Polymeric composite orthopedic implant

• US 6,602,293 B1
• Filed: 11/01/1996
• Issued: 08/05/2003
• Est. Priority Date: 11/01/1996
• Status: Expired due to Term

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Corvelli, Amy A., Biermann, Paul J., Roberts, Jack C.
• Primary Examiner(s): Willse, David H.
• Application Number:
  US08/742,733
• Time in Patent Office: 2,468 Days
• Field of Search: 606/72, 623/FOR.16, 623/20.US, 623/23.US, 623/20-5-, 623/22-1-, 623/23.18, 623/23.44, 623/23.5, 623/23.51, 623/23.58
• US Class Current: 623/23.5
• CPC Class Codes: A61B 17/72 Intramedullary pins, nails or other devices A61B17/744 takes precedence
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• 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 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/468 Testing instruments for artificial joints for testing non-implantable prostheses A61F2/76
• CPC Class Codes: A61F 2002/30065 thermoplastic, i.e. softening or fusing when heated, and hardening and becoming rigid again when cooled
• CPC Class Codes: A61F 2002/30171 rosette- or star-shaped
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30289 helically-coiled
• CPC Class Codes: A61F 2002/30321 differing in roughness
• CPC Class Codes: A61F 2002/30367 with additional means for preventing said rotation
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/3082 Grooves
• CPC Class Codes: A61F 2002/30878 with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2002/30906 shot- sand- or grit-blasted
• CPC Class Codes: A61F 2002/30925 etched
• CPC Class Codes: A61F 2002/30955 using finite-element analysis
• CPC Class Codes: A61F 2002/30957 using a positive or a negative model, e.g. moulds
• CPC Class Codes: A61F 2002/30975 : made of two halves
• CPC Class Codes: A61F 2210/0071 : thermoplastic
• 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 2220/005 : using adhesives
• CPC Class Codes: A61F 2230/005 : Rosette-shaped, e.g. star-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0091 : helically-coiled or spirally-coiled, i.e. having a 2-D spiral cross-section
• CPC Class Codes: A61F 2250/0025 : differing in roughness
• 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: Y10S 606/907 : Composed of particular material or coated
• CPC Class Codes: Y10S 606/91 : Polymer

Abstract

An orthopedic implant comprising a thermoplastic polymer or a composite comprising, in one embodiment, polyetheretherketone reinforced with 10% by volume of glass fibers, with an elastic modulus approximating the elastic modulus of bone. A porous coating is formed on the implant surface by creating a roughness thereon, by coating the surface with hydroxyapatite or by embedding a biocompatible material such as titanium in the surface. A two piece embodiment of the implant is joined and locked together, after the opposite ends of each piece are inserted in the medullary canal, using an interlocking mechanism comprising a fluted protrusion on one piece and a corresponding fluted cavity in the other piece with the fluted portions being complementarily tapered.

Claims

1. An orthopedic implant for replacing a missing or diseased portion of bone, the implant comprising:

a thermoplastic polymer having an elastic modulus approximating the elastic modulus of bone;

a biocompatible material partially embedded in a surface of the implant;

a first piece and a second piece, the first and second pieces being joined and locked together by an interlocking means comprising;

a protruding member on the first piece; and

a cavity in the second piece for receiving the protruding member; and

means for resisting rotation between the first and second pieces, wherein the rotation resisting means comprises a flute on the protruding member and a corresponding fluted opening in the cavity.

2. An orthopedic implant for replacing a missing or diseased portion of bone, the implant comprising:

a thermoplastic polymer having an elastic modulus approximating the elastic modulus of bone;

a biocompatible material partially embedded in a surface of the implant;

a first piece and a second piece, the first and second pieces being joined and locked together by an interlocking means comprising;

a protruding member on the first piece; and

a cavity in the second piece for receiving the protruding member,

wherein the protruding member and the cavity are complementarily tapered; and

means for resisting rotation between the first and second pieces.

3. The implant as recited in claim 2, wherein the end opposite the protruding member on the first piece and the end opposite the cavity on the second piece are both fluted.

4. An intramedullary implant for replacing a missing or diseased portion of bone comprising:

a first piece comprising a first end for insertion into the medullary cavity of a bone and a second end having a protruding member thereon;

a second piece comprising a first end for insertion into the medullary cavity of a bone and a second end having a cavity formed therein for receiving the protruding member on the second end of the first piece; and

means for resisting rotation between the first and second pieces;

wherein the rotation resisting means comprises a flute on the protruding member and a corresponding fluted opening in the cavity.

