Artificial femoral ball head with multi-layer shell core composite structure

Abstract

An artificial femoral ball head having a multilayer shell-core composite structure includes a spherical shell layer, a transition layer and an inner core. The inner core is made of a toughened ceramic, the spherical shell layer is made of a ceramic material, and the transition layer is made of a composite material comprising materials of the inner core and the spherical shell layer. The artificial femoral ball head is manufactured through sintering a green body of successively stacked layers of the spherical shell layer, the transition layer and the inner core, and the green body of successively stacked layers is obtained through a powder co-injection molding process. The spherical shell layer of the artificial femoral head has a high rigidness, corrosion-proof and wear-proof performance. The inner core of the artificial femoral head has a high toughness and shockresistant performance.

Claims

1. An artificial femoral ball head (2) having a multilayer shell-core composite structure, comprising: a spherical shell layer (2-1), a transition layer (2-5) and an inner core (2-2); wherein the inner core (2-2) is made of a toughened ceramic material, the spherical shell layer (2-1) is made of a ceramic material, the transition layer (2-5) is made of a composite material comprising materials of the inner core (2-2) and the spherical shell layer (2-1); wherein the ceramic material of the spherical shell layer (2-1) comprises high-purity and superfine alumina ceramic, the composite material of the transition layer (2-5) comprises ZrO.sub.2(3Y.sub.2O.sub.3) with 80 vol. % Al.sub.2O.sub.3, and the toughened ceramic material of the inner core (2-2) comprises ZrO.sub.2(3Y.sub.2O.sub.3) with 20 vol. % Al.sub.2O.sub.3; wherein the artificial femoral ball head (2) is manufactured through sintering a green body of successively stacked layers of the spherical shell layer (2-1), the transition layer (2-5) and the inner core (2-2), and the green body of successively stacked layers of the spherical shell layer (2-1), the transition layer (2-5) and the inner core (2-2) is obtained through a powder co-injection molding process.

2. The artificial femoral ball head (2) according to claim 1, wherein the transition layer (2-5) has a single-layer or multi-layer structure.

3. The artificial femoral ball head (2) according to claim 1, wherein the spherical shell layer (2-1) has a thickness ranging from 0.1 mm to 20 mm.

4. The artificial femoral ball head (2) according to claim 1, wherein a Vickers-hardness of the spherical shell layer (2-1) is greater than 1900.

5. The artificial femoral ball head (2) according to claim 1, wherein a fracture toughness of the inner core (2-2) is greater than 10 MPa.Math.m.sup.1/2.

6. The artificial femoral ball head (2) according to claim 1, wherein a high-purity and superfine alumina powder employed to form both the spherical shell layer (2-1) and the transition layer (2-5) has a purity greater than 99.9 wt. % and a particle size ranging from 0.5 m to 10 m; and a ZrO.sub.2 powder employed to form both the inner core (2-2) and the transition layer (2-5) has a purity greater than 99.8 wt. % and a particle size ranging from 0.5 m to 10 m.

7. The artificial femoral ball head (2) according to claim 1, wherein the transition layer (2-5) has a thickness ranging from 0.1 mm to 20 mm.

8. The artificial femoral ball head (2) according to claim 1, wherein the inner core (2-2) has a thickness ranging from 0.1 mm to 20 mm.

9. The artificial femoral ball head (2) according to claim 1, wherein an interface (2-8) between the spherical shell layer (2-1) and the transition layer (2-5) or an interface (2-9) between the transition layer (2-5) and the inner core (2-2) comprises a cylindrical surface.

10. The artificial femoral ball head (2) according to claim 1, wherein the transition layer (2-5) has a uniform thickness along radial directions.

11. The artificial femoral ball head (2) according to claim 1, wherein the artificial femoral ball head (2) is a one-piece component.

12. The artificial femoral ball head (2) according to claim 1, wherein the artificial femoral ball head (2) has an exterior convex surface (2-4), an interior concave surface (2-6), and a bottom surface (2-7) connecting an edge of the exterior convex surface (2-4) and an edge of the interior concave surface (2-6), the interior concave surface (2-6) defines a bore-hole (2-3), and the bore-hole (2-3) has an opening surrounded by the bottom surface (2-7); and the spherical shell layer (2-1), the transition layer (2-5) and the inner core (2-2) are successively stacked between the exterior convex surface (2-4) and the interior concave surface (2-6).

