阅读说明：本技术 人工膝关节 (Artificial knee joint ) 是由 清友大惟 井上贵之 于 2020-02-18 设计创作，主要内容包括：一种人工膝关节(1)包括：股骨组件(2),其包括内侧髁(22)和外侧髁(23)；以及胫骨组件(3),其包括承受内侧髁(22)的内侧滑动面(51)和承受外侧髁(23)的外侧滑动面(52)。内侧滑动面(51)和外侧滑动面(52)的内外方向的曲率半径在前后方向的规定范围内从前方朝向后方变大。在内外方向上,以使伸展位置的内侧髁(22)的最低点(22a)与外侧髁(23)的最低点(23a)的中间点(20)相对于胫骨组件(3)的中心(30)位于胫骨组件(3)的宽度的2%～10%内方的形式,内侧滑动面(51)和外侧滑动面(52)向内方靠近。(An artificial knee joint (1) comprising: a femoral component (2) comprising a medial condyle (22) and a lateral condyle (23); and a tibial component (3) comprising a medial sliding surface (51) to receive the medial condyle (22) and a lateral sliding surface (52) to receive the lateral condyle (23). The radii of curvature in the inward and outward directions of the inner sliding surface (51) and the outer sliding surface (52) increase from the front to the rear within a predetermined range in the forward and rearward directions. The medial sliding surface (51) and the lateral sliding surface (52) are adjacent to each other in the medial-lateral direction such that a midpoint (20) between a lowest point (22 a) of the medial condyle (22) and a lowest point (23 a) of the lateral condyle (23) in the extended position is located inward of 2% to 10% of the width of the tibial component (3) with respect to the center (30) of the tibial component (3).)

1. An artificial knee joint is provided with:

a femoral component comprising a medial condyle and a lateral condyle; and

a tibial component having a medial sliding surface for receiving the medial condyle and a lateral sliding surface for receiving the lateral condyle, wherein the medial sliding surface and the lateral sliding surface have a curvature radius in the medial-lateral direction that increases from the front to the rear within a predetermined range in the anterior-posterior direction;

the medial sliding surface and the lateral sliding surface are located inwardly with respect to the center of the tibial component so that a midpoint between a lowest point of the medial condyle and a lowest point of the lateral condyle in the extension position is located inwardly of 2% to 10% of the width of the tibial component in the medial-lateral direction.

2. The artificial knee joint according to claim 1,

in the antero-posterior direction, a contact position of the medial condyle with the medial sliding surface in the extended position is in a range of 40% to 65% of a length of the tibial component from a posterior end of the tibial component.

3. The artificial knee joint according to claim 1 or 2,

an end portion of the upper surface of the tibial component, which extends outward from the femoral component, is formed with an inclined surface that is inclined downward in the outward direction.

4. The artificial knee joint according to any one of claims 1 to 3,

a lowest point line connecting lowest points of the inner sliding surface in the inward and outward directions in the front-rear direction is curved inward toward the front.

Technical Field

The invention relates to an artificial knee joint.

Background

The artificial knee joint replaces the knee joint of a patient suffering from knee osteoarthritis, rheumatoid arthritis, bone tumor, or a patient with trauma or the like. The artificial knee joint includes a femoral component that replaces a portion of the femur and a tibial component that replaces a portion of the tibia. Depending on the circumstances, artificial knee joints sometimes include a patellar component.

Generally, a femoral component includes a medial condyle and a lateral condyle, and a tibial component includes a medial sliding surface for receiving the medial condyle and a lateral sliding surface for receiving the lateral condyle (see patent document 1).

Prior art documents:

patent documents:

patent document 1: japanese patent No. 3781186.

Disclosure of Invention

The problems to be solved by the invention are as follows:

however, even though the conventional artificial knee joint can achieve the operation of the knee joint close to the healthy state, it is desired to further improve the reproducibility.

Accordingly, an object of the present invention is to provide an artificial knee joint capable of performing the same operation as a healthy knee joint.

The technical means for solving the problems are as follows:

in order to solve the above problems, the present inventors have conducted extensive studies and found that in a healthy knee joint, the center in the medial-lateral direction of the distal portion of the femur (the end portion on the tibia side) is located more medial than the center in the medial-lateral direction of the proximal portion of the tibia (the end portion on the femur side) in the extended position. On the other hand, in the conventional artificial knee joint, the center of the femoral component and the center of the tibial component are aligned in the medial-lateral direction. Therefore, it is considered that if the centers in these medial-lateral directions are shifted, it is not possible to achieve the same operation as a healthy knee joint. The present invention has been completed based on such a point.

