Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
1999-08-13
2002-10-01
McDermott, Corrine (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C428S404000, C423S305000
Reexamination Certificate
active
06458162
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the preparation of composite shaped bodies, especially those having at least a portion comprising a calcium phosphate-containing material. This invention also relates to methods for preparing the bodies and to methods for use thereof. In accordance with certain embodiments of this invention, shaped bodies are provided which are at once, possessed of two or more portions having different properties. In accordance with other preferred embodiments, at least one portion of the composite is highly porous and uniform in composition. The shaped bodies can be produced in a wide range of geometric configurations through novel, low temperature techniques. The shaped bodies of the invention can have portions which are highly and uniformly porous while being self-supporting. They can be strengthened further using a variety of techniques, thereby forming porous composite structures. Such composite structures are useful as cell growth scaffolds, bone grafting materials, drug delivery vehicles, biological separation/purification media, catalysis and other supports and in a wide range of other uses. One of the most preferred uses for the composite structures of this invention is in the field of orthopaedic, restorative and reconstructive surgery. Thus the present invention provides shaped bodies having highly suitable combinations of properties which make those bodies extraordinarily useful for bone replacement, spinal repair, reconstructive, cosmetic and other surgeries.
BACKGROUND OF THE INVENTION
There has been a continuing need for improved methods for the preparation of mineral compositions, especially calcium phosphate-containing minerals. This long-felt need is reflected in part by the great amount of research found in the pertinent literature. While such interest and need stems from a number of industrial interests, the desire to provide materials which closely mimic mammalian bone for use in repair and replacement of such bone has been a major motivating force. Such minerals are principally calcium phosphate apatites as found in teeth and bones. For example, type-B carbonated hydroxyapatite [Ca5(PO04)3-x(CO03)x(OH) ] is the principal mineral phase found in the body, with variations in protein and organic content determining the ultimate composition, crystal size, morphology, and structure of the body portions formed therefrom.
Calcium phosphate ceramics have been fabricated and implanted in mammals in various forms including, but not limited to, shaped bodies and cements. Different stoichiometric compositions such as hydroxyapatite (HAp), tricalcium phosphate (TCP), tetracalcium phosphate (TTCP), and other calcium phosphate salts and minerals, have all been employed to this end in an attempt to match the adaptability, biocompatibility, structure, and strength of natural bone. The role of pore size and porosity in promoting revascularization, healing, and remodeling of bone is now recognized as a critical property for bone replacement materials. Despite tremendous efforts directed to the preparation of porous calcium phosphate materials for such uses, significant shortcomings still remain. This invention overcomes those shortcomings and describes porous calcium phosphate and a wide variety of other inorganic materials which, in the case of calcium phosphates, closely resemble bone, and methods for the fabrication of such materials as shaped bodies for biological, chemical, industrial, and many other applications.
Early ceramic biomaterials exhibited problems derived from chemical and processing shortcomings that limited stoichiometric control, crystal morphology, surface properties, and, ultimately, reactivity in the body. Intensive milling and comminution of natural minerals of varying composition was required, followed by powder blending and ceramic processing at high temperatures to synthesize new phases for use in vivo.