13. The artificial femoral ball head (2) according to claim 12, wherein the spherical shell layer (2-1) fully covers the transition layer (2-5) and the inner core (2-2) at the bottom surface (2-7), an interface (2-8) between the transition layer (2-5) and the spherical shell layer (2-1) and an interface (2-9) between the transition layer (2-5) and the inner core (2-2) terminate on the interior concave surface (2-6).

14. The artificial femoral ball head (2) according to claim 12, wherein the bore-hole (2-3) is taper shaped.

15. The artificial femoral ball head (2) according to claim 12, wherein the bore-hole (2-3) is configured to receive a femoral stem.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 and FIG. 2 schematically illustrate exploded perspective views of two kinds of artificial hip joints composed of multilayer shell-core composite structural components according to embodiments of the present disclosure;

(2) FIG. 3 and FIG. 4 schematically illustrate part cross-sectional views of two kinds of artificial acetabulums having a multilayer shell-core composite structure which respectively have a multiple-head convex screw thread and a multiple-head concave screw thread disposed thereon according to embodiments of the present disclosure;

(3) FIG. 5 and FIG. 6 schematically illustrate part cross-sectional views of two kinds of artificial acetabulums having a multilayer shell-core composite structure which respectively have a multiple-head convex screw thread and a multiple-head concave screw thread disposed thereon according to embodiments of the present disclosure;

(4) FIG. 7 to FIG. 11 schematically illustrate cross-sectional views of five kinds of artificial femoral ball heads composed of multilayer shell-core composite structural components according to embodiments of the present disclosure; and

(5) FIG. 12 schematically illustrates a flow chart of a method for manufacturing an artificial femoral ball head according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

(6) Hereinafter, the disclosure will be described in detail with several embodiments in conjunction with the accompanying drawings.

(7) FIG. 1 and FIG. 2 schematically illustrate exploded perspective views of two kinds of artificial hip joints composed of multilayer shell-core composite structural components according to embodiments of the present disclosure. Both of the two kinds of artificial hip joints include an artificial acetabulum 1 having a multilayer shell-core composite structure and an artificial femoral ball head 2 having a multilayer shell-core composite structure. The artificial acetabulum 1 has two kinds of structures: multiple-head convex screw thread (shown in FIG. 1) or multiple-head concave screw thread (shown in FIG. 2) disposed on a surface of a shell 1-4, which may be selected based on actual requirements. The artificial acetabulum 1 and the artificial femoral ball head 2 constitute a movable joint, thanks to a concave spherical surface of an artificial acetabular liner layer 1-1 and a convex spherical surface of an artificial femoral ball head shell layer 2-1 being fit slidingly. The concave spherical surface of the artificial acetabular liner layer 1-1 and the convex spherical surface of the artificial femoral ball head shell layer 2-1 are processed into mirror surfaces and can slide freely relative to each other. When the artificial hip joint is implanted, the artificial acetabulum 1 is fixed at the location of the original acetabulum of the human body, and the artificial femoral ball head 2 is fixed at a neck of the artificial femoral stem which is matched with femoral medullary cavity. Then, the artificial femoral ball head 2 is mounted in the artificial acetabular liner layer 1-1, so as to achieve physical function of the artificial hip joint.

Embodiment One

(8) An artificial acetabulum having a multilayer shell-core composite structure in an artificial hip joint composed of multilayer shell-core composite structural components, includes an acetabular liner layer 1-1 made of high-purity and superfine alumina ceramic, a transition layer 1-2 made of alumina-based (25 vol % niobium) cermet, a transition layer 1-3 made of alumina-based (65 vol % niobium) cermet, and a metal shell layer 1-4 made of niobium porous. Multiple-head convex screw thread (shown in FIG. 3) or multiple-head concave screw thread (shown in FIG. 4) may be disposed on a surface of the shell layer 1-4, which may be selected based on actual requirements. The high-purity and superfine alumina powder may have a purity greater than 99.9 wt %, and have a particle size ranging from 0.5 m to 10 m. The niobium metal powder may have a purity greater than 99.8 wt %, and have a particle size ranging from 0.5 m to 20 m. All of the acetabular liner layer 1-1 made of high-purity and superfine alumina ceramic, the transition layer 1-2 made of alumina-based (25 vol % niobium) cermet, the transition layer 1-3 made of alumina-based (65 vol % niobium) cermet, and the metal shell layer 1-4 made of niobium porous are injection molded into one piece layer by layer using multi-material powder co-injection molding. The liner layer 1-1, the transition layers 1-2 and 1-3, and the shell layer 1-4 are overlapped parallelly at the edges of an acetabulum opening.