That is, the knee joint of the present invention is characterized by comprising: a femoral component comprising a medial condyle and a lateral condyle; and a tibial component having a medial sliding surface for receiving the medial condyle and a lateral sliding surface for receiving the lateral condyle, wherein the medial sliding surface and the lateral sliding surface have a curvature radius in the medial-lateral direction that increases from the front to the rear within a predetermined range in the anterior-posterior direction; the medial sliding surface and the lateral sliding surface are located inwardly with respect to the center of the tibial component so that a midpoint between a lowest point of the medial condyle and a lowest point of the lateral condyle in the extension position is located inwardly of 2% to 10% of the width of the tibial component in the medial-lateral direction.

According to the above configuration, in the medial-lateral direction, the relative positional relationship between the femur and the tibia of the patient with the artificial knee joint attached thereto is the same as the relative positional relationship between the femur and the tibia of a healthy person in the extended position. With respect to the flexion position, it is known that the femoral component moves rearward as the knee flexes. Since the radii of curvature in the medial-lateral direction of the medial sliding surface and the lateral sliding surface are larger in the posterior direction than in the anterior direction, when the femoral component moves in the posterior direction in accordance with the flexion of the knee, the constraining force of the femoral component in the medial-lateral direction decreases. As a result, the femoral component is easily moved in the medial-lateral direction due to tension of soft tissues including ligaments and a joint capsule. That is, even when the knee is flexed, the relative positional relationship between the femur and the tibia of the patient with the artificial knee joint attached thereto may be the same as the relative positional relationship between the femur and the tibia of a healthy person. Therefore, the balance of tension and relaxation of the soft tissue when the artificial knee joint is installed is similar to that of a healthy knee joint. Therefore, the same operation as that of a healthy knee joint can be achieved.

In the anteroposterior direction, a contact position between the medial condyle and the medial sliding surface in the extended position may be in a range of 40% to 65% of a length of the tibial component from a posterior end of the tibial component. According to this configuration, even in the anteroposterior direction, the relative positional relationship between the femur and the tibia of the patient with the artificial knee joint attached thereto is the same as the relative positional relationship between the femur and the tibia of a healthy person.

An end portion of the upper surface of the tibial component extending outward of the femoral component may be formed with an inclined surface inclined downward outward. According to this structure, the collision of the lateral collateral ligament with the tibial component can be avoided.

A lowest point line connecting lowest points of the inner sliding surface in the inward and outward direction in the front-rear direction may be curved inward toward the front. According to this configuration, the femoral component can be guided outward as the femoral component moves rearward when the knee is flexed.

The invention has the following effects:

according to the present invention, the same operation as that of a healthy knee joint can be realized.

Drawings

FIG. 1 is an exploded perspective view of an artificial knee joint according to one embodiment of the present invention;

fig. 2 is a sectional view showing an installed state of the artificial knee joint shown in fig. 1;

FIG. 3 is a cross-sectional view (femoral and tibial omissions) taken along line III-III of FIG. 2;

FIG. 4 is a top view of the tibial component;

FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4;

fig. 6 is a sectional view taken along line VI-VI of fig. 4.

Detailed Description

Fig. 1 shows an artificial knee joint 1 according to an embodiment of the present invention. The artificial knee joint 1 of the present embodiment is used for the left foot, and the lower left direction in fig. 1 is the inward direction, the upper right direction is the outward direction, the lower right direction in fig. 1 is the forward direction, and the upper left direction is the rearward direction. Fig. 2 is a sectional view showing the state in which the artificial knee joint 1 is attached.

The artificial knee joint 1 includes: a femoral component 2 that replaces a portion of the resected femur 11; and a tibial component 3 that replaces a portion of the resected tibia 12. In fig. 2, reference numeral 13 denotes a lateral collateral ligament, reference numeral 14 denotes a medial collateral ligament, reference numeral 15 denotes an anterior cruciate ligament, and reference numeral 16 denotes a posterior cruciate ligament.

