Laser-produced porous surface

• US 20070142914A1
• Filed: 12/06/2005
• Published: 06/21/2007
• Est. Priority Date: 12/06/2005
• Status: Active Grant

• Current Assignee: University of Liverpool
• Original Assignee: University of Liverpool
• Inventors: Stamp, Robin, Jones, Eric, Sutcliffe, Christopher
• Granted Patent: US 8,728,387 B2
• Time in Patent Office: Days
• US Class Current: 623/14.130
• CPC Class Codes: A61F 2/30 Joints
• CPC Class Codes: A61F 2/30756 Cartilage endoprostheses A61F2/3603 takes precedence
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30907 Nets or sleeves applied to surface of prostheses or in cement
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3877 Patellae or trochleae
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30199 Three-dimensional shapes
• CPC Class Codes: A61F 2002/30243 the overall spherical surface being composed of a plurality of adjacent circular or polygonal segments, e.g. football-like shaped
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/3028 polyhedral different from parallelepipedal and pyramidal
• CPC Class Codes: A61F 2002/30329 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30594 slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30915 made of a stack of bonded perforated sheets, grids or wire meshes
• CPC Class Codes: A61F 2002/3092 having an open-celled or open-pored structure
• CPC Class Codes: A61F 2002/30968 Sintering
• CPC Class Codes: A61F 2002/3097 : using laser
• CPC Class Codes: A61F 2002/30971 : Laminates, i.e. layered products
• CPC Class Codes: A61F 2002/3401 : with radial apertures, e.g. radial bores for receiving fixation screws
• CPC Class Codes: A61F 2002/3425 : the outer shell having non-meridian protrusions, e.g. fins or wings, located in planes inclined or perpendicular with respect to the equatorial plane
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/0063 : Three-dimensional shapes
• CPC Class Codes: A61F 2230/0071 : spherical
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0023 : differing in porosity
• CPC Class Codes: A61L 27/306 : Other specific inorganic materials not covered by A61L27/303 - A61L27/32
• CPC Class Codes: A61L 27/56 : Porous materials, e.g. foams or sponges
• CPC Class Codes: B22F 10/28 : Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/32 : of the atmosphere, e.g. composition or pressure in a building chamber
• CPC Class Codes: B22F 10/36 : of energy beam parameters
• CPC Class Codes: B22F 10/366 : Scanning parameters, e.g. hatch distance or scanning strategy
• CPC Class Codes: B22F 10/38 : to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures
• CPC Class Codes: B22F 10/62 : by chemical means
• CPC Class Codes: B22F 10/64 : by thermal means control of energy beam parameters for post heating B22F10/364
• CPC Class Codes: B22F 12/41 : characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B22F 2207/11 : Gradients other than composition gradients, e.g. size gradients
• CPC Class Codes: B22F 2999/00 : Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/1109 : Inhomogenous pore distribution composite layers of porous nature B22F7/002
• CPC Class Codes: B22F 5/10 : of articles with cavities or holes, not otherwise provided for in the preceding subgroups
• CPC Class Codes: B23K 26/382 : by boring
• CPC Class Codes: B29C 2045/14327 : anchoring by forcing the material to pass through a hole in the article
• CPC Class Codes: B29C 37/0082 : Mechanical anchoring B29C66/303 takes precedence
• CPC Class Codes: B29C 45/14311 : using means for bonding the coating to the articles B29C45/14795 takes precedence
• CPC Class Codes: B29L 2031/7532 : Artificial members, protheses
• CPC Class Codes: B33Y 10/00 : Processes of additive manufacturing
• CPC Class Codes: B33Y 70/00 : Materials specially adapted for additive manufacturing
• CPC Class Codes: B33Y 80/00 : Products made by additive manufacturing
• CPC Class Codes: C23C 24/10 : with intermediate formation of a liquid phase in the layer
• CPC Class Codes: C23C 26/02 : applying molten material to the substrate
• CPC Class Codes: C23C 4/02 : Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• CPC Class Codes: C23C 4/18 : After-treatment
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method of forming an implant having a porous tissue ingrowth structure and a bearing support structure. The method includes depositing a first layer of a metal powder onto a substrate, scanning a laser beam over the powder so as to sinter the metal powder at predetermined locations, depositing at least one layer of the metal powder onto the first layer and repeating the scanning of the laser beam.

