JP5399189B2 - Artificial joint components - Google Patents

Description

  The present invention relates to a prosthetic joint component that is used in an artificial joint and has a distal end inserted into a medullary cavity of a bone and fixed by bone cement, and connected to another component on the opposite side of the distal end.

  Conventionally, artificial hip joints, artificial knee joints, artificial elbow joints, artificial shoulder joints, artificial fingers for patients with abnormalities in hip joints, knee joints, elbow joints, shoulder joints, finger joints, ankle joints, etc. Surgery to which artificial joints such as joints and artificial ankle joints are applied is performed. In the artificial joint as described above, a prosthetic joint component is used in which the distal end side is inserted into the medullary cavity of the bone and fixed by bone cement and connected to other components on the opposite side of the distal end side. (For example, see Patent Document 1).

  Patent Document 1 discloses a femoral component for an artificial hip joint used in an artificial hip joint as the above-described artificial joint component. The component for an artificial joint disclosed in Patent Document 1 has a distal end inserted into a femur and fixed with or without bone cement, and is placed on the acetabulum side of the pelvis and formed into a ball shape. It is comprised so that it may connect with the other component provided as a ball member. And the component for artificial joints as disclosed by patent document 1 is equipped with the connection part connected with another component, and the stem part formed integrally with this connection part. The stem portion is formed as an axial portion that is inserted into and fixed to the medullary cavity portion of the bone on the distal end side opposite to the connecting portion side. In the artificial joint component disclosed in Patent Document 1, a groove formed in a recess so as to be partially cut out in order to adjust the bending rigidity of the stem portion is provided in the middle portion of the side surface of the stem portion. One is formed.

Japanese National Patent Publication No. 8-503859

  When the stem portion of the artificial joint component as disclosed in Patent Document 1 is inserted into the bone marrow cavity and fixed with bone cement, the bone marrow cavity is first filled with bone cement. Then, the operator who performs the operation inserts the distal end side of the stem portion into the medullary cavity portion. At this time, the surgeon inserts the distal end side of the stem portion into the medullary cavity portion while allowing bone cement corresponding to the volume displaced by the inserted stem portion to flow out of the medullary cavity portion.

In order to secure the state of fixation of the artificial joint component by bone cement firmly and stably, a high pressure is applied from the bone cement over the entire side surface of the stem portion inserted into the medullary cavity. It is desirable to insert the stem portion into the medullary cavity while maintaining the working state. However, in the medullary cavity filled with bone cement, the pressure of bone cement is considerably high in the back area where the inserted stem part does not reach, but between the side of the stem part and the medullary cavity part. In the region where the bone cement flows, the pressure of the bone cement is greatly reduced due to the increase in flow resistance during the flow of the bone cement. For this reason, it is difficult to insert the stem portion into the medullary cavity portion while maintaining high pressure from the bone cement over the entire side surface of the stem portion that is inserted into the medullary cavity portion. It becomes difficult to make the fixing by the good state. In particular, when the stem portion is formed as a cylindrical portion and the flow channel area in which the bone cement flows between the side surface of the stem portion and the medullary cavity portion is substantially constant, this tendency is likely to be remarkable.

  In the case of the component for an artificial joint disclosed in Patent Document 1, as described above, one groove that is partially recessed for adjusting the bending rigidity is formed in the middle portion of the side surface of the stem portion. . In this case, the flow resistance at the time of the flow of the bone cement decreases in a region lateral to the groove partially provided at one place on the side surface of the stem portion. However, in other regions around the side surface of the stem portion, the flow resistance during the flow of the bone cement increases, resulting in a pressure drop of the bone cement. For this reason, in the same manner as described above, the stem portion is inserted into the medullary cavity portion while maintaining a state in which high pressure acts from the bone cement over the entire side surface of the stem portion that is inserted into the medullary cavity portion. It is difficult to fix the bone cement in a good state.

  In view of the above circumstances, the present invention inserts the stem portion into the medullary cavity portion while maintaining high pressure from the bone cement over the entire side surface of the stem portion inserted into the medullary cavity portion. It is an object of the present invention to provide a component for an artificial joint that can be easily realized and can easily achieve a good state of fixation with bone cement.

The component for an artificial joint according to the present invention for achieving the above object is used in an artificial joint, and the distal end side is inserted into the medullary cavity of a bone and fixed by bone cement, and the other side is opposite to the distal end side. A component for an artificial joint that is connected to a component, and is formed as a connecting portion that is connected to another component in the artificial joint, and a shaft-like portion that is inserted into the medullary cavity of the bone and fixed by bone cement And a stem portion formed integrally with the connecting portion or fixed to the connecting portion at an end opposite to the tip side. The artificial joint component according to the present invention is formed on the side surface of the stem portion so as to be recessed inward with respect to the surface of the side surface, and from the distal end side to the connecting portion side connected to the connecting portion. At least two grooves formed so as to extend along the axial direction of the stem portion are provided, and the grooves are positioned at an equal angle with respect to the axial center in the circumferential direction around the axial center of the stem portion. Each of the grooves has a cross-sectional area of a groove cross section which is a recessed region with respect to the surface of the side surface in a cross section perpendicular to the axial direction of the stem portion, from the tip side of the stem portion to the connecting portion side. It is formed so that it may decrease gradually.

  According to this invention, when the operator inserts the distal end side of the stem portion into the medullary cavity portion of the bone, the bone cement that is pushed away as the stem portion is inserted flows between the side surface of the stem portion and the medullary cavity portion. At the same time, the fluid flows while passing through a groove formed in the stem portion along the axial direction. These grooves are formed such that the cross-sectional area of the groove cross section gradually decreases from the tip end side of the stem portion to the connecting portion side. For this reason, in the region on the side of the distal end side of the stem portion, the flow path area through which the bone cement flows is increased, the flow rate of the bone cement is decreased, and the shear rate is also decreased. The flow resistance at becomes smaller. On the other hand, in the region on the side of the connecting portion side of the stem portion, contrary to the above, the flow channel area where the bone cement flows is reduced, the bone cement flow rate is increased, and the shear rate is increased, The flow resistance increases when the bone cement flows. For this reason, the pressure of the bone cement is lowered in the lateral region on the distal end side of the stem portion close to the region on the far side where the pressure of the bone cement is high and the inserted stem portion has not reached, and the connecting portion of the stem portion The bone cement pressure can be gradually increased in the lateral region toward the side. Therefore, in the region between the side surface of the stem portion and the medullary cavity portion, the pressure can be efficiently dispersed and acted from the tip end side to the connecting portion side of the stem portion.

