(English captions by Trisha Paul from the University of Michigan)

With the patient supine, the leg can be fully extended to assess better for

joint effusion.

Compress the suprapatellar pouch, pushing
the contents distally, and assess for

increased fluid.

Patellar ballottement can also be performed by
compressing the patella and releasing

quickly. Observe for rapid rebound, which
also indicates increased fluid pressure.

If a quicker tap is felt, a larger fusion is present, also called the ballottable

patella.