JP2005278874A - Artificial joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an artificial joint having an excellent fracture resistance and improved safety toward the living body capable of preventing the generation of wear powder at a sliding section of the artificial joint. <P>SOLUTION: An artificial bone 5 comprising a caput 2, a neck 3 following the caput 2, and a stem 4 neighboring the neck 3 is provided. The surface of the caput is made of composite structures formed by surrounding the circumference of core materials 11 made of a first material and arranged regularly with a coating material 12 made of a material different from the first material. The caput 2 of the artificial bone is enganged with and connected rotatably to a recess 7 of a socket 6 to form the artificial joint 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an artificial joint that replaces a bone joint of a living body.

Treatments for replacing the deformation and loss of bone joints in the human body with artificial joints are widely performed in orthopedics and the like. For example, for the femoral head necrosis, after removing the necrotic head, the stem portion of the artificial joint having the head and stem portion is embedded and fixed in the bone marrow cavity of the femur, and the cup (socket) is attached to the hip bone. Frequently, an artificial joint having a structure in which a bone head is fitted to a concave portion of the socket and is pivotably connected to the prosthesis is restored to restore the joint function.

  Such artificial joints have mechanical strength, elasticity (toughness), durability, in-vivo stability (no corrosion or deterioration against body fluids), biocompatibility (bone-promoting action and other surrounding tissues) Compatibility), safety (no toxicity, degradability, etc.) and processability are required.

  At present, as a constituent material of an artificial joint, in particular, as a constituent material of a bone head, an organic resin, or a metal such as stainless steel, cobalt-chromium alloy, titanium, titanium alloy or alumina as described in Patent Document 1, or alumina Although ceramics such as apatite are used, there is no material that satisfies all the required characteristics.

  Among the above materials, the artificial joint made of resin or metal is worn on the sliding surface by sliding between the bone head and the socket that is fitted and rotatably connected thereto, and this wear powder bites the sliding surface. There is a problem that the wear further progresses.

On the other hand, the artificial joint made of ceramics has high hardness and excellent slidability, but has a problem of poor durability such as low toughness and chipping. In Patent Document 2, glass ceramics is used instead of alumina. It is described.
JP-A-5-92018 Special table hei 5-504271

  However, the bone head made of the glass ceramic disclosed in Patent Document 2 can suppress the wear of the sliding portion as in Patent Document 1 and is excellent in wear resistance, but is inferior in fracture resistance, exercise, etc. There is a problem that there is a risk of loss when a larger impact is applied.

  The object of the present invention is that the sliding part of an artificial joint such as a bone head and a socket has high slidability and can prevent generation of wear powder, and has excellent fracture resistance and improves safety to the living body. It is to provide an artificial joint that can be used.

  With regard to the above-mentioned problems, the present invention relates to an outer periphery of a core material made of a first material regularly arranged on a sliding portion of an artificial joint such as a bone head, that is, a bone head surface, and the first material. Is composed of a composite structure surrounded by a skin material made of different materials, which can prevent the generation of abrasion powder in the sliding part and can improve the safety to the living body with excellent fracture resistance. It becomes a prosthetic joint that can be made.

  That is, the artificial joint of the present invention has a surface with a composite structure in which the outer periphery of the core material made of the first material regularly arranged is surrounded by the outer skin material made of a material different from the first material. The bone head of an artificial bone composed of a bone head, a neck portion following the bone head, and a stem portion following the neck portion is fitted into a recess of the socket so as to be rotatable. Is.

  Here, it is desirable that the inner surface of the concave portion of the socket is made of the composite structure in terms of preventing wear at the sliding portion of the socket.

  The composite structure core material has a porosity of 5% or less, and the outer skin material has a porosity of 25% or more and has pores which are three-dimensionally communicated, and has excellent mechanical strength and biocompatibility. This is desirable because it promotes bone regeneration.