  In addition, according to the present invention, the above-described groove reduces the pressure of bone cement in the region on the back side where the inserted stem portion does not reach and the region on the distal end side of the stem portion. Such an increase in pressure can be suppressed. Thereby, in the above-mentioned region, the integrated amount of the flow resistance of the bone cement, that is, the insertion resistance, which is the resistance when the artificial joint component is inserted into the bone cement in the medullary cavity, can be reduced. Then, while reducing the insertion resistance due to the flow resistance of bone cement in the above region, as described above, the flow resistance of the bone cement is gradually increased from the distal end side of the stem portion to the connecting portion side to efficiently pressurize the bone cement. Can be dispersed. For this reason, it is easy to maintain a state in which high pressure acts from the bone cement over the entire side surface inserted into the medullary cavity portion of the stem portion, while suppressing an increase in the total amount of insertion resistance. The stem can be inserted into the medullary cavity. Thereby, the fixed state by bone cement can be made into the favorable state firmly fixed stably. Conventionally, since the insertion resistance in the region on the back side where the stem part does not reach and the region on the tip side of the stem part is too large, the viscosity of the bone cement filled in the medullary cavity is sufficiently high There was a problem that it was difficult to perform the insertion work after waiting for it to rise. However, as described above, while maintaining that the total amount of insertion resistance increases, the state in which high pressure is applied from the bone cement over the entire side surface of the stem portion inserted into the medullary cavity is maintained. Since the stem portion can be easily inserted into the medullary cavity portion as it is, the insertion operation can be performed after waiting for a sufficiently high level of viscosity.

  Further, at least two grooves of the stem portion are provided, and these are arranged at equal angular positions in the circumferential direction with respect to the axial center of the stem portion. For this reason, when inserting the stem portion into the medullary cavity, the pressure of the bone cement acting on the side surface of the stem portion is suppressed from acting in the circumferential direction. Thereby, the operation | work which inserts a stem part straight with respect to the depth direction of a medullary cavity part can be performed easily, maintaining a stable attitude | position. In addition, after the stem portion is inserted and fixed in the medullary cavity portion, the artificial joint component is fixed to the bone by the bone cement that has entered and hardened into the plurality of grooves. For this reason, it can also suppress that the component for artificial joints displaces in a rotation direction within a bone, and the fixability of the rotation direction of the component for artificial joints can also be improved. In addition, the groove | channel of a structure different from this invention can also be formed in a stem part only for the purpose of the improvement of the fixation property of the rotation direction of the component for artificial joints. However, in this case, the stem portion is inserted into the medullary canal while maintaining high pressure from the bone cement over the entire side surface of the stem that is inserted into the medullary canal as in the conventional case. It is difficult to go through, and fixing with bone cement is difficult.

  Therefore, according to the present invention, it is possible to insert the stem portion into the medullary cavity portion while maintaining high pressure from the bone cement over the entire side surface of the stem portion that is inserted into the medullary cavity portion. It becomes easy to provide a component for an artificial joint that can easily achieve a good state of fixation with bone cement.

Artificial joints for components according to the present invention, each of the front Kimizo, toward connecting portion side from the front end side of the stem portion, by being formed as a groove depth becomes gradually shallower, the cross-sectional of the groove section It is preferable that the area is reduced.

  According to the present invention, a groove shape that gradually decreases the cross-sectional area of the groove cross section can be easily formed by gradually decreasing the groove depth from the distal end side of the stem portion to the connecting portion side. Further, by adjusting the gradient of the groove depth, it is possible to easily adjust the distribution of pressure from the bone cement acting on the side surface of the stem portion from the distal end side to the connecting portion side to have a desired distribution.

Artificial joints for components according to the present invention, each of the front Kimizo, toward connecting portion side from the front end side of the stem portion, it is formed so as groove width is gradually narrowed, the cross-sectional area of the groove section It is preferable to form so as to decrease.

  According to the present invention, a groove shape that gradually decreases the cross-sectional area of the groove cross section can be easily formed by gradually narrowing the groove width from the distal end side of the stem portion to the connecting portion side. Further, by adjusting the inclination of the change in the groove width dimension, it is possible to easily adjust the distribution of pressure from the bone cement acting on the side surface of the stem portion from the distal end side to the connecting portion side to be a desired distribution. it can.

Artificial joints for components according to the present invention, the shape of the groove in the cross section perpendicular to the axial direction of the front Symbol stem portion, toward connecting portion side from the front end side of the stem portion, the arc of the same radius of curvature of the circle It is preferable that it is formed as.

  According to the present invention, the cross-sectional shape of the groove is formed as a circular arc of the same radius of curvature from the tip side to the connecting portion side in the stem portion. For this reason, a general-purpose tool having an arcuate blade shape is moved along the axial direction while changing the relative position with respect to the axial center of the stem portion, thereby gradually changing the groove depth and groove width. Can be processed. Since the cross-sectional shape of the groove changes in an arc shape, the groove inside the stem portion formed as the shaft-shaped portion is efficiently utilized to make the groove that the groove depth and groove width gradually change into the stem portion. Can be formed. Therefore, the groove | channel which makes the pressure distribution of the bone cement which acts on the side surface of a stem part from the front end side to the connection part side desired distribution can be formed easily.

Artificial joints for components according to the present invention, the front Symbol stem, which is preferably formed as a cylindrical shaft-like portion.

  According to the present invention, in the stem portion formed as a cylindrical shaft-shaped portion, a plurality of grooves are formed in which the cross-sectional area of the groove section gradually decreases from the tip side to the connecting portion side along the axial direction. Become. For this reason, the flow channel area where the bone cement flows between the side surface of the stem portion and the medullary cavity portion is not substantially constant, and the flow resistance during the flow of the bone cement is reduced at the distal end side of the stem portion. It can be made smaller in the region and gradually increased over the region on the connecting portion side. Thereby, even if it is a component for artificial joints which has a stem part formed as a cylindrical shaft-like part, a state in which high pressure acts from the bone cement over the entire side surface inserted into the medullary cavity part in the stem part It is easy to insert the stem portion into the medullary cavity portion while maintaining the same, and it is possible to easily achieve a good state of fixation with bone cement.