Embodiment Two

(9) An artificial acetabulum having a multilayer shell-core composite structure in an artificial hip joint composed of multilayer shell-core composite structural components, includes an acetabular liner layer 1-1 made of high-purity and superfine alumina ceramic, a transition layer 1-2 made of Ti6Al4V-60 vol. % Al.sub.2O.sub.3, a transition layer 1-3 made of Ti6Al4V-20 vol. % Al.sub.2O.sub.3, and a shell layer 1-4 made of Ti6Al4V. Multiple-head convex screw thread (shown in FIG. 5) or multiple-head concave screw thread (shown in FIG. 6) may be disposed on a surface of the shell layer 1-4, which may be selected based on actual requirements. The high-purity and superfine alumina powder may have a purity greater than 99.9 wt %, and have a particle size ranging from 0.5 m to 10 m. The Ti6Al4V powder may have a purity greater than 99.0 wt %, and have a particle size ranging from 5 m to 25 m. All of the acetabular liner layer 1-1 made of high-purity and superfine alumina ceramic, the transition layer 1-2 made of Ti6Al4V-60 vol. % Al.sub.2O.sub.3, the transition layer 1-3 made of Ti6Al4V-20 vol. % Al.sub.2O.sub.3, and the shell layer 1-4 made of Ti6Al4V are injection molded into one piece layer by layer using multi-material powder co-injection molding. The acetabular liner layer 1-1 made of high-purity and superfine alumina ceramic fully covers the transition layers 1-2 and 1-3 and the shell layer 1-4.

Embodiment Three

(10) An artificial femoral ball head 2 having a multilayer shell-core composite structure in an artificial hip joint composed of multilayer shell-core composite structural components, includes a spherical shell layer 2-1 made of high-purity and superfine alumina ceramic, a transition layer 2-5 made of ZrO.sub.2 (3Y.sub.2O.sub.3) 80 wt. % Al.sub.2O.sub.3 toughened ceramic, and an inner core 2-2 made of ZrO.sub.2 (3Y.sub.2O.sub.3) 20 wt. % Al.sub.2O.sub.3 toughened ceramic. The high-purity and superfine alumina powder may have a purity greater than 99.9 wt %, and have a particle size ranging from 0.5 m to 10 m. The ZrO.sub.2 powder may have a purity greater than 99.8 wt %, and have a particle size ranging from 0.5 m to 10 m. All of the spherical shell layer 2-1 made of high-purity and superfine alumina ceramic, the transition layer 2-5 made of ZrO.sub.2 (3Y.sub.2O.sub.3) 80 wt. % Al.sub.2O.sub.3 toughened ceramic, and the inner core 2-2 made of ZrO.sub.2 (3Y.sub.2O.sub.3) 20 wt. % Al.sub.2O.sub.3 toughened ceramic are injection molded into one piece layer by layer using multi-material powder co-injection molding. Five kinds of multilayer shell-core composite structures are illustrated in FIG. 7 to FIG. 11, which may be selected based on actual requirements.

(11) According to embodiments shown in FIGS. 9, 10 and 11, the artificial femoral ball head 2 may have an exterior convex surface 2-4, an interior concave surface 2-6, and a bottom surface 2-7 connecting an edge of the exterior convex surface 2-4 and an edge of the interior concave surface 2-6, the interior concave surface 2-6 defines a bore-hole 2-3, and the bore-hole 2-3 has an opening surrounded by the bottom surface 2-7. The spherical shell layer 2-1, the transition layer 2-5 and the inner core 2-2 are successively stacked between the exterior convex surface 2-4 and the interior concave surface 2-6. A convex surface of the spherical shell layer 2-1 serves as the exterior convex surface 2-4, a concave surface of the inner core 2-2 serves as the interior concave surface 2-6, and a planar bottom surface of the spherical shell layer 2-1 serves as the bottom surface 2-7. At the bottom surface 2-7 surrounding the opening, the spherical shell layer 2-1 fully covers the transition layer 2-5 and the inner core 2-2, an interface 2-8 between the transition layer 2-5 and the spherical shell layer 2-1 and an interface 2-9 between the transition layer 2-5 and the inner core 2-2 terminate at the interior concave surface 2-6.

(12) According to embodiments shown in FIGS. 7 and 9, an interface 2-8 between the spherical shell layer 2-1 and the transition layer 2-5 and an interface 2-9 between the transition layer 2-5 and the inner core 2-2 may be a curved surface, for example, a spherical surface. According to embodiments shown in FIGS. 8, 10 and 11, an interface 2-8 between the spherical shell layer 2-1 and the transition layer 2-5 and an interface 2-9 between the transition layer 2-5 and the inner core 2-2 may include a cylindrical surface and a curved surface.

