Method for producing an osteoinductive calcium phosphate and products thus obtained

1. An osteoinductive material, prepared by a method comprising the steps of:

providing a sintered biphasic calcium phosphate (BCP) starting material of β-tricalcium phosphate and hydroxyapatite, wherein the sintered BCP comprises 4-20 wt. % of hydroxyapatite, the sintered BCP starting material having a surface topography consisting of calcium phosphate grains, and

subjecting the sintered BCP starting material to a hydrothermal treatment at a temperature equal to or higher than 125° C. for a duration sufficient to change calcium phosphate grains on the surface of the sintered BCP starting material into a coating layer of hydroxyapatite needles, to obtain said osteoinductive material.

2. The osteoinductive material of claim 1 , wherein the sintered BCP starting material has an average grain size in a range of 0.1-3.0 μm.

3. The osteoinductive material of claim 1 , wherein the sintered BCP starting material is porous.

4. The osteoinductive material of claim 1 , wherein the sintered BCP starting material comprises macropores in a size range of 50-1500 μm.

5. The osteoinductive material of claim 1 , which has a specific surface area at least 10-50% higher than that of the sintered BCP starting material.

6. The osteoinductive material of claim 5 , which has a specific surface area at least 80-100% higher than that of the sintered BCP starting material.

7. The osteoinductive material of claim 1 , which has a protein adsorption capacity at least 10-50% higher than that of the sintered BCP starting material.

8. The osteoinductive material of claim 7 , which has a protein adsorption capacity at least 80-100% higher than that of the sintered BCP starting material.

9. The osteoinductive material of claim 1 , wherein the needles of the coating layer have a diameter of 10-1500 nm.

10. The osteoinductive material of claim 1 , wherein the sintered BCP starting material is resorbable.

11. The osteoinductive material of claim 1 , wherein the coating layer has a BET specific surface area above 0.9 m 2 /g.

12. The osteoinductive material of claim 1 , the density of needles in the coating layer is lower than 0.45/μm 2 .

13. An osteoinductive material comprising an outer layer comprising hydroxyapatite needles and an inner layer that is in contact with the outer layer, wherein the inner layer comprises a sintered biphasic calcium phosphate (BCP) of β-tricalcium phosphate and hydroxyapatite, wherein the sintered BCP comprises 4-20 wt. % of hydroxyapatite; whereby the outer layer is a precipitate of hydroxyapatite needles from the sintered BCP of the inner layer following the hydrothermal treatment thereof at a temperature equal to or higher than 125° C.

14. The osteoinductive material of claim 13 , wherein the hydroxyapatite needles have an average diameter of between 10-1500 nm.

15. The osteoinductive material of claim 13 , wherein the density of hydroxyapatite needles of the outer layer is lower than 0.45/μm 2 .

16. The osteoinductive material of claim 13 , wherein the thickness of the outer layer is between 1 and 1000 μm.

17. The osteoinductive material of claim 13 , wherein the outer layer has a BET specific surface area above 0.9 m 2 /g.

18. The osteoinductive material of claim 13 , which further comprises a core abutting said inner layer.

19. An osteoinductive material comprising at least an outer layer of hydroxyapatite needles attached to or exposed on a core material, wherein said outer layer of hydroxyapatite needles is prepared by a method comprising the steps of:

providing a sintered biphasic calcium phosphate (BCP) starting material of β-tricalcium phosphate and hydroxyapatite, wherein the sintered BCP comprises 4-20 wt. % of hydroxyapatite, the sintered BCP starting material having a surface topography consisting of calcium phosphate grains, and

subjecting the sintered BCP starting material to a hydrothermal treatment at a temperature equal to or higher than 125° C. for a duration sufficient to change calcium phosphate grains on the surface of the starting material into said outer layer of hydroxyapatite needles.

20. The osteoinductive material of claim 19 , which further comprises an inner layer of sintered BCP disposed between said core material and said outer layer.

21. The osteoinductive material of claim 19 , wherein said core material is a metal or plastic.

22. An implantable object comprising the osteoinductive material of claim 1 .

23. An implantable object comprising the osteoinductive material of claim 13 .

24. An implantable object comprising the osteoinductive material of claim 19 .