CLIAMS:1. A composite material for producing acetabular cup, comprising:
60 to 80 % by weight of high density polyethylene;
10 to 30 % by weight of hydroxyapatite;
10 to 30 % by weight of alumina; and
0.5 to 5 % by weight of titanate coupling agent.
2. The composite material of claim 1, comprising:
55 to 60 % by weight of high density polyethylene;
15 to 20 % by weight of hydroxyapatite;
15 to 20 % by weight of alumina; and
1 to 2 % by weight of titanate coupling agent.
3. The composite material of claim 1 or 2, wherein said titanate coupling agent is titanium IV, 2-propanolato, trisiso-octadecanoato-O.
4. An acetabular cup, comprising a composite material as claimed in claim 1.
5. Aprocess for producing a composite material, comprising the steps of:
(a) forming a first mixture comprising a coupling agent and a solvent;
(b) admixing said first mixture and one or more ceramic fillers to obtain a second mixture;
(c) wet milling said second mixture to obtain a slurry containing modified ceramic filler particles;
(d) dryingsaid slurry obtained from (c) to obtain dried filler particles; and
(f) dry milling said filler particles obtained from (d) with a high density polyethylene polymer to obtain said composite material.
6. The process of claim 5, wherein said coupling agent is titanate coupling agent.
7. The process of claim 6, wherein said titanate coupling agent is titanium IV, 2-propanolato, trisiso-octadecanoato-O.
8. The process of claim 5, wherein said solvent is isopropyl alcohol.
9. The process of claim 5, wherein said ceramic filler is selected from the group consisting of hydroxyapatite, alumina and mixture thereof.
10. An acetabular cup, comprising a composite material produced by a process as claimed in claim 5.
11. A process for producing an acetabular cup, comprising the steps of:
(a) providing a composite material, comprising:
60 to 80 % by weight of high density polyethylene;
10 to 30 % by weight of hydroxyapatite;
10 to 30 % by weight of alumina; and
0.5 to 5 % by weight of titanate coupling agent
(b) placing said composite material into a mold cavity, designed on the basis of the patient-specific acetabular socket; and
(c) compression molding said composite material to obtain said acetabular up.
12. The process of claim 11, wherein said composite material is compression molded in step (c) into acetabular cups of different clinically relevant sizes using specific mold fabricated through computer-aided design approach.
13. The process of claim 11, wherein said compression molding is performed at a temperature ranging from 160° C to 200° C.
14. The process of claim 13, wherein said compression molding is performed at a temperature of 190° C.
15. The process of claim 11, wherein said compression molding is performed at a pressure ranging from 3 to 7 MPa.
16. The process of claim 15, wherein said compression molding is performed at a pressure of 5 MPa.
,TagSPECI:FIELD OF THE INVENTION

[0001] The present disclosure pertains to a composite material for use in orthopedic prostheses. In particular, the present disclosure pertains to a polymer-ceramic based hybrid composite material for producing acetabular cups for total hip joint replacement, and a process for producing such composite material. The present disclosure also pertains to a method of fabricating patient-specific acetabular cups for total hip replacement.

BACKGROUND OF THE INVENTION

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Total hip joint replacement is an orthopedic procedure in which an orthopedic prosthesis replaces a worn, damaged, or diseased hip joint in a patient. The surgically implanted prosthesis is expected to restore the functions of the replaced hip joint, including support and joint articulation. Orthopedic prosthesis for total hip joint replacement typically includes an acetabular cup, a liner, a femoral head, and a femoral stem. The acetabular cup is a socket implanted into the hip that receives the femoral head having a smooth hemispherical surface adapted for articulation with the acetabular cup. The opposite end of the femoral head is attached to a fitting on the femoral stem, which is attached at its other end to the femur of a patient.