  Further, the inside of the bone head is made of a uniform tissue formed of the first material constituting the core material, the strength of the bone head itself is high, and the adhesion between the inside of the bone head and the surface tissue Is desirable in terms of enhancing.

  Furthermore, it is desirable that the thickness of the composite structure on the surface of the bone head is 100 to 500 μm because the lubricant can enter the sliding surface and ensure the sliding property of the bone head.

  Furthermore, the average diameter of the core material of the composite structure is 10 to 1000 μm, and the area ratio of the core material on the surface of the bone head is 60 to 95 area%. This is desirable in terms of optimization.

  Further, the neck portion and / or the stem portion is composed of a composite fiber body in which a plurality of single core fiber bodies formed by covering the outer periphery of a long core material with a skin material, Or it is desirable at the point which can improve toughness and improve mechanical strength in the state which maintained the hardness of the stem part.

  In the artificial joint of the present invention, the outer periphery of the core material made of the first ceramic material regularly arranged on the sliding portion of the artificial joint, particularly the bone head surface, like the bone head and the socket, By using a composite structure surrounded by a shell material made of a material different from the ceramic material, it is possible to prevent the generation of wear powder and to improve the safety to the living body with excellent fracture resistance. It can be an artificial joint.

  Hereinafter, the artificial joint of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

  1 is a front view showing a configuration example of the artificial joint of the present invention, FIG. 2 is a cross-sectional view taken along the line aa in FIG. 1, and FIG. 3 is a diagram of the surface of the bone head in the artificial joint of FIG. The principal part enlarged view of this, (b) is a perspective view of a composite fiber body.

  As shown in FIG. 1, the artificial joint 1 has an artificial bone 5 composed of a bone head 2, a neck portion 3 that follows the bone head 2, and a metal stem portion 4 that follows the bone portion 2 at a predetermined position of the pelvis A. These are fitted in a recess 7 of a socket 6 provided as a separate body, and these are rotatably connected.

  The bone head 2 is a member having a substantially spherical curved surface, and the stem portion 4 is a portion that is embedded and fixed in the bone marrow cavity 8 of the femur B, and has a stem base portion 9 on the neck portion 3 side. It is comprised with the stem front-end | tip part 10. FIG. Since the outer periphery of the stem base 9 and the bone marrow cavity are in close contact with each other, the stem base 9 is thicker than the neck part 3 and the stem tip part 10, and the shape thereof matches the shape of the bone marrow cavity to be implanted. Molded. Moreover, since the stem tip portion 10 is inserted to the back of the bone marrow cavity, it has a tapered shape.

  On the other hand, the neck portion 3 is a member that connects the bone head 2 and the stem portion 4 and has a substantially cylindrical shape. The neck portion 3 is preferably formed integrally with the stem portion 4 continuously. The axis of the stem tip 10 is inclined with respect to the axis of the neck 3 by, for example, about 15 to 35 degrees.

  According to the present invention, as shown in FIG. 2 and FIG. 3 (a), the outer surface of the core material 11 made of the first ceramic material in which the surface of the bone head 2 is regularly arranged The main feature is that it is composed of a composite structure 13 surrounded by an outer skin material 12 made of a material different from the ceramic material 1, and this causes generation of wear powder in the sliding portion between the bone head 2 and the socket 6. In addition to being able to prevent, it is excellent in chipping resistance and improves safety to the living body.

  That is, in the composite structure 13, the core materials 11 made of the first ceramic material having high hardness are regularly arranged, and the outer periphery thereof is surrounded by the skin material 12 made of a material having a different biocompatibility having a different composition. It is a structure.

 In FIG. 2, the outer surface of the composite structure 13 is originally curved, but is simply illustrated as a straight line.

  According to the present invention, since the nuclear materials 11 are regularly arranged, there is an advantage that there is no local wear bias and the generation of osteoblasts is uniform compared to the irregular arrangement. Further, since the core material 11 is surrounded by the outer skin material 12, there is little risk of loss even when an impact is applied to the surface of the bone head 2.

