NPR intern Poncie Rutsch takes a crack at making a big sound. Meredith Rizzo/NPR hide caption

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Shots - Health News

Why Knuckles Crack

A little MRI video seems to settle the decades-old debate about that loud pop of the joints: It's all about bubbles. But imagine an air bag inflating, not the bursting of a balloon.

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With osteoarthritis, knees become swollen and stiff, and cartilage can degenerate. Ted Kinsman/Science Source hide caption

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Here's an evidence-based test with no dangerous side effects. But some common orthopedic treatments don't work. Selim Ucar/CAM/ hide caption

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Rheumatoid arthritis is an autoimmune disease that can cause painful inflammation in the fingers and other joints. Richard Rudisill/ hide caption

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Swimming is one form of exercise that can help prevent arthritis from getting worse, doctors say. hide caption

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Walking can actually be good medicine for osteoarthritis. hide caption

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