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.
Key points. 1  A popliteal cyst, also known as a Bakerâs cyst, is a fluid-filled swelling that causes a lump at the back of the knee. 2  Common causes of a popliteal cyst include damage to the kneeâs cartilage and rheumatoid arthritis.