What term describes the escape of fluid into the joint space?

• A. Edema
• B. Synovitis
• C. Hemarthrosis
• D. Effusion

Answer: (D)

Fluid in a joint cavity is called an effusion. This term describes the accumulation of excess fluid within the joint space, often resulting in swelling and stiffness after inflammation or injury. It’s distinct from edema, which is swelling in tissues outside the joints; from synovitis, which is inflammation of the synovial lining itself; and from hemarthrosis, which is specifically blood in the joint space from bleeding. When the fluid is blood, it’s a hemarthrosis, a particular type of effusion.