JPH08308866A - Medullary plug - Google Patents

Abstract

PURPOSE: To provide a medullary plug which can exhibit blocking-up performance and can prevent infiltration of blood or the like and can effectively prevent a fracture of a joint part by forming a conical medullary plug composed of a sintered compact or a hardened body of a calcium phosphate type compound whose Ca/P mole ratio is a specific value as a taper shaft shape whose maximum diameter and length are a specific value. CONSTITUTION: A medullary plug 1 is composed of a sintered compact or a hardened body of a calcium phosphate type compound whose Ca/P mole ratio is 1.5 to 2.0, and has a taper shaft shape whose maximum diameter is 10 to 20mmϕ and length is not less than 40mm. The calcium phosphate type compound is formed as hydroxyapatite. A bottomed hole 2 formed on an end surface 1b on the maximum diameter side of the medullary plug 1 is used when the medullary plug 1 is inserted into a medullary cavity while preventing a slip by striking the other end of a bar by inserting the bar or the like when the medullary plug 1 is inserted into a medullary cavity. This medullary plug exhibits high blocking-up performance when it is applied to a medullary cavity, and can effectively prevent infiltration of blood or the like.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a bone marrow plug for blocking a drill hole in a bone marrow and stopping hemostasis in artificial joint replacement, which is a kind of joint arthroplasty.

[0002]

2. Description of the Related Art Conventionally, joint arthroplasty has been performed in order to reconstruct a joint that has been functionally impaired by various diseases or to restore its function. Among joint arthroplasties, artificial joint replacement using artificial biomaterials has recently become popular. Knee joints and hip joints are often used as artificial joints. Since the hip joint is heavily loaded with weight, the artificial hip joint is large in size, and a type in which a long stem portion is inserted into the femoral bone marrow cavity to fix the joint is mainly used. The inserted stem part may be fixed with bone cement or may be fixed by mechanical fitting without using cement (cementless type). When inserting the stem part, first make a stem-length hole in the femoral bone marrow cavity with a special drill, but in the case of the cementless type, in order to prevent the stem from moving downward, A method of applying a bone marrow plug to the tip of the is often used.

Further, when attaching the artificial knee joint, since liquid such as blood overflows from the end of the bone marrow, it is necessary to block and stop the bleeding with a bone marrow plug.

As bone marrow plugs, calcium phosphate-based ceramics, especially hydroxyapatite ceramics, which are excellent in autogenous bone and biocompatibility, are used. But,
A conventional bone marrow plug made of hydroxyapatite ceramics has a porous structure, and thus has not fulfilled a sufficient function in terms of blockade. That is, there is a problem that blood or the like infiltrates into the bone marrow plug, and further passes through the bone marrow plug to reach around the stem portion.

On the basis of the above awareness of the problem, the applicant of the present invention has proposed a bone marrow plug capable of enhancing the sealing property and preventing the infiltration of blood and the like.
A bone marrow plug having a truncated cone shape, which is composed of a sintered body or a hardened body of a calcium phosphate compound having a Ca / P molar ratio of 1.5 to 2.0, has been proposed (Japanese Patent Application No. 5-15298, Japanese Utility Model Publication No. 6). -74116).

[0006]

It is an object of the present invention to further advance this proposal, and to obtain a bone marrow plug capable of effectively preventing fracture of joints as well as sealing property and prevention of infiltration of blood and the like.

[0007]

SUMMARY OF THE INVENTION The present invention has a Ca / P molar ratio of 1.5 to
This is the result of research on the maximum diameter and length of a conical bone marrow plug made of a sintered body or a hardened body of a calcium phosphate compound of 2.0, and the maximum diameter is 10 to 2
It is characterized by having a taper shaft shape of 0 mmφ and a length of 40 mm or more.

The material for the bone marrow plug of the present invention is a calcium phosphate-based compound having a Ca / P molar ratio of 1.5 to 2.0, which is excellent in biocompatibility. Examples of the calcium phosphate-based compound include apatites such as hydroxyapatite and fluoroapatite, tricalcium phosphate, tetracalcium phosphate, and the like, and one or more of these can be used. In the present invention, these calcium phosphate compounds are sintered to obtain a relative density of 7
It is used as a sintered body of 0% or more, preferably 80% or more, or is used as a hardened body by hardening hydraulic calcium phosphate. If the relative density of the sintered body is less than 70%, the possibility of the presence of open pores increases and the sealing performance deteriorates. In the case of a sintered body, it is more preferable to make it dense. Further, the latter cured body may have a few pores, but since these pores are not in communication with each other, blood or the like does not infiltrate into the bone marrow plug, and for the purpose of the present invention. It is compatible.

The bone marrow plug of the present invention has a tapered shaft shape tapered toward the insertion direction so that it can be stably fixed in the bone marrow cavity, and its maximum diameter is 10 to 20 m.
mφ and length are 40 mm or more. Below this diameter and length, it is not possible to effectively prevent fractures when a load is applied to the vicinity of the joint in the state where the artificial joint is mounted. The minimum diameter is preferably in the range of 5 to 15 mm. More preferably, the length is 8 mm or more. Maximum length is limited by the length of the femur, but is approximately 150m
m or less. The tapered shaft shape can also be used with a sharp tip such as a cone.

The bone marrow plug of the present invention can be manufactured by various methods, and the manufacturing method is not particularly limited, but an example of the manufacturing method will be described using hydroxyapatite as a raw material and a sintered bone marrow plug as an example. First, a hydroxyapatite slurry is obtained from a phosphate and a calcium salt by a known method by a wet synthesis method. The obtained slurry is dried using a rotary drum dryer to obtain a hydroxyapatite powder, and this powder is molded into the bone marrow plug shape of the present invention by, for example, a dry hydrostatic press. The molded body is 1000 to 12 in the electric furnace.
The bone marrow plug is obtained by baking in the range of 00 ° C. In addition to this, as a molding method, a casting method, an injection molding method, a method of molding a green compact by lathe processing, or the like can be adopted.
Further, for example, α-tricalcium phosphate powder is kneaded with water to which an acid is added as a coagulant, if necessary, to prepare a hardened body, which is then processed into the bone marrow plug shape of the present invention, or The above cured product can be produced in a mold.

