Laser-produced porous surface

• US 8,728,387 B2
• Filed: 12/06/2005
• Issued: 05/20/2014
• Est. Priority Date: 12/06/2005
• Status: Active Grant

• Current Assignee: University of Liverpool
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation), University of Liverpool
• Inventors: Jones, Eric, Sutcliffe, Christopher J., Stamp, Robin
• Primary Examiner(s): Kastler, Scott
• Assistant Examiner(s): LUK, VANESSA TIBAY
• Application Number:
  US11/295,008
• Publication Number:
  US 20070142914A1
• Time in Patent Office: 3,087 Days
• Field of Search: 2191216-122, 264413-414, 264/497, 419/1, 419/2, 419/5, 419/6, 419/8, 419/27, 419/47, 623/22.21, 623/22.32, 623/22.33, 623/23.3, 623/23.5, 623/23.55, 148/513, 148/514, 148/516, 148/524, 148/525, 148527-537, 148/902, 148/903, 427 224- 227, 427/554, 428/547, 428/550, 428/613, 428/304.4
• US Class Current: 419/2
• 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 high energy beam over said first layer of said metal powder so as to melt said metal powder at predetermined locations to form at least portions of struts, said struts forming portions of unit cells;

depositing successive layers of said metal powder onto a previous layer;

repeating said laser scanning step for each successive layer to form additional portions of unit cells until a porous first layer of a predetermined structure having a first surface is constructed;

repeating said laser scanning step for each successive layer to form additional portions of unit cells until an almost non-porous second layer of said predetermined structure is constructed;

repeating said laser scanning step for each successive layer to form additional portions of struts for forming unit cells until a porous third layer of said predetermined structure having a second surface is constructed;

varying porosity within said three-dimensional porous tissue in-growth structure by at least one of (i) forming a unit cell in one powder layer having at least one of (a) a different shape from a unit cell within a successive powder layer and (b) at least one strut having a different length from a corresponding strut of a unit cell of the same shape within a successive powder, (ii) applying a random perturbation in any direction to vertices of the unit cells to randomize the geometry of the unit cells, and (iii) randomly forming spots on one of the deposited powder layers, the spots being joined to produce struts or portions of struts which constitute a portion of a unit cell of the three-dimensional structure;

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

cooling said flowable polymer such that said flowable polymer adheres to said second surface of said structure, wherein said first, second, and third layers form a gradient porosity within said predetermined structure such that said flowable polymer cannot 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.

2. 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.

3. The method according to claim 2, 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.

4. 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 transferring said flowable polymer onto said second surface.

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 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.

6. The method according to claim 1, wherein said third layer has a porosity approximately between 60% to 80% and the first layer has a porosity approximately higher than 80%.

7. The method according to claim 1, wherein said third layer has a pore size distribution in the range of 80 μ

m to 800 μ

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

m.

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

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

10. The method according to claim 1, wherein the at least one of the porous tissue ingrowth and the bearing support structure has a gradient porosity.

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

12. The method according to claim 1, wherein said high energy beam is a laser beam.

13. The method according to claim 1, wherein said high energy beam is an e-beam.

14. The method according to claim 1, wherein said step of repeating said laser scanning step for each successive layer until an almost non-porous second layer of said three-dimensional porous tissue in-growth structure is constructed is performed after said porous first layer is constructed, and wherein said step of repeating said laser scanning step for each successive layer until a porous third layer of said predetermined structure having a second surface is constructed is performed after said almost non-porous second layer is constructed.

15. The method according to claim 1, wherein said step of varying porosity within said three-dimensional porous in-growth structure by step (i) includes forming said unit cell in said one powder layer having at least one strut non-parallel to the substrate.

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

determining said 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;

determining a layered configuration of unit cells, struts, 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, each of the layer configurations having corresponding pore characteristics;

depositing a first layer of metal powder onto a substrate;

scanning said first layer of metal powder with a high energy beam so as to melt said metal powder to form at least portions of struts, said struts forming portions of said unit cells in said metal powder corresponding to said first layer configuration;

depositing successive layers of said metal powder onto a previous layer;

scanning each said successive layer or portion thereof using said high energy beam so as to melt said metal powder to form additional portions of said unit cells in said metal powder corresponding to respective successive layer configurations until a porous inner layer of said three-dimensional porous tissue in-growth structure is constructed, said porous inner layer having a first surface;

repeating said scanning step for each successive layer until an almost non-porous intermediate layer of said three-dimensional porous tissue in-growth structure is constructed;

repeating said scanning step for each successive layer until a porous outer layer of said three-dimensional porous tissue in-growth structure is constructed, said porous outer layer having a second surface;

varying porosity within said three-dimensional porous tissue in-growth structure by at least one of (i) forming a unit cell in one powder layer having at least one of (a) a different shape from a unit cell within a successive powder layer and (b) at least one strut having a different length from a corresponding strut of a unit cell of the same shape within a successive powder layer, (ii) applying a random perturbation in any direction to vertices of the unit cells to randomize the geometry of the unit cells, and (iii) randomly forming spots on one of the deposited powder layers, the spots being joined to produce struts or portions of struts which constitute a portion of a unit cell of the three-dimensional structure, wherein said three-dimensional porous tissue in-growth structure resembles said file component representation and has varying pore characteristics corresponding to said file component representation;

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

solidifying said flowable polymer to form a bearing surface adjacent to said three-dimensional porous tissue in-growth structure, wherein said three-dimensional porous tissue in-growth structure has a gradient porosity between the second surface and the first surface such that said flowable polymer cannot leech through said intermediate layer from said inner layer to said outer layer when said flowable liquid polymer is placed in contact with said inner layer.

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

18. The method according to claim 17, further comprising varying said 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 17 further comprising varying said pore 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 16, wherein said 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 20, further comprising melting at least a portion of said first layer of powder to said base or core.

22. The method according to claim 16, wherein said high energy beam is a laser beam.

23. The method according to claim 16, wherein said high energy beam is an e-beam.

24. The method according to claim 16, wherein said step of repeating said laser scanning step for each successive layer until an almost non-porous intermediate layer of said three-dimensional porous tissue in-growth structure is constructed is performed after said porous inner layer is constructed, and wherein said step of repeating said laser scanning step for each successive layer until a porous outer layer of said predetermined structure having a second surface is constructed is performed after said almost non-porous intermediate layer is constructed.

25. The method according to claim 16, wherein said step of varying porosity within said three-dimensional porous in-growth structure by step (i) includes forming said unit cell in said one powder layer having at least one strut non-parallel to the substrate.