METHOD FOR ALIGNING A PROSTHESIS

• US 20080140221A1
• Filed: 09/11/2007
• Published: 06/12/2008
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Orthocare Innovations, LLC
• Original Assignee: CYMA Corporation (Orthocare Innovations, LLC)
• Inventors: Boone, David Alan, Macomber, Ben Gilbert
• Granted Patent: US 7,922,774 B2
• Time in Patent Office: Days
• US Class Current: 623/27
• CPC Class Codes: A61F 2/60 Artificial legs or feet or parts thereof
• CPC Class Codes: A61F 2/66 Feet; Ankle joints
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2/76 Means for assembling, fitting or testing prostheses, e.g. for measuring or balancing, e.g. alignment means
• CPC Class Codes: A61F 2002/5021 for adjusting a position by translation along an axis
• CPC Class Codes: A61F 2002/5023 along two perpendicular axes
• 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 2002/7635 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 2002/7695 Means for testing non-implantable prostheses for testing implantable prostheses A61F2240/008; for implanting artificial joints A61F2/468
• CPC Class Codes: G01B 21/24 for testing alignment of axes
• CPC Class Codes: G01L 1/2218 the supports being of the column type, e.g. cylindric, adapted for measuring a force along a single direction
• CPC Class Codes: G01L 1/2231 the supports being disc- or ring-shaped, adapted for measuring a force along a single direction
• CPC Class Codes: G01L 5/162 of piezoresistors
• CPC Class Codes: G06F 30/17 Mechanical parametric or variational design

Abstract

A computerized prosthesis alignment system includes a transducer that can measure socket reactions in the anterior/posterior plane and the right/left planes, while canceling or reducing the transverse forces on the measurements of these socket reactions. In addition, the transducer is also capable of determining the axial load or weight experienced by the prosthesis. The computerized prosthesis alignment system is in communication with a host computer. The moment data from the transducer is interpreted by the user via a computer interface. The host computer includes memory for storing one or more applications. These applications receive data from the transducer, interpret the data with discrete algebraic or fuzzy logic algorithms, and display the output numerically and graphically. Applications may also interpret the data to provide analyses to the user for aligning the prosthesis.

Claims

1. A method for aligning a prosthesis, comprising:

coupling a transducer that measures moments in the anterior/posterior plane and right/left plane to a prosthesis, the transducer having an initial alignment;

attaching the prosthesis to a patient;

obtaining signals representative of moments in the anterior/posterior plane and right/left plane as the patient walks along a line of progression;

comparing the signals representative of moments obtained during walking to a model of alignment; and

making an adjustment to the initial alignment to bring the initial alignment closer to the model of alignment.

2. The method of claim 1, further comprising providing instructions that specify the manner of making the adjustment.

3. The method of claim 1, further comprising providing instructions that specify the direction and amount that one or more set screws are to be adjusted.

4. The method of claim 1, further comprising providing patient weight information.

5. The method of claim 1, further comprising applying a correction factor to the moments that account for angular deviation from the line of progression.

6. The method of claim 1, further comprising determining the initial contact of a step during walking and the toe-off of a step during walking and determining the anterior/posterior moment and the right/left moment during the step.

7. The method of claim 1, further comprising aligning the transducer along the line of progression prior to walking.

8. The method of claim 1, further comprising measuring the angular deviation of the transducer from the line of progression during walking.

9. The method of claim 1, further comprising replacing the transducer with a substitute pyramid adaptor that is similar in height to maintain an alignment achieved with the transducer.

10. The method of claim 1, further comprising obtaining the height of the transducer.

11. The method of claim 1, further comprising obtaining the orientation of an inverted pyramid mounted to the transducer.

12. The method of claim 1, further comprising obtaining the weight of the patient automatically.

13. The method of claim 1, further comprising obtaining the midstance phase of a step of the patient and obtaining the weight of the patient at midstance.

14. The method of claim 1, further comprising projecting a laser light, line, beam or spot parallel to the line of progression.

