EDGE-DETECT RECEIVER FOR ORTHOPEDIC PARAMETER SENSING

• US 20100326194A1
• Filed: 06/29/2010
• Published: 12/30/2010
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: OrthoSensor, Inc (Stryker Corporation)
• Original Assignee: OrthoSensor, Inc (Stryker Corporation)
• Inventors: Stein, Marc, Kelly, Andrew
• Granted Patent: US 8,490,488 B2
• Time in Patent Office: Days
• US Class Current: 73/584
• 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 sensor system uses positive closed-loop feedback to provide energy waves into a medium. A sensor comprises a transducer (604), a propagating structure (602), and a reflecting surface (606). A parameter is applied to the propagating structure that affects the medium. The sensor is coupled to a propagation tuned oscillator (416) that forms the positive closed-loop feedback path with the sensor. The propagation tuned oscillator (416) includes an edge-detect receiver (200) that generates a pulse upon sensing a wave front of an energy wave in propagating structure (602). The edge-detect receiver (100) is in the feedback path that continues emitting energy waves into the propagating structure (602). The edge-detect receiver (200) comprises a preamplifier (212), a differentiator (214), a digital pulse circuit (216), and a deblank circuit (218). The transit time, phase, or frequency is measured of the propagating energy waves and correlated to the parameter being measured.

Claims

1. An integrated edge-detect receiver to detect wave fronts of pulses of energy waves, the edge-detect receiver comprising:

a preamplifier operatively coupled to receive a pulsed energy wave;

a differentiator operatively coupled to the preamplifier to detect a change in slope;

a pulse circuit operatively coupled to the differentiator to generate a pulse on the wave front of the pulsed energy wave; and

a deblank circuit that desensitizes the preamplifier after the pulse is generated.

2. The receiver of claim 1, enables capturing of parameters including, but not limited to, transit time, phase, or frequency of the energy waves.

3. The receiver of claim 1 where the change in slope detected by the differentiator comprises a change in current.

4. The receiver of claim 3 where the change in current corresponds to a current being detected.

5. The receiver of claim 1 where the pulse circuit generates a pulse on a leading edge of the pulsed energy wave.

6. The receiver of claim 1 where the deblank circuit is operatively coupled to the preamplifier to blank the preamplifier from amplifying a remaining portion of the pulsed energy wave.

7. The receiver of claim 6 where the preamplifier disregards changes in voltage or current corresponding to the pulsed energy wave.

8. The receiver of claim 6 where the deblank circuit blanks the preamplifier for a predetermined time.

9. The receiver of claim 1 where the pulsed energy wave propagates through a waveguide.

10. The receiver of claim 1 where the pulsed energy wave measures a parameter of the muscular-skeletal system.

11. A method of propagating a plurality of pulsed energy waves into a medium comprising the steps of:

providing at least one energy wave in the medium at a first location;

sensing a propagated energy wave;

maintaining positive closed-loop feedback with an edge-detect receiver where at least one energy wave is provided at the first location after sensing the propagated energy wave.

12. The method of claim 11 further including the steps of:

detecting a wave front of each propagated energy wave;

generating a digital pulse corresponding to each detected wave front;

generating an energy wave upon generating the digital pulse; and

providing the energy wave at the first location.

13. The method of claim 12 further including a step of ignoring detection of secondary waves of each energy wave after detecting the wave front.

14. The method of claim 13 further including a step of blanking the edge-detect receiver for a predetermined time period where a magnitude of the secondary waves falls below a predetermined threshold before the predetermined time period.

15. The method of claim 11 further including a step of breaking the positive closed loop feedback to stop the propagation of energy waves in the medium.

16. The method of claim 11 further including a step of measuring one of transit time, phase, or frequency of each propagated energy wave.

17. A sensor for measuring a parameter of the muscular-skeletal system comprising:

a medium as a propagation path of pulsed energy waves where the medium is coupled to or is part of the muscular-skeletal system and where a change in the medium affects at least one of the transit time, phase, or frequency of the pulsed energy waves; and

an edge-detect receiver to detect wave fronts of pulsed energy waves from the medium while disregarding secondary waves of each pulsed energy wave where the edge-detect receiver is coupled in a positive closed-loop feedback path with the medium for continued generation and propagation of pulsed energy waves through the medium.

18. The sensor of claim 17 where the pulsed energy waves are provided at a first location of the medium, where the edge-detect receiver is coupled to a second location of the medium, where the edge-detect receiver initiates a pulsed energy wave being provided at the first location upon detecting a wave front at the second location, and where the sensor measures one of distance, weight, strain, pressure, wear, vibration, viscosity, and density.

19. The sensor of claim 17 where the edge detect receiver comprises:

a preamplifier operatively coupled to the second location to receive a pulsed energy wave;

a differentiator operatively coupled to the preamplifier to detect a change in slope;

a pulse circuit operatively coupled to the differentiator to generate a pulse on a wave front of a pulsed energy wave; and

a deblank circuit that desensitizes the preamplifier after the pulse is generated.

20. The sensor of claim 17 further including a digital counter operatively coupled to count pulsed energy waves.