JP4041190B2 - Artificial joint correction tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an artificial joint correction device having a pan-shaped support member, in which a ceramic insert is fixedly seated and arranged in the inner chamber of the support member via a conical clamp portion. About things.
[0002]
[Prior art]
An artificial joint correction tool having a metal support member and an insert inserted into the support member is known. A metal support member is secured within the patient's bone. The insert is formed with a wear-resistant sliding surface against which a bone joint head or other artificial joint correction tool is pressed. In the case of a so-called hard sliding pair, the insert is also made of metal. In order to fix the metal insert in the metal support member, a polyethylene connection member is used. The connecting member made of polyethylene is subjected to an abrasion action due to relative fine movement with respect to the insert. This wear is not as pronounced as frictional wear, but the seating surface of the insert becomes loose and the wear fines reach the tissue or joint (glenoid).
[0003]
In the case of the artificial joint correction device described in US Pat. No. 5,282,864, a metal insert is fixed to a metal support member using a screw. The insert is made of cobalt-chromium alloy, and the support member is made of titanium alloy. If the artificial joint corrector is configured in this way, there is a risk of corrosion due to friction and contact corrosion of dissimilar metals. When corrosion occurs, the metal can generate toxic ions that can harm the patient.
[0004]
In order to prevent this drawback, a ceramic insert is inserted into the metal support member. Since ceramic materials are difficult to machine, they are usually fixed in the support member via a conical clamp. An example of this is described in European Patent Office No. 0649641.
[0005]
In the case of a conical clamp, since the introduction of force cannot be controlled, a significant tensile stress is generated in a specific zone of the insert. Ceramic materials are extremely hard and have pressure resistance, but their ability to receive tensile force is limited. As a result, it is technically impossible to construct a thin wall ceramic insert.
[0006]
[Problems to be solved by the invention]
The problem underlying the present invention is to configure the joint between the support member and the insert so that a reproducible joint is achieved and the insert can be removed at the same time.
[0007]
[Means for Solving the Problems]
According to the present invention, the angle of the clamp surface of the insert is made different from the angle of the clamp surface of the support member , and the support member is fixed in the bone . of the clamping surface, in the area which is located on the opening side of the artificial joint correction device, by close contact with the clamping surface of the support member, causing the conical clamping portion, the clamping surface of the insert is to clamping surface of the support member 1 was resolved by Rukoto extend at an angle of 20 minutes.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In an advantageous embodiment of the invention, the connection between the support member and the insert is configured in the area on the opening side of the prosthetic joint corrector. In this case, both clamping surfaces do not touch in the area opposite the opening. The advantage of this configuration is that the force to be received by the prosthesis correction device is evenly distributed along the circumference and introduced into a specific, nearly linear area.
[0009]
The load supporting surface of the support member can be a rough surface structure having a surface roughness of 20 μm, for example. As a result, for example, irregularities in force transmission caused by a shape deviation in the micro region can be prevented.
[0010]
To improve the friction characteristics, the clamping surface of the support member can be ultra-precision rolled or polished to a surface roughness of 0-4μ.
[0011]
Advantageously, the insert has a radius of curvature or a slight additional slope at the end of the clamping surface opposite the opening. This prevents the inserted body from tilting and moving when inserted or loaded. This can also be realized by making an annular recess follow the end of the support member clamping surface opposite to the opening side.
[0012]
When the insert is worn, it must be replaced. In order to minimize the burden on the patient, the insert is removed from the support member while the support member remains fixed in the bone. In order to make it easier to remove the insert, according to a special embodiment of the invention, at least one notch is provided in the support member, this notch being located on the interface between the insert and the support member from the opening side. Along each of the clamping surfaces, it should extend to the end opposite to the opening side. A swing lever is arranged at the inner end of the notch opposite to the opening side, and this swing lever engages with the clamp surface of the insert from behind. When removing the insert from the support member, use a tool such as a wedge-shaped member, for example, to move the lever in the notch and press the end of the insert against the insert. Remove.
[0013]
【Example】
In the following, the configuration of the present invention will be specifically described based on the embodiments shown in the drawings.
[0014]
1 includes a pan-shaped metal support member 2 and a ceramic insert 3 that forms an artificial joint (glenoid). The insert 3 is disposed in the inner chamber 4 of the support member 2. The inner surface of the insert 3 is configured as a spherical socket that receives the joint head of the joint from the opening side 5. The insert 3 is fixed in the support member 2 via a conical clamp.
[0015]
The clamping surface 6 of the insert 3 extends at an angle α with respect to the clamping surface 7 of the support member 2 (FIG. 2). The angle formed by the clamp surface 6 of the insert with the joint axis 8 of the artificial joint correction tool is larger than the angle formed by the clamp surface 7 of the support member 2 with the joint axis 8. For this reason, the insert 3 is pressed against the support member 2 only in a relatively small contact area 9 at the opening side 5. The size of the contact area 9 can be changed by changing the angle α. If the angle α is decreased, the contact area 9 is increased .
[0016]
The clamping surface 7 of the support member 2 has a surface roughness of about 20μ. Thereby, the shape deviation of the insert 3 is compensated.
[0017]
The clamping surfaces 6 and 7 shown in FIGS. 3 and 4 are shown parallel to each other and not shown as rough surfaces for the sake of clarity. However, in practice, the connecting portion between the insert 3 and the support member 2 has the form shown in FIG. In the case of FIG. 3, a curved surface 10 having a radius of curvature R continues in the lower end area of the clamping surface 6 of the insert 3. By rounding the lower edge of the clamp surface 6 in this way, when the insert 3 is inserted into the support member 2, it can be prevented that the insert 3 is tilted and does not move within the support member 2. This prevention can also be realized by providing an annular recess 11 in the lower end area of the clamping surface 7 of the support member 2 in the support member 2.
[0018]
FIG. 5 shows another embodiment of the artificial joint correction tool. The support member 2 has an elongated notch 12 extending in parallel with the clamp surface 6 of the insert 3 in the boundary area between the support member 2 and the insert 3. The notch 12 is open toward the opening side 5 of the artificial joint correction tool. A swing lever 13 is disposed at the lower end of the notch 12, and the swing lever 13 is composed of two legs 13a and 13b that form an obtuse angle. The leg 13 a is engaged behind the clamp surface 6 of the insert 3 and is fastened between the insert 3 and the support member 2. The second leg 13 b enters the notch 12. The angles of both legs 13 a and 13 b are configured such that the second leg 13 b extends substantially parallel to the notch 12.
[0019]
FIG. 6 shows a state in which a wedge-shaped tool is used to move the swing lever 13. In this case, the wedge-shaped tool 14 is inserted into the notch 12 and the tip of the wedge is press-fitted between the support member 2 and the second leg 13 b of the swing lever 13. By further pressing the wedge-shaped tool 14, the second leg 13 b is pressed toward the insertion body 3. As a result, the first leg 13 a is also moved, and the insert 3 is pushed out of the support member 2.
[0020]
【The invention's effect】
In the case of the artificial joint correction tool according to the present invention, the ceramic insert is mounted in the pan-like support member via the conical clamp, and the clamp surface angle of the insert is the clamp surface angle of the support member. The insert is coupled to the support member only through a relatively small, generally linear area. This makes it possible to control the transmission of force from the insert to the support member. The axially acting joint forces are mostly distributed along the circumference and act as compressive stresses, and the generation of tensile stress in the insert is minimized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an artificial joint correction device having a support member having an insert fixed inside.
FIG. 2 is an enlarged view of a conical clamp portion.
FIG. 3 is an enlarged view of a lower end portion of a clamp surface of the insert.
FIG. 4 is an enlarged view of a lower end portion of a clamp surface of a support member.
FIG. 5 is an enlarged view of a prosthetic joint corrector having a notch and a wobbling in the notch for removing the insert.
FIG. 6 is an enlarged view showing an artificial joint correction tool and a tool for moving a lever to a lever.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Artificial joint correction tool, 2 Support member, 3 Insert body, 4 Inner chamber, 5 Open side, 6 Clamp surface of insert body, 7 Clamp surface of support member, 8 Joint axis, 9 Contact area, 10 Curved surface, 11 Ring Recess, 12 notch, 13 swinging lever, 13a and 13b leg, 14 wedge-shaped tool