Artificial joints for components according to the present invention is used in artificial hip joints, the tip end is inserted into the femur marrow cavity and fixed by bone cement, it is placed in the acetabulum side of the pelvis to the ball-like It is provided as a femoral component for an artificial hip joint, in which the connecting portion is connected to another component provided as a formed head ball member, and the groove is formed on the human body in a state where the stem portion is implanted in the femur. It is preferable that the at least one of the front-rear direction and the inner-outer direction is disposed at a point-symmetrical position about the axial center of the stem portion.

According to the present invention, in the femoral component for a hip prosthesis, the stem portion is moved to the medullary cavity portion while maintaining high pressure from the bone cement over the entire side surface of the stem portion inserted into the medullary cavity portion. It becomes easy to insert, and it can be easily realized that the fixed state by the bone cement is in a good state. In the case of a femoral component for an artificial hip joint, the connecting portion is disposed so as to protrude obliquely with respect to the axial direction of the stem portion, and is disposed corresponding to the front-rear direction and the inner-outer direction of the human body. There is a need. On the other hand, according to the present invention, the plurality of grooves are disposed at point-symmetrical positions around the axial center of the stem portion in at least one of the front-rear direction and the inner-outer direction of the human body. For this reason, when inserting the stem portion into the medullary cavity portion, the pressure of the bone cement acting on the side surface of the stem portion is prevented from acting in a biased manner in the front-rear direction and the inner-outer direction. Thereby, the operation | work which inserts a stem part straight with respect to the depth direction of the medullary cavity part of a femur can be performed easily, maintaining a stable attitude | position.

  According to the present invention, it becomes easy to insert the stem portion into the medullary cavity portion while maintaining a state in which high pressure is applied from the bone cement over the entire side surface of the stem portion that is inserted into the medullary cavity portion. In addition, it is possible to provide a component for an artificial joint that can easily realize a state in which the bone cement is fixed in a good state.

It is sectional drawing which shows the component for artificial joints concerning 1st Embodiment of this invention, Comprising: It is the figure illustrated with a part of cross section of the femur and pelvis typically shown. It is a front view of the component for artificial joints shown in FIG. It is a side view of the component for artificial joints shown in FIG. It is a bottom view of the component for artificial joints shown in FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, a cross-sectional view taken along line BB, and a cross-sectional view taken along line CC. It is the front view shown in the state which decomposed | disassembled the component for artificial joints concerning 2nd Embodiment of this invention, and is the figure illustrated with the other component. It is a front view which shows the state by which the component for work joints shown in FIG. 6 and the other component were assembled. FIG. 8 is a side view of FIG. 7. It is a bottom view of the component for artificial joints shown in FIG. It is the front view and bottom view of the simulation stem part for a test. It is the front view, bottom view, and side view of the simulation stem part for a test. It is the front view, bottom view, and side view of the simulation stem part for a test. It is a front view which shows the state by which the simulation stem part is inserted in the bone model which comprises the simulated spinal cavity part for a test. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 10 into the simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 10 into the simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 10 into the simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 11 into the simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 11 into the simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 11 into the simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 12 into a simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 12 into a simulation medullary cavity part. It is the figure which showed the test result about the pressure of the bone cement at the time of inserting the simulation stem part shown in FIG. 12 into a simulation medullary cavity part. It is the figure which showed the test result about the indentation load at the time of inserting the simulation stem part shown in FIG. 10 into a simulation medullary cavity part. It is the figure which showed the test result about the indentation load at the time of inserting the simulation stem part shown in FIG. 11 into a simulation medullary cavity part. It is the figure which showed the test result about the pushing load at the time of inserting the simulation stem part shown in FIG. 12 into a simulation medullary cavity part.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is widely used as a component for an artificial joint that is used in an artificial joint, and the distal end side is inserted into the medullary cavity of a bone and fixed with bone cement, and connected to other components on the opposite side to the distal end side. It can be applied.

(First embodiment)
FIG. 1 is a cross-sectional view showing the artificial joint component 1 according to the first embodiment of the present invention, and shows a part of the cross section of the femur 100 and the pelvis 101 schematically shown. The artificial joint component 1 is provided as a femoral component for an artificial hip joint used in an artificial hip joint. The artificial joint component 1 is inserted at the distal end side into the medullary cavity portion 100 a of the femur 100 and fixed by the bone cement 104. The artificial joint component 1 is connected to another component provided as a head ball member 102 which is disposed on the acetabulum 101a side of the pelvis 101 and formed in a ball shape. That is, the artificial joint component 1 is applied as an element on the femur 100 side of the artificial hip joint in a state where it is combined with the head bone member 102.

  In an artificial hip joint replacement operation in which the hip joint is replaced with an artificial hip joint, the shape of the medullary cavity 100a is adjusted using only a surgical file and the artificial joint component 1 is inserted and implanted. Further, the head ball member 102 disposed on the acetabulum 101a side of the pelvis 101 is a spherical portion of the outer shape with respect to the two-layered cup 103 having the shell 103a and the liner 103b disposed on the acetabulum 101a. Is arranged to slide.

  FIG. 2 shows a front view of the artificial joint component 1. 3 shows a side view of the artificial joint component 1, and FIG. 4 shows a bottom view of the artificial joint component 1. The artificial joint component 1 shown in FIGS. 1 to 4 includes a connecting portion 11 and a stem portion 12. In addition, the component 1 for artificial joints is formed with metals, such as a titanium alloy, a cobalt chromium alloy, and stainless steel which obtained the approval approval as a medical device for living body implantation.

  The connection part 11 is formed as a part connected to the head ball member 102 which is another component in the artificial hip joint. As illustrated in FIG. 1, the connecting portion 11 has an end portion having a side surface formed so as to form a part of a conically curved surface that is gradually tapered, and the head ball member 102 is formed at the end portion. By fitting into the fitting hole 102a formed in the opening, the head head ball member 102 is connected.

The stem portion 12 is formed as an axial portion whose distal end side is inserted into the medullary cavity portion 100a of the femur 100 and fixed by the bone cement 104, and at the end opposite to the distal end side, the connecting portion 11 is formed. And is integrally formed. In the artificial joint component 1 provided as a femoral component for an artificial hip joint, the stem portion 12 is perpendicular to the axial direction of the stem portion 12 from the distal end side to the connecting portion side continuous with the connecting portion 11. The cross-sectional area in the cross section is formed so as to gradually increase. Further, the connecting portion 11 is integrally formed with the stem portion 12 so as to protrude and extend obliquely with respect to the axial direction of the stem portion 12.

