Propagation tuned oscillator for orthopedic parameter measurement

• US 8,324,975 B2
• Filed: 06/29/2010
• Issued: 12/04/2012
• 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
• Primary Examiner(s): Gannon, Levi
• Application Number:
  US12/825,913
• Publication Number:
  US 20100331718A1
• Time in Patent Office: 889 Days
• Field of Search: 331/1.R, 331/96, 331/154, 331/187, 324/629, 324/633, 324/636, 324/637, 324/639, 324/642, 324/644, 324/647, 600/587, 600/595, 606/53, 606/60, 606/87, 606/88, 606/102, 623/20.14
• US Class Current: 331/96
• 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 configured to couple to the muscular-skeletal system such that detection of a propagated energy wave initiates an energy wave emission into the medium, where the medium is configured to measure a parameter of the muscular-skeletal system, and where the parameter affects 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 2 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 configured to drive at least one transducer for the emission of energy waves into the medium, the energy propagating structure, and a zero-crossing receiver configured 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 configured to drive at least one transducer for the emission of energy waves into the medium, the energy propagating structure, and a edge-detect receiver configured 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 is configured not to 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;

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 and where the wireless sensing assembly comprises 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.

12. The wireless assembly of claim 11 where the medium is a waveguide.

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

14. 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.

15. The method of claim 14 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.

16. The method of claim 14 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.

17. The method of claim 14 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.

18. The method of claim 14 further including a step of propagating energy waves through a compressible waveguide.