Musculoskeletal (MSK) Knee Practice Test

The test detects even a small amount of knee fluid by how it shifts when you stroke the joint. When there’s a very small amount of effusion, a tiny wave appears along the medial side as you perform the downstroke. That subtle medial wave with the downstroke is what defines a trace finding. It signals minimal fluid in the joint, less than what would produce a larger bulge or more obvious sign. If there were no wave, that would suggest no detectable effusion; a larger bulge on the medial side would indicate more fluid; and a description like fluid returning to the medial side after an upstroke points to a different pattern not used for the trace grade.