In this disease uric acid, in the form of urate of sodium, is deposited in the tissues of the joints. It is first deposited in the cartilage, and, according to Charcot, always, to begin with, at the middle of the articulating surface, that being the point furthest removed from the bloodvessels. The urate is sometimes in the form of stellate crystals (Fig. 295), the cartilage cells forming the middle points of the bunches of crystals. But the salt is also deposited in the matrix and often in the form of irregular needles. It is also frequently deposited in the synovial membrane, and in the bones, ligaments, and soft parts around the joints. Sometimes the salts are deposited even under the skin, forming visible projections (the so-called tophi or chalkstones).

According to Moore the deposition of urates is always preceded by degenerative changes in the cartilage. This author also associates gout very intimately with chronic interstitial nephritis, pulmonary emplrysema, and chronic inflammation of the aortic valves.

The deposition seems to lead to an acute irritation of the structures of the joint, chiefly an intense hyperemia, often with serous exudation.

It never goes on to suppuration, however. Complete recovery usually takes place, but sometimes there remains a chronic inflammation, leading to stiffness and deformity of the joint.