[0004] There have been several composite materials developed in the art using metals/alloys, polymers and ceramics for producing acetabular cups for total hip replacement. Among these, polymer based composite materials have gained increasing importance in recent years. Although biocompatible, the desired physical or mechanical properties of acetabular cups made of known polymeric materials are often unsatisfactory. For instance, the wear of acetabular cups fabricated of ultrahigh molecular weight polyethylene (UHMWPE) introduces wear particles into the surrounding tissues. Such wear debris particles induce inflammation of the host tissues resulting in osteolysis of the bone. Eventually, the prosthesis becomes painfully loose and needs to be replaced, and thereby useful lifetime of the prosthetic joint is decidedly shortened.This would necessitate the patient to undergo revision surgery.
[0005] There is thus a need in the art for a composite material useful for producing orthopedic prosthesis such as, acetabular cups with excellent biocompatibility, compressive strength, flexural strength and wear resistance. Also, there is a need for a method of fabricating patient specific acetabular cups that is reproducible, faster, and more economical than known methods and also eliminates the need of additional machining of the finished product.
[0006] The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

OBJECTS OF THE INVENTION

[0007] It is an object of the present disclosure to provide a composite material for producing acetabular cup that exhibits high level of biocompatibility with surrounding tissues.
[0008] It is a further object of the present disclosure to provide a composite material for producing acetabular cup with highest possible mechanical properties, such as compressive strength and flexural strength as well as wear resistance properties.
[0009] It is another object of the present disclosure to provide a composite material for producing acetabular cup having extended functional lifetime.
[0010] It is another object of the present disclosure to provide a composite material for producing acetabular cup that alleviates problems associated with aseptic loosening of implants and thus extend their useful working life.
[0011] It is another object of the present disclosure to provide a method of producing a composite material useful for producing biocompatible acetabular cups having improved mechanical properties.
[0012] It is another object of the present disclosure to provide asimple and economic method of fabricating acetabular cup for use in total hip replacement.

SUMMARY OF THE INVENTION

[0013] The present disclosure provides a composite material for producing a biocompatible orthopedic prosthesis such as acetabular cup with highest possible mechanical properties, such as compressive strength, flexural strength as well as wear resistance properties, wherein the composite material can include 60 to 80 % by weight of high density polyethylene, 10 to 30 % by weight of hydroxyapatite, 10 to 30 % by weight of alumina and 0.5 to 5 % by weight of titanate coupling agent.
[0014] In a preferred exemplary embodiment, the composite material for producing acetabular cup can be formulated using 55 to 60 % by weight of high density polyethylene, 15 to 20 % by weight of hydroxyapatite, 15 to 20 % by weight of alumina and 1 to 2 % by weight of titanate coupling agent.
[0015] In another aspect, the present disclosure provides a process for producing a composite material, wherein the process can include the following sequential steps, (a) forming a first mixture comprising a coupling agent and a solvent; (b) admixing the first mixture and one or more ceramic fillers to obtain a second mixture; (c) wet milling the second mixture to obtain a slurry containing modified ceramic filler particles; (d) drying the slurry obtained from (c) to obtain dried filler particles; and (f) dry milling the filler particles obtained from (d) with a high density polyethylene polymer to obtain the composite material.
[0016] In an exemplary embodiment, titanium IV, 2-propanolato, trisiso-octadecanoato-O can be used as the coupling agent and isopropyl alcohol can be used as the solvent.
[0017] In a preferred exemplary embodiment, the mold assembly can be fabricated based on the computer-aided design file of a patient-specific acetabular cup.
[0018] In another aspect, the present disclosure provides a process for producing an acetabular cup, wherein the process can include the following sequential steps: (a) providing a composite material, comprising: 60 to 80 % by weight of high density polyethylene, 10 to 30 % by weight of hydroxyapatite, 10 to 30 % by weight of alumina and 0.5 to 5 % by weight of titanate coupling agent; (b) placing the powder feedback into a compression molding press; and (c) compression molding the composite material to obtain the acetabular cup.
