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.
Inner Knee Pain. Inner knee pain. Inner knee pain refers to pain that occurs on the inner side of the knee. It is also called medial knee pain and inside knee pain as well. Inner knee pain can either be acute (develops suddenly after a knee injury) or chronic (develops gradually over time).