  The core material 11 has, for example, a hexagonal cross-sectional shape in FIG. 3 (a), but the present invention is not limited to this, and is circular or other polygonal, and further elongated in one direction. You may have done.

  As a constituent material of the core material 11, ceramics such as alumina, zirconia, silicon nitride, silicon carbide and the like can be used for the reason of excellent hardness. However, in the present invention, the strength is particularly high and stable. Alumina is particularly preferred. On the other hand, as the constituent material of the outer skin material 12, it is desirable to use a material having higher toughness or biocompatibility than the core material 11, for example, a ceramic material such as zirconia or a calcium phosphate compound, or a metal or an organic resin is also used. be able to.

  Here, when the socket 6 is also made of artificial bone, it is desirable that the inner surface of the recess 7 of the socket 6 is made of the composite structure 13 in terms of preventing wear at the sliding portion of the socket 6.

  The porosity of the core material 11 of the composite structure 13 is 5% or less, particularly 2% or less, and the porosity of the outer skin material 12 is 25% or more, particularly 40 to 90%, and further 45 to 70%. It is desirable to have pores that communicated with each other in terms of excellent mechanical strength, enhanced biocompatibility, and promoted osteoblast proliferation and bone regeneration. Here, there is an effect that the pores in the outer skin material 12 can be filled with a lubricating liquid to improve the slidability of the bone head 2 surface.

  The bone head 2 can be entirely composed of the composite structure tissue 13, but since the bone head surface has a curved surface, the inside of the bone head 2 has a composite structure in terms of surface tissue control. It is desirable to be composed of an organization different from the organization 13.

  In addition, as a constituent material of the bone head 2, for example, stainless steel (for example, SUS316, SUS316L), cobalt-chromium alloy, cobalt-chromium-nickel alloy, titanium, titanium alloy (for example, Ti-6% Al-4% V) ) And the like, and materials having excellent strength and hardness such as ceramics such as alumina, zirconia, silicon nitride, silicon carbide, etc. can be used. However, the bone head 11 itself has a high hardness, and the inside of the bone head 11 and the surface structure (composite structure tissue 13) are formed of the first material forming the core material 11 described above. ) Is desirable in terms of enhancing the adhesive strength. Further, the inside of the bone head 2 may be hollow or solid.

  Further, when the thickness of the composite structure 13 on the surface of the bone head 11 is 100 to 500 μm, the lubricant sufficiently enters the composite structure 13 that is the surface tissue to ensure the slidability of the surface of the bone head 2. It is possible and desirable.

  Furthermore, the average diameter of the core material 11 of the composite structure 13 is 10 to 1000 μm, and the area ratio of the core material 11 on the surface of the bone head 2 is 60 to 95 area%. Is desirable.

  Here, when the area ratio c1 / s1 between the area c1 of the core material 11 and the area s1 of the outer skin material 12 in the cross section of the composite structure 13 is between 1 and 10, the wearability is excellent and the biocompatibility is high. It is preferably 1 to 5, and more preferably 1 to 3.

  In the present invention, the skin material 12 (or the skin material 16 of the composite fiber body 18) and the core material 11 (or the core material 15 of the composite fiber body 18) in the cross section of the composite structure 13 (or the composite fiber body 18 described later). For example, the sum of the cross-sectional areas of the respective core materials 11 observed in a scanning electron microscope (SEM) photograph in an arbitrary cross section of the composite structure 13 is calculated as c. The area s of the outer skin 12 can be calculated by subtracting the area c of the core material 11 from the total cross-sectional area of the arbitrary cross section of the structural structure 13. It can be easily obtained by an image analysis method or the like.

  Further, the neck portion 3 and / or the stem portion 4 has a plurality of single-core fiber bodies 17 in which the outer periphery of the long core material 15 is covered with the skin material 16 as shown in FIG. Consisting of the converged composite fiber body 18 can maintain the hardness of the neck portion 3 and suppress wear of the neck portion 3 at the connecting portion between the bone head 2 and the stem portion 4 and increase the toughness of the member. It is desirable in that it can improve durability when a sudden load is generated.

