The patella feels like it is "floating." You will feel it move through fluid, click against the femur, and then rebound or "ballotte" back toward your finger.
This is the most frequent use of the term. It is used to identify a "floating" kneecap, which indicates a moderate-to-large accumulation of fluid (effusion) within the knee joint. ballottement
Performed by applying a sharp tap to the abdominal wall to feel the fetus move away and return. 3. Abdominal Ballottement The patella feels like it is "floating