On the nature and significance of bony proliferation in "rheumatoid variant" disorders.

Radiographic and pathologic abnormalities of the peripheral joints in a cadaver with ankylosing spondylitis are described. Bony proliferation about involved articulations is is characteristic of all "rheumatoid variant" disorders and results from subchondral bony hyperplasia and periosteal new bone formation. Such proliferation may be related to the presence of the histocompatibility antigen B27 in these diseases.