Title of Invention	AN OSTEOCONDUCTIVE COMPOSITE MATERIAL
Abstract	An osteoconductive composite material for use as a bone substitute, having a tensile strength of 3-30 MPa and elongation at break of 2 to 25%, characterized in that it comprises a bloceramic material incorporated into a polymer matrix having a weight average molecular weight of 10,000 to 10,00,000.

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cl This invention relates to osteoconductive composite materials and a process for the preparation thereof. This invention further relates to a bioceramic filled polymeric composite for bone substitute applications, and a process for the preparation thereof. BACKGROUND OF THE INVENTION Bioceramic in the form of granules, blocks etc. has been used for the treatment of bone defects. Numerous bone substitutes are disclosed In the art. According to EP 1374922 is disclosed polymer bioceramic composite for orthopedic applications and method of manufacture thereof. The bone substitute comprises a porous ceramic matrix having pores and a polymer moulded into the pores by squeeze-flow compression moulding. Further, US 5947893 discloses a biodegradable composition onto and into a micro-porous surface of a metal or joint replacement prosthesis. EP 1277450 also discloses a prosthetic implant, and the process of preparation thereof. The patent refers to "composite scaffold with post anchor for the repair and regeneration of tissue" herein the composite is a foamed polymer-ceramic composite and is manufactured by pouring the polymer solution to the fabricated ceramic. The ceramic body with holes and a fixed set of pores Is provided and the anchoring post is introduced through the hole in the ceramic body such that the scaffold support contacts the ceramic body. Thereafter, the support scaffold and ceramic body are placed In contact with the polymer solution whereby, the polymer solution partially infuses into the pores in the ceramic body and foaming the polymer solution. The prior art discloses process ehere the polymer or polymer-drug composition are infused or impregnated into the ceramic body having pores therein. This infusion is partial and is not homogeneous mixture. Therefore, there are problems in handling them because of brittle nature and contouring difficulties. For many of the bone substitute applications, bioceramic Incorporated into a polymeric matrix would be preferred because these materials could alleviate the above mentioned difficulties. There is always demand for bone substitutes because of accidents, trauma, etc. The major disadvantage associated with the currently available metal Implants Is their modulus mismatch, and that of ceramic materials are their brittle nature and that of polymeric materials are their inertness. The bioceramic used is hydroxyapatlte Caio(PO4)6(OH)2 or other bloceramtcs, glasses or glass ceramics or their mixtures. To qualify further these may be prepared either by spray drying or freeze drying technique. OBJECTS OF THE INVENTION It is therefore an object of this invention to propose an osteoconductive composite which is pliable and overcomes contouring difficulties. It is a further object of this invention to propose an osteoconductive composite, which is not brittle and allows easy shaping into desired shapes. Y^ another object of this invention is to propose an osteoconductive composite which overcomes the drawbacks associated with the prior art. These and other objects of the Invention will be more apparent from the ensuing description. At the outset of the description, which follows, it is to be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only an exemplary embodiment and the teachings of the invention is not intended to be taken restrictively. BRIEF DESCRIPTION OF THE INVENTION This according to this invention is provided an osteoconductive composite material for use as a bone substitute, having a tensile strength of 3-30 MPa and elongation at break of 2 to 25%, characterized in that it comprises a bioceramic material incorporated into a polymer matrix having a weight average molecular weight of 10,000 to 10,00,000. According to this invention Is further provided a process for the preparation of an osteoconductive composite material as claimed in claim 1, comprising melting a polymer followed by adding a bioceramic material thereto and mixing followed by spreading the mix to obtain a sheet and moulding the same to obtain the composite material. In accordance with this invention, the osteoconductive composite material consists of a discontinuous phase of bioceramic and a continuous phase of a polymeric material, by appropriately incorporating the bioceramic Into a suitable polymeric matrix preferably a thermoplastic. The co-polymers of ethylene desirably with a polar co-monomer like vinyl acetate or acyiic acid or the like are used. The second monomer desirably a polar co-monomer can be varied in weight percentage say from 6%-60%, preferably in the range 12-45%. The bioceramic material can be varied from 10-90 volume %, especially from 20-70%. The polymeric matrix has a weight average molecular weight of 10,000 to 10,00,000, preferably greater than 50,000 but less than 5,00,000 the polymer matrix could be a polymer blend comprising of the above mentioned polymers or a polyelectrolyte complex comprising of anionic and cationic polymers. The bioceramic used Is hydroxyapatite, tricaicium phosphate or a composite of these two or bioactive glass or glass ceramic system. The calcium phosphate used has a calcium to phosphate ratio that may vary from 1 to 1.67. The bioceramic particle size may vary from 0.05µm to 150µn. The bioceramic particle may be prepared by suitable chemical synthesis procedures followed by spray drying or freeze