JPH0654898A - Mylocavity plug for calcium phosphate cement packing material - Google Patents

Abstract

PURPOSE:To attain insertion with high reliability by forming the mylocavity plug of the same compsn. as the compsn. of the calcium phosphate cement packing material and constituting the mylocavity plug in such a manner that the plug can freely be inserted into the prescribed section within the mylocavity by an inserting implement at the time of fixing a stem part for joint substitution by using the calcium phosphate cement packing material. CONSTITUTION:This mylocavity plug 1 is used in order to fix the stem part 7 for joint substitution into the mylocavity 9 by using the calcium phosphate cement packing material 6. The mylocavity plug is formed to, for example, a circular truncated cone shape having a wide front surface by using the material of the same compsn. as the compsn. of the calcium phosphate cement packing material 6 and is provided with a recessed fitting part 2 which can be inserted with the inserting implement 3, such as stainless steel pipe, in the upper part thereof. The joint substituting means is constituted by pushing the mylocavity plug 1 down to the prescribed position within the mylocavity 9 in the state of fitting the inserting implement 3 into a fitting part 2, then removing the inserting implement 3 from the mylocavity plug 1, packing the packing material 6 therein, inserting the stem part 7 into the upper part thereof and fixing the stem part 7 by curing the packing material 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bone marrow cavity plug for a calcium phosphate cement filler for fixing a stem portion for joint replacement in a bone marrow cavity with a calcium phosphate cement filler in joint replacement surgery.

[0002]

2. Description of the Related Art Conventionally, a hip joint provided with a stem portion has been used in an orthopedic surgery for replacing the joint at the joint between the femur and the pelvis. At this time, a method is used in which a filler such as bone cement is injected and filled into the bone marrow cavity of the femur, and then the stem portion is embedded in the upper portion of the filler and fixed in the bone marrow cavity. In the surgery, in order to stably use the hip joint for a long period of time, the stem portion and the filler and the bone marrow cavity inner surface and the filler are sufficiently crimped,
It is necessary to press fit the filler into the irregularities on the surface of the stem to prevent infiltration of body fluid or the like between the inner surface of the bone marrow cavity and the filler.

However, in the above method, when the stem portion is implanted after filling the filler into the bone marrow cavity, the filler is pressed into the deep portion of the bone marrow cavity to firmly fix the stem portion to the filler. However, there are problems that a stable replacement joint cannot be obtained, and a large amount of filler to be injected into the bone marrow cavity is required.

Therefore, a method has been proposed in which a high-density polyethylene bone marrow cavity plug for sealing the filler is inserted at an appropriate position in the bone marrow cavity (US Pat. No. 4,29).
3,962). Furthermore, JP-A-59-18984
Japanese Patent Publication No. 1 discloses a bone marrow cavity plug made of calcium phosphate ceramics which is more excellent in biocompatibility. In addition, as a bone marrow cavity plug having excellent biocompatibility, metals such as titanium and stainless steel, and plastics such as polyethylene and polycarbonate are used.

However, the high density polyethylene bone marrow cavity plug and the calcium phosphate ceramics bone marrow cavity plug have problems such as poor processability and high manufacturing cost.

On the other hand, as a filler, calcium phosphate cement, which has a higher biocompatibility than bone cement, has come to be used. When the metal bone marrow cavity plug, the plastic bone marrow cavity plug, etc. are used, the calcium phosphate cement filler is used. Due to its low affinity with, the filler and the bone marrow cavity plug have poor bonding properties, are easily peeled off, and have different mechanical properties such as elastic modulus and coefficient of thermal expansion, resulting in destruction of the bone marrow cavity plug or filler. Occurs, which is not suitable for long-term use.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to tightly fill a calcium phosphate cement filler in the bone marrow cavity when fixing the stem part for joint replacement in the bone marrow cavity using the calcium phosphate cement filler. Another object of the present invention is to provide a bone marrow cavity plug for a calcium phosphate cement filler, which is capable of firmly fixing the joint replacement stem portion.

Another object of the present invention is to provide a bone marrow cavity plug for a calcium phosphate cement filler which does not cause peeling or destruction at the joint surface with the calcium phosphate cement filler.

Yet another object of the present invention is to provide a bone marrow cavity plug for a calcium phosphate cement filler which is easy to manufacture and inexpensive.

[0010]

According to the present invention, there is provided a bone marrow cavity plug for fixing a stem part for joint replacement in a bone marrow cavity using a calcium phosphate cement filler, which is the same as the calcium phosphate cement filler. A bone marrow cavity plug for a calcium phosphate cement filler, which has a composition and is provided with a fitting portion for an instrument for inserting the plug at a desired position in the bone marrow cavity, in at least a part of the plug. Provided.

