to the head part 43. According to these configurations, it becomes possible to set the rotation angle θ of the rotator 4 to an optimum value in accordance with the amount of soft tissue excised during surgery.

  Specifically, if a plurality of shoulder portions 42 having different W and / or curvature radii are prepared in advance, the rotation angle θ of the rotator 4 from the plurality of shoulder portions 42 is optimal in accordance with the amount of soft tissue resection during surgery. It is possible to select the shoulder portion 42 so as to obtain a correct value. When the rotator 4 is assembled using the selected shoulder portion 42, the assembled rotator 4 is connected to the rotating shaft portion 41 and the head portion 43 as described above, and the shoulder portion 42 is connected to the head portion 43. Therefore, only the head portion 43 can be prevented from rotating, and as a result, it functions in the same manner as the integrally formed rotator. Therefore, according to the above-described configuration, it is possible to set the rotation angle θ of the rotator 4 to an optimal value in accordance with the amount of soft tissue excised during surgery.

  Moreover, according to the structure mentioned above, the following effects are also acquired. That is, the rotator 4 has a complicated shape. In the present embodiment, the rotator 4 can be disassembled into the rotating shaft part 41, the shoulder part 42, and the head part 43. Therefore, since the rotating shaft part 41, the shoulder part 42, and the head part 43 which comprise the rotator 4 can be manufactured separately, manufacture becomes easy rather than the case where the rotator by which these are integrally molded is manufactured, and is being manufactured. Thus, it is possible to reduce the load applied to each member and suppress the occurrence of defective parts. Moreover, even if a defective part occurs in the rotator 4, only the member in which the defective part has occurred in the rotator 4 needs to be recreated. Therefore, the manufacturing time can be shortened compared with the case where the entire rotator formed integrally is recreated. And when adjusting the rotation angle θ of the rotator 4, when preparing a plurality of shoulder portions 42 having different W and / or curvature radii, in the present embodiment, it is only necessary to manufacture a plurality of shoulder portions 42. The manufacturing cost can be reduced as compared with the case of manufacturing a plurality of molded rotators.

  In addition, the rotating shaft portion 41 of the present embodiment has a screw hole 412 that opens to the upper end portion 411 thereof. The head portion 43 of the present embodiment extends downward from the lower portion 432 and is connected to the connecting shaft portion 433 inserted through the through-hole 423 and the lower portion of the outer periphery of the connecting shaft portion 433. 412, and a screw portion 434 that can be screwed into the frame 412. In the present embodiment, the upper end portion 411 of the convolution shaft portion 41 has an outer diameter that is larger than the inner diameter of the through hole 423. In the present embodiment, when the connecting shaft portion 433 is inserted through the through hole 423, the screw portion 434 is exposed from the lower surface 425 of the shoulder portion 42. According to these configurations, the rotating shaft portion 41 and the head portion 43 can be detachably connected to each other in a state where the connection shaft portion 433 is inserted through the through hole 423.

  The shoulder portion 42 of the present embodiment has two first concave portions 426 and 426 located on the upper surface 424 thereof. In addition, the head portion 43 of the present embodiment has two second convex portions 435 and 435 that are located in the lower portion 432 and can be engaged with the two first concave portions 426 and 426 described above. According to these structures, the shoulder part 42 can be unevenly fitted to the head part 43, and it can suppress that only the head part 43 rotates.

  In the present embodiment, the two first concave portions 426 and 426 are both positioned away from each other through the through hole 423 and are positioned on the straight line M perpendicular to the rotation axis S. According to such a configuration, the load applied to the fitting portion can be distributed with a good balance. From the viewpoint of improving this effect, in the present embodiment, the two first concave portions 426 and 426 both reach the outer peripheral portion 421 from the inner peripheral surface of the through hole 423.

  Examples of the constituent material of the rotator 4 include a Co—Cr—Mo alloy and a titanium alloy. The titanium alloy is preferably ion implanted. The ion implantation treatment is a surface treatment technique that hardens the material surface by irradiating the material surface with accelerated ions to improve wear characteristics.