As the skin material 16 of the composite fiber body 18 used in the present invention, a calcium phosphate compound generally known as a biocompatible porous ceramic is suitable, for example, tricalcium phosphate TCP (Ca ₃ (PO ₄ ) ₂ ). , tetracalcium phosphate _{(Ca 4 (PO 4) 2} O), octacalcium phosphate _{(Ca 8 H 2 (PO 4} ) 6 · 5H 2 O), calcium hydrogen phosphate (CaHPO _4), dihydrogen phosphate Inorganic materials such as calcium (Ca (H ₂ PO ₄ ) · H ₂ O), hydroxyapatite HAP (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ), zirconia (ZrO ₂ ), or polyether ketone, polyether Ketone resins such as ether ketone and polyallyl ether ketone, polyphenylene sulfide, polysulfone, etc. It includes thermoplastic resins. In the present invention, one or more of these can be used in any combination. Various additives such as stabilizers and reinforcing materials may be added to the biomedical resin material 8.

On the other hand, the material of the core material 15 is a material that is not harmful to the living body and is preferably a dense ceramic or metal having biocompatibility. For example, alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silica ( SiO ₂ ) and titania (TiO ₂ ). These ceramics may contain auxiliary agents such as Ti, Mg, Zr, Hf, and Y as appropriate. Examples of the metal include stainless steel (for example, SUS316, SUS316L), cobalt-chromium alloy, cobalt-chromium-nickel alloy, titanium, titanium alloy (for example, Ti-6% Al-4% V, Ti-49 to 51%). A metal having excellent corrosion resistance such as Ni) can be used. Among them, it is particularly preferable to use a shape memory alloy (Ti-49 to 51% Ni). Since this shape memory alloy has excellent followability to repeated loads, resilience, and fatigue characteristics, stability and durability are improved during long-term embedding.

  The core material 11 of the composite structure 13 and the core material 15 of the composite fiber body 18, and the skin material 12 of the composite structure 13 and the skin material 16 of the composite fiber body 18 may be formed of the same material. In this case, it is desirable in that the composite structure 13 and the composite fiber body 18 can be produced by the same manufacturing method halfway.

  The average secondary particle size of the ceramic crystal particles forming the skin material 16 is 10 to 300 μm, preferably 50 to 200 μm, in order to maintain pores necessary for growing osteoblasts. On the other hand, the dense ceramic or metal forming the core material 15 is preferably 0.1 to 10 [mu] m, particularly 0.5 to 3 [mu] m in terms of improving toughness and strength.

  Further, the size of the composite fiber body 18 is changed in accordance with the part and shape of the living bone to be supplemented. However, since the pore size of the porous ceramic of the skin material 16 is 50 to 200 μm, it is 0 as the single core fiber body 17. About 5-5mm is good.

  Here, when the area ratio c / s between the area c of the core material 15 and the area s of the skin material 16 in the cross section of the composite fiber body 18 is between 1 and 10, strength and biocompatibility suitable as a bone grafting material. And is preferably 1 to 5, more preferably 1 to 3. When the area ratio c / s is less than 1, the ratio of dense ceramics decreases and the strength of the composite structure itself decreases, and may be below, for example, 30 MPa required as an artificial bone filling material. On the other hand, when the area ratio c / s exceeds 10, the strength is sufficient, but since the density of pores in the composite structure is low, the growth of osteoblasts is suppressed and a long time is required for healing. It comes to be.

  Furthermore, the Young's modulus of the composite structure can be adjusted by controlling the area ratio between the core material c and the skin material s of the present invention and the porosity of each, and for example, the Young's modulus of living bone is controlled to about 30 GPa. As a result, it becomes more suitable as a bone filling material.