The present invention will be described in detail below.

The bone marrow cavity plug for calcium phosphate cement filler of the present invention (hereinafter referred to as bone marrow cavity plug) is a calcium phosphate cement filler for joint replacement (hereinafter referred to as filler) during femoral joint replacement surgery or the like. (Referred to as an agent) when fixing in the bone marrow cavity of the femur or the like, a filler for preventing the filler from being pressed deep into the bone marrow cavity and firmly fixing the stem part with a bone marrow cavity plug. And a fitting part made of a hardened cement having the same composition as that of the filler, and fitted with an instrument (hereinafter referred to as an insertion instrument) for inserting at a desired position in the bone marrow cavity. To do.

The composition of the cement hardened body constituting the above-mentioned bone marrow cavity plug is not particularly limited as long as it has the same composition as the calcium phosphate cement filler to be used, but specifically, for example, α-type tricalcium phosphate, Tetracalcium phosphate or a mixture thereof, a mixture of α-type third calcium phosphate and a second calcium phosphate and / or a first calcium phosphate, a calcium phosphate cement containing a fourth calcium phosphate and a second calcium phosphate and / or a first calcium phosphate as a main component, etc. Can be preferably mentioned. The calcium phosphate cement that constitutes the above-mentioned bone marrow cavity plug may be used as a powder, or may be used as a granule by subjecting the powder to pressure molding and then pulverization. The particle size of the calcium phosphate cement powder is 1 to
100 μm, particularly 3 to 50 μm is preferable, and the particle size of the granules is preferably 100 to 700 μm. When the granules are used, a bone marrow cavity plug of a porous body is obtained, and the contact area with the filler is increased, so that the filler can be densely packed, and the stem part can be more firmly fixed. You can

The shape of the medullary cavity plug is not particularly limited as long as it can receive the pressure applied from the insertion direction when the stem portion is embedded in the filler, and is designed according to the shape of the medullary cavity to be inserted. However, a truncated cone, a cylinder, a combination thereof, or the like is preferable. The bone marrow cavity plug of the present invention is provided with a fitting portion with the insertion tool in order to accurately insert the insertion tool into a desired position in the bone marrow cavity. The fitting portion can be formed of a hardened cement material having the same composition as the bone marrow cavity plug, but a metal such as stainless steel, titanium, or a titanium alloy; a biocompatible material such as a plastic such as polyethylene, high-density polyethylene, or polycarbonate. The fitting portion can also be formed of a material having excellent properties. The fitting portion is not particularly limited as long as it has a shape capable of being removably fitted to the insertion tool, and specifically, for example, a concave portion or a protruding portion can be preferably mentioned. Specifically, for example, as shown in FIG. 1, a recessed fitting portion 2 into which an insertion tool 3 such as a stainless pipe can be inserted is provided above a medullary cavity plug 1 having a wide truncated cone shape. May be. When the material forming the fitting portion is the metal, plastic, or the like, as shown in FIGS. 2 and 3, for example, insertion tools 13, 23 such as a stainless pipe and the bone marrow cavity plugs 11, 21 are used.
In order to enable detachable fitting with
Inside the recessed portion of the protrusion outer peripheral surface 14 forming the fitting portions 12 and 22 of the bone marrow cavity plugs 11 and 21, the screw portions 14 and 24 that are screwed into the screw portions 15 and 25 provided in the lower fitting portions 3 and 23 are formed. It is desirable to provide it on the peripheral side surface 24.

To produce the bone marrow cavity plug of the present invention, for example, a calcium phosphate cement composition such as α-type tribasic calcium phosphate, quaternary calcium phosphate or a mixture thereof is classified to a desired particle size and mixed with water. Then, a cement paste can be obtained, and the cement paste can be manufactured by pouring the cement paste into a mold having a desired size such as a truncated cone and curing the same. Further, when a hardened cement product having the same composition is used as the fitting part when the fitting part is provided, a fitting part having a desired shape may be provided at a desired position of the obtained hardened product by using a drill, a lathe, or the like. it can. When metal, plastic, or the like is used as the fitting portion, a screw portion or the like that is screwed with a fitting screw portion of an insertion tool or the like is provided in advance, and the metal or the like processed into a desired shape is used in the mold. It can be manufactured by burying it in the cement paste poured into and curing it at the same time. In addition, the mixing ratio when mixing with water is preferably 0.3 to 1.0 part by weight of water with respect to 1 part by weight of the calcium phosphate cement composition, and the mixing ratio is 0.
When it is less than 3 parts by weight, the cement paste is too hard to form a desired shape of the medullary cavity plug, and when it exceeds 1.0 part by weight, the mechanical strength of the medullary cavity plug is lowered, which is not preferable.