A number of patents have issued which relate to ceramic biomaterials and are incorporated herein by reference. Among these are U.S. Pat. No. 4,880,610, B. R. Constantz ,“In situ calcium phosphate minerals—method and composition;” U.S. Pat. No. 5,047,031, B. R. Constantz, “In situ calcium phosphate minerals method;” U.S. Pat. No. 5,129,905, B. R. Constantz, “Method for in situ prepared calcium phosphate minerals;” U.S. Pat. No. 4,149,893, H. Aoki, et al, “Orthopaedic and dental implant ceramic composition and process for preparing same;” U.S. Pat. No. 4,612,053, W. E. Brown, et al, “Combinations of sparingly soluble calcium phosphates in slurries and pastes as mineralizers and cements;” U.S. Pat. No. 4,673,355, E. T. Farris, et al, “Solid calcium phosphate materials;” U.S. Pat. No. 4,849,193, J. W. Palmer, et al., “Process of preparing hydroxyapatite;” U.S. Pat. No. 4,897,250, M. Sumita, “Process for producing calcium phosphate;” U.S. Pat. No. 5,322,675, Y. Hakamatsuka, “Method of preparing calcium phosphate;” U.S. Pat. No. 5,338,356, M. Hirano, et al “Calcium phosphate granular cement and method for producing same;” U.S. Pat. No. 5,427,754, F. Nagata, et al., “Method for production of platelike hydroxyapatite;” U.S. Pat. No. 5,496,399, I. C. Ison, et al., “Storage stable calcium phosphate cements;” U.S. Pat. No. 5,522,893, L. C. Chow. et al., “Calcium phosphate hydroxyapatite precursor and methods for making and using same;” U.S. Pat. No. 5,545,254, L. C. Chow, et al., “Calcium phosphate hydroxyapatite precursor and methods for making and using same;” U.S. Pat. No. 3,679,360, B. Rubin, et al., “Process for the preparation of brushite crystals;” U.S. Pat. No. 5,525,148, L. C. Chow, et al., “Self-setting calcium phosphate cements and methods for preparing and using them;” U.S. Pat. No. 5,034,352, J. Vit, et al., “Calcium phosphate materials;” and U.S. Pat. No. 5,409,982, A. Imura, et al “Tetracalcium phosphate-based materials and process for their preparation.”
Several patents describe the preparation of porous inorganic or ceramic structures using polymeric foams impregnated with a slurry of preformed ceramic particles. These are incorporated herein by reference: U.S. Pat. No. 3,833,386, L. L. Wood, et al, “Method of preparing porous ceramic structures by firing a polyurethane foam that is impregnated with inorganic material;” U.S. Pat. No. 3,877,973, F. E. G. Ravault, “Treatment of permeable materials;” U.S. Pat. No. 3,907,579, F. E. G. Ravault, “Manufacture of porous ceramic materials;” and U.S. Pat. No. 4,004,933, F. E. G. Ravault, “Production of porous ceramic materials.” However, none of aforementioned art specifically describes the preparation of porous metal or calcium phosphates and none employs the methods of this invention.
The prior art also describes the use of solution impregnated-polymeric foams to produce porous ceramic articles and these are incorporated herein by reference: U.S. Pat. No. 3,090,094, K. Schwartzwalder, et al, “Method of making porous ceramic articles;” U.S. Pat. No. 4,328,034 C. N. Ferguson, “Foam Composition and Process;” U.S. Pat. No. 4,859,383, M. E. Dillon, “Process of Producing a Composite Macrostructure of Organic and Inorganic Materials;” U.S. Pat. No. 4,983,573, J. D. Bolt, et al, “Process for making 90° K superconductors by impregnating cellulosic article with precursor solution;” U.S. Pat. No. 5,219,829, G. Bauer, et al, “Process and apparatus for the preparation of pulverulent metal oxides for ceramic compositions;” GB 2,260,538, P. Gant, “Porous ceramics;” U.S. Pat. No. 5,296,261, J. Bouet, et al, “Method of manufacturing a sponge-type support for an electrode in an electrochemical cell;” U.S. Pat. No. 5,338,334, Y. S. Zhen, et al, “Process for preparing submicron
anosize ceramic powders from precursors incorporated within a polymeric foam;” and S. J. Powell and J. R. G. Evans, “The structure of ceramic foams prepared from polyurethane-ceramic suspensions,” Materials & Manufacturing Processes, 10(4):757 (1995). The focus of this art is directed to the preparation of either metal or metal oxide foams and/or particles. None of the disclosures of these aforementione
Dychala David H.
Erbe Eric M.
Koblish Antony
Sapieszko Ronald S.
McDermott Corrine
Stewart A.
Vita Special Purpose Corporation
Woodcock & Washburn LLP
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