  The composite fiber body 18 may be either a short fiber or a long fiber, and may be linear or have a bent portion as in bulky processing. In addition, the aggregate form of the composite fiber body 18 is not particularly limited, and the single core fiber body 17 may be simply bundled, but may be a woven fabric, a knitted fabric, or a net (mesh) of the single core fiber body 17. . This increases the strength, particularly the strength in the axial direction of the stem portion 4 and the direction perpendicular thereto.

  Although the suitable range of the diameter of the single core fiber body 17 is based also on the kind of constituent metal, it is preferable that it is 0.01-2.0 mm normally, and it is 0.1-1.0 mm. More preferred. When the diameter of the metal fiber 7 is less than 0.01 mm, mixing with the powder becomes difficult at the time of sintering, and when it exceeds 2.0 mm, the strength as a composite with the resin decreases. Further, the number of single-core fiber bodies 17 in the composite fiber body 18 is not particularly limited, but in the case of the single-core fiber bodies 17 having the above-mentioned diameter, it is preferably about 4 million to 100, particularly about 400 to 40000. .

Stem portion 4, in particular, the density of arrangement of the single-core fiber body 7 in stem base 9 is not particularly limited 20-100 million units / cm ^2, particularly preferably set to 100 to 10,000 present / cm ^2. Note that the arrangement density of such metal fibers 7 may be different between the central portion and the peripheral portion of the stem portion 4.

  When the artificial joint 1 is embedded and fixed in, for example, the femur, the stem distal end portion 10 is inserted up to a dense portion (compact bone), and the upper stem base portion 9 is located in the cancellous bone portion. In the cancellous bone, since the bone marrow cavity is enlarged by reaming, the contact area with the outer periphery of the stem base 9 is increased, and therefore, the balance of the bending elastic modulus between the artificial joint 1 and the living bone becomes important. In order to prevent bone destruction and resorption (particularly resorption of the bone in the calcar part) due to excessive bending elastic modulus as seen in the metal stem part, it is above the little trochanter at the time of artificial joint implantation. It is particularly effective to improve the bending elastic modulus of the stem base 9.

  The artificial joint of the present invention is not limited to the above-mentioned artificial bone head, for example, an artificial knee joint, an artificial shoulder joint, an artificial elbow joint, an artificial finger joint, an artificial hip joint, or a part of an acetabular cup embedded in a hipbone It can also be applied to.

(Production method)
Next, a method for producing the artificial joint of the present invention will be described with a suitable example.

  First, a method for producing a composite surface structure that forms the surface of the bone head will be described with reference to the schematic diagram of FIG. 4 taking as an example the case where the core material is alumina and the outer skin material is hydroxyapatite.

  First, an auxiliary agent is appropriately added to and mixed with alumina powder having an average particle diameter of 0.01 to 3.5 μm, and paraffin wax, polystyrene, polyethylene, ethylene-ethyl acrylate, ethylene-vinyl acetate, polybutyl methacrylate, polyethylene are added thereto. An organic binder such as glycol or dibutyl phthalate is added and kneaded to produce a core material molding 21 in a cylindrical shape by a molding method such as press molding, extrusion molding or casting.

  On the other hand, a hydroxyapatite raw material powder having an average particle size of 0.1 to 100 μm is appropriately added with a dispersant, a foaming agent, and an antifoaming agent in addition to the above-mentioned binder and kneaded, and press molding, extrusion molding, or cast molding. Two molded bodies 22 for the outer skin material are produced by a molding method such as the above.

  According to the present invention, when the raw material for the outer shell material molding 22 is mixed in order to control the porosity of the outer skin material 12 to 25% or more, the amount of the organic binder added is 100 to 200 parts by volume, particularly It is desirable to set it as 120-150 volume parts. The hydroxyapatite raw material powder is preferably granulated to have a secondary particle size of 20 to 400 μm, particularly 50 to 200 μm, in terms of producing a uniform pore size and structure.

