Improvements in or Relating to Joints and/or Implants

• US 20110125284A1
• Filed: 09/08/2008
• Published: 05/26/2011
• Est. Priority Date: 05/28/2008
• Status: Active Grant

• Current Assignee: Renishaw PLC
• Original Assignee: University of Bath
• Inventors: Gabbrielli, Ruggero, Turner, Irene Gladys, Magalini, Emanuele, Bowen, Christopher Rhys
• Granted Patent: US 9,370,426 B2
• Time in Patent Office: Days
• US Class Current: 623/23.4
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/367 Proximal or metaphyseal parts of shafts trochanteric devices connected to said proximal parts A61F2/30739
• CPC Class Codes: A61F 2/3672 Intermediate parts of shafts
• CPC Class Codes: A61F 2/3676 Distal or diaphyseal parts of shafts
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30322 differing in surface structures
• CPC Class Codes: A61F 2002/30838 Microstructures
• CPC Class Codes: A61F 2002/3092 having an open-celled or open-pored structure
• CPC Class Codes: A61F 2002/30962 using stereolithography
• CPC Class Codes: A61F 2002/3611 Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2250/0023 differing in porosity
• CPC Class Codes: A61F 2250/0026 differing in surface structures
• CPC Class Codes: A61F 2310/00011 Metals or alloys
• CPC Class Codes: A61F 2310/00017 Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00203 : containing alumina or aluminium oxide
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00329 : Glasses, e.g. bioglass
• CPC Class Codes: B22F 7/004 : comprising at least one non-porous part
• CPC Class Codes: Y10T 29/4978 : Assisting assembly or disassembly

Abstract

A joint part (1) has a porous portion (2) that is defined by a multiplicity of solid regions where material is present and a remaining multiplicity of pore regions where material is absent, the locations of at least most of the multiplicity of solid regions being defined by one or more mathematical functions. The nature of the porous portion can be varied systematically by changing one or more constants in the mathematical functions and the part is made by a process of solid freeform fabrication.

Claims

1. A joint part having a porous portion that is defined by a multiplicity of solid regions where material is present and a remaining multiplicity of pore regions where material is absent, the locations of at least most of the multiplicity of solid regions being defined by one or more mathematical functions.

2. A joint part according to claim 1, in which all the solid regions of the implant are defined mathematically.

3. A joint part according to claim 1, in which the one or more mathematical functions define a periodic nodal surface as a boundary surface between solid and pore regions.

4. A joint part according to claim 3, in which the periodic nodal surface is selected from the group comprising the primitive (P) surface, the diamond (D) surface and the gyroid (G) surface having interconnectivity orders equal to 6, 4 and 3 respectively.

5. A joint part according to claim 1, in which the joint part includes a porous portion and a solid portion which are part of the same single piece.

6. A joint part accordingly to claim 5, in which the porous portion has a porosity in the region bordering the solid region substantially equal to the porosity of the solid portion and increases in porosity away from the solid portion.

7. A joint part according to claim 1, which is a ball and socket joint.

8. A joint part according to claim 7, in which the porous part defines a socket of the ball and socket joint.

9. A joint part according to claim 8, in which the socket has a concave load-bearing cup portion which is solid and a porous portion extending outwardly from the cup portion to a peripheral outer surface.

10. A joint part according to claim 7, in which the porous part defines a ball of the ball and socket joint.

11. A joint part according to claim 10, in which the ball has a convex load-bearing ball portion which is solid and a porous portion extending away from the ball portion.

12. A joint part according to claim 1, in which the joint part is a load-bearing implant suitable for implanting in a human body.

13. A load-bearing implant having a porous portion that is defined by a multiplicity of solid regions where material is present and a remaining multiplicity of pore regions where material is absent, the locations of at least most of the multiplicity of solid regions being defined by one or more mathematical functions.

14. A load-bearing implant according to claim 13, in which all the solid regions of the implant are defined mathematically.

15. A load-bearing implant according to claim 13, in which the one or more mathematical functions define a periodic nodal surface as a boundary surface between solid and pore regions.

16. A load-bearing implant according to claim 15, in which the periodic nodal surface is selected from the group comprising the primitive (P) surface, the diamond (D) surface and the gyroid (G) surface having interconnectivity orders equal to 6, 4 and 3 respectively.

17. A load-bearing implant according to claim 13, in which the implant is made of metal.

18. A load-bearing implant according to claim 13, in which the implant is made of ceramic material.

19. A load-bearing implant according to claim 13, in which the implant is made of polymeric material.

20. A load-bearing implant according to claim 13, in which the implant includes a porous portion and a solid portion which are part of the same single piece.

21. A load-bearing implant according to claim 20, in which the porous portion has a porosity in the region bordering the solid region substantially equal to the porosity of the solid portion and increases in porosity away form the solid portion.

22. A load-bearing implant according to claim 20, in which the solid portion defines a cup which provides part or all of the socket of a ball and socket joint.

23. A load-bearing implant according to claim 22, in which the cup has a concave load bearing cup portion which is solid and a porous portion extending outwardly from the cup portion to a peripheral outer surface.

24. A load-bearing implant according to claim 22, in which the cup is an acetabular cup.

25. A load-bearing implant according to claim 13, in which the solid portion defines a ball which provides part or all of the ball of a ball and socket joint.

26. A load-bearing implant according to claim 25, in which the ball has a convex load bearing ball portion which is solid and a porous portion extending away from the ball portion.

27. (canceled)

28. A method of making a joint part having a porous portion defined by a multiplicity of solid regions where material is present and a remaining multiplicity of pore regions where material is absent, the method including the step of depositing solid material in the multiplicity of solid regions during a process of solid freeform fabrication in which one or more mathematical functions are used to determine at least most of the multiplicity of regions where material is present.

29. A method according to claim 28, further including the step of modifying one or more of the mathematical functions to vary the porosity and/or strength of the porous portion, calculating the porosity and/or strength of the modified porous and making the joint part with the modified porous, the method including the step of depositing solid material during a process of solid freeform fabrication in which the one or more modified mathematical functions are used of determine at least most of the multiplicity of regions where material is present.

30. A method according to claim 28, in which the implant includes a solid portion and a porous portion, the solid portion and the porous portion being formed in the same process of solid freeform fabrication to provide a one-piece integrated structure.

31. A method according to claim 28, in which the joint part has a porous portion that is defined by a multiplicity of solid regions where material is present and a remaining multiplicity of pore regions where material is absent, the locations of at least most of the multiplicity of solid regions being defined by one or more mathematical functions, and in which all the solid regions of the implant are defined mathematically.

32. A method according to claim 28, in which the joint part is a load-bearing implant having a porous portion that is defined by a multiplicity of solid regions where material is present and a remaining multiplicity of pore regions where material is absent, the locations of at least most of the multiplicity of solid regions being defined by one or more mathematical functions.