IMPLANTABLE BIOMIMETIC PROSTHETIC BONE

• US 20090177282A1
• Filed: 01/13/2006
• Published: 07/09/2009
• Est. Priority Date: 01/14/2005
• Status: Abandoned Application

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: Bureau, Martin N., Legoux, Jean-Gabriel, Denault, Johanne
• Application Number:
  US11/813,827
• Publication Number:
  US 20090177282A1
• Time in Patent Office: Days
• US Class Current: 623/16.110
• CPC Class Codes: A61L 27/446 with other specific inorganic fillers other than those covered by A61L27/443 or A61L27/46
• CPC Class Codes: A61L 27/46 with phosphorus-containing inorganic fillers
• CPC Class Codes: B29C 43/003 characterised by the choice of material
• CPC Class Codes: B29C 70/025 with particular filler
• CPC Class Codes: B29C 70/58 comprising fillers only , e.g. particles, powder, beads, flakes, spheres B29C70/025 takes precedence, agglomerating hollow spheres to produce synthetic foam B29C70/66; compounding ingredients per se C08K
• CPC Class Codes: B29C 70/64 the filler influencing the surface characteristics of the material, e.g. by concentrating near the surface or by incorporating in the surface by force
• CPC Class Codes: B29K 2503/04 Inorganic materials
• CPC Class Codes: B29K 2705/00 Use of metals, their alloys or their compounds, for preformed parts, e.g. for inserts
• CPC Class Codes: B29K 2709/00 Use of inorganic materials not provided for in groups B29K2703/00 - B29K2707/00, for preformed parts, e.g. for inserts
• CPC Class Codes: B29L 2031/7532 Artificial members, protheses
• CPC Class Codes: C08J 5/124 using adhesives based on a macromolecular component
• CPC Class Codes: C08K 3/013 Fillers, pigments or reinforcing additives
• CPC Class Codes: C23C 4/10 Oxides, borides, carbides, nitrides or silicides; Mixtures thereof
• CPC Class Codes: C23C 4/12 characterised by the method of spraying
• CPC Class Codes: C23C 4/134 Plasma spraying
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/31507 Of polycarbonate
• CPC Class Codes: Y10T 428/31678 Of metal
• CPC Class Codes: Y10T 428/31721 : Of polyimide
• CPC Class Codes: Y10T 428/31725 : Of polyamide
• CPC Class Codes: Y10T 428/31855 : Of addition polymer from unsaturated monomers

Abstract

Bone tissue at the interface of a bone implant is shielded from stresses found in normal bone because of the higher stiffness or rigidity in the implant versus in bone. The resulting “stress shielding” of the bone by the implant eventually results in resorption of bone at the bone-implant interface and ultimately necessitates replacement of the bone implant. To overcome these problems, an implantable biomimetic prosthetic bone having a porous surface, a fiber-reinforced composite structure, and a polymer-based core is disclosed. The prosthetic bone is a good match for structure, stiffness, viscoelastic properties, specific weight and overall structure as real bone or host tissues adjacent to the prosthetic bone. The prosthetic bone may be formed as a total hip prosthesis.

Claims

1. An implantable biomimetic prosthetic bone formed of a hollow fiber-reinforced thermoplastic composite having an inner and an outer surface, and an osteo-conductive region on the outer surface, wherein the hollow fiber-reinforced thermoplastic composite has a stiffness that matches stiffness of bone to be replaced.

2. The prosthetic bone of claim 28 wherein the osteo-conductive region of the surface comprises a region of porosity.

3. The prosthetic bone of claim 2 wherein the region of porosity comprises about 10% porosity.

4. The prosthetic bone of claim 28 wherein the osteo-conductive region of the surface comprises a region of roughness.

5. The prosthetic bone of claim 4 wherein the region of roughness comprises meso (100-500 μ

m), micro (1-50 μ

m) or nano (<

1 μ

m) roughness.

6. The prosthetic bone of claim 28 wherein the surface comprising an osteo-conductive porous region is bonded to the thermoplastic composite using a tie layer comprising a compatible polymeric matrix and 2-70% filler.

7. The prosthetic bone of claim 1 wherein the surface additionally comprises an osteo-inductive porous region.

8. The prosthetic bone of claim 1 wherein the osteo-conductive porous region comprises ceramic, or a combination of ceramic with metal or polymer.