  5 is a cross-sectional view taken along line AA in FIG. 2 (FIG. 5A), a cross-sectional view taken along line BB (FIG. 5B), and a cross-sectional view taken along line CC (FIG. 5). 5 (c)). As shown in FIGS. 2 to 5, the side surface of the stem portion 12 is formed so as to be recessed inward with respect to the surface 12 a (see FIG. 5) of the side surface, and from the tip side to the connecting portion side. Four grooves 13 formed so as to extend along the axial direction of the stem portion 12 are provided. These grooves 13 are arranged at positions at equal angles with respect to the axial center P in the circumferential direction centering on the axial center P of the stem portion 12 (indicated by a point P in FIGS. 5A to 5C). ing. That is, the four grooves 13 provided in the stem portion 12 are arranged at positions shifted by 90 degrees with respect to the axial center P in the circumferential direction centering on the axial center P.

  Further, in the stem portion 12, the two grooves 13 a that are half of the four grooves 13 are in the front-rear direction of the human body in a state where the stem portion 12 is implanted in the femur 100 (both ends in FIG. 5). Arranged in a point-symmetrical position about the axis center P in the direction of arrow E). And about two grooves 13b of the remaining half of the four grooves 13, the inner / outer direction of the human body in the state where the stem portion 12 is implanted in the femur 100 (the direction of the double-headed arrow F in FIG. 5). In FIG. 2, the optical axis is arranged at a point-symmetrical position about the axis center P.

  Further, as shown in FIG. 5, each of the grooves 13 has a cross-sectional area of the groove cross section which is a recessed area with respect to the surface 12 a of the side surface in a cross section perpendicular to the axial direction of the stem section 12. It is formed so as to gradually decrease from the side to the connecting portion side. Each of the grooves 13 is formed so that the groove depth gradually decreases from the distal end side to the connecting part side in the stem portion 12, and the groove width is gradually decreased. It is formed so that the cross-sectional area of the groove cross section is reduced.

  Accordingly, the groove depth dimension Dc of the groove 13 in the cross section shown in FIG. 5 (c), the groove depth dimension Db of the groove 13 in the cross section shown in FIG. 5 (b), and the groove in the cross section shown in FIG. 5 (a). The relationship of Dc> Db> Da is established with the groove depth dimension Da of 13. Then, the groove width dimension Wc of the groove 13 in the cross section shown in FIG. 5C, the groove width dimension Wb of the groove 13 in the cross section shown in FIG. 5B, and the groove width dimension Wa shown in FIG. In this case, the relationship of Wc> Wb> Wa is established. In FIG. 5, the groove depth dimension of the groove 13b and the groove width dimension of the groove 13a are illustrated, but the groove depth dimension of the groove 13a and the groove width dimension of the groove 13b are configured similarly.

  The shape of the groove 13 in the cross section perpendicular to the axial direction of the stem portion 12 is formed as a circular arc of the same curvature radius from the distal end side to the connecting portion side in the stem portion 12. Therefore, the curvature radius dimension Ra of the arc portion defining the groove 13 in the cross section shown in FIG. 5A, the curvature radius dimension Rb of the arc portion defining the groove 13 in the cross section shown in FIG. In relation to the radius of curvature Rc of the arc portion defining the groove 13 in the cross section shown in (c), the relationship Ra = Rb = Rc is established. In FIG. 5, the radius of curvature of the arc portion defining the groove 13b is illustrated, but the radius of curvature of the arc portion defining the groove 13a is configured similarly.

Next, the operation and effect when the distal end side of the artificial joint component 1 is inserted into the medullary cavity 100a of the femur 100 and fixed by the bone cement 104 in the hip replacement will be described. In this case, first, bone cement 104 is filled into the medullary cavity 100a. Then, the surgeon inserts the distal end side of the stem portion 12 into the medullary cavity portion 100a in a state where the viscosity of the bone cement 104 has reached the desired level of viscosity.

  When the operator inserts the distal end side of the stem portion 12 into the medullary cavity portion 100a of the femur 100, the bone cement 104 that is pushed away as the stem portion 12 is inserted is between the side surface of the stem portion 12 and the medullary cavity portion 100a. And also flows while passing through the groove 13 formed in the stem portion 12 along the axial direction. These grooves 13 are formed so that the cross-sectional area of the groove cross section gradually decreases from the distal end side of the stem portion 12 to the connecting portion side. For this reason, in the lateral region on the distal end side of the stem portion 12, the flow path area through which the bone cement 104 flows is increased, the flow rate of the bone cement 104 is decreased, and the shear rate is also decreased. The flow resistance at the time of flow is reduced. On the other hand, in the region on the side of the connecting portion side of the stem portion 12, contrary to the above, the flow channel area through which the bone cement 104 flows is reduced, the flow rate of the bone cement 104 is increased, and the shear rate is increased, Thereby, the flow resistance in the flow of the bone cement 104 increases. For this reason, the pressure of the bone cement 104 is decreased in the lateral region on the distal end side of the stem portion 12 close to the region on the far side where the pressure of the bone cement 104 is high because the inserted stem portion 12 has not reached, and the stem The pressure of the bone cement 104 can be gradually increased in the region on the side of the connecting portion of the portion 12. Therefore, according to the component 1 for artificial joints, in the region between the side surface of the stem portion 12 and the medullary cavity portion 100a, the pressure is efficiently dispersed over the entire region from the distal end side of the stem portion 12 to the connecting portion side. Can be made.

  Further, according to the artificial joint component 1, the groove 13 reduces the pressure of the bone cement 104 in a region on the back side where the inserted stem portion 12 does not reach or a region on the distal end side of the stem portion 12. It is possible to suppress an increase in pressure as in the conventional case. Thereby, in the above-mentioned region, it is possible to reduce the integrated amount of the flow resistance of the bone cement 104, that is, the insertion resistance that is the resistance when the artificial joint component 1 is inserted into the bone cement 104 of the medullary cavity 100a. it can. Then, while reducing the insertion resistance due to the flow resistance of the bone cement 104 in the above region, as described above, the flow resistance of the bone cement 104 is gradually increased from the distal end side of the stem portion 12 to the connecting portion side. The pressure can be dispersed efficiently. For this reason, while maintaining that the total amount of insertion resistance increases, it maintains in the state where high pressure acts from the bone cement 104 over the whole side surface inserted in the medullary cavity part 100a in the stem part 12. The stem portion 12 can be easily inserted into the medullary cavity portion 100a. Thereby, the fixation state by the bone cement 104 can be made into the favorable state fixed firmly stably. Further, according to the artificial joint component 1, high pressure is applied from the bone cement 104 over the entire side surface inserted into the medullary cavity portion 100a of the stem portion 12 while suppressing an increase in the total amount of insertion resistance. Since the stem portion 12 can be easily inserted into the medullary cavity portion 100a while maintaining the operating state, the insertion operation can be performed after waiting for a sufficiently high level of viscosity.

