any one of a group of conditions characterized by inflammation of the joints lasting longer than six weeks and occurring before the age of 16. The causes are unknown but immunological and infective mechanisms are suspected. JCA can affect either four or fewer joints (pauciarticular JCA) or more than four (polyarticular JCA). There are two recognized types of pauciarticular JCA: type 1, which generally affects girls below the age of four; and type 2 (juvenile-onset spondylarthropathy), which generally affects boys over the age of nine. There are also two types of polyarticular JCA, depending on the presence or absence of a particular antibody in the blood. There is a great range of severity of these diseases. Treatment consists of pain management and prevention of subsequent deformity or limitation of movement (e.g. contractures).
Medical dictionary. 2011.