Arthrogryposis is a general or descriptive term for the development of nonprogressive contractures affecting one or more areas of the body. A contracture is a condition in which a joint becomes permanently fixed in a bent (flexed) or straightened (extended) position, completely or partially restricting the movement of the affected joint. When congenital contractures occur only in one body area, it is not referred to as arthrogryposis but rather an isolated congenital contracture. The most common form of an isolated congenital contracture is clubfoot. When arthrogryposis affects two or more different areas of the body, it is referred to as arthrogryposis multiplex congenita (AMC). The most common form of AMC is amyoplasia. Arthrogryposis and arthrogryposis multiplex congenita are sometimes used interchangeably.
The symptoms of AMC are present at birth (congenital). However, specific symptoms and physical findings can vary greatly in range and severity from one person to another. In most cases, affected infants have contractures of various joints. The joints of the legs and arms are usually affected, the legs are affected more often than the arms. The joints of the shoulders, elbows, knees, wrists, ankles, fingers, toes, and/or hips are also commonly affected. In addition, the jaws and back are also often affected in individuals with AMC. In most cases, AMC occurs randomly, for no apparent reason (sporadic). More than 300 different conditions can cause isolated or multiple contractures and the causes, genetics, specific symptoms, and severity of these disorders vary dramatically.