Patella balloting is a condition in which the patella sinks into the joint during pressure until it contacts the underlying bones, and when the pressure stops, it rises back. Indicates the presence of fluid in the joint. It is caused by the accumulation of blood - hemarthrosis or inflammatory fluid - synovitis. It occurs with injuries, degenerative and inflammatory diseases of the joint, and some other pathologies. To diagnose diseases accompanied by balloting of the patella, radiography, ultrasound, CT, MRI, puncture, arthroscopy and other procedures are prescribed. Before making a diagnosis, it is necessary to ensure the rest of the limb.