JPS58192544A - Joint slide member and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a joint sliding member, particularly a joint sliding member (socket or cup) that provides a sliding seat for an artificial femoral head in vivo, and a method for manufacturing the same.

The history of artificial joints to be used in living bodies began in 1891 with G.
Luck is said to have been the first to use an ivory artificial bone head (I-ru) and socket (cup).

After that, various materials were tested, but with the development of petrochemistry, relatively better results were obtained than the combination of metal and polymer materials.
Since ARNLY developed the combination of a stainless ψ steel head and a polyethylene socket, it has become popular as a practical solution. In particular, ultra-high molecular weight polyethylene having a molecular weight of 1 million or more is known as an excellent socket material having self-lubricating properties, biocompatibility, and mechanical strength.

However, such sockets made of ultra-high molecular weight I-lyeethylene are still far from satisfactory in terms of durability. 1-Although the ultra-high molecular weight polyethylene molded product has excellent mechanical properties, it still suffers from creep deformation when subjected to repeated loads, and when used for a long period of time, it does not form close contact with the femoral head. It also causes loss of sex and dislocation. In addition, due to this type of leap deformity, it is recommended that artificial joints be installed in women who weigh less than 90cm, have a height of 180mm or less, are at least as talented as an artist, and are inactive if possible. .

However, in reality, artificial joints must be installed when it is necessary to eliminate pain caused by joint defects or to restore activity levels, and in this sense, artificial joints can be installed on young people. Joints are needed.

In order to solve the above problems by increasing the rigidity of the entire socket, the following method can also be considered.

1) Use a highly rigid material other than ultra-high molecular weight I-lyethylene for the entire socket.

2) Insert a core of iron or ceramics into the center of the socket of ultra-high molecular weight I-ethylene.

Among the above methods, method 1) requires consideration of biocompatibility, so materials cannot be selected based solely on stiffness issues. Metal materials are generally used, but stainless steel 8U8316.8U8316L has relatively good biocompatibility and has a proven track record.

SUB 317, Conort chrome alloy H8-21, H
There is lm-25°HP35. In addition, titanium alloy,
Tantalum and other metals are also used, but they are difficult to manufacture, are not suitable for mass production, are expensive, and have problems with corrosion resistance from body fluids if the oxide film breaks, making it difficult to implant similar metals into the body. Otherwise, there is a problem that galvanic corrosion may occur due to body fluid, which is a type of electrolyte. In addition, pitting corrosion (Pitt
l■), crevice corrosion due to relative movement (er*vie@
eorroslsn) etc. may occur, and it is also considered inappropriate from the viewpoint of friction and wear.

It is thought that then. In the case of ceramic core, it is weak against impact strength, so if it is used for socket materials that are often subjected to forces 5 to 6 times the body weight, there is a drawback that the strength of the socket as a whole cannot be guaranteed if it breaks internally. be.

The purpose of the present invention is to basically use ultra-high molecular weight 4-lyethylene, which has excellent self-lubricating properties and biocompatibility, as a basic material, and to
Composite joint sliding members with improved resistance to creep deformation, especially female joint members (sockets) that prevent loss of adhesion or loosening between the male member and the male member due to creep deformation.
The object of the present invention is to provide a method for manufacturing the same.

As a result of research for the above-mentioned purpose, the present inventors have found that by embedding carbon fiber cloth approximately parallel to the sliding surface of a joint sliding member made of an ultra-high molecular weight polyethylene molded body, the creep deformation resistance of the joint sliding member can be significantly improved. discovered a joint sliding member and its manufacturing method (Showa 5).
Patent Application No. 681).

However, articulating sliding members according to the above-mentioned technology are not without problems, mainly related to their manufacturing method. That is, the above-mentioned joint sliding member is manufactured by sandwiching a carbon fiber cloth between 4-lyethylene powder having a molecular weight of 1 million or more divided into at least two parts, and heating and compression molding the mixture between a core mold and a cavity molder. However, it is not always easy to cut such carbon fiber cloth to a desired size and place it in a predetermined position in a mold, resulting in a complicated process.

A further object of the present invention is to provide a technique for more easily manufacturing a polyethylene joint sliding member with improved creep deformation resistance.

