Radiological Diagnosis

Juvenile Rheumatoid arthritis

Polyarticular involvement in children is similar to that in adults and affects mainly the smaller joints of the hands and feet. Involvement of the proximal interphalangeal joint and associated periarticular swelling producing fusiform appearance is the characteristic early manifestation. A thin unilaminar periosteal reaction surrounding the proximal phalanges, metacarpals and metaphyses occurs early in this disease [1]. Late onset disease in wrist has a distinct pattern of intercarpal and carpometacarpal joint cartilage loss, fine erosions and ankylosis [2]. Monoarticular involvement occurs in 30% cases in JRA in contrast to predominant polyarticular presentation in adults. The large joints are usually involved in monoarticular involvement and joint effusion within a knee and ankle in a young child 3-5 years of age is frequently the presenting finding [1].

The spine and most specifically the cervical vertebrae are commonly affected in JRA in contrast to adult form [1]. In fact many block vertebrae encountered in adult represent arrested JRA. The vertebral bodies may decrease in size and intervertebral disc space becomes narrow. These manifestation may resemble those of congenital fusion but clinical picture makes the diagnosis. Inflammatory process also involves surrounding ligaments and its attachments. Some degree of sclerosis of neural arch is produced by JRA [Figure - 4]. Peripheral joints are more often involved but the cervical spine is involved in approximately 15% of the patients. Unlike rheumatoid spondylitis, the process begins in the cervical spine and rarely involves the lumbar region, though present in our case. The apophyseal joints are involved in the disease leading to destruction of joint, adjacent sclerosis and eventual fusion in more severe cases. Involvement of the ligamentous supports of the atlantoaxial junction is frequent. Subluxation of the first and second cervical vertebrae may then occur with severe consequences and is most frequent in seropositive patients [1]. Growth disturbances and ankylosis may result in undeveloped vertebral bodies. Ankylosis affects both disc and apophyseal joints, frequently affecting segments of two or more vertebrae. Adjoining open disc spaces are frequently wider than normal but degenerative changes affecting both disc and apophyseal joints tend to occur early, presumably as a result of increased mechanical stress and mobility [3]. Patients of JRA are generally less than 16 years. A small group of patients may present after age 16 [2]. They are subdivided according to the presence (approximately 10%) or absence (approximately 90%) of rheumatoid factor and according to clinical presentation. Clinical onset may be as a systemic disease (approximately 20%) at which time radiological findings are usually absent [4].