Medical implant
Medical implant which at least partially comprises a biocompatible, electrically conductive polymer with electrical resistivity p, having the property of being able to be heated and softened by a flow of current through the polymer.
1. A medical implant comprising:
a biocompatible self-conductive polymer element comprising a first conductive tube having a first resistivity, and a second conductive tube coaxial with said first conductive tube and having a second resistivity greater than the first resistivity, said second conductive tube defining a longitudinal passageway configured to
have a distal end inserted within a cavity of a bone,
heat and soften in response to an application of current flow therethrough, and
fill the cavity in the bone with softened biocompatible self-conductive polymer from the distal end of the biocompatible self-conductive polymer element;
an electrically conductive element configured to be inserted in the longitudinal passageway and to be coupled to said biocompatible self-conductive polymer element; and
an electrode coupled to the biocompatible self-conductive polymer element via said electrically conductive element and configured to apply the current flow to said biocompatible self-conductive polymer element within the cavity of the bone;
said biocompatible self-conductive polymer element configured to be advanced into the cavity of the bone as the distal end is softened to fill the cavity.
2. The medical implant according to claim 1 , wherein said biocompatible self-conductive polymer element is configured to soften below a temperature of 250° C.
3. The medical implant of claim 1 wherein at least a portion of the biocompatible self-conductive polymer element has a specific electrical resistivity p; and wherein the specific electrical resistivity p is greater than 1,500 Ohm-cm.
4. The medical implant of claim 1 wherein the biocompatible self-conductive polymer element has a surface resistivity of at least 10 2 Ohm/square.
5. The medical implant of claim 1 wherein the biocompatible self-conductive polymer element has a volume conductivity of at least 10 −4 S/m.
6. The medical implant of claim 1 wherein the biocompatible self-conductive polymer element comprises a thermoplastic material.
7. The medical implant of claim 6 , wherein the thermoplastic material comprises at least one of polyacetylenes, polyanilines, poly(ethylenedioxythiophenes), poly(phenylenevinylines), polyarylenes, polyspirobifluorenes, polydialkylfluorenes, polythiophenes or polypyrroles.
8. The medical implant of claim 1 wherein the biocompatible self-conductive polymer element comprises an implant coating.
9. The medical implant of claim 1 wherein the biocompatible self-conductive polymer element comprises zones with a variable specific electrical resistivity p.
10. The medical implant of claim 1 further comprising an electrically non-conductive coating over said biocompatible self-conductive polymer element.
11. The medical implant of claim 10 , wherein the electrically non-conductive coating comprises at least one of an osteoconductive material, an osteoinductive material, and an osteogenic material.
12. The medical implant of claim 10 , wherein the electrically non-conductive material comprises at least one of a polylactide, and a hydroxyapatite.
13. The medical implant of claim 1 wherein the biocompatible self-conductive polymer element has a bar shape.
14. The medical implant of claim 1 wherein an alternating current with a frequency greater than 20,000 Hz applied to the biocompatible self-conductive polymer element causes the biocompatible self-conductive polymer element to heat and soften.
15. A medical implant comprising:
a biocompatible self-conductive thermoplastic polymer element comprising a first conductive tube having a first resistivity, and a second conductive tube coaxial with said first conductive tube and having a second resistivity greater than the first resistivity, said second conductive tube defining a longitudinal passageway configured to
have a distal end inserted within a cavity of a bone,
heat and soften in response to an application of current flow therethrough, and
fill the cavity in the bone with softened biocompatible self-conductive thermoplastic polymer from the distal end of the biocompatible self-conductive thermoplastic polymer element;
an electrically conductive element configured to be inserted in the longitudinal passageway and to be coupled to said biocompatible self-conductive thermoplastic polymer element; and
an electrode coupled to the biocompatible self-conductive thermoplastic polymer element via said electrically conductive element and configured to apply the current flow to said biocompatible self-conductive thermoplastic polymer element within the cavity of the bone;
said biocompatible self-conductive thermoplastic polymer element configured to be advanced into the cavity of the bone as the distal end is softened to fill the cavity;
wherein an alternating current with a frequency greater than 20,000 Hz applied to the biocompatible self-conductive thermoplastic polymer element causes the biocompatible self-conductive thermoplastic polymer element to heat and soften.
16. The medical implant according to claim 15 , wherein said biocompatible self-conductive thermoplastic polymer element is configured to soften below a temperature of 250° C.
17. The medical implant of claim 15 wherein at least a portion of the biocompatible self-conductive thermoplastic polymer element has a specific electrical resistivity p; and wherein the specific electrical resistivity p is greater than 1,500 Ohm-cm.
18. The medical implant of claim 15 wherein the biocompatible self-conductive thermoplastic polymer element has a surface resistivity of at least 102 Ohm/square.
19. The medical implant of claim 15 wherein the biocompatible self-conductive thermoplastic polymer element has a volume conductivity of at least 10-4 S/m.