Claims

1. A method of forming an implant having a porous tissue ingrowth structure and a bearing support structure, the method comprising:

depositing a first layer of a metal powder onto a substrate;

scanning a laser beam over said powder so as to sinter said metal powder at predetermined locations;

depositing at least one layer of said metal powder onto said first layer;

repeating said laser scanning step for each successive layer until a predetermined structure having a first surface and a second surface is constructed;

placing a flowable polymer into contact with said second surface of said predetermined structure; and

cooling said flowable polymer such that said flowable polymer adheres to said second surface of said structure.

2. The method according to claim 1, wherein said laser scanning step includes scanning said laser beam onto said metal powder to form a portion of a plurality of predetermined unit cells within said metal powder.

3. The method according to claim 1, further comprising placing said predetermined structure into a cavity of a die and depositing a polymer onto said second surface of said predetermined structure within said cavity of said die.

4. The method according to claim 3, wherein the step of placing a flowable polymer in contact with said second surface of said predetermined structure includes applying pressure and heat to said polymer in said cavity of said die.

5. The method according to claim 1, wherein the step of placing said flowable polymer in contact with said second surface of said predetermined structure includes transfers said flowable polymer onto said second surface.

6. The method according to claim 1, wherein the step of placing said flowable polymer in contact with said second surface of said predetermined structure includes placing said second surface of said predetermined structure adjacent a polymer structure, applying heat to said polymer structure and allowing the polymer structure to engage the predetermined structure.

7. The method according to claim 1, wherein said predetermined structure includes an outer layer, an intermediate layer and an inner layer, said outer layer and said inner layer being relatively porous and said intermediate layer being relatively dense such that said flowable polymer cannot substantially leech through said intermediate layer from said inner layer to said outer layer.

8. The method according to claim 7, wherein said outer layer has a porosity approximately between 60% to 80% and the inner layer has a porosity approximately higher than 80%.

9. The method according to claim 7, wherein said outer layer has a pore size distribution in the range of 80 μ

m to 800 μ

m and said inner layer has a pore size distribution higher than approximately 800 μ

m.

10. The method according to claim 1, wherein said predetermined structure is configured to represent an acetabular cup.

11. The method according to claim 1, wherein said predetermined structure is configured to represent a baseplate of a tibial component.

12. The method according to claim 1, wherein the predetermined structure has a gradient porosity.

13. The method according to claim 11, wherein said gradient porosity of said predetermined structure includes a first layer that is substantially porous, a second layer that is substantially non-porous, a third layer that is substantially porous such that said flowable polymer cannot substantially leech through said second layer from said third layer to said first layer when said flowable liquid polymer is placed in contact with said third layer.

14. The method according to claim 1, further comprising molding said flowable polymer into a form of a bearing surface

15. A method of forming a three-dimensional porous tissue in-growth structure with varying pore characteristics, said method comprising:

predetermining the varying pore characteristics of said three-dimensional porous tissue in-growth structure;

providing a file component representation of said three-dimensional porous tissue in-growth structure comprising said varying pore characteristics;

predetermining a layered configuration of unit cells and portions thereof corresponding to said file component representation such that each layer corresponds to said pore characteristics in that layer, said layered configuration having a first layer configuration and successive layer configurations;

depositing a first layer of metal powder onto a substrate;

scanning said first layer of metal powder with a laser beam to form said unit cells and portions thereof in said metal powder corresponding to said first layer configuration;

depositing successive layers of metal powder onto a previous layer, wherein each layer or portion thereof is scanned using said laser beam and forms unit cells corresponding to each successive layer configuration;

depositing and scanning said metal layers to form said three-dimensional porous tissue in-growth structure which resembles said file component representation and has varying pore characteristics corresponding to said file component representation;

placing a flowable polymer against said three-dimensional porous tissue in-growth structure; and

solidifying said flowable polymer to form a bearing surface adjacent said three-dimensional porous tissue in-growth structure.

