IMPLANTABLE MEDICAL DEVICES

• US 20110022180A1
• Filed: 07/24/2009
• Published: 01/27/2011
• Est. Priority Date: 07/24/2009
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Dunkley, Ian R., Melkent, Anthony J., Smith, Timothy J.N., Thoren, Brian R., Grant, Ian D.
• Granted Patent: US 9,399,086 B2
• Time in Patent Office: Days
• US Class Current: 623/23.5
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2002/30028 differing in tissue ingrowth capacity, e.g. made from both ingrowth-promoting and ingrowth-preventing parts
• CPC Class Codes: A61F 2002/30032 differing in absorbability or resorbability, i.e. in absorption or resorption time
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30187 D-shaped or half-disc-shaped
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30957 using a positive or a negative model, e.g. moulds
• CPC Class Codes: A61F 2002/30973 Two joined adjacent layers having complementary interlocking protrusions and recesses
• CPC Class Codes: A61L 2400/08 Methods for forming porous structures using a negative form which is filled and then removed by pyrolysis or dissolution
• CPC Class Codes: A61L 2400/18 Modification of implant surfaces in order to improve biocompatibility, cell growth, fixation of biomolecules, e.g. plasma treatment
• CPC Class Codes: A61L 2420/02 Methods for coating medical devices
• CPC Class Codes: A61L 2420/04 Coatings containing a composite material such as inorganic/organic, i.e. material comprising different phases
• CPC Class Codes: A61L 27/425 of phosphorus containing material, e.g. apatite
• CPC Class Codes: A61L 27/46 with phosphorus-containing inorganic fillers
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 27/58 Materials at least partially resorbable by the body
• CPC Class Codes: A61L 31/121 having an inorganic matrix
• CPC Class Codes: B05D 1/18 performed by dipping
• CPC Class Codes: B05D 3/0272 with ovens
• CPC Class Codes: B29C 2045/0058 : removing material
• CPC Class Codes: B29C 45/0055 : Shaping
• CPC Class Codes: B29C 45/14795 : Porous or permeable material, e.g. foam
• CPC Class Codes: B29K 2071/00 : Use of polyethers , e.g. PEEK, i.e. polyether-etherketone or PEK, i.e. polyetherketone or derivatives thereof, as moulding material
• CPC Class Codes: B29L 2031/7532 : Artificial members, protheses
• CPC Class Codes: C04B 2235/606 : Drying
• CPC Class Codes: C04B 38/0051 : characterised by the pore size, pore shape or kind of porosity
• CPC Class Codes: C04B 41/4586 : Non-chemical aspects relating to the substrate being coated or impregnated
• CPC Class Codes: C04B 41/81 : Coating or impregnation
• CPC Class Codes: C08L 71/12 : Polyphenylene oxides

Abstract

Implantable medical devices are provided. In one embodiment, a device includes a body having an external surface defining an outer profile of the device. The body includes a porous matrix including a series of interconnected macropores defined by a plurality of interconnected struts each including a hollow interior. A filler material substantially fills at least a portion of the series of interconnected macropores. The external surface of the body includes a plurality of openings communicating with the hollow interior of at least a portion of the plurality of interconnected struts. In a further aspect of this embodiment, the external surface includes exposed areas of the filler material and porous matrix in addition to the exposed openings. In another aspect, the porous matrix is formed from a bioresorbable ceramic and the filler material is a biologically stable polymeric material. Still, other aspects related to this and other embodiments are also disclosed.

Claims

1. An implantable medical device, comprising:

a body including an external surface defining an outer profile of said device, said body further including;

a porous matrix including a series of interconnected macropores defined by a plurality of interconnected struts each including a hollow interior;

a filler material substantially filling at least a portion of said series of interconnected macropores; and

a plurality of openings extending through at least a portion of said external surface and communicating with said hollow interior of at least a portion of said plurality of interconnected struts.

2. The device of claim 1, wherein said hollow interiors of said plurality of interconnected struts are interconnected and in communication with one another.

3. The device of claim 2, wherein said hollow interiors are isolated from said series of interconnected macropores.

4. The device of claim 1, wherein said hollow interiors of said plurality of interconnected struts are substantially free of said filler material.

