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.
In pregnancy, ballottement is a "probable sign" used to detect the fetus as it floats in amniotic fluid. ballottement
Suspected knee trauma, arthritis flare-up, or unexplained swelling. Technique: The patella feels like it is "floating
The patella is already in contact with the bone; there is no sensation of floating or clicking. click against the femur
The patient lies flat (supine) with the leg fully extended and relaxed.