16. The method according to claim 15, further comprising forming said three-dimensional porous tissue in-growth structure as an acetabular cup shell having an inner layer and an outer bone contacting layer.

17. The method according to claim 16, further comprising varying said pore characteristics of said file component representation such that said acetabular cup shell inner layer is dense and said outer bone contacting layer is porous.

18. The method according to claim 16, further comprising varying aid pore characteristics of said file component representation such that said acetabular cup shell outer bone contacting layer has a first porosity adjacent an equatorial region of said shell and a second porosity adjacent a polar region of said shell, said second porosity being greater than said first porosity.

19. The method according to claim 16 further comprising varying said ore characteristics of said acetabular cup file component representation such that said shell porous outer bone contacting layer has a first porosity adjacent an equatorial region of said shell and a second porosity adjacent a polar region of said shell, said second porosity being greater than said first porosity.

20. The method of producing a three-dimensional porous tissue in-growth structure according to claim 15, wherein aid substrate is a base or core made of a metal selected from the group consisting of titanium, titanium alloys, stainless steel, cobalt chrome alloys, tantalum and niobium, wherein said first layer is fused to said base or core.

21. The method of producing a three-dimensional porous tissue in-growth structure according to claim 15, further comprising sintering at least a portion of said first layer of powder to said base or core.

22. A medical implant comprising:

a metal insert having a bone ingrowth structure, an intermediate structure and a bearing support structure, said bone ingrowth structure having a porosity sufficient to promote bone ingrowth;

a bearing surface formed from a polymer material, said bearing surface being attached to said bearing support structure;

wherein said intermediate structure has a porosity sufficient to inhibit said polymer material from translating through said bearing support structure to said bone ingrowth structure.

23. The medical implant according to claim 22, wherein said intermediate structure is designed to facilitate a specific stiffness characteristic to an overall construct.

24. The medical implant according to claim 22, wherein said intermediate structure includes two barrier layers and a bridging section.

25. The medical implant according to claim 23, wherein a bone cement is deposited onto said bearing support structure.

26. The medical implant according to claim 25, wherein said bearing surface is part of a liner, said liner having an exterior and an interior, said interior adapted to act as a bearing surface, said exterior adapted to engage said bone cement.

27. The medical implant according to claim 22, wherein said metal insert is in a shape of an actebular cup.

28. The medical implant according to claim 22, wherein said metal insert is in the shape of a cartilage plug.

29. The medical implant according to claim 22, wherein said metal insert is in the shape of a patella component.

30. The medical implant according to claim 22, wherein said bearing support structure includes at least one lattice.

31. The medical implant according to claim 22, wherein said bone ingrowth structure has a graded porosity.

32. The medical implant according to claim 22, wherein said bone ingrowth structure includes a first portion having a first porosity and a second portion having a second porosity, said first porosity being different than said second porosity.

33. The medical implant according to claim 22, wherein said bone ingrowth structure has a thickness of between 1 mm and 2 mm, said intermediate structure has a thickness of less than approximately 0.25 mm, said bearing structure has a thickness greater than approximately 0.5 mm.

34. The medical implant according to claim 22, wherein said bone ingrowth structure has a thickness of less than 1.5 mm, said intermediate structure has a thickness of less than approximately 5 mm, said bearing structure has a thickness greater than approximately 0.5 mm.

35. The medical implant according to claim 22, wherein said metal insert and said bearing surface have a thickness of less than 4 mm.

36. The medical implant according to claim 22, wherein said bone ingrowth structure has a pore size distribution in the range of 80 μ

m to 800 μ

m, said bearing support structure has a pore size distribution higher than 800 μ

m.