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Sound diagnosis of arthritis.

Sound diagnosis of arthritis

Doctors may soon use the sound of arthritis to detect the disease in joints before obvious--and more severe--symptoms appear, thanks to a device invented by Manuel Casanova of Johns Hopkins Medical Institutions in Baltimore. In tests conducted on 19 patients, the device detected abnormalities in the knee joints of all eight patients who had been previously diagnosed as arthritic.

Called a rectifying-demodulating phonopneumograph (RDP), the shoebox-sized device can produce either the sound or a graphic display of the vibrations a joint makes when it moves. The inexpensive device--it costs less then $200 to build --works "like a watch battery and crystal in reverse,' says the inventor. Movement in the joint, picked up by the microphone, moves the RDP's crystal to create electric impulses, which translate into sound or graphs. Nonarthritic joints sound squishy and produce a graph with both sharp peaks and smooth curves. Arthritic joints crackle like crumpled plastic and produce a graph with only sharp, multipointed peaks.

Casanova says fixed structures such as ligaments produce the multiple peaks in the sound waves of arthritic joints and may indicate the inflammation of arthritis, which, if detected early, can be brought under control with drugs. A noninvasive diagnosis additionally spares patients the usual diagnostic probes and injections.
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Publication:Science News
Date:Aug 30, 1986
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