Lower-limb prosthesis force and moment transducer

• US 7,886,618 B2
• Filed: 09/11/2007
• Issued: 02/15/2011
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Orthocare Innovations, LLC
• Original Assignee: Orthocare Innovations, LLC
• Inventors: Boone, David Alan, Macomber, Ben Gilbert, Beck, James Christian
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US11/853,707
• Publication Number:
  US 20080139970A1
• Time in Patent Office: 1,253 Days
• Field of Search: 73862041-862046
• US Class Current: 73/862.044
• 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 transducer, comprising:

a transducer body;

an adaptor on the transducer body for coupling to a prosthesis;

first and second strain-measuring devices positioned, respectively, on anterior and posterior sides of the adaptor to measure forces in a first plane; and

third and fourth strain-measuring devices positioned, respectively, on right and left sides of the adaptor to measure forces in a second plane substantially orthogonal to the first plane;

wherein the first and the second strain-measuring devices and the third and the fourth strain-measuring devices are arranged to measure right/left and anterior/posterior bending moments and reduce measuring forces in a third plane orthogonal to the first and second planes.

2. The transducer of claim 1, wherein the first plane is the anterior/posterior plane, the second plane is the right/left plane, and the third plane is the transverse plane.

3. The transducer of claim 1, further comprising a load-bearing member disposed over the first and second strain-measuring devices.

4. The transducer of claim 1, comprising fifth, sixth, seventh and eighth strain-measuring devices, wherein a pair of strain-measuring devices is provided on each of the anterior, posterior, right, and left sides of the transducer.

5. The transducer of claim 1, comprising a beam disposed on each of the anterior, posterior, right and left sides, wherein the beams support the adaptor.

6. The transducer of claim 1, comprising a beam disposed on each of the anterior, posterior, right and left sides, wherein the beams support the adaptor, each beam having a strain-measuring device positioned on at least two opposite side surfaces of each beam.

7. The transducer of claim 1, wherein the adaptor is an inverted pyramid.

8. The transducer of claim 1, wherein the transducer body comprises a beam aligned in the anterior/posterior plane.

9. The transducer of claim 1, wherein the transducer body comprises a beam aligned in the right/left plane.

10. The transducer of claim 1, further comprising memory to store data.

11. The transducer of claim 1, comprising a first and a second strain gage on a beam on the anterior side, a third and fourth strain gage on a beam on the posterior side, a fifth and sixth strain gage on a beam on the right side, and a seventh and eighth strain gage on a beam on the left side.

12. The transducer of claim 11, wherein two sets of four strain gages is each arranged in a balanced bridge, and each balanced bridge produces a voltage output representative of a moment in a plane.

13. The transducer of claim 12, further comprising amplification circuits for amplifying the output from the balanced bridges and an analog-to-digital conversion circuit that receives the amplified output from the balanced bridges.

14. The transducer of claim 13, further comprising a digital-to-analog conversion circuit connected to the amplification circuit of each balanced bridge to apply an offset voltage to calibrate the output from the amplification circuit.

15. The transducer of claim 1, further comprising circuitry to measure the axial load on the transducer.

16. A transducer for coupling to a prosthesis, comprising:

a transducer body;

an adaptor on the transducer body for coupling to a prosthesis;

means for measuring moments in the anterior/posterior plane and the right/left plane, and reducing measuring moments in the transverse plane, wherein said means comprises first and second strain-measuring devices positioned, respectively, on anterior and posterior sides of the adaptor and third and fourth strain-measuring devices positioned, respectively, on right and left sides of the adaptor.