JP2000217848A - Pulp chamber plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely fix a pulp chamber plug in a desired position and prevent leakage of cement by making at least the upper surface or the lower surface of the pulp chamber plug as a slant intersecting the central axis of a cylindrical body. SOLUTION: A through hole 12 with a diameter about 2 mm is formed in the axial direction of a cylindrical body formed of calcium phosphate family crystallized porous body with the mean pore size of about 200 μm and with porosity of about 50 vol.%. The cylindrical body is cut obliquely at an angle of about 37 deg. to the central axis to obtain a first pulp chamber plug 10 having an inclined lower surface 11 and a second pulp chamber plug 20 having an inclined upper surface 21 which have the same shape, The lower surface 11 and the upper surface 21 of both pulp chambers plugs 10, 20 abut on each other to form a cylindrical body, and inserted in the pulp chamber of the thighbone in such a state. The upper pulp chamber plug is pressed to slide the respective plugs 10, 20 outward and be made closely adhere to the inner wall of the pulp chamber, and cement is filled to press in an artificial hip joint stem. Thus, the plug can be surely fixed without leakage of cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medullary plug to be inserted into a medullary canal of a human bone.

[0002]

2. Description of the Related Art With the advent of an aging society, the number of patients suffering from rheumatoid arthritis and osteoporosis is increasing. Along with this, joint disorders such as hip joints, elbow joints, and knee joints and bone diseases such as fractures due to weak external force are increasing.

[0003] Surgical treatment is one of the treatments for joint disorders and bone diseases. For example, in the case of severe joint disorders, artificial joint replacement is generally performed. The artificial joint is fixed in the medullary cavity of the bone with bone cement.In order to make the fixation more firm, after inserting the medullary plug into the medullary cavity in advance, filling the bone cement, (Stem part) is press-fitted. FIG. 3 shows an example of hip replacement, in which 1 is a medullary plug, A is a femur, B is a bone cement, and C is a stem portion of a hip joint.

[0004]

A medullary cavity plug is made of a resin-based material such as high-density polyethylene (HDPE), an artificial material such as a ceramic-based material such as hydroxyapatite, the same kind of bone, the patient's own bone, and the like. You.

However, the medullary cavity varies in size and shape depending on the individual, and a medullary cavity plug made of an artificial material made into a fixed shape such as a cylindrical body may not fit the shape of the medullary cavity. If the medullary plug does not match the shape of the medullary cavity, the filling pressure of the cement will cause the medullary plug to shift from a predetermined position. In addition, bone cement leaked from the gap,
In the event that components of the prosthesis cannot be press-fitted or even leak out of the bone cement, it may be difficult to remove the bone cement when a revision of the prosthesis is required in the future.

When allogeneic bone or autologous bone is used, it is necessary to perform bone extraction and shaping to the shape and size of the medullary cavity, and it is necessary to lengthen the operation time and increase the amount of bleeding of the patient. , Increase the physical burden. In addition, allogeneic bones have infection and compatibility issues.

An object of the present invention is to provide a medullary cavity plug made of an artificial material that can be securely fixed at a desired position and that can prevent leakage of cement.

[0008]

The medullary cavity plug of the present invention comprises:
A medullary cavity plug made of a columnar body, wherein at least one of an upper surface and a lower surface is a slope intersecting with a central axis of the columnar body.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The intrathecal plug of the present invention is used in combination of a plurality. For example, the slopes of two plugs (FIG. 1) are brought into contact with each other to form a massive columnar body (FIG. 2A), and inserted into the medullary cavity in this state. Subsequently, when the plugs are pressed from above, the respective plugs slide outward, the axes of both plugs are shifted, and the apparent cross-sectional area increases (FIG. 2C). Therefore, the plug can be brought into close contact with the inner wall of the medullary cavity. 2 (b) and 2 (d)
FIG. 2 is an explanatory diagram when FIG. 2A and FIG. 2C are viewed from below. In addition, not only a method of inserting into a lump of a columnar body and then inserting, but also a method of inserting one by one can be adopted.

In the present invention, the shape of the medullary cavity plug may be such that at least one of the upper surface and the lower surface forms a slope obliquely intersecting the axial direction of the medullary cavity when inserted into the medullary cavity.
For example, in a columnar body, at least one of the upper surface and the lower surface may be an inclined surface that intersects the center axis of the columnar body. Note that the columnar body only needs to have a cross-sectional shape that reduces the gap with the shape of the medullary cavity when slid. For example, a columnar body having a cross-sectional shape such as a circle or an ellipse can be used.

The angle between the central axis of the column and the slope is
It is preferably in the range of 5 to 85 °, especially 10 to 60 °. In other words, if this angle is smaller than 5 °, the width of the lateral expansion when pressed in the medullary cavity is reduced, and a sufficient effect cannot be obtained. If it is larger than 85 °, it is difficult to slide when pressed.

