The clinical significance of the floating patella test is primarily to determine the amount of fluid in the knee joint. If the floating patella test is positive, it can generally be judged that the amount of fluid accumulation is excessive. Because there is about 4-5 ml of fluid in the normal knee joint, if the intra-articular fluid accumulation reaches or exceeds 40-50 ml, it can be called a positive floating patella test. If the amount of fluid in the knee joint is even greater, then in addition to a positive floating patella test, there may also be a sinking of the patella. The specific test is performed by straightening the patient’s knee joint to relax the quadriceps muscle, the examiner squeezes the suprapatellar capsule with one hand to make the joint fluid accumulate behind the patella, and lightly presses the patella with the index finger with the other hand, if there is a floating sensation, that is, the sound of the patella colliding with the femur can be felt, and the patella floats when the pressure is released.