The arthropathy of hemochromatosis.

Five cases of hemochromatosis arthropathy are presented and the distinctive radiological features of the disease are described. Although the condition is typically degenerative, showing subchondral cyst formation, sclerosis, and thinning of cartilage, its distribution is characteristic. Selective degenerative changes of the second and third metacarpophalangeal joints are striking, particularly in the hands, while abnormalities in the intercarpal joints are variable and the interphalangeal joints are spared. Chondrocalcinosis involving both fibrous and hyaline cartilage is frequently seen as well, particularly in the large joints. The calcification is due to deposition of calcium pyrophosphate crystals, perhaps resulting from iron inhibition of pyrophosphatase.