[0019] In an exemplary embodiment, the compression molding to obtain dense patient-specific acetabular cup at a temperature ranging from 160° C to 200° C, and a pressure ranging from 3 to 7 MPa.
[0020] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification.
[0022] FIG. 1 is an enlarged and exploded perspective view showing components of a typical prosthetic total hip joint.
[0023] FIG. 2a illustrates preferred geometry of an acetabular cup formed of the composite material of the present disclosure.
[0024] FIG. 2b is a top plan view of an acetabular cup formed of the composite material of the present disclosure.
[0025] FIG. 2c is a bottom plan view of the acetabular cup of FIG. 2b.
[0026] FIG. 2d is a plan and perspective view of the acetabular cup of FIG. 2b with femoral head.
[0027] FIG. 3a is an exemplaryexploded perspective view of a compression molding apparatus in accordance with embodiments of the present disclosure.
[0028] FIGs.3b-e are exemplary plan and perspective view of top plate, bottom plate, cavity mold, core mold of the molding apparatus 3a, respectively.
[0029] FIG. 3f illustrates plan and perspective view of the mold assemblyin accordance with embodiments of the present disclosure.
[0030] FIGs.4a-b are exemplary illustrations of fully assembled compression molding apparatus in accordance with embodiments of the present disclosure.
[0031] FIGs. 5a - c are exemplary graphs illustrating wear rates of high density polyethylene (HDPE)-based composites filled with different amounts of ceramic fillers, against alumina, zirconia and steel counterbody, respectively.
[0032] FIG. 6a is schematic of fretting mode (ball-on-flat) measurement of wear resistance of a flat sheet formed of the composite materialof the present disclosure.
[0033] FIGs. 6b - d are exemplary graphs illustrating relationship between hardness and wear rate of a flat sheet formed of the composite material of the present disclosure against alumina, zirconia and steel counterbody, both in air and simulated body fluid (SBF) environment.
[0034] FIG. 7a is a scanning electron microscope (SEM) image illustrating Saos-2 (Sarcoma osteogenic) cells adhesion and growth on HDPE-20%HA-20%Al2O3, in accordance with embodiments of the present disclosure.
[0035] FIG. 7b is an exemplary MTT assay graph showing the cell viability/proliferation onthe composite material at different incubation periods, in accordance with embodiments of the present disclosure.
[0036] FIGs.8a - b are digital camera images showing a rabbit’s tibia zone with cylindrical long segmental defect along with an implant formed of the composite material of the present disclosure, before implantation and after implantation respectively.
[0037] FIG. 8c is an X-ray radiograph of a rabbit’s tibia after 14 weeks of implantation of a prosthesis formed of the composite material of the present disclosure.
[0038] FIG. 8d is an optical microscopic image of a rabbit’s tibia after 14 weeks of implantation of a prosthesis formed of the composite material of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0039] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0040] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0041] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0042] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0043] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
[0044] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0045] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0046] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0047] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0048] In one aspect, the present disclosure provides a composite material for producing a biocompatible orthopedic prosthesis such as, acetabular cup with highest possible mechanical properties, such as compressive strength, flexural strength as well as wear resistance properties. The composite material of the present disclosure can exhibit ultra low wear as a consequence of joint articulation over an extended service life or duty cycle. According to embodiments, the composite material can include 60 to 80 % by weight of high density polyethylene (HDPE), 10 to 30 % by weight of hydroxyapatite (Ca10(PO4)6(OH)2), 10 to 30 % by weight of alumina (Al2O3) and 0.5 to 5 % by weight of titanate coupling agent.
[0049] Hydroxyapatite and alumina are ceramic fillers that can be used in the form of ground particles, wherein the particle size may preferably range from 500 µm to 1.0 µm, more preferably from 50 µm to 0.1 µm. Hydroxyapatite and alumina particles can be homogeneously distributed in the HDPE polymer to facilitate shaping or fabrication of the composite material with a better combination of mechanical properties.