  Further, four grooves 13 that are two or more are provided in the stem portion 12, and these are arranged at equal angular positions in the circumferential direction with respect to the axial center P of the stem portion 12. For this reason, when inserting the stem portion 12 into the medullary cavity portion 100a, the pressure of the bone cement 104 acting on the side surface of the stem portion 12 is suppressed from acting in a circumferential direction. Thereby, the operation | work which inserts the stem part 12 straight with respect to the depth direction of the medullary cavity part 100a can be easily performed, maintaining a stable attitude | position. In addition, after the stem portion 12 is inserted and fixed in the medullary cavity portion 100a, the artificial joint component 1 is fixed to the femur 100 by the bone cement 104 that has entered and hardened into the plurality of grooves 13. Become. For this reason, it can also suppress that the component 1 for artificial joints displaces in the rotation direction within the femur 100, and the fixability of the component 1 for artificial joints in the rotation direction can also be improved.

  Therefore, according to the artificial joint component 1, the stem portion 12 is maintained in a state where high pressure is applied from the bone cement 104 over the entire side surface of the stem portion 12 inserted into the medullary cavity portion 100a. It becomes easy to insert into 100a, and it can be easily realized that the fixed state by the bone cement 104 is in a good state.

  Further, according to the artificial joint component 1, the groove shape that gradually decreases the cross-sectional area of the groove cross section by gradually decreasing the groove depth and reducing the groove width from the distal end side of the stem portion 12 to the connecting portion side. It can be formed easily. Also, by adjusting the gradient of the groove depth and the change in the groove width dimension, the distribution of pressure from the bone cement 104 acting on the side surface of the stem portion 12 from the distal end side to the connecting portion side can be easily achieved. Can be adjusted.

  Further, according to the artificial joint component 1, the cross-sectional shape of the groove 13 is formed as a circular arc having the same radius of curvature from the distal end side to the connecting portion side in the stem portion 12. For this reason, the groove depth and the groove width are gradually changed by moving a general-purpose tool having an arcuate blade shape along the axial direction while changing the relative position of the stem portion 12 with respect to the axis center. The groove 13 can be processed. And since the cross-sectional shape of the groove | channel 13 changes with circular arc shape, the groove | channel 13 from which the groove | channel depth and groove width change gradually using the area | region inside the stem part 12 formed as an axial part efficiently is used. The stem portion 12 can be formed. Therefore, the groove 13 having a desired distribution of the pressure distribution of the bone cement 104 acting from the distal end side to the connecting portion side on the side surface of the stem portion 12 can be easily formed.

  In addition, since the artificial joint component 1 is provided as a femoral component for an artificial hip joint, the connecting portion 11 is disposed so as to protrude obliquely with respect to the axial direction of the stem portion 12, and thus the front-rear direction of the human body And it is necessary to be arranged corresponding to the inner and outer directions appropriately. On the other hand, according to the artificial joint component 1, the plurality of grooves 13 are arranged at point-symmetrical positions around the axial center P of the stem portion 12 in the front-rear direction and the inner-outer direction of the human body. For this reason, when the stem portion 12 is inserted into the medullary cavity portion 100a, the pressure of the bone cement 104 acting on the side surface of the stem portion 12 may be biased in the front-rear direction and the inner-outer direction. It is suppressed. Thereby, the operation | work which inserts the stem part 12 straight with respect to the depth direction of the medullary cavity part 100a of the femur 100 can be performed easily, maintaining a stable attitude | position.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 6 is a front view showing the artificial joint component 2 according to the second embodiment of the present invention in an exploded state, and is shown together with a plate member 105 that is another component connected to the artificial joint component 2. ing. FIG. 7 is a front view showing a state in which the artificial joint component 2 and the plate member 105 are assembled, and FIG. 8 is a side view of FIG.

  The artificial joint component 2 shown in FIGS. 6 to 8 is provided as a artificial knee joint tibial component used in an artificial knee joint. The artificial joint component 2 is inserted into the medullary cavity of the tibia (not shown) at the distal end side and fixed with bone cement. The artificial joint component 2 is connected to another component provided as a plate member 105 arranged so as to slide with the end of the artificial knee joint femoral component attached to the femur (not shown). That is, the artificial joint component 2 is applied as an element on the tibia side of the artificial knee joint in a state of being combined with the plate member 105.

In the artificial knee joint replacement method in which the knee joint is replaced with the artificial knee joint, the medullary cavity of the tibia is trimmed using only a surgical file and the artificial joint component 2 is inserted and buried. Planted. The plate member 105 is formed of, for example, a resin such as polyethylene, and is provided with a plate portion 105a formed in a plate shape and a protruding portion 105b formed in a protruding shape protruding from the plate portion 105a. The plate member 105 is coupled to the artificial joint component 2 by, for example, a screw or a fitting (not shown) at the end of the plate portion 105a opposite to the side where the protruding portion 105b is provided. Connected. The plate member 105 slides with the end of the femoral component for artificial knee joint (not shown) at the end of the plate portion 105a on the side where the projection 105b is provided and the projection 105b. Placed in.

  The artificial joint component 2 shown in FIGS. 6 to 8 includes a connecting portion 21 and a stem portion 22. In addition, the component 2 for artificial joints is formed with metals, such as a titanium alloy, a cobalt chromium alloy, and stainless steel which obtained the approval approval as a medical device for living body implantation.

  The connection part 21 is formed as a part connected to the plate member 105 which is another component in the artificial knee joint. The connecting portion 21 includes a tray portion 21a formed in a flat plate shape, and a protruding shaft portion 21b formed in a protruding shape protruding in an axial shape from one end surface of the tray portion 21a in the vertical direction. Is provided. Then, as described above, the plate member 105 is coupled to and connected to the connecting portion 21 on the end surface of the tray portion 21a opposite to the side on which the protruding shaft portion 21b is provided. Further, at the end of the protruding shaft portion 21b opposite to the side integrated with the tray portion 21a, there is a female screw portion that engages with a male screw portion 22a formed at the end portion of the stem portion 22 described later. A screw hole (not shown) formed in the inner periphery is formed as an opening. The artificial joint component 2 may further include a separate block member (not shown) for adjusting the engagement state with the end of the tibia more firmly to an appropriate state. The block member is attached to the tray portion 21a with screws or the like on the base side of the protruding shaft portion 21b with respect to the connecting portion 21.

