Osteointegrative interface for implantable prostheses and a method for the treatment of the osteointegrative interface

• US 20050143743A1
• Filed: 12/17/2004
• Published: 06/30/2005
• Est. Priority Date: 06/21/2002
• Status: Active Grant

• Current Assignee: Politecnico di Milano
• Original Assignee: Politecnico di Milano
• Inventors: Santin, Matteo, Sandrini, Enrico, Cigada, Alberto, Rondelli, Gianni, Chiesa, Roberto
• Granted Patent: US 7,740,481 B2
• Time in Patent Office: Days
• US Class Current: 606/76
• CPC Class Codes: A61L 27/047 Other specific metals or alloys not covered by A61L27/042 - A61L27/045 or A61L27/06
• CPC Class Codes: A61L 27/06 Titanium or titanium alloys
• CPC Class Codes: A61L 27/306 Other specific inorganic materials not covered by A61L27/303 - A61L27/32
• CPC Class Codes: A61L 27/32 Phosphorus-containing materials, e.g. apatite
• CPC Class Codes: C25D 11/26 of refractory metals or alloys based thereon

Abstract

A biomimetic osteointegrative interface comprising a substrate of biocompatible material such as titanium, tantalum or their alloys comprising, on the surface of the substrate, a first layer having a first concentration of oxide of the biocompatible material, enriched with a second concentration of phosphorus and with a third concentration of calcium, the ratio between the concentration of calcium and the concentration of phosphorus being greater than two. The biomimetic osteointegrative interface further comprises a second layer having a first surface in contact with the first layer and a second surface. The second layer has a fourth concentration of oxide enriched with a fifth concentration of calcium and a sixth concentration of phosphorus. The fourth concentration is less than the fifth and sixth concentrations and the ration between the fifth concentration of calcium and the sixth concentration of phosphorus is no less than three.

Claims

1. A biomimetic osteointegrative interface comprising a substrate (3) of biocompatible material such as titanium, tantalum, or their alloys, comprising, on the surface (3bis) of the substrate (3), a first layer (4) having a first concentration of oxide of the biocompatible material, enriched with a second concentration of phosphorus and with a third concentration of calcium, the ratio between the concentration of calcium and the concentration of phosphorus being greater than two, the biomimetic osteointegrative interface (1) further comprising a second layer (5) having a first surface (10) in contact with the first layer (4), and a second surface (11), the second layer (5) having a fourth concentration of oxide enriched with a fifth concentration of calcium and a sixth concentration of phosphorus, the fourth concentration being less than the fifth and sixth concentrations and the ratio between the fifth concentration of calcium and the sixth concentration of phosphorus being no less than three.

2. The biomimetic osteointegrative interface according to claim 1, wherein the second layer (5) has a gradient of the fifth calcium concentration and of the sixth phosphorus concentration which gradient increases from the first surface (10) towards the second surface (11) of the second layer (5).

3. The biomimetic osteointegrative interface according to claim 2, wherein the second layer (5) is hydrated and has —

OH hydroxyl chemical coupling groups suitable for forming a plurality of nucleation centers (12).

4. A method for the biomimetic treatment of an osteointegrative interface on a substrate of biocompatible metal such as titanium, tantalum, or their alloys, comprising the following steps:

a) performing a first ASD anodic deposition treatment of the osteointegrative interface (1) in a calcium glycerophosphate solution,

b) performing a second ASD anodic deposition treatment of the osteointegrative interface (1) in a calcium hydroxide solution, and

c) performing an immersion of the osteointegrative interface (1) in a potassium hydroxide solution.

5. The method for the biomimetic treatment of an osteointegrative interface according to claim 4, wherein the electrolytic solution containing calcium glycerophosphate has a concentration of 0.015±

0.005 M and a temperature T within a range where −

1°

C. <

T<

+1°

C.

6. The method for the biomimetic treatment of an osteointegrative interface according to any one of claim 4, wherein the first ASD deposition takes place with a constant current equal to a first predetermined value and with a voltage increasing freely to a first final value.

7. The method for the biomimetic treatment of an osteointegrative interface according to claim 6, wherein the first final voltage value is equal to about 350 V.

8. The method for the biomimetic treatment of an osteointegrative interface according to claim 6, wherein the first predetermined current value is equal to about 70 A/m².

9. The method for the biomimetic treatment of an osteointegrative interface according to any one of claim 4, wherein the electrolytic solution containing calcium hydroxide has a concentration of 0.1±

0.02 M and a temperature T within a range where 2°

C.<

T<

8°

C.

10. The method for the biomimetic treatment of an osteointegrative interface according to any one of claim 4, wherein the second ASD anodic deposition provides, for a first period of time, for a constant current equal to a second predetermined current value and for a voltage increasing freely to a second final value, and further provides, for a second period of time, for a current decreasing freely to a third value and for a constant voltage equal to a third predetermined voltage value.

11. The method for the biomimetic treatment of an osteointegrative interface according to 10, wherein the second predetermined current value is equal to about 70 A/m².

12. The method for the biomimetic treatment of an osteointegrative interface according to claim 10, wherein the second and third final voltage values are identical and are equal to about 370 V.

13. The method for the biomimetic treatment of an osteointegrative interface according to any one of claim 4, wherein the immersion in potassium hydroxide solution takes place for a period of at least t=24 hours and a temperature T within a range where 59°

C<

T<

61°

C.

14. A method for the biomimetic treatment of an osteointegrative interface on a substrate of biocompatible metal such as titanium, tantalum, or their alloys, comprising the following steps:

a) performing a first ASD anodic deposition treatment of the osteointegrative interface (1) in a calcium glycerophosphate solution,

b) performing a second ASD anodic deposition treatment of the osteointegrative interface (1) in a calcium hydroxide solution, and

c) performing an immersion of the osteointegrative interface (1) in a sodium hydroxide solution.

15. The method for the biomimetic treatment of an osteointegrative interface according to claim 14, wherein the electrolytic solution containing calcium glycerophosphate has a concentration of 0.015±

0.005 M and a temperature T within a range where −

1°

C.<

T<

+1°

C.

16. The method for the biomimetic treatment of an osteointegrative interface according to any one of claim 14, wherein the first ASD deposition takes place with a constant current equal to a first predetermined value and with a voltage increasing freely to a first final value.

17. The method for the biomimetic treatment of an osteointegrative interface according to claim 16, wherein the first final voltage value is equal to about 350 V.

18. The method for the biomimetic treatment of an osteointegrative interface according to 16, wherein the first predetermined current value is equal to about 70 A/m².

19. The method for the biomimetic treatment of an osteointegrative interface according to any one of claim 14, wherein the electrolytic solution containing calcium hydroxide has a concentration of 0.1±

0.02 M and a temperature T within a range where 2°

C.<

T<

8°

C.

20. The method for the biomimetic treatment of an osteointegrative interface according to any one of claim 14, wherein the second ASD anodic deposition provides, for a first period of time, for a constant current equal to a second predetermined current value and for a voltage increasing freely to a second final value, and further provides, for a second period of time, for a current decreasing freely to a third value and for a constant voltage equal to a third predetermined voltage value.

21. The method for the biomimetic treatment of an osteointegrative interface according to claim 20, wherein the second predetermined current value is equal to about 70 A/m².

22. The method for the biomimetic treatment of an osteointegrative interface according to claim 20, wherein the second and third final voltage values are identical and are equal to about 370 V.

23. The method for the biomimetic treatment of an osteointegrative interface according to claim 20, wherein the third predetermined current value is equal to half of the second predetermined current value and is equal to about 35 A/m².