Implantable prosthesis for measuring six force components

• US 6,821,299 B2
• Filed: 03/21/2003
• Issued: 11/23/2004
• Est. Priority Date: 07/24/2002
• Status: Active Grant

• Current Assignee: Zimmer Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Zimmer Technology Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Green, John, Kirking, Bryan, Bailey, Aaron, Radefeld, Robert
• Primary Examiner(s): STEWART, ALVIN J
• Application Number:
  US10/393,556
• Publication Number:
  US 20040019384A1
• Time in Patent Office: 613 Days
• Field of Search: 623/20.14, 623/20-5-, 600/587
• US Class Current: 623/20.14
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30357 Stepped cylinders, i.e. having discrete diameter changes
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30451 soldered or brazed or welded
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30604 modular
• CPC Class Codes: A61F 2002/30774 internally-threaded
• 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 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/4666 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2002/4667 for measuring torque
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• 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 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical

Abstract

An implantable knee prosthesis for in-vivo measuring force components along three different axes, the X-axis, the Y-axis, and the Z-axis. The prosthesis can measure six different force components along these axes while the prosthesis is under load.

Claims

1. An implantable knee prosthesis for measuring force components, comprising:

a tibial implant having a tray and an elongated stem extending distally from the tray, the stem has an internal cavity and a force measuring section; and

at least one force detection instrument located in the internal cavity at the force measuring section, wherein the force detection instrument is adapted to measure six different force components while the tibial implant is under load.

2. The knee prosthesis of claim 1 wherein the force measuring section is integrally formed with the stem.

3. The knee prosthesis of claim 2 wherein the force detection instrument measures deflection of the force measuring section.

4. The knee prosthesis of claim 1 wherein the force detection instrument includes four measuring sensors equally spaced and circumferentially disposed in the cavity.

5. The knee prosthesis of claim 4 wherein the measuring sensors are strain gauges.

6. The knee prosthesis of claim 1 wherein a coordinate system having an X-axis, Y-axis, and Z-axis define the tray, and the force detection instrument is adapted to measure force components along the X, Y, and Z axes.

7. The knee prosthesis of claim 6 wherein the force components includes forces and torques along the X, Y, and Z axes.

8. The knee prosthesis of claim 1 wherein the force measuring section is adjacent the tray.

9. An implantable prosthesis for measuring loads while implanted, the prosthesis comprising:

a first component adapted to be affixed to bone; and

a second component connectable to the first component, the second component including an elongated stem having a force measuring section and an internal cavity, at least one force detection instrument located in the cavity, and electronics located in the cavity and connected to the force detection instrument, wherein the force detection instrument measures six different force components defined along a coordinate system having an X-axis, Y-axis, and Z-axis.

10. The implantable prosthesis of claim 9 wherein force components include forces and torques along all of the X, Y, and Z axes.

11. The implantable prosthesis of claim 9 wherein the force measuring section is integrally formed with the stem.

12. The implantable prosthesis of claim 11 wherein the force detection instrument measures strain along the force measuring section.

13. The implantable prosthesis of claim 12 wherein the force measuring section is formed as a hollow cylinder.

14. The implantable prosthesis of claim 9 wherein the second component includes an enlarged substantially elliptical tray, and the force measuring section is adjacent the tray.

15. An implantable knee prosthesis for measuring force components, comprising:

a tibial implant having an enlarged tray and an elongated stem extending downwardly from the tray, the stem having an internal cavity and a force measuring section;

a tibial shell adapted to be implanted into an intramedullary canal of a tibia, the tibial shell connected to the tibial implant; and

at least one force detection instrument located in the internal cavity at the force measuring section, wherein the force detection instrument is adapted to measure multiple force components while the tibial shell is implanted and the tibial implant is under load.

16. The implantable knee prosthesis of claim 15 wherein the force detection instrument measures six different force components in a coordinate system with X, Y, and Z axes.

17. The implantable knee prosthesis of claim 16 wherein two different force components are measured in each of the X, Y, and Z axes.

18. The implantable knee prosthesis of claim 15 wherein the tibial shell has a cylindrical portion with a bore adapted to receive and engage the stem of the tibial implant.

19. The implantable knee prosthesis of claim 18 wherein tibial shell has a baseplate similarly shaped to the tray of the tibial implant.

20. The implantable knee prosthesis of claim 15 wherein the tibial implant is removeably connectable to the tibial shell while the tibial shell is implanted.