Importance

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Abstract

Arthritis and related diseases are diagnosed by recording sound from a joint moving against a predefined resistance or a controlled velocity, and correlating the acoustic amplitude and instantaneous frequency with the joint angle. A preferred apparatus includes an articulated restraint for receiving a limb, a hydraulic pump and flow control valve for resisting joint movement, a pressure gage for measuring the torque about the joint, a position sensor sensing the joint angle, a noise cancelling microphone or an accelerometer for sensing sound from the joint, an amplifier and filter for amplifying and filtering the acoustic signal from the microphone or accelerometer, a frequency-to-voltage converter and an amplitude detector for determining the instantaneous frequency and amplitude of the filtered acoustic signal, an analog-to-digital converter for obtaining simultaneous numerical samples of the instantaneous frequency, amplitude, and torque, and a microcomputer programmed to display and record the instantaneous frequency and amplitude as a function of the joint angle, measured by either a digital shaft encoder or a potentiometer.

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First Claim