drying or similar processes and may or may not be ball milled to small particle size. The bioceramic is incorporated into the polymeric matrix by conventional methods in plastic processing like mill mixing, mixing in an intermix or single screw extruder or twin screw extruder. The material Is compression moulded into any shape in a compression moulding press at appropriate temperature and pressure. The plaques obtained can also be shaped into any required shape by scissors. Altematively the composite can be injection moulded using appropriate moulds, into any desired shape or extruded using appropriate dies in the form of rods, tubes sheets or any desired contours as required. Altematively the compression moulded sheets can be shaped into desired three dimensional shapes required for implantation by plastic forming techniques such as thermoforming, vacuum forming, stamp forming etc. The composite can be sterilized by either ethylene oxide gas or by gamma radiation for surgical use as bone substitute. The material has a tensile strength of 3-30 MPa. The polymeric matrix used is a co-polymer of ethylene and a polar monomer like vinyl acetate or acrylic acid or the like. The melt mixing technique was used to prepare the composite. The invention will now be explained in greater details with the help of the following non-limiting example. Example: 33.97 g of co-polymer is melted in a high shear mixer with cam type rotors and 75.3 g of hydroxyapatite powder is added slowly into the melted polymer. Further they were mixed for 4 min to get a homogeneous mixture. The temperature of mixing was 120oC and the rotor speed was 40 rev min-1. The mix is then dumped and sheeted out in an open two-roll mill. The composite is then compression moulded into plaques of around 2 mm thickness using compression molding. Dumb bell specimens were cut from the sheet in order to measure the tensile properties. The biocompatibility studies showed bone growth around the Implant showing the bloactlve nature of the composites. The moulded composites have a Young's modulus of 100 to 10,000 MPa. The moulded composites can be used for surgical applications such as cranloplasty, maxillofacial or other bone substitute applications. WE CLAIM: 1. An osteoconductive composite material for use as a bone substitute, having a tensile strength of 3-30 MPa and elongation at break of 2 to 25%, characterized In that It comprises a bloceramic material Incorporated Into a polymer matrix having a weight average molecular weight of 10,000 to 10,00,000. 2. The osteoconductive composite material as claimed in claim 1, wherein the matrix polymer has a weight average molecular weight greater than 50,000 but less than 5,00,000. 3. The osteoconductive composite material as claimed in claim 1 , wherein matrix polymer is a co-polymer of ethylene and another polar monomer such as vinyl acetate, acrylic acid or the like. 4. The osteoconductive composite material as claimed In claim 1 and wherein the polymer matrix Is a polymer blend comprising of the above mentioned polymers or a polyelectrolyte complex comprising of anionic and catlonic polymers. 5. The osteoconductive composite material as claimed in claim 3 wherein the co-polymer content can vary from 6-60%. 6. The osteoconductive composite material as claimed in claim 1, wherein the bloceramic particle may be Incorporated 10-90 vol%. 7. The osteoconductive composite material as claimed in claim 1, wherein the bioceramic particle may be hydroxyapatite, tricalcium phosphate or a composite of these two or bioactive glass or glass ceramic system. 8. The osteoconductive composite material as claimed in aim 1, wherein the bioceramic particle size may vary from 0.05 µm to 150 µm. S.The osteoconductive composite materials claimed in claim 7, wherein the calcium phosphate has calcium to phosphorous ratio that may vary from 1 to 1.67. 10. An osteoconductive composite material for use as a bone substitute, substantially as herein described.. 11. A process for the preparation of an osteoconductive composite material as claimed in claim 1, comprising melting a polymer followed by adding a bioceramic material thereto and mixing followed by spreading the mix to obtain a sheet and moulding the same to obtain the composite material. 12. The process as claimed In claim 11 comprising preparing the bioceramic material by known processes followed by drying and optionally milling the same to obtain bioceramic particles. 13. The process as claimed in claim 11, wherein the mixing is done in an Intermix or single screw extruder or t^n screw extruder. 14. The process as claimed in claim 11, wherein 10 to 90% by volume of the bioceramic material is incorporated into the polymer matrix. 15. The process as claimed in claim 11, wherein the composite is moulded by compression moulding or any other plastic forming technique. 16.The process as claimed in claim 15, wherein the moulded composites have a Young's modules of 100 to 10,000 MPa. 17.The process as claimed in claim 11, wherein the moulded sheets are fabricated into any two dimensional or three dimensional shapes by special forming techniques such as thermoforming, vacuum forming, stamp forming etc. 18.The process as claimed in claim 11, wherein the composite is prepared by extrusion, injection moulding or any other plastic forming method .

Documents:

0805-che-2003 claims-duplicate.pdf

0805-che-2003 description (complete)-duplicate.pdf

805-che-2003-abstract.pdf

805-che-2003-claims.pdf

805-che-2003-correspondnece-others.pdf

805-che-2003-correspondnece-po.pdf

805-che-2003-description(complete).pdf

805-che-2003-description(provisional).pdf

805-che-2003-form 1.pdf

805-che-2003-form 26.pdf

805-che-2003-form 3.pdf

805-che-2003-form 4.pdf

805-che-2003-form 5.pdf