(13) According to embodiments shown in FIG. 7, the transition layer 2-5 may have a nonuniform thickness along radial directions. According to embodiments shown in FIGS. 8-11, the transition layer 2-5 may have a uniform thickness along radial directions.

(14) Referring to FIG. 12, a method for manufacturing an artificial femoral ball head according to an embodiment of the present disclosure may include: (1) preparing feedstocks for powder injection molding which include high-purity and superfine aluminia powder, toughened ceramic compound powder of ZrO.sub.2 (3Y.sub.2O.sub.3) 80 wt. % Al.sub.2O.sub.3, and toughened ceramic powder of ZrO.sub.2 (3Y.sub.2O.sub.3) 20 wt. % Al.sub.2O.sub.3. The prepared powders are mixed with polyoxymethylene resin binder (89 wt. % polyformaldehyde, 5 wt. % high density polyethylene and 6 wt. % other binding assistant agent). The mixture is then mixed at a temperature of about 180 C. for about two and a half hours, so that a polyaldehydes system is obtained, which has a solid loading greater than 55 vol. %.

(15) (2) by using three sets of moulds, performing injection molding successively to obtain an inner core, a transition layer and a spherical shell layer, so as to obtain a green body of the femoral ball head having a multilayer shell-core composite structure. The temperature of the injection may be in a range from about 170 C. to 180 C., the pressure of the injection may be in a range from about 110 MPa to 130 MPa, the dwell pressure may be in a range from about 70 MPa to 80 MPa, and the cooling time may be in a range from about 3 minutes to 4 minutes.

(16) (3) if necessary, performing surface finishing on a surface of the spherical shell and a bore-hole in the inner core of the green body of the femoral ball head having a multilayer shell-core composite structure.

(17) (4) performing catalytic debinding on the green body of the femoral ball head having a multilayer shell-core composite structure in an atmosphere furnace with a temperature ranging from about 110 C. to about 120 C., where hydrogen nitrate is used as a debinding catalyst, nitrogen is used as a debinding carrier gas, and the catalytic debinding may last for about 5 hours.

(18) (5) after being catalytically debound, sintering the green body of the femoral ball head having a multilayer shell-core composite structure in a controlled atmosphere Hot Isostatic Pressing (HIP) furnace, where the sintering may be performed at a temperature of about 1450 C., a pressure of about 35 MPa, and the soaking time is about 1 hour.

(19) (6) according to size requirements of the products, performing micro-machining on the surface of the spherical shell and the bore-hole of the sintered body.

(20) (7) then, polishing the surface of the spherical shell by using SiC ultrafine powder and diamond abrasive paste, to obtain the femoral ball head having a multilayer shell-core composite structure, which has a smooth finished surface, and a proper dimensional coordination between the bore-hole and the femoral stem.

Embodiment Four

(21) An artificial femoral ball head 2 having a multilayer shell-core composite structure in an artificial hip joint composed of multilayer shell-core composite structural components, includes a spherical shell layer 2-1 made of high-purity and superfine alumina ceramic, a transition layer 2-5 made of Al.sub.2O.sub.3-30 vol % (Ce-TZP) toughened ceramic, and an inner core 2-2 made of Al.sub.2O.sub.3-70 vol % (Ce-TZP) toughened ceramic. The high-purity and superfine alumina powder may have a purity greater than 99.9 wt %, and have a particle size ranging from 0.5 m to 10 m. The ZrO.sub.2 powder may have a purity greater than 99.8 wt %, and have a particle size ranging from 0.5 m to 10 m. All of the spherical shell layer 2-1 made of high-purity and superfine alumina ceramic, the transition layer 2-5 made of Al.sub.2O.sub.3-30 vol % (Ce-TZP) toughened ceramic, and the inner core 2-2 made of Al.sub.2O.sub.3-70 vol % (Ce-TZP) toughened ceramic are injection molded into one piece layer by layer using multi-material powder co-injection molding. Five kinds of multilayer shell-core composite structures are illustrated in FIG. 7 to FIG. 11, which may be selected based on actual requirements. The specific structures of the artificial femoral ball head 2 according to embodiments shown in FIG. 7 to FIG. 11 may refer to the aforementioned embodiment, which will not be described in detail herein.

(22) Although the present disclosure has been disclosed above with reference to preferred embodiments thereof, it should be understood that the disclosure is presented by way of example only, and not limitation. Those skilled in the art can modify and vary the embodiments without departing from the spirit and scope of the present disclosure.