JP2002035020A - Femur component for artificial knee joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly move a patella at a knee joint with respect to a femur and to uniformize a force loading to a patellar ligament. SOLUTION: The femur component 1A has a front joint connection plate 3, an outer distal condyle part 5 and an inner distal condyle part 6 both of which are provided connected to both side of the lower part of the plate 3 and leaving a space part between them, an outer rear condyle part 7 and an inner rear condyle part 8 both of which are connected to the rear ends of the outer and the inner distal condyle part, and an outline surface 1a in side view is formed to be nearly a circular arc. On the front surface 3a of the plate 3, a patella groove 10 which the patella component 9 contacts to is provided communicated with the space part. A notch part 11 for giving outward and backward displacement and inward inclination to the component 9 with respect to the component 1A is provided inside the outer peripheral part of the part 5 and the part 7 through the flexion angle range 100 deg. to 135 deg. of the knee joint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a femoral component of an artificial knee joint which constitutes an artificial knee joint together with a tibial component or the like.

[0002]

2. Description of the Related Art FIGS. 6 to 10 show known artificial knee joints. The knee prosthesis is mainly composed of a femoral component 1 and a tibial component 2 that supports the femoral component. The femoral component 1 has a mountain-shaped anterior joint plate 3 in a front view, and is coupled to both lower sides of the anterior joint plate 3 to be directed rearward (to the right in FIGS. 7 and 8). An outer distal condyle 5 and an inner distal condyle 6 provided with a space 4 therebetween, and are connected to the rear ends of the outer distal condyle 5 and the inner distal condyle 6 and are directed upward. Outer condyle 7 and medial posterior condyle 8, and an outer surface 1 a in a side view is formed in a substantially arc shape.

At the substantially center of the front surface (left surface in FIGS. 7 and 8) 3a of the front joint connecting plate 3, a patella groove 10 having an arc-shaped cross section with which a disc-shaped patella component 9 contacts. Are provided to communicate with the space portion 4 in the vertical direction. The portion of the patella component 9 that contacts the patella groove 10 is formed in a spherical shape. The inner surface shape of the femoral component 1 in a side view is a rear surface (the right surface in FIGS. 7 and 8) 3 b of the anterior joint plate 3 and a front surface of the lateral posterior condyle 7 and the medial posterior condyle 8. 7 and 8
7a, 8a, the upper surfaces 5a, 6a of the outer distal condyle 5 and the inner distal condyle 6, the front slope 3c connecting the upper surfaces 5a, 6a and the rear surface 3b, and the upper surface 5a. , 6
a and the rear inclined surfaces 5b and 6b connecting the front surfaces 7a and 8a.
Thus, a coupling protrusion 1b is provided substantially at the center of the upper surfaces 5a and 6a.

[0006] The femoral component 1 has an anterior articulating plate 3 on the anterior side of the cut portion of the femur A previously cut in accordance with the shape of the space S on the inner surface (showing the femur in an upright state). And is fitted to the femur A by driving in the coupling projection 1g. The patella component 9 is attached to the patella by driving the connecting projection 9a into the patella.

[0005] The tibial component 2 comprises a base plate 2a and a plate 2b made of polyethylene.
The base plate 2a is directly attached to the tibia B by screws or the like, and the plate 2b is attached to the upper surface of the base plate 2a by screws or the like. The femoral component 1 and the base plate 2a are made of a metal such as a titanium alloy.

When the femoral component 1 is assembled with the artificial knee joint, the arcuate outer surface 1a comes into contact with the tibial component 2 and rotates back and forth in accordance with the flexion and extension of the knee joint. ing. Then, when the bending angle of the knee joint becomes 90 ° or more, the patella component 9 comes off the patella groove 10 and contacts the outer peripheral portion inside the outer distal condyle 5 and the inner distal condyle 6,
Further, the outer peripheral condyle 7 and the inner posterior condyle 8 come into contact with the inner peripheral portion. Meanwhile, the outer peripheral portion inside the conventional outer distal condyle portion 5 and the inner outer peripheral portion of the medial posterior condyle portion 6 and the outer peripheral portion inside the conventional posterior condyle portion 7 and the medial posterior condyle portion 8 are formed on the outer surface 1a of the femoral component 1. It has a shape that almost follows.