15. The method of claim 1, wherein the transducer comprises memory for storing information.

16. The method of claim 1, further comprising storing information in memory housed in the transducer.

17. A method for aligning a prosthesis, comprising:

obtaining signals representative of moments in the anterior/posterior plane and right/left plane acting on the prosthesis;

obtaining corrected signals by applying a correction factor to the signals;

computing gait variables from the corrected signals; and

applying the gait variables to a model of alignment.

18. The method of claim 17, further comprising providing instructions to correct the alignment of the prosthesis.

19. The method of claim 17, wherein the correction factor is an angular deviation from a line of progression.

20. The method of claim 17, further comprising obtaining signals representative of axial forces.

21. The method of claim 17, further comprising obtaining signals representative of moments for more than one step.

22. The method of claim 17, further comprising obtaining signals representative of moments for two or more steps and the two or more steps are continuous.

23. The method of claim 17, further comprising determining the phases of a step and obtaining weight information at midstance of the step.

24. The method of claim 17, further comprising providing a user interface for obtaining input.

25. The method of claim 17, further comprising plotting the moments for one or more steps.

26. The method of claim 17, further comprising plotting the moments and the model of alignment on the same graph.

27. The method of claim 17, further comprising plotting the load being supported by the prosthesis and the opposite foot.

28. The method of claim 17, further comprising plotting a locus representing moments onto a graph having a target.

29. The method of claim 28, further comprising providing instructions to align the prosthesis to move the locus to the target.

30. The method of claim 17, wherein gait variables include one or more of anterior/posterior moment at a percent of the stance phase, right/left moment at a percent of the stance phase, maxima of anterior/posterior moment, maxima of right/left moment, minima of anterior/posterior moment, minima of right/left moment, the slope of the change in anterior/posterior moment during stance phase, the slope of the change in right/left moment during stance phase, integrated anterior/posterior moment during stance phase, or integrated right/left moment during stance phase.

31. The method of claim 17, wherein the model of alignment describes the relationships of combinations of gait variables to possible prosthesis misalignments.

32. The method of claim 31, further comprising determining whether the prosthesis is misaligned.

33. A computer readable medium having computer-executable instructions that, when executed, perform a method for analyzing misalignment of a prosthesis, the method comprising:

obtaining signals representative of moments in the anterior/posterior plane and right/left plane;

obtaining corrected signals by applying a correction factor to the signals;

computing gait variables from the corrected signals; and

applying the gait variables to a model of alignment.

34. The computer readable medium of claim 33, wherein the method further provides instructions to correct the alignment of the prosthesis.

35. The computer readable medium of claim 33, wherein the correction factor is an angular deviation from a line of progression.

36. The computer readable medium of claim 33, wherein the method further comprises obtaining signals representative of axial forces.

37. The computer readable medium of claim 33, wherein the method further comprises obtaining signals representative of moments for more than one step.

38. The computer readable medium of claim 33, wherein the method further comprises obtaining signals representative of moments for two or more steps and the two or more steps are continuous.

39. The computer readable medium of claim 33, wherein the method further comprises determining the phases of a step and obtaining weight information at midstance of the step.

40. The computer readable medium of claim 33, wherein the model of alignment describes the relationships of combinations of gait variables to possible prosthesis misalignments.

41. The computer readable medium of claim 40, wherein the method further comprises determining whether the prosthesis is misaligned.

42. A computer readable medium having computer-executable instructions that, when executed, perform a method for aligning a prosthesis, comprising:

obtaining the anterior/posterior moment and the right/left moment acting on a prosthesis when a patient walks wearing the prosthesis;

obtaining increments of the stance phases during walking;

computing gait variables from the anterior/posterior moment, the right/left moment, and stance phase increments;

applying the gait variables to a predefined model of alignment derived as a series of simultaneous equations that describe the relationships of combinations of the gait variables to possible prosthesis misalignments;

solving the equations to determine whether the prosthesis is misaligned; and

providing instructions to align the prosthesis.