(Rotation sleeve)
On the other hand, as shown in FIG. 1, the tibial component 1 of the present embodiment further includes a rotation sleeve 5. The rotation sleeve 5 is a member that protects the shoulder 42 of the rotator 4 and functions as a bearing of the rotator 4.

  The rotation sleeve 5 of the present embodiment is configured to cover the entire surface of the rotating shaft portion 41 of the rotator 4, the upper surface 424 and the lower surface 425 of the shoulder portion 42, and the vicinity of the lower portion 432 of the head portion 43. In the present embodiment, the rotating shaft portion 41 of the rotator 4 is inserted into the rotating shaft portion insertion hole 22 of the tray 2 in a state where the rotator 4 is fitted into the rotation sleeve 5. Therefore, in this embodiment, the rotation shaft portion 41 is inserted into the rotation shaft portion insertion hole 22 via the rotation sleeve 5. Further, the rotation sleeve 5 of the present embodiment is configured to be press-fitted into the rotating shaft portion insertion hole 22. Therefore, in this embodiment, the rotation sleeve 5 is held in the rotation shaft portion insertion hole 22 and functions as a bearing of the rotator 4, and only the rotator 4 rotates.

  Examples of the constituent material of the rotation sleeve 5 include the same ultra high molecular weight polyethylene resin as exemplified in the first plate 3A and the second plate 3B described above.

  In addition, the tray 2 of this embodiment mentioned above has a pair of nail | claw parts 25 and 25 located in the upper surface 21. FIG. In this embodiment, when the rotation shaft portion 41 is inserted into the rotation shaft portion insertion hole 22 with the rotator 4 fitted into the rotation sleeve 5, the rotation sleeve 5 is attached to the tray 2 by the pair of claw portions 25 and 25. Locked.

(Shaft sleeve)
Further, the tibial component 1 of the present embodiment further includes a pair of shaft sleeves 6 and 6. Each of the pair of shaft sleeves 6 and 6 is attached to the hinge shaft insertion hole 431 of the head portion 43 described above, and functions as a member that supports a hinge shaft (not shown). Examples of the constituent material of the shaft sleeve 6 include the same ultrahigh molecular weight polyethylene resin as exemplified in the first plate 3A and the second plate 3B described above.

  The tibial component 1 of the present embodiment described above can be assembled, for example, by the following procedure. First, according to the amount of soft tissue excised during surgery, a shoulder 42 is selected from a plurality of shoulders 42 having different W and / or curvature radii prepared in advance so that the rotation angle θ of the rotator 4 is an optimum value. And assemble the rotator 4. Next, the assembled rotator 4 is fitted into the rotation sleeve 5, and the rotation shaft portion 41 is inserted into the rotation shaft portion insertion hole 22 through the rotation sleeve 5. Then, the first plate 3 </ b> A and the second plate 3 </ b> B may be attached to the tray 2, and the pair of shaft sleeves 6 and 6 may be attached to the hinge shaft insertion hole 431 of the head portion 43.

<Artificial knee joint>
Next, an artificial knee joint according to an embodiment of the present invention will be described. The knee prosthesis of this embodiment includes the above-described tibial component 1 and a femoral component connected to the tibial component 1 by a hinge structure through a hinge shaft insertion hole 431.

  The artificial knee joint of this embodiment can be assembled, for example, by the following procedure. First, the condyles of the femoral component are accommodated in the recesses 3A2 and 3B2 of the first plate 3A and the second plate 3B described above. Next, the tibial component 1 and the femoral component may be connected to each other by the hinge shaft.

  As mentioned above, although some embodiment which concerns on this invention was illustrated, this invention is not limited to embodiment mentioned above, It cannot be overemphasized that it can be made arbitrary, unless it deviates from the summary of this invention. .

  For example, in the above-described embodiment, the rotation shaft portion 41 and the head portion 43 are detachably connected to each other with a part of the head portion 43 inserted through the through-hole 423. The shaft portion 41 and the head portion 43 can be detachably connected to each other in a state where a part of the rotating shaft portion 41 is inserted into the through hole 423.