[0007]

However, in the conventional femoral component 1 having the above-described structure, the patella component 9 is positioned at the time of the deep flexion of the knee joint so that the lateral distal condyle 5 and the medial distal condyle 6 are not moved. The outer peripheral surface of the femoral component 1 is simply obtained by contact between the inner peripheral portion of the femoral component and the inner peripheral portion of the lateral posterior condyle 7 and the medial posterior condyle 8.
Is moved relative to the femoral component 1 with a movement trajectory substantially along. This relative movement is significantly different from the complex relative movement of the patella to the femur at the actual knee joint of the human body, which results in an imbalance in the force acting on the patella ligament and the relative movement of the patella to the femur. There is dissatisfaction that movement cannot be performed smoothly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an artificial knee joint capable of smoothly moving the patella relative to the femur at the knee joint and balancing the forces acting on the patella ligament. The purpose of the present invention is to provide a femoral component.

[0009]

The present invention has the following features in order to solve the above-mentioned problems. That is,
The femoral component of the knee prosthesis according to claim 1,
An anterior articulating plate, an outer distal condyle and an inner distal condyle coupled to both lower sides of the anterior articulating plate and directed rearwardly and spaced apart from each other; It has an outer posterior condyle and an inner posterior condyle that are connected to the distal end of the distal condyle and the posterior end of the medial distal condyle, and are directed upward. At approximately the center of the anterior surface of the anterior articulation plate, a patella groove for contacting the patella component is provided longitudinally in communication with the space, and the arc-shaped outer surface contacts the tibia component to allow the knee to contact. The femoral component of a knee prosthesis that pivots in response to flexion and extension movements of the joint, with the cross-section facing inward along the inside of their outer periphery from the posterior to the posterior posterior condyle of the lateral distal condyle A notch that becomes an inclined surface is formed And said that you are.

In the femoral component of the artificial joint, the femoral component is fixed to the femur, and its arcuate outer surface is in contact with the upper surface of the tibia component fixed to the tibia and the patella component fixed to the patella. Is brought into contact with the patella groove of the femoral component to form an artificial knee joint. In this artificial knee joint, as the human body is bent from the upright extension position,
The femoral component pivots rearward while contacting the upper surface of the tibial component. At this time, the patella component relatively moves along the patella groove of the femoral component while contacting the femoral component, and moves from the patella groove to the space between the lateral distal condyle and the medial distal condyle. Contact the lateral and medial distal condyles,
It contacts the lateral posterior and medial posterior condyles. In the above process, when the bending angle of the human body becomes a certain angle of 90 ° or more and the patella component contacts from the posterior part of the lateral distal condyle and the medial distal condyle to the lateral posterior condyle and the medial posterior condyle. The patella component is displaced outward and posterior to the knee joint and tilted inward by a notch formed inside the outer periphery of the lateral distal condyle and the lateral posterior condyle.

According to the femoral component of the artificial joint, the patella component is disengaged from the patella groove of the femoral component, moves to the space between the outer distal condyle and the inner distal condyle, and moves to the outer distal condyle. In the range of the deep flexion of the knee joint after contact with the medial distal condyle, the notch allows the patella component to move deeply into and contact the space, thereby displacing laterally and posteriorly. Inclined and wide contact between the femoral component and the patella component reduces contact pressure, allows smooth movement of the patella relative to the femur during flexion and extension of the knee joint, and balances forces acting on the patella ligament .

According to a second aspect of the present invention, there is provided the femoral component of the artificial joint according to the first aspect, wherein the notch portion has a flexion angle of 10 degrees of the knee joint.
It is characterized in that it is formed in the range of 0 ° to 135 °. In the femoral component of the artificial joint, the movement of the patella component relative to the femoral component is realized in a state similar to the movement of the patella relative to the femur at the actual knee joint of the human body.

According to a third aspect of the present invention, there is provided the femoral component of the artificial joint according to the second aspect, wherein the notch portion has a depth that increases as the bending angle of the knee joint increases. It is characterized by being formed as follows. In the femoral component of this artificial joint, displacement of the patella due to movement of the patella component with respect to the femoral component during flexion and extension of the knee joint is always performed smoothly.

According to a fourth aspect of the present invention, there is provided the femoral component of an artificial joint according to any one of the first to third aspects, wherein the cutout portion is formed to have a concave cross-section having an arc-shaped cross section. It is characterized by having. In this femoral component of the artificial joint, the contact between the femoral component and the patella component is performed in a wide range, so that the contact surface pressure is reduced, the wear of each component is reduced, and their durability is improved. .