As a result of further research by the present inventors, it has been found that powder compression molding of ultra-high molecular weight polyethylene is considerably simpler than the above-mentioned technique of preparing and arranging vertical fiber cloth by blending short carbon fibers with ethylene powder. It has been discovered that a four-reinforced tyrene-based joint sliding member with improved creep deformation resistance and impact resistance can be obtained through the following process. In addition, short carbon fibers have a greater reinforcing effect than short glass fibers, and have greater bonding properties with ultra-high molecular weight 4-lyethylene than Selantsk powder, demonstrating superior suitability compared to other fillers. .

The joint sliding member of the present invention is based on such knowledge.
It is characterized by being composed of a molded body having a concave sliding surface of 4,000,000 or more polyethylene. More preferably, the sliding surface itself is formed of a layer of ultra-high molecular weight polyethylene that does not contain carbon fibers so that carbon fibers, whose biocompatibility is more unclear than ultra-high molecular weight polyethylene, are not exposed. Furthermore, in the method for manufacturing a joint sliding member of the present invention, when 4-lyethylene powder having a molecular weight of 1 million or more is heated and compression-molded between a core mold and a cavity mold, the 4-lyethylene powder is divided into at least two parts. However, one of the parts is blended with short carbon fibers, and this part is laminated with a polyethylene powder part not containing short carbon fibers which is in contact with the core mold, and then heated and compression molded.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of a preferred embodiment of a socket to be attached to the pelvis for supporting the femoral head (for the hip joint) as an example of the joint sliding member of the present invention. A surface layer 3at- consisting of a molded body 3 of ultra-high molecular weight polyethylene having a sliding surface 2t.
Short carbon fibers are blended in the removed portion 3b. Further, although not shown, unevenness or protrusions are provided on the surface 5 of the socket opposite to the sliding surface, as necessary, in order to increase the bonding strength with the pelvis.

The mounting structure of such a socket 1 is as shown in FIG. That is, the socket (1) is fixedly connected to the acetabulum (6) constituting the pelvis via a one-piece cement. On the other hand, a bone-1 [10] of an artificial femur 9 made of stainless steel, inserted into the proximal part 8 of the femur, is fitted and fixed to the socket 1 so as to be able to slide on its sliding surface 2. Ru.

The ultra-high molecular weight polyethylene as the main material of socket) 1 is produced by the Thiemez method and has a molecular weight of 1X10' to 8X10I', particularly 2X10' to 6, as determined by the light scattering method.
X10' is preferably used. This molded body of ultra-high molecular weight polyethylene is formed by powder compression molding as described below, and the particle size of the ultra-high molecular weight powder as a raw material is not specified, but is usually about ω to 150 μ.

However, when blended with such ultra-high molecular weight ethylene, short carbon fibers that should be used have a length of 1 to 500 μm, especially 150 to 400 μm, and a diameter of 5 to 20 μm, especially 6 to 400 μm.
10j is preferably used.

If the length is too short, the effect of increasing creep deformation resistance will be poor, and if it is too long, the mixing with polyethylene powder will be poor during compaction with 4-lyethylene powder, and the resulting molded product will have problems due to the orientation of the fibers. Directionality may occur. Such short carbon fibers have ultra-high molecular weight/
In order to increase the bonding strength with the IJ ethylene matrix,
For example, it is preferable to perform oxidation treatment or wet oxidation treatment in advance by immersing the weight in a sodium chloride 7-141GIF solution and a sulfuric acid 17-34 solution for about 15 minutes each.

The short carbon fibers have a total weight of 0.0% of the total weight of the short carbon fibers and the ethylene.
It is used in amounts of 8-119G, especially 1-4-.

If the blending amount is less than 0.8-, the effect of improving creep deformation resistance is poor, and is 11%! - If it exceeds, it becomes brittle and short carbon fibers become exposed on the surface.

