Crystalline synovitis is usually caused by the accumulation of metabolites in the joints, and common causes include gout, osteoarthritis, and joint infections. 1. Gout: Uric acid excretion obstacles in the joints to build up the formation of crystals deposited in the joints, stimulating synovial membrane hyperplasia and inflammation, joint effusion, joint swelling, joint pain, the application of uric acid-lowering drugs such as febuxostat and other treatments. 2. Osteoarthritis: joint hyperplasia, cartilage wear and tear caused by intra-articular sediment aggregation of crystals, the serious formation of free bodies can be stuck in the joints caused by flexion and extension activities are limited. 3. Joint infection: septic arthritis, joint tuberculosis, inflammatory products accumulate to stimulate synovitis inflammation, causing joint secretion of fluid, inflammatory fluid deposits can appear crystallization. Crystalline synovitis need to go to the hospital orthopedic examination, further treatment.