5. The device of claim 1, wherein said portion of said external surface is defined by said plurality of openings, exposed areas of said porous matrix, and exposed areas of said filler material.

6. The device of claim 5, wherein said portion of said external surface extends around said outer profile of said device.

7. The device of claim 5, wherein one more or of said exposed areas of said porous matrix surrounds one or more of said plurality of openings and isolates said openings from an adjacent one of said exposed areas of said filler material.

8. The device of claim 5, wherein said porous matrix comprises a ceramic material and said filler material comprises a polymeric material.

9. The device of claim 8, wherein said ceramic material is bioresorbable and said polymeric material is biologically stable.

10. The device of claim 9, wherein said ceramic material comprises a calcium-based ceramic.

11. The device of claim 10, wherein:

said calcium-based ceramic is defined by a compound that includes calcium, oxygen and phosphorous; and

a portion of at least one of said elements is substituted with an element having an ionic radius of about 0.1 to about 0.6 Å

.

12. The device of claim 11, wherein said compound has the formula:

(Ca)_i{(P<sub>1−

x−

y−

z</sub>B_xC_yD_z)O_j}₂

wherein B, C and D are selected from those elements having an ionic radius of approximately 0.1 to 0.4 Å

;

x is greater than or equal to zero but less than 1;

y is greater than or equal to zero but less than 1;

z is greater than or equal to zero but less than 1;

x+y+z is greater than zero but less than 1;

i is greater than or equal to 2 but less than or equal to 4; and

j is equal 4−

δ

, where δ

is greater than or equal to zero but less than or equal to 1.

13. The device of claim 10, wherein said polymeric material is polyetheretherketone.

14. The device of claim 9, wherein said exposed areas of said porous matrix promote cellular attachment and osteoconduction at said external surface and said plurality of openings promotes bone and tissue ingrowth into said body.

15. The device of claim 1, wherein said filler material is infused throughout and substantially fills each one of said series of interconnected macropores.

16. A method, comprising:

providing an implantable medical device that includes a body including an external surface defining an outer profile of said device, said body further including;

a porous matrix including a series of interconnected macropores defined by a plurality of interconnected struts each including a hollow interior;

a filler material substantially filling at least a portion of said series of interconnected macropores; and

a plurality of openings extending through at least a portion of said external surface and communicating with said hollow interior of at least a portion of said plurality of interconnected struts; and

positioning said device between adjacent bony portions.

17. The method of claim 16, wherein positioning said device between adjacent bony portions includes inserting said device into a disc space between adjacent vertebral bodies.

18. The method of claim 17, wherein:

said portion of said external surface is defined by said plurality of openings, exposed areas of said porous matrix, and exposed areas of said filler material; and

said exposed areas of said porous matrix promote cellular attachment and osteoconduction at said external surface and said plurality of openings promotes bone and tissue ingrowth into said body.

19. The method of claim 18, wherein said external surface of said body includes oppositely positioned bone engaging portions each including a plurality of bone engaging projections structured to engage with said vertebral bodies and resist expulsion of said device from said disc space.

20. An implantable medical device, comprising:

a body including an external surface defining an outer profile of said device, said body further including;

a bioresorbable ceramic matrix including a series of interconnected macropores defined by a plurality of interconnected struts, said interconnected struts further defining a plurality of interconnected passages isolated from said series of interconnected macropores;

a biologically stable polymeric material infused throughout and substantially filling said series of interconnected macropores; and

wherein said plurality of interconnected passages are substantially free of said polymeric material.

21. The device of claim 20, wherein at least a portion of said plurality of interconnected passages extends through and opens at said external surface.

22. The device of claim 21, wherein said body is configured to be positioned between adjacent bones or bony tissue and said external surface includes oppositely positioned bone engaging portions each including a plurality of bone engaging projections structured to engage with said adjacent bones or bony tissue.

23. The device of claim 22, wherein at least a portion of said external surface is defined by an exposed area of said polymeric material and one or more exposed areas of at least a portion of said plurality of interconnected struts, at least one of said one or more exposed areas of said portion of said plurality of interconnected struts surrounding at least one of said portion of said plurality of interconnected passages extending through and opening at said external surface.