  Next, a composite molded body 23 in which two outer shell material molded bodies 22 are arranged on the outer periphery of the core material molded body 21 is produced, and the composite molded body 23 is co-extruded (core material molded body 21, And the outer shell material molded body 22 are simultaneously extruded) to produce a single core molded body 24 in which the outer shell material molded body 22 is coated on the outer periphery of the core material molded body 21 and is elongated to a thin diameter (step (step (step)). b)). Further, in order to produce a multi-fiber (filament) type multi-core molded body 25, a plurality of the co-extruded long single-core molded bodies 24 may be converged and co-extruded again. According to this, it is possible to obtain stronger adhesion between the single-core molded bodies 24 in the molded body. (See FIG. 4 (c)).

  In the co-extrusion molding, the elongated single-core molded body 24 or the multi-core molded body 25 has a cross-sectional shape such as a circle, a triangle, a quadrangle, or a hexagon by changing the die. It is also possible to mold into a desired shape.

  In addition, according to the present invention, as shown in FIG. 3B, when the composite fiber body 18 or the composite fiber body 18 in which the single-core fiber bodies 17 are bundled into a sheet shape is formed, as described above. The composite fiber body 18 or the single-core fiber body 17 produced as described above is bundled to form an aggregate molded body. Furthermore, when producing a sheet-like molded body, when a single-core molded body 24 or a multi-core molded body 25 is aligned, it is molded into a desired complex shape in advance using a molding method such as a known rapid prototyping method. It is also possible to do.

  And the said assembly molded object is cut | disconnected in the direction orthogonal to the fiber direction of the said fiber body, and it is set as a sheet-like molded object. In that case, an adhesive such as the above binder is interposed between the aggregated molded body or the single-core fiber body 17 as desired, and pressure is applied to the sheet-shaped molded body by a cold isostatic press (CIP) or the like. However, if necessary, it is possible to roll-roll the sheet-like formed body using a roll or the like.

  Then, after performing a binder removal process in the state which affixed the said molded object on the surface of the molded object separately prepared in order to form a bone head, the said bone head can be produced by baking. As the firing method, vacuum or atmosphere firing, gas pressure firing, hot press, discharge plasma sintering, or the like is used depending on the core material and the skin material. The firing temperature is desirably 750 ° C to 1300 ° C.

  Furthermore, the artificial joint of the present invention can be manufactured by separately preparing a neck portion, a stem portion, and a socket and assembling them together with the bone head.

  A binder and a lubricant were added to the alumina powder having an average particle size of 0.3 μm in a ratio of 85 parts by mass in total and kneaded, and then a cylindrical shaped core material was produced by press molding. On the other hand, after adding and kneading a binder and a lubricant in a ratio of 120 parts by mass in total to a zirconia powder having an average particle size of 0.2 μm, 2 parts of a half-cylindrical outer shell material were formed by press molding. A composite molded body was fabricated in which the core material molded body was coated with a shell material molded body as shown in FIG.

  Next, the single-core formed bodies that are coextruded and stretched in parallel are arranged in parallel to form an aggregate molded body and subjected to CIP pressing, and then the aggregate molded body is 0.3 mm in a direction perpendicular to the fiber direction. A sheet-like molded body was obtained by slicing with a thickness.

  And after sticking this sheet-like molded object on the surface of the compact for the bone head made of separately formed alumina powder and performing a binder removal treatment by heating to 300 to 700 ° C. in 72 hours, The temperature was further raised at a rate of temperature rise of 2.5 ° C./min, calcined in vacuum at 1200 ° C. for 2 hours, and further lowered at 3 ° C./min. Further, the bone head was obtained by polishing the surface portion made of the composite structure of the bone head. The obtained bone head exhibited a good tissue state without cracking or peeling.

  The sheet-like molded body was bonded to the main surface of a simple rectangular parallelepiped-shaped molded body made of the same material as the bone head alumina molded body, and fired under the same conditions as described above.

