1727, from Japanese samurai warrior, knight, originally the military retainer of the daimio, variant of saburai, nominal form of sabura(h)u to be in attendance, to serve..
The bubbles make a noise when they burst. This is called cavitation. Another cause for painless popping in the knee is when the ligaments and tendons catch as they go over a bony lump and pop when they snap back into place. Or the clicking and popping may be caused by catching on soft tissue or scar tissue within the knee.
Another common problem that results in a popping or grinding sensation is roughness on the undersurface of the patella that used to be called chondromalacia and is often labeled as patellofemoral pain syndrome, or runnerâs knee. Often you may feel the popping, grinding or crunching more than you can hear it. To feel this, try squatting with your hand flat over the front of your knee. Real worry: When a patient says to me, âDoc, I heard a pop and my knee swelled,â it is definitely a cause for concern.