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 show one embodiment of a femoral component of a knee prosthesis according to the present invention. In the femoral component 1A of the artificial joint according to this embodiment, a notch 11 is provided inside the outer periphery of the lateral distal condyle 5 and the lateral posterior condyle 7. Other configurations are the same as those of the conventional femoral component 1 of the knee prosthesis, and therefore, the same components are denoted by the same reference numerals and detailed description thereof will be omitted.

The notch 11 will be described more specifically. The notch 11 extends from the extended position (flexion angle 0 °) P1 of the knee joint shown in FIG. 1 to the deepest position shown in FIG. In the bending position angle range up to the bending position (bending position angle 135 °) P2, the bending position angle α is 100 ° to 13 °.
At 5 °, the patella component 9 is provided over the area in contact with the femoral component 1A.
The range in which the notch 11 is provided corresponds to the range in which the center of the patella component 9 moves, but in practice, the size of the patella component 9 is taken into consideration.
It is formed over a wide range extending before and after the range of the bending angle. The bending angle range of 100 ° to 135 ° in which the notch 11 is provided is the femur when a plurality of human bodies are actually bent and extended at the knee joint by MRI (Magnetic Resonance Imaging Diagnostic Apparatus) or the like. By observing the relative movement between the patella and the patella, the bending position angle at which the displacement of the patella with respect to the femur toward the outside, the rear, and the inward tilt appear is set.

As shown in FIG. 4, the notch 11 is formed by cutting out a portion e on the inner side (the left side in FIG. 4) of the outer peripheral condyle 5 and the outer posterior condyle 7 as shown in FIG. The inclined surface 11a is formed to be inclined so as to face inward. Further, the notch portion 11 is formed such that the notch amount (depth) in the direction of the arrow D increases as the bending position angle increases while the inclination angle θ of the inclined surface 11a is constant.

In the femoral component 1A having the above-described configuration, the femoral component 1A rotates in contact with the tibial component 2 to extend the knee joint in the upright state of the human body shown in FIG. ) When gradually bent from P1, the femoral component 1A rotates rearward while contacting the upper surface of the tibial component 2 (the upper end side of the anterior joint connecting plate 3 rotates clockwise in FIG. 1). The patella component 9 slides relatively within the patella groove 10 of the femoral component 1A, and after exiting the patella groove 10, the lateral distal condyle 5 and the medial distal condyle 6
To the space 4 between the outer distal condyle 5 and the inner distal condyle 6
To contact with the outer peripheral portions 5c and 6c inside the. further,
Outer peripheral portion 7c inside lateral posterior condyle 7 and medial posterior condyle 8;
8c, and finally reaches the state shown in FIG. 4 where the bending angle of the deepest bending position P2 becomes 135 °.

In the above process, the bending position angle of the human body is 100 °
When the patella component 9 comes into contact from the posterior part of the lateral distal condyle 5 and the medial distal condyle 6 to the posterior posterior condyle 7 and the medial posterior condyle 8 at the bending position P3 or more, the patella Notch 1 in which outer portion 9c of component 9 is formed inside lateral distal condyle 5 and lateral posterior condyle 7
1, the patella component 9 is displaced outward and rearward of the knee joint (indicated by arrows C and D in FIG. 4) and inwardly inclined (as shown by the arrow E in FIG. 4). And is deeply sunk in the space 4. Each of the displacements of the patella component 9 with respect to the femoral component 1A increases as the bending angle of the knee joint increases.

The femoral component 1A of the artificial joint
According to the above, the patella component 9 is disengaged from the patella groove 10 of the femoral component 1A, moves to the space 4 between the outer distal condyle 5 and the inner distal condyle 6, and moves away from the outer distal condyle 5 and the medial distance. In the bending angle range of 100 ° to 135 ° in the deep bending position of the knee joint after the contact with the condyle part 6, the notch 11 causes the patella component 9 to be displaced outward and rearward of the knee joint and incline. Then, the femoral component 1A and the patella component 9 come into wide contact with each other by sinking deeply into the space portion 4 and making contact. For this reason, the contact pressure between the femoral component 1A and the patella component 9 decreases, and the patella moves smoothly with respect to the femur during the flexion and extension movements of the knee joint in a state close to the actual movement of the human body at the knee joint. In addition to this, it can be expected that the forces acting on the patella ligament are balanced, the movement distance of the patella during bending is reduced (short cut), and the range of motion is increased.

