Psoriasis and Arthritis: A Study of the Radiographic Appearances

The radiographic appearances in 39 patients with psoriasis and arthritis, whose hands, feet, sacro-iliac and other involved joints were X-rayed, have been analysed. Six with degenerative arthritis and one with gout showed radiographic changes typical of these conditions.

The radiographic changes in the 32 patients with psoriasis and erosive arthritis were usually less severe than in patients with uncomplicated rheumatoid arthritis. The degree of soft tissue swelling around a joint without damage of the underlying bone was often striking. Less commonly, however, a grossly destructive, deforming arthritis was seen.

The earliest changes were marginal erosions at the edge of the articular surfaces, but they were by no means pathognomonic of the syndrome. They appeared most frequently in the distal interphalangeal joints for which there was a predilection. Both in these joints and other phalangeal joints the base of the phalanx was sometimes expanded, giving the appearance of an inverted golf tee.

Not only the distal interphalangeal joints but the tips of the terminal phalanges were sometimes eroded, progressing to a shortened, pointed bone which appeared to have been whittled down. This advanced appearance was not seen in a group of unselected patients with rheumatoid arthritis. The involvement of the terminal phalanges and the distal interphalangeal joints was sometimes related topographically to involvement of the nails.

There was a relatively high incidence of clinical ankylosing spondylitis among those patients with psoriasis and erosive arthritis and an even higher incidence of involvement of the sacro-iliac joints as seen radiographically.