5. The intramedullary implant as recited in claim 4, wherein the fluted protruding member of the first piece and the fluted cavity of the second piece are complementarily tapered.

6. The intramedullary implant as recited in claim 5, wherein the first ends of the first and second pieces are fluted.

7. The intramedullary implant as recited in claim 5, further comprising a porous coating on a surface of the implant.

8. The intramedullary implant as recited in claim 7, wherein the porous coating comprises hydroxyapatite.

9. The intramedullary implant as recited in claim 7, wherein the porous coating comprises a roughness formed on the surface of the implant.

10. The intramedullary implant as recited in claim 7, wherein the porous coating comprises a biocompatible material partially embedded in the surface of the implant.

11. The intramedullary implant as recited in claim 10, wherein the biocompatible material is titanium.

12. The intramedullary implant as recited in claim 11, wherein the titanium comprises a coil.

13. The intramedullary implant as recited in claim 12, wherein the coil is embedded to a depth of between ⅓

to ½

of the diameter of the coil.

14. The intramedullary implant as recited in claim 13, wherein, prior to being embedded, the coil is wrapped around the implant.

15. The intramedullary implant as recited in claim 13, wherein, after the coil is embedded in the surface of the implant, the interstices between the nonembedded portions of the coil range from 150 to 200 micrometers.

16. The intramedullary implant as recited in claims 4, 7, 10, or 15, further comprising a thermoplastic polymer having an elastic modulus approximating the elastic modulus of bone.

17. The intramedullary implant as recited in claims 4, 7, 10 or 15 further comprising a fiber reinforced polymer, wherein the fiber reinforced polymer has an elastic modulus approximating the elastic modulus of bone.

18. The intramedullary implant as recited in claim 17, wherein the polymer comprises polyetheretherketone (PEEK).

19. The intramedullary implant as recited in claim 18, wherein the reinforcing fiber comprises glass.

20. The intramedullary implant as recited in claim 19, wherein the glass fibers comprise 10% of the implant by volume.

21. An orthopedic implant for replacing a missing or diseased portion of bone, the implant comprising a composite comprising:

a thermoplastic polymer;

a material for reinforcing the polymer;

a biocompatible material partially embedded in a surface of the implant;

a first piece and a second piece, the first and second pieces being joined and locked together by an interlocking means comprising;

a protruding member on the first piece; and

a cavity in the second piece for receiving the protruding member; and

means for resisting rotation between the first and second pieces, wherein the rotation resisting means comprises a flute on the protruding member and a corresponding fluted opening in the cavity;

wherein the composite has an elastic modulus approximating the elastic modulus of bone.

22. An orthopedic implant for replacing a missing or diseased portion of bone, the implant comprising a composite comprising:

polyetheretherketone (PEEK);

glass fibers for reinforcing the polymer, the glass fibers comprising 10% of the implant by volume;

a biocompatible material partially embedded in a surface of the implant;

a first piece and a second piece, the first and second pieces being joined and locked together by an interlocking means comprising;

a protruding member on the first piece; and

a cavity in the second piece for receiving the protruding member; and

means for resisting rotation between the first and second pieces, wherein the rotation resisting means comprises a flute on the protruding member and a corresponding fluted opening in the cavity;

wherein the composite has an elastic modulus approximating the elastic modulus of bone.

23. An orthopedic implant for replacing a missing or diseased portion of bone, the implant comprising a composite comprising:

a thermoplastic polymer;

a material for reinforcing the polymer;

a biocompatible material partially embedded in a surface of the implant;

a first piece and a second piece, the first and second pieces being joined and locked together by an interlocking means comprising;

a protruding member on the first piece; and

a cavity in the second piece for receiving the protruding member wherein the protruding member and the cavity are complementarily tapered; and

means for resisting rotation between the first and second pieces;

wherein the composite has an elastic modulus approximating the elastic modulus of bone.

24. An orthopedic implant for replacing a missing or diseased portion of bone, the implant comprising a composite comprising:

polyetheretherketone (PEEK);

glass fibers for reinforcing the polymer, the glass fibers comprising 10% of the implant by volume; and

a biocompatible material partially embedded in a surface of the implant;

a first piece and a second piece, the first and second pieces being joined and locked together by an interlocking means comprising;

a protruding member on the first piece; and

a cavity in the second piece for receiving the protruding member, wherein the protruding member and the cavity are complementarily tapered; and

means for resisting rotation between the first and second pieces;

wherein the composite has an elastic modulus approximating the elastic modulus of bone.