Erosion number and area progression in the wrists and hands of rheumatoid patients: a quantitative microfocal radiographic study.

Microfocal radiography has been used to evaluate the relation between erosion number and erosion area in the hands and wrists of 51 patients with early to moderately advanced rheumatoid arthritis. The hands of these patients showed different patterns of erosion progression, in terms of the relation between changes in number and area, and included those showing a decrease in one or both of the erosion parameters. The mean number of erosions in the group increased between the first and second visits. By the third visit (a mean of 48 months from the onset of symptoms) the mean number of erosions in the wrist and hand of the group had approached a constant value of 75 erosions. Over the same period the mean erosion area of the group continued to increase. Measurement of changes in erosion area is a more sensitive indicator of erosion progression than erosion number, both within the group and in individual patients.