Why your knees crack and what it means | Joint noises explained

Noisy knees, cracking knuckles, and popping necks are common but harmless for most people, a physiotherapist and chronic joint pain researcher assured, debunking fears of arthritis or damage.

In an analysis, University of Limerick's Clodagh Toomey, who studies joint issues, explained that sounds like the classic "crack" stem from cavitation -- gas bubbles forming and collapsing in synovial fluid within joint capsules.

This takes about 20 minutes to reset, preventing repeat pops. Tendons snapping over bones or cartilage grinding (crepitus, especially in knees) cause other noises, often from muscle imbalances or poor tracking of the kneecap.

"Noise on its own is rarely a problem," Toomey wrote. Worry only if accompanied by pain, swelling, locking, or reduced function.

Myths on Arthritis and Cracking Debunked

Studies show no link between habitual joint cracking and osteoarthritis, grip strength loss, or joint laxity. The satisfying pop offers short-term relief via increased motion, muscle relaxation, and neurological feedback – but doesn't fix underlying issues.

Spinal manipulation by professionals uses the same mechanism for temporary pain relief, though neck procedures carry rare risks like stroke.

Age-related cartilage changes and weaker muscles make noises more common, and those with knee osteoarthritis and crepitus report slightly more pain—possibly psychological—without differences in strength or walking speed.

Stay Active, Skip Unproven Supplements

Toomey urged against fearing "wear and tear," emphasizing exercise as key to joint health. Cartilage needs movement for nutrients, and guidelines recommend it first for osteoarthritis. Consistency trumps type.

Supplements like collagen or fish oils lack evidence for reducing noise or pain at scale, though safe; they're often not worth the cost.

"Joint noises are usually harmless," the expert concluded. "Staying active is one of the best things you can do for your joints, whether they crack, pop, crunch or stay silent."

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