The femoral component 2 is made of a metal such as cobalt-chromium alloy or titanium alloy. The femoral component 2 includes: an anterior wall 21 fixed to the anterior resection surface of the femur 11; and a medial condyle 22 and a lateral condyle 23 extending from the lower end of the anterior wall 21 through the inferior aspect of the femur 11 to the posterior aspect of the femur 11.

The medial 22 and lateral 23 condyles diverge from one another in the medial-lateral direction. The gap between the medial 22 and lateral 23 condyles serves to avoid interference with the anterior 15 and posterior 16 cruciate ligaments. In addition, a patella groove for sliding the patella or patella component is formed in the lower portion of the anterior wall 21 to extend in the anterior-posterior direction through between the medial condyle 22 and the lateral condyle 23.

The lateral surface of the medial condyle 22 is a three-dimensional curved surface that curves in the anterior-posterior direction and the medial-lateral direction. Similarly, the lateral surface of the lateral condyle 23 is a three-dimensional curved surface curved in the anterior-posterior direction and the medial-lateral direction.

In this embodiment, the tibial component 3 is of the type in which the anterior cruciate ligament 15 is resected and the posterior cruciate ligament 16 is preserved. However, the tibial component 3 may also be of the type in which both the anterior cruciate ligament 15 and the posterior cruciate ligament 16 are resected. In the case of the both-resected type, an upwardly protruding projection is formed substantially in the center of the tibial component 3. Alternatively, the tibial component 3 may be of the type that preserves both the anterior cruciate ligament 15 and the posterior cruciate ligament 16, or of the type that preserves the posterior cruciate ligament 16 and reconstructs the anterior cruciate ligament 15.

The tibial component 3 includes a base 4 made of a metal such as a cobalt-chromium alloy or a titanium alloy, and a resin plate 5 made of polyethylene or the like. The base 4 includes a plate portion 41 fixed to the upper resection surface of the tibia 12 and a rod (stem) 42 extending downward from substantially the center of the plate portion 41. The base 4 further includes a triangular keel 43 connected to the plate portion 41 and the rod 42. The base 4 may also include a pair of peg (peg) 44 located below the inner sliding surface 51 and the outer sliding surface 52, which will be described later, in addition to or instead of the rod 42 and the keel 43.

The resin plate 5 has an outline having the same shape as the plate portion 41 of the base 4 in a plan view. A medial sliding surface 51 for receiving the medial condyle 22 of the femoral component 2 and a lateral sliding surface 52 for receiving the lateral condyle 23 of the femoral component 2 are formed on the upper surface of the resin plate 5.

The inner sliding surface 51 is a three-dimensional curved surface curved in the front-rear direction and the inner-outer direction. Similarly, the outer sliding surface 52 is a three-dimensional curved surface curved in the front-rear direction and the inner-outer direction.

More specifically, as shown in fig. 4 to 6, the radius of curvature MR in the inward-outward direction of the inner sliding surface 51 increases from the front to the rear within a predetermined range in the forward-rearward direction. The predetermined range is, for example, a central region obtained by trisecting the inner sliding surface 51 in the front-rear direction.

Similarly, the radius of curvature LR in the inward-outward direction of the outer sliding surface 52 increases from the front to the rear within a predetermined range in the forward-rearward direction. The predetermined range is, for example, a central region obtained by trisecting the outer sliding surface 52 in the front-rear direction.

The inner sliding surface 51 and the outer sliding surface 52 are not provided at left-right symmetrical positions, but are located inward. More specifically, as shown in fig. 2, the medial sliding surface 51 and the lateral sliding surface 52 are inwardly adjacent in the medial-lateral direction such that a midpoint 20 between a lowest point 22a of the medial condyle 22 and a lowest point 23a of the lateral condyle 23 in the extended position is located 2% to 10% of the width W (see fig. 4) of the tibial component 3 relative to the center 30 of the tibial component 3. In other words, the distance D between the medial point 20 and the center 30 of the tibial component 3 in the medial-lateral direction is 0.02W or more and 0.1W or less. The center 30 of the tibial component 3 in the medial-lateral direction is a line that bisects the width W of the tibial component 3 in the medial-lateral direction.

Further, as shown in fig. 3, the contact position of the medial condyle 22 with the medial sliding surface 51 in the extended position (also the lowest point 22a of the medial condyle 22) is in the range of 40% to 65% of the length L of the tibial component from the posterior end of the tibial component 3 in the anterior-posterior direction. In other words, the distance L1 from the posterior end of the tibial component 3 to the contact position is 0.4L or more and 0.65L or less.