[0050] The volume % of the ceramic fillers in the composite material can be optimized in such a way that the composite material has desired modulus and sufficient moldability to shape or fabricate into an acetabular cup. It may be advantageous for the composite material of the present disclosure to contain a total of 40% by weight of hydroxyapatite and/or alumina particles.
[0051] The titanate coupling agent can facilitate formation of a covalent linkage between the polymer matrix and the filler particles and thereby, through the use of titanate coupling agent, improves the polymer-filler interface. The ceramic fillers need to be necessarily treated with the titanate coupling agent before its incorporation into the polymer matrix. In a preferred embodiment, the titanate coupling agent used in the preparation of the composite material can be titanium IV, 2-propanolato, trisiso-octadecanoato-O.
[0052] The composite material of the present disclosure can be optimally custom formulated with different weight ratios of the HDPE polymer and the ceramic fillers to achieve desired mechanical properties such as structural strength, toughness and wear resistance. According to preferred embodiments, a markedly improved composite material can be formulated using 55 to 60 % by weight of high density polyethylene, 15 to 20 % by weight of hydroxyapatite, 15 to 20 % by weight of alumina and 1 to 2 % by weight of titanate coupling agent.
[0053] The composite material of the present disclosure, if desired, may further include additional biocompatible components, including biocompatible binders, fibers, plasticizers, biocide agents, biostatic agents, surface active agents, bio-molecules, bioactive agents, etc, prior to, during, or after fabrication of the composite material.
[0054] The composite material of the present disclosure can be made by bonding a HDPE polymer to hydroxyapatite and alumina filler particles through titanate coupling agent. The filler particles may preferably be treated with the titanate coupling agent to link the coupling agent to the filler particles. The filler particles attached to the coupling agent can then be linked to the polymer matrix through covalent interactions to produce the composite material.
[0055] According to preferred embodiments, the coupling agent may preferably be treated with a solvent system to lower its viscosity, prior to be admixed and wet-milled with the filler particles. Suitable solventsthat can be used to modify the viscosity of the coupling agent can include, but not limited to alcohol. The ratio of coupling agent to solvent may preferably be 1:10, and it may be varied to achieve desired viscosity of the coupling agent. After treating with a solvent, the coupling agent can be wet milled with the filler particles for sufficient time until the filler particles are substantially uniformly blended with the "coupling agent-solvent" mixture.
[0056] The wet milled mixture (in the form of a slurry) containing ceramic filler particles linked to the coupling agent may be dried to remove the solvent to obtain dried modified ceramic filler particles (i.e. coupling agent-ceramic filler conjugate).The wet milled mixture may be dried in air at room temperature or in a heating oven. Oven drying can be performed in a temperature range of 40-110 °C for duration of about 10 minutes to 72 hours. The drying time can vary depending upon the type of alcohol solvent used.
[0057] The dried slurry may be ground into discrete particles using a mill or any grinding device known in the art, or the dried slurry may be directly milled with the polymer in the subsequent step. The dry blending can be performed at a temperature lower than the melting point of the HDPE polymer and continued until the ceramic filler particles are substantially uniformly dispersed in the polymer matrix. As used herein, the term "dry blending" refers to blending in the absence of any solvent and at a temperature lower than the melting point of the HDPE polymer.The process can facilitate obtaining a high volume % of filler content, preferably 40% filler content to reinforce the HDPE polymer and thereby enhance its physical properties.
[0058] According to preferred embodiments, the composite material can be produced by a process that can include the following sequential steps, (a) forming a first mixture comprising a coupling agent and a solvent; (b) admixing the first mixture and one or more ceramic fillers to obtain a second mixture; (c) wet milling the second mixture to obtain a slurry containing modified ceramic filler particles; (d) drying the slurry obtained from (c) to obtain dried filler particles; and (f) dry milling the filler particles obtained from (d) with a high density polyethylene polymer to obtain the composite material.