24. The device of claim 23, wherein biological activity that occurs when said body is positioned between adjacent bones or bony tissue progressively removes and replaces said one or more exposed areas of said portion of said plurality of interconnected struts with new bone, and creates bone and tissue ingrowth into said portion of said plurality of interconnected passages extending through and opening at said external surface.

25. The device of claim 20, wherein said ceramic matrix comprises a calcium-based ceramic selected from the group consisting of calcium sulfate, calcium carbonate, hydroxyapatite, carbonated apatite, fluroapatite, α

-tricalcium phosphate, β

-tricalcium phosphate, tetracalcium phosphate, octacalcium phosphate and Skelite®

.

26. The device of claim 20, wherein said polymeric material is selected from the group consisting of polyetheretherketone (PEEK), carbon-reinforced PEEK, and polyetherketoneketone (PEKK).

27. A method for producing a medical implant, comprising:

providing a bioresorbable ceramic matrix including a series of interconnected macropores defined by a plurality of interconnected struts, said interconnected struts including a plurality of interconnected internal passages positioned therein;

impregnating said ceramic matrix with a biologically stable polymeric material to provide a composite blank; and

processing said composite blank to provide an implant body including an external surface defining an outer profile of a desired configuration and shape for implantation, said processing including exposing at least a portion of said interconnected internal passages at said external surface.

28. The method of claim 27, wherein said external surface further includes an exposed area of said polymeric material and an exposed area of said ceramic matrix.

29. The method of claim 28, wherein said impregnating includes substantially filling said series of interconnected macropores.

30. The method of claim 27, wherein said interconnected internal passages are substantially free of said polymeric material.

31. The method of claim 27, wherein said impregnating includes injection molding said polymeric material into and around said ceramic matrix.

32. The method of claim 27, wherein said processing includes at least one of machining, cutting, etching, laser shaping and chemical degradation.

33. An implantable medical device, comprising a body including an external surface defining an outer profile of said device, said external surface including one or more exposed areas of a matrix including one or more openings and a biologically stable filler material substantially filling at least a portion of said one or more openings, wherein post-implantation said matrix undergoes a remodeling process in which osteoclast activity progressively removes portions of said matrix and osteoblast activity progressively replaces said portions of said matrix with new bone tissue, and initiation of said remodeling process is limited to said one or more exposed areas of said matrix.

34. The device of claim 33, wherein said initiation of said remodeling process is limited to said one or more areas of said matrix that are exposed upon implantation.

35. The device of claim 33, wherein said one or more openings are defined by a series of interconnected macropores defined by a plurality of interconnected struts.

36. The device of claim 35, wherein each of said plurality of interconnected struts includes a hollow interior.

37. The device of claim 33, wherein said one or more openings are defined by channels at least partially through said matrix.

38. The device of claim 33, wherein said biologically stable material is infused throughout and substantially fills each one of said one or more openings.

39. The device of claim 33, wherein substantially all of said external surface defining said outer profile of said device is defined by exposed areas of said matrix and said biologically stable filler material.

40. The device of claim 33, wherein said biologically stable filler material is selected from the group consisting of polyetheretherketone (PEEK), carbon-reinforced PEEK, and polyetherketoneketone (PEKK).

41. The device of claim 33, wherein said matrix is formed by a calcium-based ceramic material defined by a compound that includes calcium, oxygen and phosphorous, wherein a portion of at least one of said elements is substituted with an element having an ionic radius of about 0.1 to about 0.6 Å

.

42. The device of claim 41, wherein said compound has the formula:

(Ca)_i{(P<sub>1−

x−

y−

z</sub>B_xC_yD_z)O_j}₂

wherein B, C and D are selected from those elements having an ionic radius of approximately 0.1 to 0.4 Å

;

x is greater than or equal to zero but less than 1;

y is greater than or equal to zero but less than 1;

z is greater than or equal to zero but less than 1;

x+y+z is greater than zero but less than 1;

i is greater than or equal to 2 but less than or equal to 4; and

j is equal 4−

δ

, where δ

is greater than or equal to zero but less than or equal to 1.

43. The device of claim 33, wherein said matrix is formed by Skelite®

.

44. The device of claim 33, wherein said body includes a tool engagement portion substantially free of said matrix, said portion being at least partially surrounded by said matrix and filler material and including a threaded aperture formed therein.