JP2981917B2 - Artificial knee joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention restores a highly deformed joint of a knee joint such as rheumatoid arthritis, knee osteoarthritis, pseudogout, sudden osteonecrosis to normal function. The present invention relates to a knee prosthesis used for the purpose.

[Conventional technology]

In a conventional artificial knee joint, a method of controlling a femoral component by a control peg provided on a tibia component and securing a movable range has been adopted. (See, for example, JP-A-63-132651) [Problem to be Solved by the Invention] As described above, a control peg is provided on a tibia component to secure a movable range of an artificial knee joint, and a thigh is used when bending. When the bone component is braked, stress is concentrated on the brake peg because the entire load is received by the brake peg, and the brake peg is deformed or broken, so that a predetermined function cannot be obtained.

[Means for solving the problem]

To solve such problems described above, in the present invention, the artificial knee joint femoral component sphere or ellipsoidal convex sliding surface at a height T ₁ at the rear center sliding portion of the main joint surface for receiving a load of Formed with curvatures R ₁ and R ₂ , and a concave sliding surface at the rear center sliding part of the main joint surface subjected to the load of the tibial component with a depth T ₂ of a spherical or elliptical spherical shape with curvatures R ₃ and R ₄ . It is characterized by having been formed.

[Action]

The convex sliding surface at the rear of the femoral component and the concave sliding surface of the tibial component fit each other when flexing, and slide and rotate backward, thereby improving the range of motion and the relationship between the convex and concave sliding surfaces. By setting T ₁ ≦ T ₂ , R ₁ ≦ R ₃ , and R ₂ ≦ R ₄ , the load can be bent while bearing the load on the main joint surface, and a smooth sliding rotation can be realized. The dispersion of stress can be measured as compared with.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 (a), 1 (b) and 1 (c) are a plan view, a front view, and a front view, respectively, of a femoral component 1 constituting an artificial knee joint according to the present invention.
Shows a side view, in the femoral component 1, the convex sliding surface 1b is sphere or ellipsoidal height T ₁ responsible for flexing movement in the rear in the rear center sliding portion of the main joint surface 1a for receiving a load Are formed with curvatures R ₁ and R ₂ .

2 (a), 2 (b) and 2 (c) show a plan view, a front view and a side view of the tibial component 2. The tibial component 2 includes a tray member 2a for supporting a load and a femoral component. 1 and a sliding member 2b that performs a sliding motion, and the sliding member 2b has a main joint surface that receives a load.
It is formed on a sphere or an oval sphere in curvature R _3, R ₄ in the concave sliding surface 2d depth T ₂ of the order to accommodate the convex sliding surface 1b of the femoral component 1 to the rear center sliding portion 2c I have.

The tray member 2a of the femoral component 1 and the tibial component 2 is made of ceramics such as alumina and zirconia, stainless steel, COP, Co-Cr-Mo alloy, pure T
i, a metal such as a Ti alloy, or a material obtained by concentrating carbon fiber, synthetic resin or carbon fiber to a predetermined thickness, and furthermore, alumina, apatite , Glass ceramics,
It may be coated with TiN TiO ₂ or the like, and the sliding member 2b of the tibial component 2 is formed of a synthetic resin such as high-density polyethylene for sliding with the femoral component 2.

The femoral component 1 and the tibia component 2
3 is shown in FIG. 3 in a state of being attached to the femur 3 and the tibia 4 in the extended position. In this state, the load is received by the main joint surface 1a of the femoral component 1 and the main joint surface 2c of the tibia component 2. In this case, when rotating and bending from this state, the convex sliding surface 1b of the femoral component 1 is formed at the rear center sliding portion of the sliding member 2b of the tibial component 2, as shown in FIG. Since the tibial component 2 is accommodated in the concave sliding surface 2d so as to be fitted therein, it is possible to smoothly move the posterior portion of the tibial component 2 without moving forward. According to the present invention, the movable range before and after can be improved to the movable range of 135 ° C. or higher where the seat can be seated.

In this case, the relationship between the height T ₁ of the convex sliding surface of the femoral component and the depth T ₂ of the concave sliding surface of the tibial component in FIG. ₁ is T ₁ ≦ T ₂ , and the curvature is The relationship is R ₁ ≤
R ₃ , R ₂ ≦ R ₄ is desirable, and in reality, T ₁ = 2 to 10, T ₂ = 2
_{~11, R 1 = R7~R50, R} 2 = R7~R30, R 3 = R7~R55, R 4 = R
7 to R35, if this is done, the load can be received by the main joint surface even during the bending motion, and furthermore, the rotation motion is also possible. Also, by providing a flat portion 2e at the rear of the concave sliding surface of the tibia component,
Further, a flexion movement in the rearward direction becomes possible, and the original function of the knee joint can be recovered.

〔The invention's effect〕

As described above, a spherical or elliptical spherical convex sliding surface was formed at the rear central sliding portion of the femoral component, and a spherical or elliptical spherical concave sliding surface was formed at the rear central sliding portion of the tibial component. By doing so, smooth rotational movement behind the tibial component during bending becomes possible, stress dispersion can be measured, and a larger range of motion can be ensured. It is possible to bring about the same joint function and greatly contribute to human welfare.

[Brief description of the drawings]

1A, 1B, and 1C are a plan view, a front view, and a side view, respectively, of a femoral component constituting an artificial knee joint according to an embodiment of the present invention. Fig. 2 (a), (b),
(C) is a plan view, a front view, and a side view of the tibial component constituting the knee prosthesis according to the embodiment of the present invention. FIG. 3 is a side view showing a state where the artificial knee joint according to the embodiment of the present invention is attached to the femur and the tibia and in the extended position. 4th
The figure is a side view showing a state where the artificial knee joint according to the embodiment of the present invention is attached to the femur and the tibia and is in a bending position. 1: Femoral component 1a: convex sliding surface 2: tibial component 2a: concave sliding surface 3: femur 4: tibia

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) A61F 2/28-2/48

Claims (1)

(57) [Claims] 1. An artificial knee joint comprising a femoral component fixed to a distal portion of a femur and a tibial component fixed to a proximal portion of a tibia, a main joint surface receiving a load of the femoral component. In the rear center sliding part, a convex sliding surface that bears rearward bending is formed into a sphere or an elliptical sphere with curvatures R ₁ and R ₂ at height T ₁ , and the main joint surface receiving the load of the other tibial component A concave sliding surface is formed at the rear center sliding portion into a sphere or an elliptical sphere with a curvature R ₃ , R ₄ at a depth T ₂ , and the respective relationships are T ₁ ≦ T ₂ , R ₁ ≦ R ₃ , R ₂ ≦ the R _4, these projections,凹摺dynamic surface is fitted at the time of bending, the artificial knee joint which forms so as to rotate backward.