[0059] In apreferred embodiment, titanium IV, 2-propanolato, trisiso-octadecanoato-O can be mixed with isopropyl alcohol in 1:10 ratio to produce a mixture which in turn can be wet milled with hydroxyapatite and alumina particles to form a slurrycontaining modified ceramic filler particles.
[0060] In yet another aspect, the present disclosure provides a process for producing an acetabular cup from the composite material, wherein the process can include a number of sequential steps: (a) providing a composite material, comprising: 60 to 80 % by weight of high density polyethylene, 10 to 30 % by weight of hydroxyapatite, 10 to 30 % by weight of alumina and 0.5 to 5 % by weight of titanate coupling agent; (b) placing the composite material into a compression molding press; and (c) compression molding the composite material to obtain the acetabular cup.
[0061] The composite material can be converted into acetabular cup by placing the composite material in a compression mold defining a desired near net-shape and applying heat and pressure in the mold to form the acetabular cup. According to embodiments, acetabular cups can be fabricated in a shape or condition that is satisfactory for use in a prosthetic implant upon removal of the acetabular cup from the compression molding die without requiring any further manipulation or machining. FIGs. 3a-f and 4a-b illustrate preferred configurations of a molding apparatus that can be utilized to fabricate patient-specific acetabular cups from the composite material.
[0062] In a preferred exemplary embodiment, the mold assembly may be fabricated based on computer-aided design file of a patient-specific acetabular cup.
[0063] In a more specific embodiment, an acetabular socket can be shaped to different clinically relevant sizes, e.g. socket with outer diameter of 62 mm and inner diameter of 36 mm for orthopedic applications, depending on the patient’s need and this can be accomplished by adopting computer-aided design approach to fabricate specific mold.
[0064] The molding process parameters, such as, temperature and pressure can be optimized depending upon the geometry of the acetabular cup produced. FIGs. 2a -d illustrate preferred geometry, shape and size of an acetabular cup in accordance with embodiments of the present disclosure. FIGs. 2a -d are purely exemplary and the acetabular cup may take any desired geometry, shape, size and thickness to suite configuration of matching parts.
[0065] In an exemplary embodiment, the compression molding can be effectiveat a temperature ranging from 160°C to 200°C, and a pressure ranging from 3 to 7 MPa. In a more preferred embodiment, the compression molding can be effectiveat 190°C under 5 MPa pressure.
[0066] The composite material in accordance with embodiments of the present disclosure can also be used to fabricate other components of a total hip joint, such as a liner for a metal back porous coated acetabular cup. Further, the composite material can be utilized to compose both cemented and non-cemented orthopedic prostheses.

EXAMPLES
[0067] The present disclosure is further explained in the form of the following examples. However, it is to be understood that the foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.

Example 1: Preparation of composite material of the present disclosure
[0068] 8 gm of titanium IV, 2-propanolato, trisiso-octadecanoato-O was mixed with 40 ml of isopropyl alcohol at room temperature to produce a mixture. 40 gm of hydroxyapatite and 40 gm of alumina was combined and added into the above mixture and wet milled at room temperature to form an uniform slurry. The slurry was dried at 50 °C at oven for 60 minutes to yield dried particles. Thus obtained dried particles were then ball milled with 400 gm of high density polyethylene polymer for 120 minutes at room temperature using horizontal laboratory ball mill. The ball mill, powered with 1/2 H.P. geared motor, was equipped with drum that rotated with 30 rpm. The drum was filled with 12 steel balls of 3/4 inch diameter to crush the powder materials. The drum was sealed to avoid any interaction of material with outer atmosphere. Thus obtained dried particles from ball mill were characterized as 60 wt.% HDPE-20 wt.% hydroxyapatite-20 wt.% alumina-2% coupling agent. Thus produced composite material was used for the compression molding.

