PROPAGATION TUNED OSCILLATOR FOR ORTHOPEDIC PARAMETER MEASUREMENT

• US 20100331718A1
• Filed: 06/29/2010
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: OrthoSensor, Inc (Stryker Corporation)
• Inventors: Stein, Marc
• Granted Patent: US 8,324,975 B2
• Time in Patent Office: Days
• US Class Current: 600/546
• CPC Class Codes: A61B 5/4509 Bone density determination
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61B 5/6878 Bone
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 8/15 Transmission-tomography

Abstract

A measurement system for capturing a transit time, phase, or frequency of energy waves propagating through a propagation medium (702) is disclosed. The measurement system comprises two different closed-loop feedback paths. The first path includes a transducer driver (726), a transducer (704), a propagation structure (702), a transducer (706), and a zero-crossing receiver (740). The series and parallel resonance of the transducer (704) does not overlap the series and parallel resonance of the transducer (706). A second path includes a transducer driver (1126), a transducer (1104), a propagation medium (1102), a reflecting surface (1106), and an edge-detect receiver (1140). Each positive closed-loop path maintains the emission, propagation, and detection of energy waves in the propagation medium (702, 1102). In either path, a propagation tuned oscillator maintains positive closed-loop feedback of the system that sustains detection, emission, and propagation of energy waves or pulses in a medium.

Claims

1. A propagation tuned oscillator (PTO) to maintain positive closed-loop feedback of energy waves in an energy propagating structure where energy waves propagate through a medium such that detection of a propagated energy wave initiates an energy wave emission into the medium.

2. The PTO of claim 1 where the propagation tuned oscillator tunes a resonant frequency of the energy waves in accordance with physical changes in the energy propagating structure.

3. The PTO of claim 2 where an integer number of energy waves propagates in the medium when positive closed-loop feedback is applied.

4. The PTO of claim 3 where the PTO measures one of transit time, frequency, or phase of a propagated energy wave.

5. The PTO of claim 4 where a parameter to be measured is applied to the medium and where changes in the parameter affect one of transit time, frequency, or phase of a propagated energy wave.

6. The PTO of claim 4 where a positive closed-loop feedback path of the PTO comprises a transducer driver to drive at least one transducer for the emission of energy waves into the medium, the energy propagating structure, and a zero-crossing receiver to detect the propagated energy wave.

7. The PTO of claim 4 where the positive closed-loop feedback path of the PTO comprises a transducer driver to drive at least one transducer for the emission of energy waves into the medium, the energy propagating structure, and a edge-detect receiver to detect the propagated energy wave.

8. The PTO of claim 4 where the energy propagating structure comprises:

a first transducer;

the medium where the first transducer is coupled to the medium at a first location; and

a second transducer coupled to a second location of the medium.

9. The PTO of claim 8 where a series and parallel resonance of the first transducer does not overlap a series and parallel resonance of the second transducer.

10. The PTO of claim 4 where the energy propagating structure comprises:

a transducer;

the medium where the transducer is coupled to the medium at a first location; and

a reflecting surface at a second location of the medium.

11. A wireless sensing assembly comprising:

a sensor comprising;

a first transducer;

a medium where the first transducer is coupled to the medium at a first location; and

a second transducer where the second transducer is coupled to a second location of the medium and where a series and parallel resonance of the first transducer does not overlap a series and parallel resonance of the second transducer.

12. The wireless sensing assembly of claim 11 further including a propagation tuned oscillator operatively coupled to the sensor to maintain positive closed-loop feedback of energy waves in an energy propagating structure where energy waves propagate through a medium such that detection of a propagated energy wave initiates an energy wave emission into the medium.

13. The wireless sensing assembly of claim 12 where the wireless sensing assembly comprises one or more sensors, one or more load surfaces, an accelerometer, electronic circuitry, a transceiver, and an energy supply, to measure applied forces and transmit measurement data to a secondary system for further processing and display.

14. The wireless assembly of claim 12 where the medium is a waveguide.

15. The wireless assembly of claim 11 where the medium is compressible.

16. A method of measuring a parameter of the muscular-skeletal system comprising the steps of:

applying the parameter of the muscular-skeletal system to a medium;

maintaining positive closed-loop feedback to sustain the emission of energy waves in the medium;

measuring one of transit time, frequency, or phase of propagated energy waves; and

relating the transit time of one or more propagated energy waves to the parameter being measured.

17. The method of claim 16 further including the step of tuning a resonant frequency of energy waves in accordance with physical changes of the medium where a number of energy waves in the medium is an integer number.

18. The method of claim 16 further including the steps of:

detecting wave fronts of propagated energy waves; and

emitting an energy wave into the medium upon detecting a wave front.

19. The method of claim 16 further including the steps of:

detecting zero crossings of propagated energy waves; and

emitting an energy wave into the medium upon detecting a zero-crossing.

20. The method of claim 16 further including a step of propagating energy waves through a compressible waveguide.