  The stem portion 22 is formed as an axial portion whose distal end is inserted into the medullary cavity portion of the tibia and fixed by bone cement. A male screw portion 22a that is screwed into a screw hole formed in the protruding shaft portion 21b is provided at the end of the stem portion 22 opposite to the tip side. When the male screw portion 22a is screwed with the protruding shaft portion 21b, the connecting portion 21 is fixed to the stem portion 22 by screw connection. In the artificial joint component 2 provided as a tibial component for an artificial knee joint, the stem portion 22 is arranged along the circumference in a cross section in which the surface of the side surface is perpendicular to the axial direction of the stem portion 22. It is formed as a cylindrical shaft portion. And the stem part 22 and the connection part 21 are arrange | positioned so that the axial direction of the stem part 22 and the axial direction of the protrusion shaft part 21b may correspond in the state in which they were fixed.

  FIG. 9 is a bottom view of the stem portion 22. As shown in FIGS. 6 to 9, the side surface of the stem portion 22 is formed so as to be recessed inward with respect to the surface 22b (see FIG. 9) of the side surface, and connected to the connecting portion 21 from the distal end side. Four grooves 23 formed so as to extend along the axial direction of the stem portion 22 are provided on the portion side. These grooves 23 are arranged at positions that are at equal angles with respect to the axial center Q in the circumferential direction around the axial center Q of the stem portion 22 (the cylindrical axis center indicated by the point Q in FIG. 9). That is, the four grooves 23 provided in the stem portion 22 are arranged at positions shifted by 90 degrees with respect to the axial center Q in the circumferential direction centered on the axial center Q.

Further, in the stem portion 22, each of the grooves 23 is a recessed region with respect to the surface 22a of the side surface in a cross section perpendicular to the axial direction of the stem portion 22, like the groove 13 of the stem portion 12 of the first embodiment. A cross-sectional area of a certain groove cross section is formed so as to gradually decrease from the distal end side of the stem portion 22 to the connecting portion side. And each of the groove | channel 23 is formed so that a groove depth may become shallow gradually from the front end side in the stem part 22 to the connection part side similarly to the groove | channel 13 of 1st Embodiment, and groove width is gradually. As a result, the cross-sectional area of the groove cross-section is reduced. Further, the shape of the groove 23 in the direction perpendicular to the axial direction of the stem portion 22 is a circle having the same radius of curvature from the distal end side to the connecting portion side in the stem portion 22 as in the groove 13 of the first embodiment. It is formed as a circular arc.

  According to the artificial joint component 2 described above, in the stem portion 22 formed as a cylindrical shaft-shaped portion, a plurality of cross-sectional areas of the groove cross section gradually decrease from the distal end side to the connecting portion side along the axial direction. A groove 23 is formed. For this reason, the flow path area through which the bone cement flows between the side surface of the stem portion 22 and the medullary cavity portion does not become substantially constant, and the flow resistance during the flow of the bone cement is reduced. It can be reduced in the region on the side and gradually increased over the region on the connection part side. Thereby, even if it is the component 2 for artificial joints which has the stem part 22 formed as a cylindrical axial part, it inserts in the medullary cavity part in the stem part 22 similarly to the component 1 for artificial joints of 1st Embodiment. It becomes easy to insert the stem portion 22 into the medullary cavity while maintaining a state in which high pressure is applied from the bone cement over the entire side surface to be made, and the state of fixation by the bone cement is made good. Can be easily realized.

(Test results)
Next, the result of the test for verifying the effect of the artificial joint component according to the present invention will be described. In this test, three types of stem portions of the artificial joint component for testing were created as simulated stem portions, and these simulated stem portions were inserted into the simulated medullary cavity portion of the bone model for testing. The effect of the present invention was verified by measuring the pressure of the bone cement in the part and the indentation load of the simulated stem part which is the insertion resistance.

  In addition, the simulated stem part for a test was prepared by using a Ti-6Al-4V alloy as a raw material and adjusting the surface roughness (Ra) to about 0.2 μm to 0, 4 μm. The bone model constituting the simulated medullary cavity was made of acrylic. As for bone cement, it was kneaded for 1 minute and then filled into a cement gun syringe, and 3 minutes later, the simulated medullary cavity was filled with cement. Further, from one minute later, a test was performed by inserting the simulated stem portion into the simulated medullary cavity portion at a speed of 100 mm / min using a testing machine that pushes in at a constant speed.

  FIG. 10 shows a front view (FIG. 10 (a)) and a bottom view (FIG. 10 (b)) of a simulation stem portion 30 for comparison. Moreover, the simulation stem part 31 shown in FIG. 11 and the simulation stem part 32 shown in FIG. 12 show the simulation stem part corresponding to the stem part of the component for artificial joints according to the present invention. 11 shows a front view (FIG. 11A), a bottom view (FIG. 11B), and a side view (FIG. 11C) of the simulated stem portion 31. FIG. FIG. 12 shows a front view (FIG. 12A), a bottom view (FIG. 12B), and a side view (FIG. 12C) of the simulated stem portion 32.

The simulated stem portion 30 shown in FIG. 10 is formed as a cylindrical shaft-like portion in which no groove is provided on the side surface. The stem portion 31 shown in FIG. 11 is formed as a cylindrical shaft-shaped portion provided with two grooves 31a on its side surface. Each of the two grooves 31a is formed in the same shape as the grooves (13, 23) according to the first and second embodiments. The two grooves 31 a are arranged at point-symmetrical positions around the axial center of the simulated stem portion 31. The stem portion 32 shown in FIG. 12 is formed as a cylindrical shaft-shaped portion provided with four grooves 32a on the side surface. Each of the four grooves 32a is formed in the same shape as the grooves (13, 23) according to the first and second embodiments. Then, the four grooves 32a are located at positions at equal angles with respect to the axial center in the circumferential direction centered on the axial center of the simulated stem portion 32 (that is, 9
(Positions shifted by 0 degrees).

