If a small amount of fluid is suspected in the knee:
Look for Bulge Sign:
- Milk upwards, the medial aspect of the knee two to three times to displace fluid there.
- Press or tap the knee just behind the lateral margin of the patella.
- Watch for a bulge of returning fluid in the hollow medial to the patella.
A bulge indicates fluid within the knee joint.
This sign is useful for the detection of very small amounts of fluid, but may be absent when large amounts of fluid are present under pressure.
Bates, Barbara. 1974. A Guide to Physical Examination. J.B. Lippincott Company, Toronto.