9. The prosthetic bone of claim 1 having an elastic modulus of between 5 and 30 GPa.

10. The prosthetic bone of claim 1 having a specific weight of 0.4-4.0 g/cm³.

11. The prosthetic bone of claim 1 comprising an extra-osseous section and an intra-osseous section, each section having a surface thereon;

said osteo-conductive region being located on the surface of the intra-osseous section.

12. The prosthetic bone of claim 1 wherein said osteo-conductive region is bioresorbable or biodegradable.

13. The prosthetic bone of claim 1 wherein the surface additionally comprises a smooth region.

14. The prosthetic bone of claim 13 wherein the smooth region comprises a biocompatible polymer formed of thermoplastic.

15. The prosthetic bone of claim 14 wherein the biocompatible polymer comprises a composite structure including short fibers, long fibers, continuous fibers, whiskers, particles, or combinations thereof as filler therein.

16. The prosthetic bone of claim 1 wherein the composite structure comprises polymer-based oriented fibers;

mineral-based fibers;

metallic fibers;

ceramic fibers;

or polymer-based fibers with nanoreinforcement by nanoparticles, nanowhiskers, nanofibers or nanotubes.

17. The prosthetic bone of claim 1 wherein the fiber-reinforced thermoplastic composite is braided wound or filament wound around the polymer-based core.

18. The prosthetic bone of claim 1 wherein the fiber-reinforced thermoplastic composite comprises CF/PA12.

19. The prosthetic bone of claim 1 wherein the surface comprises hydroxyapatite, TiO₂ or a CaP-containing ceramic.

28. The prosthetic bone of claim 1 further comprising a polymer-based core wherein the polymer-based core is chosen to permit the prosthetic bone to match specific weight of the bone to be replaced.

20. A method for forming an implantable biomimetic prosthetic bone comprising the steps of:

molding a fiber-reinforced thermoplastic composite into a hollow stem in the form of a prosthesis,

consolidating the thermoplastic composite with application of heat at a temperature higher than the melting point of the thermoplastic;

coating the thermoplastic composite with an osteo-conductive material; and

forming a region of roughness or porosity on the surface of the fiber-reinforced thermoplastic composite;

wherein the nature and structure of the molded fiber-reinforced thermoplastic composite are selected to provide a match of stiffness and specific weight with bone to be replaced.

21. The method of claim 20 wherein the step of coating the thermoplastic composite with an osteo-conductive material comprises applying to the thermoplastic composite a tie layer comprising a compatible polymeric matrix and 2 to 70% filler and subsequently applying the osteo-conductive material.

22. The method for forming a prosthetic bone according to claim 20 wherein the step of forming a region of roughness or porosity comprises particle sintering, thermal spray coating, or milling.

23. The method for forming a prosthetic bone according to claim 20 additionally comprising the step of forming a smooth region on the surface of the thermoplastic composite layer.

24. The method of claim 20, wherein the step of forming a smooth region comprises depositing a biocompatible polymer on the thermoplastic composite.

25. The method of claim 24 wherein depositing the biocompatible polymer comprises overmolding, wrapping, thermal spraying, electrostatic coating, chemical vapour deposition (CVD), electrochemical coating, plasma-spray coating, press-fitting, polymer infiltration, or combinations of these.

26. The method of claim 20 wherein the fiber-reinforced thermoplastic composite is braided or filament wound.

29. The method of claim 20 further comprising selecting a polymer-based core for insertion into the fiber-reinforced thermoplastic composite to provide a match of stiffness and specific weight with bone to be replaced.

27. (canceled)

30. A method for forming an implantable prosthetic bone by inflatable bladder compression molding, comprising the steps of:

mounting a fiber-reinforced thermoplastic onto an internal inflatable bladder inserted in a mold cavity of a mold;

closing the mold;

placing the mold in a heat press and inflating the bladder once a predetermined temperature is reached; and

cooling and removing a hollow prosthetic bone from the mold.

31. The method of claim 30 further comprising applying a coating on an outer surface of the hollow prosthetic bone to improve an osseointegration of the hollow prosthetic bone with a bone.