Conversation: The conversation between human and AI assistant.
[|Human|] I have a large pocket of fluid on the side of my knee. When drained I typically have around 200 CC removed. It returns completely within 3 days of being drained. An MRI found Osteochrondromitotic globulets. My WBC is 18,000.  I do not remember hurting my knee in any way. The knot just showed up about a year ago. What could possibly be causing it?
[|AI|]  Knee effusion, colloquially known as water on the knee, occurs when excess fluid accumulates in or around the knee joint. There are many common causes for the swelling, including arthritis, injury to the ligaments or meniscus, or when fluid collects in the bursa. This condition is known as prepatellar bursitis. Knee effusion is a large bursa between the inferior part of the femur and the tendon of the qua Chat Doctor.  It usually communicates with the cavity of the knee joint and is pathologically distended with blood or synovial fluid in suprapatellar bursitis ("water on the knee"). A small amount of fluid exists in normal joints. When a joint is affected by arthritis, particularly an inflammatory arthritis such as rheumatoid arthritis (RA), increased abnormal amounts of fluid buildup, the knee appears swollen. The fluid is produced by the tissues that are affected by the arthritis and that line the joint.