  FIG. 13 is a front view showing a state where the simulated stem portions (30, 31, 32) are inserted into the bone model 33 constituting the simulated medullary cavity portion 33a. The bone model 33 includes a cylindrical portion 33b that defines a simulated medullary cavity portion 33a having a circular cross section with the same diameter in the axial direction, and a base portion 33c provided at the lower end of the cylindrical portion 33b. Has been. The dimensional difference between the diameter of the simulated medullary cavity portion 33a and the diameter of the simulated stem portion (30, 31, 32) is 1 mm in consideration of corresponding to the dimensional relationship between the actual medullary cavity portion and the stem portion. Set to.

  In the bone model 33, pressure gauges (34a, 34b, 34c) for detecting the pressure of the bone cement filled in the simulated medullary cavity 33a are attached to three positions in the axial direction of the cylindrical portion 33a. . The pressure gauge 34a was disposed on the insertion port side where the simulated stem portion (30, 31, 32) is inserted in the simulated medullary cavity portion 33a. The pressure gauge 34c was disposed on the back side (that is, the base portion 33c side) in the simulated medullary cavity portion 33a. The pressure gauge 34b was disposed at an intermediate position between the position of the pressure gauge 34a and the position of the pressure gauge 34c. Based on the detection results by these pressure gauges (34a, 34b, 34c), the simulated medullary cavity 33a is inserted into the simulated medullary cavity 33a filled with bone cement when the simulated stem (30, 31, 32) is inserted. The transition of the pressure of the bone cement at each of the insertion port side, the intermediate position, and the back side was measured.

  Further, the simulated stem portion (30, 31, 32) to be inserted into the simulated medullary cavity portion 33a is pushed in the direction indicated by the arrow G in FIG. 13 using the above-described testing machine (not shown). A load was applied. This indentation load was detected by a load cell provided in a testing machine (not shown). Based on the detection result of the load cell, the transition of the pushing load of the simulated stem portion (30, 31, 32) when the simulated stem portion (30, 31, 32) is inserted into the simulated medullary cavity portion 33a filled with bone cement Was measured.

  In the test using the simulated stem portion (30, 31, 32) and the simulated medullary cavity portion 33a described above, each simulated stem portion (30, 31) is considered in consideration of slight variations in the viscosity condition of the bone cement. , 32) was repeated three times. For each test, as described above, the pressure of the bone cement and the indentation load when the simulated stem portion (30, 31, 32) was inserted into the simulated medullary cavity portion 33a were measured.

  FIGS. 14 to 16 show changes in the bone cement pressure at the insertion port side, intermediate position, and back side of the simulated medullary cavity 33a when the simulated stem 30 is inserted into the simulated medullary cavity 33a. FIG. FIG. 14 shows the first test result, FIG. 15 shows the second test result, and FIG. 16 shows the third test result. FIGS. 17 to 19 show the pressures of bone cement at the insertion port side, the intermediate position, and the back side of the simulated medullary cavity 33a when the simulated stem 31 is inserted into the simulated medullary cavity 33a. It is the figure which showed transition. FIG. 17 shows the first test result, FIG. 18 shows the second test result, and FIG. 19 shows the third test result. 20 to 22 show the bone cement pressures at the insertion port side, intermediate position, and back side of the simulated medullary cavity 33a when the simulated stem 32 is inserted into the simulated medullary cavity 33a. It is the figure which showed transition. 20 shows the first test result, FIG. 21 shows the second test result, and FIG. 22 shows the third test result. 14 to 22, the transition of the bone cement pressure (hereinafter simply referred to as “pressure on the insertion port side”) at the position on the insertion port side of the simulated medullary cavity portion 33a is illustrated by a fine dotted line. Yes. Further, the transition of the bone cement pressure at the intermediate position of the simulated medullary cavity portion 33a (hereinafter simply referred to as “intermediate position pressure”) is shown by a broken line having a coarser pitch than the broken line of the pressure transition on the insertion port side. . In addition, the transition of the bone cement pressure (hereinafter simply referred to as “back side pressure”) at the position on the back side of the simulated medullary cavity portion 33a is shown by a solid line.

  FIGS. 23 to 25 are diagrams showing the transition of the pushing load when the simulated stem portion (30, 31, 32) is inserted into the simulated medullary cavity portion 33a. 23 shows the pushing load when the simulated stem portion 30 is inserted into the simulated medullary cavity portion 33a, FIG. 24 shows the pushing load when the simulated stem portion 31 is inserted into the simulated medullary cavity portion 33a, and FIG. 25 shows the simulated stem portion. The indentation load at the time of insertion to 32 simulated medullary cavity parts 33a is shown, respectively. In FIG. 23 to FIG. 25, the first test result is a fine-pitch broken line, the second test result is a coarser broken line than the first test result, and the third test result is a solid line. Each is illustrated.

  As shown in FIGS. 14 to 22, when the insertion of the simulated stem portion (30, 31, 32) into the simulated medullary cavity portion 33a is started, the pressure on the insertion port side, the pressure on the intermediate position, and the pressure on the back side are Both start rising at the same rise. When the distal end side of the simulated stem portion (30, 31, 32) to be inserted passes through the side of the pressure gauge 34a disposed at the position on the insertion port side, the pressure on the insertion port side becomes the pressure at the intermediate position and the back side. The transition starts at a pressure different from the pressure of. Furthermore, when the tip side of the simulated stem portion (30, 31, 32) passes the side of the pressure gauge 34b arranged at the intermediate position, the pressure at the intermediate position starts to change at a pressure different from the pressure at the back side. Become.

  As a result of the test, as shown in FIG. 14 to FIG. 22, as to how the bone cement pressure rises after the insertion of the simulated stem portion (30, 31, 32) into the simulated medullary cavity portion 33a, It was confirmed that the method gradually increased in the order of the portion 30, the simulated stem portion 31, and the simulated stem portion 32. That is, in the case of the simulated stem portion 30 having no groove, the pressure rises most rapidly, and in the case of the simulated stem portion 31 provided with two grooves 31a, the pressure rises more gently, and the four grooves 32a are provided. In the case of the provided simulated stem portion 32, it was confirmed that the method was the slowest rise. In the case of the simulated stem portion 30 without a groove, the pressure on the back side exceeded the upper limit pressure (5.5 MPa) that can be measured by the pressure gauge 34c.

