Palmar subluxation of the carpus in rheumatoid disease: a radiological evaluation.

The authors present a radiological assessment of palmar subluxation of the carpus in rheumatoid disease. The radiological measurements have been taken with reference to the long axis of the radius, the radiological centres of the lunate and the capitate and expressing their reciprocal distances as a ratio which we have termed the radio-carpal and inter-carpal indices. Using a control group of a 100 serial radiographs of normal wrists it was possible to determine the normal indices and their normal range. A subsequent analysis of 100 rheumatoid wrists enabled them to accurately determine the degree of anterior carpal subluxation, and allowed this form of radio-carpal malalignment to be differentiated from other forms of carpal instability.