Metabolism of crystals within the joint.

Monosodium urate (MSU), calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate (BCP) crystals deposit in joints and surrounding tissues causing acute inflammation and chronic cartilage damage. A number of endogenous substances and physicochemical conditions affect their precipitation, growth and even dissolution, regulating their metabolism and inflammatory activity. We review how MSU and calcium crystals form within the joints and the various factor which regulate their formation.