Example 2: Fabrication of acetabular cup using composite material of the present disclosure
[0069] A compression molding apparatus was equipped with a heater. Suitable configurations of compression molding apparatus have been shown in 3a and 4a-b. FIGs. 3b-e illustrate preferred configuration of top plate, bottom plate, cavity mold, core mold of the molding apparatus 3a, respectively. FIG. 3f illustrates plan and perspective view of the mold assembly. The heater was heated to 190°C. Approximately 30 gms of composite material as prepared in example 1 was charged into the cavity of the molding apparatus. The cavity was closed and the composite material was allowed to melt for 5 mins and subsequently compressed at 5 MPa pressure. Then, the heater was switched off and the mold was allowed to cool to 100°C. After cooling, the acetabular cup was ejected from the mold.The excess material was removed from the edges of cup as scrap formed in between core and cavity mold.
[0070] Mechanical and biocompatibility tests were performed to determine the performance of the acetabular cup as obtained in example 2. FIGs. 5a - c illustrate wear rates of the acetabular cup formed of the composite material (HDPE-20 wt.%hydroxyapatite-20 wt.% alumina) against alumina, zirconia and steel based femoral heads respectively. As shown in FIGs. 5a - c, the wear resistance of the composite material have been compared with high density polyethylene (HDPE) or those filled with different amounts of ceramic fillers.FIG. 6a illustrates fretting mode (ball-on-flat) measurement of wear resistance of a flat sheet formed of the composite material (HDPE-20 wt.% hydroxyapatite-20 wt.% alumina). FIGs. 6b - d illustrate friction and fretting wear of a flat sheet formed of the composite material against alumina, zirconia and steel counterbody, both in air and simulated body fluid (SBF) environment. FIG. 7a provides a scanning electron microscope (SEM) image illustrating Saos-2 ("Sarcoma osteosarcoma", a cancer cell line) cells adhesion and growth on HDPE-20 wt.%HA-20 wt.% Al2O3. The MTT assay results, as shown in FIG. 7b illustrates cell viability/proliferation of the composite material (HDPE-20 wt.% hydroxyapatite-20 wt.% alumina) at different incubation periods. FIGs. 8a - b are digital camera images showing a rabbit’s tibia zone with cylindrical long segmental defect along with an implant madeof the composite material (HDPE-20 wt.% hydroxyapatite-20 wt.% alumina) before implantation and after implantation, respectively. FIG. 8c is an X-ray radiograph of a rabbit’s tibia after 14 weeks of implantation of a prosthesis formed of the composite material (HDPE-20 wt.% hydroxyapatite-20 wt.% alumina). FIG. 8d is an optical micrograph of a rabbit’s tibia after 14 weeks of implantation of a prosthesis made of the composite material (HDPE-20 wt. % hydroxyapatite-20 wt.% alumina).
ADVANTAGES OF THE PRESENT INVENTION
[0071] xThe present disclosure provides a composite material for producing acetabular cups with highest possible mechanical properties, such as compressive strength, flexural strength as well as wear resistance properties.
[0072] The present disclosure provides a composite material for producing acetabular cup with extended functional lifetime, thus minimizing the need for revision surgery.
[0073] The present disclosure provides a composite material for producing acetabular cup, wherein the acetabular cup exhibits relatively low frictional engagement with femoral head.
[0074] The present disclosure provides a composite material for producing acetabular cup that facilitates substantial reduction of friction and wear debris of articulating joint elements under dynamic load, and thereby reducing osteolysis and inflammatory reactions.
[0075] The present disclosure provides a composite material for producing acetabular cup, wherein the acetabular cup exhibits excellent durability and is capable of maintaining high wear resistance over a long period of time.
[0076] The present disclosure provides a method of fabricating acetabular cup that is reproducible, faster, and more economical than known methods.
[0077] The present disclosure provides a method of fabricating acetabular cup that eliminates the need of additional machining of the finished product.