bone, joint, and muscle disorders
Gout
Tophi
Hard lumps of uric acid crystals (tophi) are first deposited in the joint (synovial) lining or cartilage or in bone near the joints and then under the skin around joints. Tophi can also develop in the kidney and other organs and under the skin on the ears. They commonly develop in the fingers, hands, feet, the Achilles tendon in the back of the lower leg, or around the elbows. Tophi are normally painless but can become inflamed and painful. If untreated, tophi in and around the joints can burst and discharge chalky masses of uric acid crystals through the skin and may eventually cause deformities and Osteoarthritis (OA) . 