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Child Orthopedics
Spine - Cervical
Spine - Lumbar
Spine - Thoracic

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What is the prognosis for a knee condition caused by pigmented villonodular synovitis or PVNS?

Pigmented villonodular synovitis (PVNS) is a benign disease of the joint synovium. Benign in this case means that the condition is confined to the area of involvement. It doesn't spread or travel to other parts of the body. It does not cause death but disability is possible. The synovium is the layer of soft tissue that lines the joint. It has a clear fluid that helps lubricate the joints. Symptoms usually include joint swelling of a single joint (knee, hip, ankle, shoulder, elbow -- in that order) with pain and loss of motion. Pain and loss of motion get worse as the disease progresses. X-rays often show lytic lesions (bone eaten away). But lytic lesions of the bone can be caused by cancer so an MRI and biopsy are required to make an accurate diagnosis. In the case of pigmented villonodular synovitis (PVNS), MRI findings are clear. This is because the tissue contains iron deposits called hemosiderin and the MRI signals clearly show these lesions. Synovial fluid removed from the joint was yellow, another clue as to the diagnosis. Surgery to open the joint and remove the tissue, a procedure called synovectomy is usually required. By completely removing all diseased tissue, pain free joint motion can be restored. There is a fairly substantial recurrence rate (between 40 and 46 per cent). This means the problem can come back again. Some experts believe successful treatment without recurrence is possible. The joint must be carefully and thoroughly cleaned of all diseased tissue (right down to the bone). Radiotherapy (radiation to the area) is sometimes recommended. No one really knows what causes this disease or the best treatment for it. It appears that early treatment and follow-up are the best keys to successful treatment. Recurrence can be minimized with successful removal of all diseased tissue. The natural history (what happens without treatment) is clear: the tissue continues to grow, destroying the joint and bone around it. The affected person develops severe pain, loss of motion, and loss of function.


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