SELF-FOAMING CEMENT FOR VOID FILLING AND/OR DELIVERY SYSTEMS

• US 20090239787A1
• Filed: 02/05/2009
• Published: 09/24/2009
• Est. Priority Date: 06/08/2006
• Status: Active Grant

• Current Assignee: Sanatis GmbH (Medtronic Plc), Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Sanatis GmbH (Medtronic Plc), Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Meyer, Jorg, Edidin, Avram Allan, Wenz, Robert
• Granted Patent: US 8,118,926 B2
• Time in Patent Office: Days
• US Class Current: 514/1.100
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/4631 the prosthesis being specially adapted for being cemented
• CPC Class Codes: A61F 2310/00293 containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61L 2300/406 Antibiotics
• CPC Class Codes: A61L 2430/02 for reconstruction of bones; weight-bearing implants
• CPC Class Codes: A61L 27/12 Phosphorus-containing materials, e.g. apatite
• CPC Class Codes: A61L 27/54 Biologically active materials, e.g. therapeutic substances A61L27/227 takes precedence

Abstract

A self-foaming bone cement is described herein. In one variation, the bone cements include a self setting calcium phosphate cement formulation which when cured, forms macroscopic pores of varying sizes and densities with sufficient surface area to provide substantial regions for bone turnover.

Claims

1. A composition comprising a dry element and a wet element;

wherein said dry element includes tricalcium phosphate, hydroxyapatite, strontium hydrophosphate and one or more members selected from the group consisting of strontium carbonate and sodium bicarbonate;

and wherein said wet element includes a phosphate buffer sufficient to keep the composition acidic when the dry element and the wet element are mixed together.

2. The composition of claim 1, wherein the composition is a bone cement.

3. The composition of claim 1, wherein the composition comprises 30-70 g tricalcium phosphate (TCP), 10-30 g strontium hydrophosphate (SrHPO₄), 3-15 g strontium carbonate (SrCO₃), 1-5 g precipitated hydroxyapatite (pHA), 0.5-5 g of sodium phosphate dibasic (Na₂HPO₄), and 10-30 g K₂HPO₄.

4. The composition of claim 3, further comprising 0.5 to 5% w/w of a cohesion promoter.

5. The composition of claim 1, wherein the pH of the buffer is between 6.5 and 6.9.

6. A bone cement comprising:

a dry element comprising tricalcium phosphate, hydroxyapatite, strontium hydrophosphate and one or more members selected from the group consisting of strontium carbonate and sodium bicarbonate;

and a wet element comprising a phosphate buffer sufficient to keep the composition acidic when the dry element and the wet element are mixed together, wherein the calcium phosphate cement is configured for placement in a void inside a bone in a patient'"'"'s body, and wherein the calcium phosphate cement, when cured, forms macroscopic pores of varying sizes and densities with sufficient surface area to provide regions for bone remodeling.

7. The bone cement of claim 6, wherein the macroscopic pores are between about 4 and 200 microns in diameter.

8. The bone cement of claim 6, wherein the calcium phosphate bone cement is made from a composition that comprises a wet element and a dry element and the dry element includes 30-70 g tricalcium phosphate (TCP), 10-30 g strontium hydrophosphate (SrHPO₄), 3-15 g strontium carbonate (SrCO₃), 1-5 g precipitated hydroxyapatite (pHA), 0.5-5 g of sodium phosphate dibasic (Na₂HPO₄), and 10-30 g K₂HPO₄.

9. The bone cement of claim 6, wherein the phosphate buffer is buffered to a pH of between about 6.5 and 6.9.

10. The bone cement of claim 6, further comprising 0.5 to 5% w/w of a cohesion promoter.

11. The bone cement of claim 6, further comprising an antibiotic.

12. The bone cement of claim 11, wherein the antibiotic is one or more members selected from the group consisting of gentamicin, gentamicin sulfate, erythromycin, tobramycin, vancomycin, cefazolin, oxacillin, cefotaxime, colistin, clindamycin, and fusidic acid.

13. A method of making a bone cement comprising:

mixing together a dry element and a wet element;

wherein said dry element includes tricalcium phosphate, hydroxyapatite, strontium hydrophosphate and one or more members selected from the group consisting of strontium carbonate and sodium bicarbonate;

and wherein said wet element includes a phosphate buffer sufficient to keep the cement composition acidic while curing to generate a foamed cement.

14. The method of claim 13, wherein the dry element contains both strontium carbonate and sodium bicarbonate.

15. The method of claim 13, wherein the dry element contains 30-70 g tricalcium phosphate (TCP), 10-30 g strontium hydrophosphate (SrHPO₄), 3-15 g strontium carbonate (SrCO₃), 1-5 g precipitated hydroxyapatite (pHA), 0.5-5 g of sodium phosphate dibasic (Na₂HPO₄), and 10-30 g K₂HPO₄.

16. The method of claim 13, further comprising 0.5 to 5% w/w of a cohesion promoter.

17. The method of claim 13, wherein the pH of the buffer is between 6.5 and 6.9.

18. The method of claim 13, wherein the bone cement is self curing.

19. A kit comprising a dry element and a wet element, wherein when the dry element comprises tricalcium phosphate, hydroxyapatite, strontium hydrophosphate and one or more members selected from the group consisting of strontium carbonate and sodium bicarbonate and the wet element comprises a phosphate buffer sufficient to keep the composition acidic when the dry element and the wet element are mixed together resulting in a foamed cement that is suitable for bone remodeling.

20. The kit of claim 32, further comprising an antibiotic.

21. The kit of claim 20, wherein the antibiotic is one or more members selected from the group consisting of gentamicin, gentamicin sulfate, erythromycin, tobramycin, vancomycin, cefazolin, oxacillin, cefotaxime, colistin, clindamycin, and fusidic acid.