As shown in fig. 2 and 4, an inclined surface 53 is formed on the upper surface of the resin plate 5 (also, the upper surface of the tibial component 3) at an end portion extending outward from the femoral component 2, and the inclined surface 53 is inclined downward outward. In the present embodiment, the outer sliding surface 52 is adjacent to the inclined surface 53, and a ridge is formed by these boundaries.

As shown in fig. 3 and 4, an inclined surface 53 inclined downward outward is also formed at the front end portion on the upper surface of the resin plate 5.

Furthermore, a recess 31 is provided in the tibial component 3 for avoiding interference with the posterior cruciate ligament 16. The recess 31 is recessed from the posterior end of the tibial component 3 towards the anterior. That is, the cutouts having the same shape as the recesses 31 are formed in both the plate portion 41 of the base 4 and the resin plate 5. The recess 31 is inwardly closer than the center 30 of the tibial component 3 in the medial-lateral direction, as are the medial 51 and lateral 52 sliding surfaces.

As described above, in the artificial knee joint 1 of the present embodiment, the medial sliding surface 51 and the lateral sliding surface 52 of the tibial component 3 are inwardly adjacent. Therefore, in the medial-lateral direction, the relative positional relationship of the femur 11 and the tibia 12 of the patient with the artificial knee joint 1 mounted thereon is the same as the relative positional relationship of the femur and the tibia of a healthy person in the extended position. With respect to the flexion position, it is known that the femoral component 2 moves rearward as the knee flexes. Since the radii of curvature MR and LR in the medial-lateral direction of the medial sliding surface 51 and the lateral sliding surface 52 are larger in the posterior direction than in the anterior direction, when the femoral component 2 moves in the posterior direction in accordance with flexion of the knee, the constraint force of the femoral component 2 in the medial-lateral direction decreases. As a result, the femoral component 2 is easily moved in the medial-lateral direction due to tension of soft tissues including ligaments and a joint capsule. That is, even when the knee is flexed, the relative positional relationship between the femur 11 and the tibia 12 of the patient to whom the artificial knee joint 1 is attached may be the same as the relative positional relationship between the femur and the tibia of a healthy person. Therefore, the balance between tension and relaxation of the soft tissue when the artificial knee joint 1 is attached is similar to that of a healthy knee joint. Therefore, the same operation as that of a healthy knee joint can be achieved.

In the present embodiment, the contact position of the medial condyle 22 with the medial sliding surface 51 in the extended position is within the range of 40% to 65% of the length L of the tibial component 3 from the posterior end of the tibial component 3. Therefore, the relative positional relationship between the femur 11 and the tibia 12 of the patient with the artificial knee joint 1 attached thereto is also the same as the relative positional relationship between the femur and the tibia of a healthy person in the anteroposterior direction.

Further, since the inclined surface 53 is formed at the outer end portion of the upper surface of the tibial component 3, the collision of the lateral collateral ligament 13 with the tibial component 3 can be avoided.

(modification example)

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, the artificial knee joint 1 may include a patellar component in addition to the femoral component 2 and the tibial component 3.

Further, the medial sliding surface 51 of the tibial component 3 may be configured to: the lowest point line connecting the lowest points of the inner sliding surfaces 51 in the inward-outward direction in the front-rear direction is curved inward in the forward direction (i.e., in the direction opposite to the outer sliding surface 52). According to this configuration, the femoral component 2 can be guided outward as the femoral component 2 moves rearward when the knee is flexed.

In the case where the tibial component 3 is of the type that stores both the anterior cruciate ligament 15 and the posterior cruciate ligament 16, the tibial component 3 has a substantially U-shape in plan view in which a groove that opens rearward is formed between the inner sliding surface 51 and the outer sliding surface 52. In this case, the bar 42 and the keel 43 are omitted.

Description of the symbols:

1: an artificial knee joint;

2: a femoral component;

20: a middle point;

22: a medial condyle;

22 a: a lowest point;

23: the lateral condyle;

23 a: a lowest point;

3: a tibial component;

30: a center;

51: an inner sliding surface;

52: an outer sliding surface;

54: an inclined surface.