  Further, as shown in FIG. 23 to FIG. 25, regarding the pushing load during the insertion of the simulated stem portion (30, 31, 32) into the simulated medullary cavity portion 33a, the simulated stem portion 30, the simulated stem portion 31, the simulated stem It was confirmed that the size gradually decreased in the order of the portion 32. That is, in the case of the simulated stem portion 30 having no groove, the indentation load is the largest, and in the case of the simulated stem portion 31 having two grooves 31a, the indentation load can be further reduced, and the simulation having four grooves 32a is provided. In the case of the stem part 32, it was confirmed that the pushing load could be reduced most.

  Further, as shown in FIGS. 14 to 22, the maximum pressure of the bone cement reached during the insertion of the simulated stem portion (30, 31, 32) into the simulated medullary cavity portion 33a is applied to the simulated stem portion 30 having no groove. On the other hand, in the simulation stem part (31, 32) provided with the groove (31a, 32a), it was confirmed that the pressure on the back side can be lowered and the pressure on the insertion port side can be raised. That is, the pressure of the bone cement is reduced in the region on the distal end side (the back side of the simulated medullary cavity portion 33) of the simulated stem portion (31, 32) to be inserted, and the simulated stem portion (31, 32) is connected to the connection portion side ( It was confirmed that the bone cement pressure can be increased in the region of the simulated medullary cavity 33). Therefore, in the region between the side surface of the simulated stem portion (31, 32) and the simulated medullary cavity portion 33a, the pressure is efficiently distributed over the entire portion from the distal end side to the connecting portion side of the simulated stem portion (31, 32). It was confirmed that it can be made to act. Further, regarding the tendency to decrease the pressure on the back side and increase the pressure on the insertion port side, the simulated stem portion 32 provided with four grooves 32a as compared with the simulated stem portion 31 provided with two grooves 31a. In this case, it was possible to confirm more clearly.

As described above, as a result of performing the above-described test and verifying the effect of the present invention, according to the present invention, a state in which a high pressure acts from the bone cement over the entire side surface inserted into the medullary cavity portion in the stem portion. It is easy to insert the stem portion into the medullary cavity portion while maintaining the same, and it is possible to provide a component for an artificial joint that can easily achieve a good state of fixation by bone cement. I was able to confirm that it was possible.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, the following modifications can be made.

(1) In the present embodiment, the case where the present invention is applied as a femoral component for an artificial hip joint and a tibial component for an artificial knee joint has been described as an example, but this need not be the case. That is, the present invention may be applied as a femoral component for an artificial knee joint, and an artificial joint other than an artificial hip joint and an artificial knee joint (an artificial elbow joint, an artificial shoulder joint, an artificial finger joint, an artificial ankle joint, etc.) The present invention may be applied as a component for artificial joints.

(2) In the present embodiment, an example has been described in which, on the side surface of the stem portion, four grooves whose cross-sectional area of the groove cross section decreases from the distal end side to the connecting portion side are provided at equal angular positions in the circumferential direction. However, this need not be the case. In other words, the effect of the present invention can be achieved if at least two grooves having a cross-sectional area of the groove cross-section decreasing from the tip side to the connecting portion side are provided at equal circumferential positions on the side surface of the stem portion. .

(3) The shape of the groove provided on the side surface of the stem portion is not limited to the shape exemplified in the present embodiment, and various shapes are possible as long as the cross-sectional area of the groove cross section decreases from the tip side to the connecting portion side. It can be changed and implemented. Moreover, in the middle where the cross-sectional area of the groove cross-section gradually decreases from the front end side to the connecting portion side, a portion where the cross-sectional area does not change may be partially provided.

  INDUSTRIAL APPLICABILITY The present invention is widely used as a prosthetic joint component that is used in an artificial joint and has a distal end inserted into the medullary cavity of a bone and fixed by bone cement and connected to another component on the opposite side of the distal end. Is something that can be done.

DESCRIPTION OF SYMBOLS 1 Component for artificial joints 11 Connection part 12 Stem parts 13, 13a, 13b Groove 100 Femur (bone)
100a Spinal cavity 102 Bone head ball member (other components)

Claims (4)

A component for an artificial joint used in an artificial joint, the distal end side being inserted into the medullary cavity of a bone and fixed by bone cement, and connected to another component on the opposite side of the distal end side,
A connecting part connected to other components in the artificial joint;
The distal end side is formed as a shaft-like portion that is inserted into the medullary cavity of the bone and fixed by bone cement, and is formed integrally with the connecting portion at the end opposite to the distal end side or the connecting portion A stem portion to which
With
The side surface of the stem portion is formed so as to be recessed inward with respect to the surface of the side surface, and is formed so as to extend along the axial direction of the stem portion from the distal end side to the connecting portion side connected to the connecting portion. Provided with at least two grooves,
The groove is disposed at a position that is an equal angle with respect to the axial center in the circumferential direction around the axial center of the stem portion,
Each of the grooves has a cross-sectional area of a groove cross section which is a recessed area with respect to the surface of the side surface in a cross section perpendicular to the axial direction of the stem portion, and gradually decreases from the distal end side of the stem portion to the connecting portion side Formed , and
Each of the grooves is formed so that the groove depth gradually decreases and the groove width gradually decreases from the distal end side to the connecting portion side in the stem portion, so that the groove cross section Is formed so that the cross-sectional area of
When the stem portion is inserted into the medullary cavity portion of the bone, and bone cement that is pushed away as the stem portion is inserted flows between the side surface of the stem portion and the medullary cavity portion, in the area of the side, the flow passage area of the bone cement to flow is increased, in the region of the side of the connecting portion side of the stem portion, the flow passage area of the bone cement to flow is characterized by Rukoto a small, Components for artificial joints. The component for an artificial joint according to claim 1 ,
The shape of the groove in a cross section perpendicular to the axial direction of the stem portion is formed as a circular arc of the same radius of curvature from the distal end side to the connecting portion side in the stem portion. Components for artificial joints. The artificial joint component according to claim 1 or 2 ,
The prosthetic component, wherein the stem portion is formed as a cylindrical shaft portion. The artificial joint component according to claim 1 or 2 ,
In addition to being used in artificial hip joints, the tip side is inserted into the medullary cavity of the femur and fixed with bone cement, and is placed on the acetabulum side of the pelvis and provided as a ball head ball member formed in a ball shape The connecting part is connected to the component of
The groove is disposed at a point-symmetrical position about the axial center of the stem portion in at least one of the front-rear direction and the inner-outer direction of the human body in a state where the stem portion is implanted in the femur. An artificial joint component characterized by the above.

Images