As the material of the artificial femur 9 including the bone ill 10 used in combination with the socket 1, in addition to the above-mentioned stainless steel, a co-alt chrome alloy, a titanium alloy, tantalum, etc. are used in consideration of biocompatibility. When considering sliding suitability with such a metal material femoral head 1o, it is not necessarily preferable that the ultra-high molecular weight polyethylene blended with short carbon fibers directly constitute the sliding surface 2t. This is because, if the short carbon fibers blended into the sliding surface 2 are exposed, the wear and creep of the socket 1 itself are reduced, but the oxide film of the femoral head material may be damaged and the surface of the femoral head may be corroded. In order to avoid such a long time, K should be set at a thickness of 0.2 to 10111 mm from the sliding surface 2, as shown in FIG. 1.
．． Preferably, the layer of 0.3 to 0.7B is composed of ultra-high molecular weight ethylene excluding short carbon fibers. This makes it possible to better balance sliding suitability and creep deformation resistance. Such a layer structure is also preferable in that the sliding surface is made only of ultra-high molecular weight polyethylene, which is less problematic than carbon fiber in terms of biocompatibility. From the same considerations, it is also possible to provide an ultra-high molecular weight ethylene layer excluding short carbon fibers on the surface 5 of the socket 1 on the opposite side to the sliding surface 2.

Next, a method of manufacturing the socket illustrated in FIG. 1 will be explained.

FIG. 3 is a partially cutaway front view showing the state of the mold during final molding. The mold consists of a base 11, a cavity mold 12, and a core mold 13. The cavity mold 12 further includes a bottom member 12m and a side member 12b. Further, the core mold 13 is composed of a main member 13m and an auxiliary member 13b.

The socket 1 is manufactured according to the method for manufacturing a joint member of the present invention.
It is manufactured by compression molding using such a mold as follows (note that illustration of intermediate steps is omitted). Compression molding is used for ultra-high molecular weight polyethylene (
This is because the melt viscosity of (hereinafter simply referred to as 4-lyethylene) is high, making it difficult to apply ordinary melt molding methods such as injection molding and extrusion molding.

According to the present invention, first, the short carbon fibers as described above are subjected to oxidation treatment and water washing as described above, as necessary.
After drying, it is dry mixed with dilyethylene powder. l
The particle size of the ethylene powder is not particularly limited, but is usually 60
Approximately 150 voices are used. 4 liters of ethylene powder containing such short carbon fibers, the amount used is 70
~85- (the same shall apply below: lF amount-1) is charged into the cavity mold 12, and compression molded between it and the core mold 13m to obtain a carbon fiber compounded preform. The molding conditions were: temperature 150-170℃, pressure (material) ~90, -2, 6
Approximately 70 minutes or so is suitable. The preform thus obtained is porous and looks like sintered polyethylene powder. On the other hand, in the same manner, the above-mentioned single powder of ethylene ethylene was charged into the capacity mold 12 in an amount ranging from 70 to 85% of the amount to be used, and compression molded under the same conditions as above. A plain preform is obtained.

Next, the remainder of the carbon fiber blended ethylene powder, the carbon fiber blended preform, the polyethylene plain preform, and the remainder of the polyethylene plain powder are inserted into the cavity mold 12, and the cavity temperature is 170 to 230°C, and the core Temperature 140~170℃, Pressure (capital) ~170#, 4"
, a socket as shown in FIG. 1 can be obtained by compression molding under the conditions of 6 to (a) for a time of 6 to (a). The reason why the core temperature is lower than the cavity temperature as described above is because the molding material for the cavity type is larger in quantity than the molding material for the core side. This is because the molding material on the core side will be excessively heated, which is undesirable.

When the above molding method is carried out, the sliding surface layer made solely of I-lyeethylene and the bulk layer made of I-lyeethylene blended with short carbon fibers are integrated, and peeling due to repeated loads does not occur at the interface between the two. . In addition, if the socket is obtained by one compression molding, the volumetric shrinkage during molding will be large and the dimensional accuracy will be reduced. Further, the reason why the above-mentioned preforming is performed is to form a monolayer of polyethylene having a uniform thickness. For the same reason, in the final molding, it is preferable to charge the polyethylene single powder and the carbon fiber blended ethylene powder into the prison via a preform so that they do not come into direct contact with each other. can be inserted between a pair of preforms. In addition, as mentioned above, since plain ethylene powder is used in place of the remainder of the carbon fiber-mixed ethylene powder used in the final molding, the surface 5 on the opposite side to the sliding surface is also formed of a single layer of polyethylene. ) can be obtained.

