Implantable orthopedic prosthesis with textured polymeric surfaces

• US 20040102854A1
• Filed: 11/22/2002
• Published: 05/27/2004
• Est. Priority Date: 11/22/2002
• Status: Active Grant

• Current Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Zhu, Mengke
• Granted Patent: US 6,974,482 B2
• Time in Patent Office: Days
• US Class Current: 623/23.15
• CPC Class Codes: A61F 2/30734 Modular inserts, sleeves or augments, e.g. placed on proximal part of stem for fixation purposes or wedges for bridging a bone defect
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/34 Acetabular cups
• 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 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30112 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2002/30113 circular
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30322 differing in surface structures
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30367 with additional means for preventing said rotation
• CPC Class Codes: A61F 2002/30736 Augments or augmentation pieces, e.g. wedges or blocks for bridging a bone defect
• CPC Class Codes: A61F 2002/30828 parallel
• CPC Class Codes: A61F 2002/30831 : perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30892 : parallel
• CPC Class Codes: A61F 2002/30906 : shot- sand- or grit-blasted
• CPC Class Codes: A61F 2002/3097 : using laser
• CPC Class Codes: A61F 2002/3429 : with an integral peripheral collar or flange, e.g. oriented away from the shell centre line
• CPC Class Codes: A61F 2002/3611 : Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 : Necks
• CPC Class Codes: A61F 2002/365 : Connections of heads to necks
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0004 : Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2230/0006 : circular
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2230/0026 : trapezoidal
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0024 : made from both porous and non-porous parts, e.g. adjacent parts
• CPC Class Codes: A61F 2250/0026 : differing in surface structures
• CPC Class Codes: A61F 2310/00011 : Metals or alloys
• 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 2310/00407 : Coating made of titanium or of Ti-based alloys
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: A61F 2310/00976 : Coating or prosthesis-covering structure made of proteins or of polypeptides, e.g. of bone morphogenic proteins BMP or of transforming growth factors TGF
• CPC Class Codes: A61L 27/04 : Metals or alloys
• CPC Class Codes: A61L 27/16 : obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/56 : Porous materials, e.g. foams or sponges
• CPC Class Codes: C08L 23/06 : Polyethene

Abstract

Implantable prostheses fully or partially formed of polymer having a textured or porous outer surface. The surface permits and encourages osteogenesis into the prosthesis and enables it to become firmly and permanently anchored into surrounding bone. The prostheses include a femoral hip stem formed of a metallic core and a polymeric proximal body with a textured or porous surface formed from a laser texturing, machining, or grit blasting.

Claims

1. A prosthetic femoral hip stem, comprising:

a metal core having an elongated body extending from a proximal portion to a distal portion, the distal portion adapted to be inserted into an intramedullary canal of a patient; and

a proximal body connected to the proximal portion, the proximal body being formed entirely of polymer and having an external surface adapted to engage bone in the intramedullary canal, wherein the external surface is textured with a laser.

2. The implant as defined in claim 1 wherein the external surface is textured with the laser to have a multitude of pores adapted to induce growth of cancellous and cortical bone into the external surface.

3. The implant as defined in claim 2 wherein the external surface has a textured thickness from about 0.05 mm to about 5 mm.

4. The implant as defined in claim 3 wherein the pores have an average pore diameter from about 40 μ

m to about 1000 μ

m.

5. The implant as defined in claim 4 wherein the pores have a porosity ranging from about 40% to about 65%.

6. The implant as defined in claim 5 wherein the pores have interconnections with an average diameter of greater than about 50 microns.

7. The implant as defined in claim 2 wherein the pores are coated with one of plasma sprayed titanium or hydroxyapatite.

8. A femoral hip stem, comprising:

a metal core having an elongated body extending from a proximal portion to a distal portion, the distal portion adapted to be inserted into an intramedullary canal of a patient; and

a proximal body connected to the proximal portion, the proximal body formed of polymer with an external surface adapted to engage bone in the intramedullary canal, wherein the external surface is machine texturized with at least one of cutting, drilling, knurling, and milling to produce an array of pores adapted to encourage bone growth into the external surface.

9. The implant as defined in claim 8 wherein the proximal body is formed of ultra high molecular weight polyethylene.

10. The implant as defined in claim 9 wherein the proximal body has a tensile elastic modulus of less than about 940 MPa.

11. The implant as defined in claim 9 wherein the array of pores covers substantially all of the external surface.

12. The implant as defined in claim 11 wherein the external surface has a textured thickness from about 0.05 mm to about 5 mm.

13. The implant as defined in claim 8 wherein the proximal body has a series of bosses forming a grid of numerous columns and rows;

and wherein each boss has an undercut adapted to receive bone growth.

14. The implant as defined in claim 12 wherein the pores have an average pore diameter from about 40 μ

m to about 1000 μ

m.

15. The implant as defined in claim 14 wherein the wherein the pores have a porosity ranging from about 40% to about 65%.

16. A prosthetic acetabular cup, comprising:

a shell having a hemispherical shape defined by an outer surface adapted to engage bone and a smooth inner surface adapted to articulate with a head of a femoral hip stem, wherein the outer surface is texturized with a laser to produce an array of pores adapted to encourage bone growth into the external surface.

17. The acetabular cup of claim 16 wherein the shell is formed entirely of ultra-high-molecular-weight polyethylene.

18. The acetabular cup of claim 17 wherein the pores have an average pore diameter from about 40 μ

m to about 1000 μ

m.

19. The acetabular cup of claim 18 wherein the wherein the pores have a porosity ranging from about 40% to about 65%.

20. The acetabular cup of claim 19 wherein the pores cover substantially all the outer surface.