In the above-described embodiment, the notch 11 is formed as a flat inclined surface 11a. However, the present invention is not limited to this, and the notch 11 may be formed as a convex surface. It may be formed in a concave shape having a radius of curvature larger than the radius of curvature of 9b. When the concave surface is formed, the contact surface between the spherical portion 9b and the notch 11 is elastically deformed at the time of contact, the contact surface therebetween is widened, the contact pressure is reduced, and the abrasion of the contact portion is reduced. The durability of the component can be improved.

In the above embodiment, the depth of the notch 11 is changed and the inclination angle θ of the inclined surface 11a is changed as the bending position angle increases in the bending position angle range of 100 ° to 135 ° of the knee joint. The notch 11
May be increased such that the inclination angle θ of the inclined surface 11a increases as the bending position angle increases.

[0023]

As described above, according to the present invention, the following excellent effects can be obtained. According to the femoral component of the artificial joint according to the first aspect, the patella component is disengaged from the patella groove of the femoral component and moves to the space between the lateral distal condyle and the medial distal condyle to cause the lateral distal condyle. In the range of the deep flexion position of the knee joint after contacting the part and the medial distal condyle, the notch provided inside the lateral distal condyle and the lateral posterior condyle allows the patella component to be inserted into the space. By contacting deeply, it can be displaced inward and outward and tilted inward, allowing the femoral component and the patella component to come into wide contact with each other. The movement of the patella relative to the femur can be performed smoothly, and the forces acting on the patella ligament can be balanced.

According to the femoral component of the artificial joint according to the second aspect, the movement of the patella component relative to the femoral component can be realized in a state close to the movement of the patella relative to the femur at the actual knee joint of the human body. . According to the femoral component of the artificial joint according to the third aspect, displacement of the patella accompanying movement of the patella component with respect to the femoral component during flexion and extension of the knee joint can be always performed smoothly.

According to the femoral component of the artificial joint according to the fourth aspect, since the contact between the femoral component and the patella component can be performed in a wider range, the contact surface pressure can be reduced as much as possible. Can reduce the wear of each component and improve their durability.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a femoral component of an artificial joint according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a view as viewed in the direction of the arrow A in FIG. 1;

FIG. 4 is a sectional view taken along line XX of FIG. 3;

FIG. 5 is a side view showing the femur component of FIG. 1 in a deepest flexion position;

FIG. 6 is a front view of a conventional artificial knee joint.

FIG. 7 is a side view of the artificial knee joint of FIG. 6;

FIG. 8 is a plan view of the femoral component of FIG. 6;

FIG. 9 is a front view of the femoral component of FIG. 6;

FIG. 10 is a view as seen from the arrow B in FIG. 7;

[Explanation of symbols]

 Reference Signs List 1, 1A femoral component 1a external surface 2 tibial component 3 anterior articulating plate 4 space 5 outer distal condyle 6 inner distal condyle 7 outer posterior condyle 8 medial posterior condyle 9 patella component 10 patella groove 11 Notch 11a Inclined surface α Bending position angle θ Inclination angle

Claims (4)

[Claims] 1. An anterior articulating plate, an outer distal condyle and a medial distal condyle joined to opposite sides of a lower portion of the anterior articulating plate and directed rearwardly and spaced apart from each other Department and
An outer posterior condyle and a medial posterior condyle that are connected to the posterior ends of the lateral distal condyle and the medial distal condyle and are directed upward, and the outer surface in a side view is formed in a substantially arc shape At the substantially center of the anterior surface of the anterior articulation plate, a patella groove for contacting the patella component is provided in longitudinal communication with the space, and the arc-shaped outer surface contacts the tibial component. A femoral component of a knee prosthesis that rotates in response to flexion and extension movements of the knee joint. A femoral component of a knee joint prosthesis, characterized in that a notch serving as an inclined surface facing is formed. 2. The notch has a knee joint bending angle of 1 °.
The femoral component of a knee prosthesis according to claim 1, wherein the femoral component is formed in the range of 00 to 135 degrees. 3. The femoral component of an artificial knee joint according to claim 2, wherein the notch is formed so that the depth increases as the bending angle of the knee joint increases. . 4. The femoral component of an artificial knee joint according to claim 1, wherein the notch has a concave cross-section having an arc-shaped cross section.