When using the medullary cavity plug of the present invention, for example, the insertion tool 3 such as stainless steel shown in FIG. 1 is fitted into the medullary cavity plug fitting portion 2, and as shown in FIG. After being pushed into a predetermined position 8 in the inside, the insertion instrument 3 is inserted into the bone marrow cavity plug fitting portion 2
Then, the bone marrow cavity plug 1 is fixed to the predetermined position 8 in the bone marrow cavity 9. Then, a calcium phosphate cement filler 6 having the same composition as that of the bone marrow cavity plug 1 is poured into the bone marrow cavity 9 to which the bone marrow cavity plug 1 is fixed, and the stem portion 7 is embedded above the filler, and at the same time with the filler 6. By curing, the stem portion 7 can be firmly fixed.

[0017]

EFFECTS OF THE INVENTION The bone marrow cavity plug for calcium phosphate cement filler of the present invention has the same composition as the calcium phosphate cement filler used when fixing the joint replacement stem portion in the bone marrow cavity using the calcium phosphate cement filler. , The bone marrow cavity can be densely filled with the filler, and peeling or destruction of the joint surface with the filler does not occur, so that the joint replacement stem portion can be firmly fixed. .

[0018]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited thereto.

[0019]

[Example 1] Calcium hydroxide (Wako Pure Chemical Industries, special grade) 4
Molar and phosphoric acid (manufactured by Wako Pure Chemical Industries, special grade) were wet-synthesized and then calcined at 1450 ° C. for 3 hours to obtain quaternary calcium phosphate and dicalcium phosphate dihydrate (manufactured by Wako Pure Chemical Industries,
(Special grade) was mixed at a weight ratio of 70:30 to obtain calcium phosphate cement powder, and then classified with a sieve to have a particle size of 100 μm or less. The classified cement powder and water were kneaded at a weight ratio of 2.5: 1 to obtain a cement paste, which was then molded (top diameter 10 mmφ, bottom diameter 12 m).
mφ, height 10 mm) and cured. After curing, a recess (4 mmφ, depth 5 mm) was formed using a drill in the center of the bottom surface of the cured product taken out from the mold to form a fitting part, and a bone marrow cavity plug for a calcium phosphate cement filler was produced.

[0020]

[Example 2] Calcium phosphate cement powder was wet-synthesized with 3 mol of calcium hydroxide (manufactured by Wako Pure Chemical Industries, special grade) and 2 mol of phosphoric acid (manufactured by Wako Pure Chemical Industries, special grade) and calcined at 1250 ° C for 3 hours. The same as in Example 1 except that the calcium phosphate cement powder obtained by mixing the α-type tribasic calcium phosphate and the dibasic calcium phosphate dihydrate (manufactured by Wako Pure Chemical Industries, special grade) obtained by the above in a weight ratio of 95: 5 was used. Then, a bone marrow cavity plug for a calcium phosphate cement filler was prepared.

[0021]

[Embodiment 3] On the outer periphery of the upper cylinder of a stainless steel pipe (a pipe having a total length of 7 mm, in which an upper cylinder having a top diameter of 3 mmφ x height of 5 mm and a bottom cylinder having a bottom diameter of 5 mmφ x height of 2 mm are integrally formed) A fitting portion having a screw portion corresponding to the insertion instrument screw portion was prepared. The calcium phosphate cement pastes obtained in Examples 1 and 2 are poured into the molds used in Example 1, respectively, and then the lower cylindrical body of the stainless pipe is embedded in the upper portion of the cement paste, and simultaneously cured to give a calcium phosphate cement filler. A bone marrow cavity plug was prepared.

In addition, a stainless block (upper cube 4
mm x 4 mm x 4 mm and lower rectangular parallelepiped 6 mm x 6 mm x
1 mm and a block integrally formed), a recess (2.5 mmφ, depth 2 mm) is formed in the central portion of the upper cube upper surface,
A fitting part was produced. Then, the upper cube was embedded in the cement paste so that the upper surface of the cube was aligned with the surface of the cement paste to prepare a bone marrow cavity plug for a calcium phosphate cement filler.

