Incidence and size of erosions in the wrist and hand of rheumatoid patients: a quantitative microfocal radiographic study.

Quantitative macroradiographic examination of a group of early to moderately advanced rheumatoid patients showed the wrist and hand to have an average of 75 (SD 26) erosions out of 142 possible sites. Joint involvement was greatest in the wrist followed by the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints respectively. In the wrist erosion distribution was concentrated in the radiocarpal and medial carpometacarpal complex, in the hand it tended to be located at the second and third MCP and third PIP joints. No difference was observed in erosion number and area between the right and left extremities. The distribution of the lesions is discussed in relation to the intra-articular pressures on normal hand function. The similarity of erosion development, across the joints at the different regions of the hand, suggests the presence of factors other than mechanical pressure. In general, erosions were widespread, and the largest erosions occurred in the larger bones of the wrist and hand.