Claims (9)

An artificial joint correction device having a pan-like support member (2), wherein a ceramic insert (3) is fixedly seated in the inner chamber of the support member (2) via a conical clamp. The angle of the clamp surface (6) of the insert (3) is different from the angle of the clamp surface (7) of the metal support member (2), and the metal support member ( 2) is fixed in the bone, and the clamping surface (6) of the insert (3) is supported in the area where the clamping surface is located on the open side (5) of the prosthesis corrector. in close contact with the clamping surface of the member (2) (7), causing the conical clamping portion, that you have extends from 1 to 20 minutes of angle relative to the clamping surface (7) of the support member (2) (alpha) A prosthetic joint correction tool.   The artificial joint correction device according to claim 1, wherein the clamping surface (6) of the insert (3) extends at an angle (α) of 1 to 5 minutes with respect to the clamping surface (7) of the support member (2). The artificial joint correction tool according to claim 1 or 2 , wherein the clamping surface (7) of the support member (2) is finely roughened. The artificial joint correction device according to claim 3 , wherein the clamping surface (7) of the support member (2) has a surface roughness of 20µ. The artificial joint correction tool according to any one of claims 1 to 4 , wherein the clamping surface (7) of the support member (2) is smooth. 6. The artificial joint correction device according to claim 5 , wherein the clamping surface (7) of the support member (2) has a roughness of 0 to 4 [mu]. The insertion body (3) is tilted and cannot move when the insertion body (3) is inserted into the support member (2) in the end region where the diameter of the conical clamping surface (6) is smaller. The artificial joint correction device according to any one of claims 1 to 6 , wherein the artificial joint correction device has a radius of curvature (R) to be prevented or a slight additional inclined portion (10). The support member (2) according to any one of claims 1 to 7 , wherein the support member (2) has an annular recess (11) in the end area of the clamping surface (7) towards the inner chamber (4). Artificial joint correction tool. At least one notch (12) extends from the opening side (5) toward the inner chamber (4) along the clamping surface (7) of the support member (2), and is formed at the inner end of the notch (12). Is provided with a swing lever (13) which is engaged with the clamp surface (6) of the insert (3) from behind, and this swing lever (13) is used to remove the insert (3) from the support member (2). The artificial joint correction tool according to any one of claims 1 to 8 , wherein the tool can be used for lever movement.

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