[0023]

[Example 4] The calcium phosphate cement paste obtained in Example 2 was used as a mold (top diameter 5.5 mmφ, bottom diameter 4.5 m).
mφ, height 5 mm) to obtain a cured product, and a recess (2 mmφ, depth 3 m) in the center of the upper surface of the cured product using a drill.
m) was formed as a fitting part to prepare a bone marrow cavity plug for a calcium phosphate cement filler.

The head of the left femur of the dog was cut, and a stainless steel pipe (1.9) was cut to a depth of 50 mm in the femoral bone marrow cavity.
The prepared bone marrow cavity plug for a calcium phosphate cement filler was inserted and installed using an insertion instrument having a diameter of mmφ and a length of 120 mm. Then, a calcium phosphate cement filler having the same composition as that of the bone marrow cavity plug was poured into the femoral bone marrow cavity in which the bone marrow cavity plug was inserted, and the artificial joint stem portion for dog was embedded in the filler upper part. At this time, the filler was not pressed into the deep part of the bone marrow cavity, and the stem part could be firmly fixed. Three months after the operation, the dog was slaughtered,
Observation of the left femoral surgical site showed no peeling or destruction at the joint surface between the bone marrow cavity plug and the filler, and the stem part was also firmly fixed.

[0025]

[Example 5] A calcium phosphate cement filler was prepared in the same manner as in Example 4 except that the same calcium phosphate cement powder as in Example 2 was pressure-molded and then pulverized to use granules classified to have a particle size of 300 to 500 µm. A bone marrow cavity plug was made.
The medullary cavity plug was a porous body in which granule gaps were formed as pores.

Next, using the prepared bone marrow cavity plug for a porous calcium phosphate cement filler, a dog left femur was treated in the same manner as in Example 4. Observation of the left femoral surgical site at 3 months after the operation revealed that the filler was infiltrated and joined into the hole of the bone marrow cavity plug, and no peeling or destruction at the joint surface was observed. The stem part was also firmly fixed.

[0027]

Comparative Example 1 Hydroxyapatite powder (particle size 149μ
m or less) mold (upper surface diameter 5.5 mmφ, bottom surface diameter 4.5 m
mφ, height 5 mm), and using a hydrostatic pressing device (manufactured by Japan Research & Development Co., Ltd.), pressure 1000 kgf / cm
It was pressed by ² and fired at 1200 ° C. for 1 hour to form a truncated cone shape. Next, ultrasonic processing machine (Co., Ltd.)
A "500C type" manufactured by JEOL Ltd.) was used to form a recess (2 mmφ, depth 3 mm) in the central portion of the upper surface of the truncated cone to form a fitting portion, and a bone marrow cavity plug was produced.

Then, using the prepared bone marrow cavity plug, the left femur of the dog was treated in the same manner as in Example 4, and the surgical site was observed 3 months after the surgery. As a result, peeling of about 0.5 mm was observed at the joint between the filler and the marrow cavity plug.

[0029]

Comparative Example 2 A truncated cone having a top surface diameter of 5.5 mmφ, a bottom surface diameter of 4.5 mmφ and a height of 5 mm was produced by lathing using a polycarbonate rod (6 mmφ). Then, using a drill, a recess (2 m
mφ, depth 3 mm) was formed as a fitting part to prepare a bone marrow cavity plug. Then, using the prepared bone marrow cavity plug, the left femur of the dog was treated in the same manner as in Example 4, and the surgical site was observed 3 months after the surgery. As a result, peeling of about 1 mm was observed at the joint between the filler and the bone marrow cavity plug.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing one embodiment of a bone marrow cavity plug for a calcium phosphate cement filler according to the present invention.

FIG. 2 is a schematic perspective view showing another embodiment of the bone marrow cavity plug for a calcium phosphate cement filler according to the present invention.

FIG. 3 is a schematic perspective view showing another embodiment of the bone marrow cavity plug for a calcium phosphate cement filler according to the present invention.

FIG. 4 is a schematic cross-sectional view showing a usage state of the bone marrow cavity plug for calcium phosphate cement filler of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiyasu Takeuchi 2270 Yokose, Yokose-cho, Chichibu-gun, Saitama Sanryo Materials Co., Ltd. Ceramics Laboratory

Claims (1)

[Claims] 1. A bone marrow cavity plug for fixing a joint replacement stem portion in a bone marrow cavity using a calcium phosphate cement filler, which has the same composition as the calcium phosphate cement filler, wherein the plug is a bone marrow cavity. A bone marrow cavity plug for a calcium phosphate cement filler, characterized in that at least a part of the plug is provided with a fitting portion for fitting with an instrument to be inserted into a desired position therein.