  In the above-described embodiment, the shoulder portion 42 is fitted to the head portion 43, but instead, the shoulder portion 42 can be fitted to the convoluted shaft portion 41.

  Further, in the above-described embodiment, the shoulder portion 42 is concavo-convexly fitted to the head portion 43, but instead, the shoulder portion 42 can be taper-fitted to the head portion 43. In this embodiment, the shoulder portion 42 has a first tapered surface located on the inner peripheral surface of the through hole 423, and the head portion 43 extends downward from the lower portion 432 and is inserted into the through hole 423. And a second taper surface that is located on the outer periphery of the connection shaft portion 433 and can be taper-fitted to the first taper surface. According to such a configuration, the shoulder portion 42 can be taper-fitted to the head portion 43, and only the head portion 43 can be prevented from rotating.

  In addition, the structure of the tibial component 1 in the above-mentioned embodiment is applicable also to an artificial elbow joint.

DESCRIPTION OF SYMBOLS 1 Tibial component 2 Tray 21 Upper surface 22 Rotation shaft part insertion hole 23 Lower surface 24 Stem 25 Claw part 3A 1st plate 3A1 Upper surface 3A2 Recessed part 3A3 Inner wall part 3B Second plate 3B1 Upper surface 3B2 Concave part 3B3 Inner wall part 31 Rotating patella rotation part 4 Shaft portion 411 Upper end portion 412 Screw hole 42 Shoulder portion 421 Outer peripheral portion 422 Corner portion 423 Through hole 424 Upper surface 425 Lower surface 426 First concave portion 43 Head portion 431 Hinge shaft insertion hole 432 Lower portion 433 Connection shaft portion 434 Screw portion 435 Second convex portion 5 Rotation sleeve 6 Shaft sleeve

Claims (7)

A tray having a convoluted shaft insertion hole that is open at a substantially central portion of the upper surface;
A first plate and a second plate, which are attached to the tray so that the inner wall portions extending along the front-rear direction face each other and the rotation shaft portion insertion hole is exposed from between the inner wall portions;
A rotation shaft portion inserted into the rotation shaft portion insertion hole, and a substantially rectangular shape positioned between the first plate and the second plate so that an outer peripheral portion along the longitudinal direction faces the inner wall portion. A rotator having a shoulder portion and a head portion having a hinge shaft insertion hole in order, and
When the distance between the first plate and the second plate is L and the width of the shoulder is W, the L and the W have a relationship of L ≧ W,
The shoulder portion has a through hole located at a substantially central portion thereof,
The rotating shaft portion and the head portion are detachably connected to each other with at least one part inserted through the through hole, and the shoulder portion is fitted to the rotating shaft portion or the head portion. The tibial component. The convoluted shaft portion has a screw hole opened at an upper end portion thereof,
The head portion extends downward from a lower portion thereof and is connected to the connecting shaft portion that is inserted into the through hole, and a screw portion that is positioned at a lower portion of the outer peripheral portion of the connecting shaft portion and can be screwed into the screw hole. The tibial component of claim 1, comprising: The shoulder portion has at least one first convex portion or first concave portion located on an upper surface thereof,
3. The head according to claim 1, wherein the head portion has at least one second concave portion or second convex portion that is located at a lower portion of the head portion and can be engaged with the at least one first convex portion or the first concave portion. The tibial component as described. The shoulder has two first recesses located on a straight line that are located apart from each other through the through hole and perpendicular to the rotation axis,
The tibial component according to claim 3, wherein the head portion includes two of the second convex portions.   The tibial component according to claim 4, wherein each of the two first recesses extends from the inner peripheral surface of the through hole to the outer peripheral portion. The shoulder portion has a first tapered surface located on the inner peripheral surface of the through hole,
The head portion extends downward from a lower portion thereof, and is connected to the connecting shaft portion inserted through the through hole, and a second portion that is positioned on the outer peripheral portion of the connecting shaft portion and can be taper-fitted to the first tapered surface. The tibial component according to claim 1, wherein the tibial component has a tapered surface. A tibial component according to any of claims 1-6;
And a femoral component coupled to the tibial component by a hinge structure through the hinge shaft insertion hole.

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