[Differential diagnosis of post-traumatic hydrarthrosis of the knee joint].

You can diagnose the post-traumatic effusion in a knee-joint generally without difficulty. The fresh effusion is very often bloody. Reflections concerning differential diagnosis are necessary to recognize heavy injuries of soft-tissue and bony injuries. For the diagnostic special X-rays are useful, the arthroscopy and the arthrography. The joint must immediately be unburdened because the effusion can take a negative effect on the articular.