Why do my joints crack?

The pop is usually physics, not damage. Joints sit in fluid, and stretching a joint changes pressure enough to form a tiny gas bubble that collapses with a crack - called cavitation. Tendons and ligaments snapping over bony bumps as you move make the other common noise, especially in knees, shoulders, and ankles. Both are normal, painless, and harmless. The myth to retire: habitual knuckle cracking does not cause arthritis - a doctor famously cracked the knuckles of one hand for 50 years and developed no arthritis in either, and larger studies back him up. The caveat is that cracking with force can strain ligaments, which is a reason not to yank joints aggressively, not a reason to fear the sound. When joint noise matters: cracking accompanied by pain, swelling, catching, or the joint giving way suggests something structural - a meniscus tear in a knee, loose cartilage, or early osteoarthritis, where NIAMS notes joint noise can come with stiffness and pain. Noise that started after an injury also deserves an exam. The rule of thumb: painless noise is a quirk; painful noise is a symptom. Pymander is a free AI doctor, 24/7 by text. Describe which joint and what comes with the sound, and it can help you decide.