Pigmented villonodular synovitis or PVNS is a joint disease characterized by inflammation and overgrowth (non-cancerous) of the joint lining. It usually affects the hip or knee. It can also occur in the shoulder, ankle, elbow, hand or foot. In PVNS, the lining of the joint, called the synovium, becomes swollen and grows.
This growth harms the bone next to the joint. The lining also makes extra fluid that can cause swelling and make movement painful. Surgery can help but, even with treatment, PVNS comes back about half the time. If the pain remains then radiation therapy may help. In the worst cases the joint must be replaced.
In general, PVNS often manifests initially as sudden onset, unexplained joint swelling and pain. The joint swelling is disproportionate to the amount of pain the patient feels at first. Decreased motion and increased pain occur as the disorder progresses as well as locking of the joint.
The exact cause of PVNS is unknown. Risk factors for PVNS developing are also not yet understood. Very little research has been carried out. However, a common theme in patients is a trauma experienced to the joint prior to the onset of symptoms.
PVNS is radiologically diagnosed by magnetic resonance imaging (MRI). However, other tests can be conducted first to eliminate other causes such as gout.
Once PVNS is confirmed by biopsy of the synovium of the affected joint, a synovectomy (removal of growth via arthroscopic technique ie. keyhole surgery) of the affected area is the most common treatment.
Bone lesions caused by the disorder are removed and bone grafting is performed as needed. Sometimes, radiation therapy may be considered as a treatment option. In some cases, a total joint replacement is needed to relieve symptoms when PVNS causes significant joint destruction.