Systems and methods of loading fluid in a prosthetic knee

• US 7,198,071 B2
• Filed: 05/06/2005
• Issued: 04/03/2007
• Est. Priority Date: 05/02/2003
• Status: Active Grant

• Current Assignee: Ossur hf
• Original Assignee: Ossur Engineering Incorporated
• Inventors: Bisbee, Charles R. III, Hsu, Henry H.
• Primary Examiner(s): Douglas; Steven O
• Application Number:
  US11/124,610
• Publication Number:
  US 20060074493A1
• Time in Patent Office: 697 Days
• Field of Search: 141/4, 141/7, 141/8, 141/65, 141/39, 141/67, 128/DIG.12, 252/62.52, 623/24, 623/26, 623/39
• US Class Current: 141/8
• CPC Class Codes: A61F 2/5044 Designing or manufacturing processes
• CPC Class Codes: A61F 2/64 Knee joints
• CPC Class Codes: A61F 2/68 Operating or control means
• CPC Class Codes: A61F 2002/5004 operated by electro- or magnetorheological fluids
• CPC Class Codes: A61F 2002/5033 for adjusting damping damping means A61F2002/5003
• CPC Class Codes: A61F 2002/5073 Helical springs, e.g. having at least one helical spring
• CPC Class Codes: A61F 2002/6818 for braking
• CPC Class Codes: A61F 2002/704 computer-controlled, e.g. robotic control
• CPC Class Codes: A61F 2002/705 Electromagnetic data transfer for implantable prostheses A61F2250/0002
• CPC Class Codes: A61F 2002/7625 for measuring angular position
• CPC Class Codes: A61F 2002/7635 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2002/7645 for measuring torque, e.g. hinge or turning moment, moment of force
• CPC Class Codes: A61F 2002/769 Displaying measured values

Abstract

The invention in some embodiments relates to systems and methods of loading fluid in a prosthetic knee. A vacuum fill technique is utilized in one embodiment to load magnetorheological fluid within small gaps in a chamber of a prosthetic knee. Advantageously, this allows for an efficient loading scheme thereby desirably allowing for faster manufacturing speed. Another advantage is that the magnetorheological fluid is substantially uniformly distributed within the small gaps thereby desirably providing consistent production.

Claims

1. A method of loading a magnetorheological fluid in a prosthetic knee, comprising:

providing a prosthetic knee actuator comprising a plurality of first blades and second blades with gaps therebetween in a chamber of an outer housing with at least one of said plurality of first blades and said plurality of second blades being rotatable;

providing a magnetorheological fluid in a channel that is in fluid communication with said chamber; and

applying a vacuum over said prosthetic knee actuator and said channel to force said fluid into said chamber.

2. The method of claim 1, wherein after forcing said fluid into said chamber said fluid is substantially uniformly distributed in said gaps between said blades.

3. The method of claim 1, wherein providing a prosthetic knee actuator comprises providing an actuator that is capable of shearing said fluid in said gaps between said blades.

4. The method of claim 1, wherein said gaps have a size of about 18 μ

m (0.0007 inches).

5. The method of claim 1, wherein providing a magnetorheological fluid comprises providing a magnetorheological fluid having a volume in the range from about 1 mL to about 10 mL.

6. The method of claim 1, wherein prior to providing a magnetorheological fluid said method comprises applying a vacuum to said fluid to substantially degas said fluid.

7. The method of claim 6, wherein applying a vacuum to said fluid comprises applying a vacuum at about 29.4 inches mercury.

8. The method of claim 6, wherein applying a vacuum to said fluid comprises applying a vacuum for about 30 minutes.

9. The method of claim 1, wherein applying a vacuum comprises applying a vacuum at about 28 inches mercury.

10. The method of claim 1, wherein said method further comprises agitating said prosthetic knee actuator to facilitate settling of said fluid.

11. The method of claim 10, wherein agitating said prosthetic knee actuator comprises agitating said prosthetic knee actuator while said prosthetic knee actuator is under vacuum.

12. The method of claim 11, wherein agitating said prosthetic knee actuator comprises rotating said prosthetic knee actuator in a back and forth manner.

13. The method of claim 1, wherein said method further comprises feeding a substantially inert gas into said vacuum and releasing said vacuum to further force said fluid into said gaps and allow said gas to occupy a portion of said chamber.

14. The method of claim 13, wherein releasing said vacuum comprises releasing said vacuum at a rate of about 2 inches mercury per 10 seconds.

15. The method of claim 13, wherein feeding a substantially inert gas comprises feeding nitrogen.

16. The method of claim 1, wherein said method further comprises capping a fill hole of said outer housing to sealingly contain said fluid in said chamber.

17. The method of claim 16, wherein prior to capping a fill hole said method comprises pressure testing said prosthetic knee actuator with said fluid therein.

18. The method of claim 1, wherein prior to providing a magnetorheological fluid said method comprises pressure testing said prosthetic knee actuator.