The obtained sintered body (test piece) was processed into a size of φ10 × 30 mm and subjected to a three-point bending test based on JIS R1601, and the bending strength was measured. Moreover, it was 393 GPa when the Young's modulus based on JISR1602 was also measured using the strain gauge method in that case. Furthermore, when a pin-on-disk test based on JIST0303 was performed, the amount of wear was 0.2 × 10 ⁻¹⁰ mm ² / N.

  Furthermore, the polished cross section of the obtained composite structure was observed with a metal microscope or a scanning electron microscope, and the area ratio c / s between the core material and the skin material was calculated by an image analysis method. c / s was 5. Moreover, when the area ratio of the pores contained in the core material was measured from the structure observation photograph to calculate the porosity in the core material, it was 0.2%. Furthermore, the porosity was calculated by mercury porosimetry, and the porosity of the outer skin material was calculated together with the area ratio of the core material and the outer skin material and the estimation of the porosity of the core material. Was 0.1%.

(Comparative Example 1)
Without sticking the sheet-like molded body of Example 1 to the surface of the bone head, a bone head and a test piece were produced using only a uniform alumina molded body.

As a result of evaluation in the same manner as in Example 1, the three-point bending strength was 660 MPa, the Young's modulus was 396 GPa, and the wear amount by the pin-on-disk test was 0.3 × 10 ⁻¹⁰ mm ² / N.

(Comparative Example 2)
The bone head and test piece of Example 1 were made of zirconia and evaluated in the same manner as in Example 1. As a result, the three-point bending strength was 1200 MPa, the Young's modulus was 200 GPa, and the amount of wear by the pin-on-disk test was 1. It was 5 × 10 ⁻¹⁰ mm ² / N.

It is a schematic perspective view which shows the example of a suitable embodiment of the artificial joint of this invention. It is a schematic sectional drawing of the bone head of FIG. (a) is a principal part enlarged view which shows the surface of the bone head of FIG. 1, (b) is a perspective view of a composite fiber body. It is process drawing for demonstrating the manufacturing method of the composite structure of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Artificial joint 2 Bone head 3 Neck part 4 Stem part 5 Artificial bone 6 Socket stem front-end | tip part 7 Recessed part 9 Stem base part 10 Stem front-end | tip part 11 Core material 12 Outer skin material 13 Composite fiber structure 15 Core material 16 Outer skin material 17 Single core fiber body 18 Composite fiber body 21 Molded body for core material 22 Molded body for skin material 23 Composite molded body 24 Single-core molded body 25 Multi-core molded body 28 Collective molded body

Claims (8)

A bone head having a surface composed of a composite structure in which an outer periphery of a core material made of a first ceramic material regularly arranged is surrounded by a skin material made of a material different from the first ceramic material; An artificial joint in which the bone head of an artificial bone comprising a neck portion following the bone head and a stem portion following the neck portion is fitted in a recess of a socket so as to be rotatable. The artificial joint according to claim 1, wherein the inner surface of the concave portion of the socket is made of the composite structure. The artificial joint according to claim 1 or 2, wherein the core material has a porosity of 5% or less, and the outer skin material has a porosity of 25% or more and has pores communicating in three dimensions. The artificial joint according to any one of claims 1 to 3, wherein the inside of the bone head is made of a uniform tissue formed of the first material constituting the core material. The artificial joint according to claim 4, wherein the thickness of the composite structure tissue on the surface of the bone head is 100 to 500 µm. The artificial joint according to any one of claims 1 to 5, wherein an average diameter of the core material of the composite structure is 10 to 1000 µm, and an area ratio of the core material on the surface of the bone head is 60 to 95 area%. The said neck part consists of a composite fiber body which bundled the single core fiber body which coat | covers the outer periphery of a elongate core material with a skin material, The one in any one of Claim 1 thru | or 6 characterized by the above-mentioned. The described artificial joint. The said stem part consists of the composite fiber body which bundled the single core fiber body which coat | covers the outer periphery of a elongate core material with a skin material, The one in any one of Claim 1 thru | or 6 characterized by the above-mentioned. The described artificial joint.

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