The mold for preforming and the mold for final molding are substantially the same and can be used for both the same gold mt, but for practical production they should be separate molds. is preferred.

In the above, a socket for a hip joint and a method for manufacturing the same have been described by taking the present invention as an example. However, the joint sliding member of the present invention utilizes the biocompatibility and self-lubricating properties of ultra-high molecular weight I-lyethylene, and can be used not only in joints in other parts of the body, but also as joint female members in drive mechanisms outside of the body. It is available.

As mentioned above, according to the present invention, while maintaining all the biocompatibility, self-lubricating properties, and other excellent properties of ultra-high molecular weight 4-lyethylene, there are no problems when using it as a female joint member (socket) in a living body. The present invention provides a joint sliding member made of an ultra-high molecular weight 4-lyethylene substrate that solves the disadvantages such as dislocation due to lack of creep deformation resistance by incorporating 1-carbon short fibers, and a method for manufacturing the same.

Hereinafter, an actual manufacturing example of the joint sliding member of the present invention will be described.

Production Example Ultra-high molecular weight polyethylene manufactured by Hoechst Co., Ltd., Hostal@n GUR412 (molecular weight 6 million, average particle diameter 100μ), short carbon fiber (Torayka Ml manufactured by Toshisha Co., Ltd., D-300° average diameter 7μ, (about 300μ in length) were dry mixed at a ratio of 3% (based on the total amount with polyethylene powder). The short carbon fibers used were oxidized by immersing them in a 14% dichromic acid mixture and a 35% sulfuric acid solution for 15 minutes each, followed by washing with water for I minutes and drying.

A hip joint socket was manufactured using the above mixed powder and/or monolithic ethylene powder by substantially the method described above.

That is, using 10.5 g of the above mixed powder and 0.56 g'i of monolithic ethylene powder, each was heated at 160°C.
A preform was obtained under the conditions of #70 and - (-. Then, 4.5 g of the above mixed powder, a carbon fiber blended preform, a polyethylene single preform, and a polyethylene single powder of 0.7 g were placed in a cavity mold. Charge 24g'i sequentially to reach core temperature 1
50℃, capacity temperature 190℃, pressure 160kf/c
Compression molding was carried out under the conditions of ``m'' to obtain a socket tube.

The artificial hip joint socket obtained as described above was applied with a joint simulator from 0 to 400 k#, and as a result of applying a repetitive load of 6 x 10' times, the sinkage t (creep deformation amount) was found to be The IA was reduced to ~1/4 compared to that of a conventional socket.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a hip joint socket which is an embodiment of the joint sliding member of the present invention, Fig. 2 is a partial sectional view showing how the socket is attached to the human body, and Fig. 3 is a partial sectional view of the socket. FIG. 3 is a partially cutaway front view of the mold during the manufacturing process. 1... Socket (joint sliding member), 2... Sliding movement,
3... Polyethylene molded body, 4... Carbon fiber cloth, 6
... hip bone, 7 ... Zane cement, 9 ... artificial femur, 10 ... femoral head, 12 ... capitei type, 13
...Core type. Applicant's agent Kiyoshi Inomata

Claims (1)

[Scope of Claims] 1. A joint sliding member comprising a molded body having a concave sliding surface made of polyethylene having a molecular weight of 11 million or more and containing short carbon fibers. 2. The joint sliding member according to item 1 above, wherein a layer of the polyethylene containing no short carbon fibers is formed on the sliding surface. 3. The joint sliding member according to item 1 or 2 above, wherein a layer of polyethylene ethylene containing no short carbon fibers is formed on the surface opposite to the sliding surface. 4. When heat compression molding polyethylene powder with a molecular weight of 1 million or more between the core mold and the capacity mold, the polyethylene powder is divided into two parts, one of which is
One part contains short carbon fibers, and this part is laminated with the 4-reproduced ethylene powder part that does not contain short carbon fibers and is in contact with the core mold, and then heated and compression molded. A method for manufacturing a joint sliding member.