The material constituting the medullary cavity plug is not particularly limited as long as it has good biocompatibility.
Ceramic materials such as zirconia, hydroxyapatite, calcium phosphate, and tetracalcium phosphate; glass materials such as calcium phosphate glass and calcium phosphate crystallized glass; resin materials such as HDPE and polylactic acid; and metal materials such as stainless steel and titanium. Materials can be used. In particular, hydroxyapatite, calcium phosphate, tetracalcium phosphate, calcium phosphate glass,
It is preferable to use a material having bioactivity such as calcium phosphate crystallized glass, since direct bonding with bone becomes possible. Absorbable materials such as polylactic acid also have the advantage of being absorbed and replaced by bone in the future.

Preferably, the medullary cavity plug is made of a porous material having a three-dimensional continuous pore structure. In other words, with such a porous body, new bone can penetrate into the pores and a strong bond can be expected. The average pore diameter is 50-6.
It is preferable that the porosity is 00 μm and the porosity is 10 to 80% by volume.

If a through hole is formed in the central axis of the medullary cavity plug, a jig can be inserted into the through hole, and handling when inserting two plugs as a lump into the medullary cavity becomes easy.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

First, the average pore diameter is 200 μm and the porosity is 50
A columnar body made of a volume% calcium phosphate-based crystallized glass body is prepared. In addition, a through hole having a diameter of 2 mm is formed in the cylindrical body in the axial direction.

Next, the cylindrical body is set at 37 ° with respect to its central axis.
The first and second medullary plugs 10 and 20 having the same shape are produced by obliquely cutting at an angle of ° (FIG. 2). The first medullary plug 10 is 3
The second plug 20 has an upper surface 21 that forms an angle of 37 degrees with respect to the central axis. Also, the first and second plugs 10, 20 are:
It has through holes 12 and 22.

Next, an example of a method for using the obtained medullary cavity plug will be described.

First, the lower surface 11 of the first medullary cavity plug 10 and the upper surface 21 of the second medullary cavity plug 20 are brought into contact with each other so that they come into contact with each other, so that a columnar body (FIGS. 2A and 2B) is obtained. ), And the patient is inserted into the medullary cavity of the femur A while maintaining this state. Further, the upper intramedullary plug is pressed, and each plug is slid outwardly (FIGS. 2C and 2D) to make close contact with the inner wall of the medullary cavity.

Thereafter, the cement B is filled and the stem C of the artificial hip joint is further press-fitted (FIG. 3).

[0021]

According to the medullary cavity plug of the present invention, the medullary cavity plug can be in close contact with and occupy the medullary cavity of various sizes. For this reason, the filling pressure of the cement does not cause inconveniences such as displacement of the medullary canal plug from a predetermined position, leakage of the bone cement, and inability to press-fit the components of the artificial joint. Strength can be improved.

Further, since it is made of an artificial material, the mental and physical burden on the patient due to bone mining and molding of allogeneic bone and autogenous bone is reduced, and there is no problem of infection or compatibility caused when using allogeneic bone. .

Further, the medullary cavity plug of the present invention is not limited to the above-described artificial joint replacement, but can be used for, for example, treatment of a fracture. When the femur fractures,
It is known to use an intramedullary nail after reduction and fix it internally at the reduction position, and then remove the intramedullary nail after fusion. However, in this technique, healing of the defect is slow because the intramedullary nail does not conform to the shape of the medullary cavity. In addition, secondary surgery to remove the intramedullary nail is required. Thus, by combining a plurality of intramedullary plugs of the present invention in the same manner as described above and inserting the same into a fracture, bone reduction and internal fixation can be performed simultaneously and more strongly. Moreover, a material having bioactivity such as calcium phosphate crystallized glass and an absorbent material such as polylactic acid do not require a secondary operation for removal.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a medullary cavity plug of the present invention.

FIGS. 2A and 2B are explanatory views showing a use state of a medullary cavity plug of the present invention, wherein FIG. 2A is a perspective view showing an insertion form into a medullary cavity, FIG. 2B is a bottom view thereof, and FIG. c) is a perspective view showing the state after pressing in the medullary cavity, and FIG. 2 (d) is a bottom view of the same.

FIG. 3 is an explanatory view showing a usage example of a medullary cavity plug.

[Explanation of symbols]

 Reference Signs 1 1 medullary cavity plug 10, 20 medullary cavity plug of the present invention 11 lower surface 21 upper surface 12, 22 through hole

Claims (7)

[Claims] 1. A medullary cavity plug comprising a columnar body, wherein at least one of an upper surface and a lower surface is a slope intersecting a central axis of the columnar body. 2. The medullary cavity plug according to claim 1, wherein the angle between the axial direction of the columnar body central axis and the slope is 5 to 85 °. 3. The medullary cavity plug according to claim 1, wherein the columnar body is a cylindrical body. 4. The medullary cavity plug according to claim 1, wherein the columnar body is formed of a porous body having a three-dimensional continuous pore structure. 5. The medullary cavity plug according to claim 1, wherein the column is made of a bioactive material. 6. The medullary cavity plug according to claim 1, wherein the column is made of an absorbent material. 7. A medullary cavity plug, wherein at least one of the upper surface and the lower surface forms a slope obliquely intersecting the axial direction of the medullary cavity when inserted into the medullary cavity.