A case of Inflammatory Arthritis

A 34 year old male has a long history of several subacute attacks of self-limited inflammatory arthritis. Crystals have been retrieved from a joint aspirate. Radiography of his knee is likely to demonstrate:

a) subperiosteal thickening
b) marginal articular erosions
c) central articular erosions
d) chondrocalcinosis
e) subchondral bony sclerosis

The correct answer is D

Explanation
Chondrocalcinosis is simply the term for the finding of radio-opaque crystals in hyaline or fibrocartilage. These salts may consist of calcium pyrophosphate dihydrate, dicalcium phosphate dihydrate or hydroxyapatite. Crystals may also be deposited in bursae, capsules, ligaments and tendons.
Chondrocalcinosis may accompany a variety of diseases, but is not a disease entity merely a physical sign thereof. Used properly, the term pseudogout refers to the clinical syndrome of one or more acute or subacute attacks of self-limited inflammatory arthritis caused by crystal-induced synovitis, proven by recovery of the crystals from a joint aspirate. Most people with chondrocalcinosis never have a single acute episode of pseudogout.

CPPD crystal deposition disease is the general term that encompasses chondrocalcinosis, pseudogout, a distinctive arthropathy and a host of variations. During acute attacks (pseudogout) of crystal-induced synovitis, the usual radiological findings are soft-tissue oedema and joint effusion. Chondrocalcinosis may or may not be present. The cartilage and articular bone are often normal. The chronic arthropathy is more distinctive. It is most frequent in the patellofemoral, radiocarpal metacarpophalangeal and elbow joints.

Although the findings superficially resemble osteoarthritis, there are several important differences beyond the unique distribution. The arthropathy is characterized by cartilage loss, multiple subchondral cystic rarefactions, structural collapse of the articular surface, and the presence of many small intra-articular fragments, all without much bone sclerosis. In addition to the usual target sites, these changes may be observed in the hips, knees and sacroiliac joints. Chondrocalcinosis, which does not have to accompany the arthropathy, is seen most commonly in the large joints such as the knee, hip and shoulder as well as the symphysis pubis.