[0011]

EXAMPLES Next, the present invention will be described in detail based on examples. Example 1 A hydroxyapatite slurry was wet-synthesized by a known method. This slurry was dried with a spray dryer to obtain a hydroxyapatite powder. The obtained powder was pressed with a mold to produce a green compact having a diameter of 35 mm and a length of 45 mm. The green compact is processed into a desired size and shape by an NC lathe in consideration of shrinkage by firing, and fired at 1100 ° C for 2 hours in an electric furnace to produce a bone marrow plug made of a sintered body shown in Figs. 1 and 2. did.

FIG. 1 is a side view of a bone marrow plug showing an embodiment of the present invention. The bone marrow plug 1 shown in FIG. 1 is for the femur of a knee joint, and the diameter A (minimum diameter) of the insertion side hemispherical end surface 1a is 9.5 mm and the maximum diameter B of the opposite end surface 1b is 1.
It has a taper shaft shape of 4.5 mm and a length C of 75 mm. A bottomed hole 2 can be formed in the end surface 1b on the maximum diameter side of the bone marrow plug 1 as shown by a chain line. When the bone marrow plug 1 is inserted into the bone marrow cavity, a rod or the like is inserted when the bone marrow plug 1 is inserted into the bone marrow cavity and the other end of the rod is tapped to prevent slippage while inserting the bone marrow plug 1 into the bone marrow cavity. use. This bone marrow plug was used together with several cases of artificial joint replacement surgery such as knee joint disease, and good results were obtained. FIG. 2 is a schematic view when the bone marrow plug 1 of FIG. 1 is used for artificial joint replacement of the knee joint, and the bone marrow plug 1 is inserted into the bone marrow hole 10a at the center of the femur 10 from the lower end surface thereof. . The outer circumference of the lower end portion of the femur 10 is cut to fit the artificial joint 11, and the artificial joint 11 is fixed to the outer side thereof. Reference numeral 12 is a tibia, and an artificial joint 13 paired with the artificial joint 11 is fixed to the upper end of the tibia.

A plurality of artificial joints 11 and 13 (usually two)
Projections 11a and 13a of the femur 10 and the tibia 12, and the insertion holes 10b, which correspond to the projections 11a and 13a.
12b is processed. FIG. 3 shows a jig 20 for forming the insertion hole 10b in the femur 10. This jig 2
0 is a protrusion 22 on the substrate 21 that is inserted into the bone marrow hole 10a.
And a hole 23 for forming the insertion hole 10b.
Has been drilled. The protrusion 22 is inserted into the bone marrow hole 10a, the substrate 21 is brought into contact with the lower end surface of the femur 10, and in that state, a drill is inserted through the hole 23 to form the insertion hole 10b.

Example 2 An aqueous phosphoric acid solution and a calcium hydroxide suspension were reacted by a known method and dried to obtain hydroxyapatite having a Ca / P molar ratio of 1.67. This hydroxyapatite was calcined at a temperature of 1200 ° C. and a pressure of 1.3 × 10 ⁻⁴ Pa for 1 hour. As a result, a mixture of α-tricalcium phosphate and tetracalcium phosphate produced by thermal decomposition of hydroxyapatite was obtained. The thus obtained mixture of α-tricalcium phosphate and tetracalcium phosphate was used as a dusting agent, and was kneaded with an aqueous solution containing 45% citric acid, 15% glucose and 1% chitosan at a powder-liquid ratio of 2: 1. I made it This kneaded product has a diameter of 10 mm at the end surface on the insertion side and a diameter of 1 at the upper surface.
It was put into a split mold (made of polyacetal) having a diameter of 5 mm and a length of 75 mm, which was hollowed out, and cured, and after about 10 minutes, it was completely cured and taken out from the mold to obtain a desired cured body having a tapered shaft shape.

[0015]

The bone marrow plug of the present invention comprises a sintered body or a hardened body of a calcium phosphate compound having a Ca / P molar ratio of 1.5 to 2.0, and therefore has a high sealing property when applied to a bone marrow cavity. It can effectively prevent the infiltration of blood and the like, prevent bleeding from the bone marrow, maintain stable fixation of artificial joints such as artificial knee joints and artificial hip joints for a long time,
The burden on the operator and the patient can be significantly reduced. Furthermore, the bone marrow plug of the present invention has a maximum diameter of 10 to 20 mm and 4
Since it has a tapered shaft shape with a length of 0 mm or more, it is possible to reinforce the joint portion and effectively prevent the fracture thereof.

[Brief description of drawings]

FIG. 1 is a front view of a bone marrow plug showing an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a state in which the bone marrow plug of FIG. 1 is used in a knee joint artificial joint replacement operation.

FIG. 3 is a perspective view showing an example of a jig for forming a hole for fixing an artificial joint in a bone.

[Explanation of symbols]

 1 Bone marrow plug 2 Bottomed hole

Claims (2)

[Claims] 1. A taper shaft shape having a maximum diameter of 10 to 20 mmφ and a length of 40 mm or more, which is made of a sintered body or a hardened body of a calcium phosphate compound having a Ca / P molar ratio of 1.5 to 2.0. A bone marrow plug characterized by having. 2. The bone marrow plug according to claim 1, wherein the calcium phosphate compound is hydroxyapatite.