What's it for?
Tests for presence of effusion* at the knee joint
How does it work?
Any excess fluid is squeezed out of the suprapatella pouch by sliding the index finger and thumb from 15cm above the knee to level with the upper boarder of patella.
Then press two fingers and thumb down (tripod) on the patella and quickly jerk it downwards.
A 'click' sound indicates the presence of effusion
NB: The test will be negative if the effusion is gross/tense e.g. haemarthrosis of the knee (blood within the joint) following an ACL rupture.
Escaped fluid from blood vessels or lymphatics and its collection into tissues or a cavity*