[Surface width index of the distal radius joint surface]

A new roentgenographic index for evaluation of the distal radial joint surface is described. The breadth of the carpal lunate bone und the breadth of the distal articular surface of the radius are measured on an X-ray in a typical lateral view. The quotient of these two measurements is the desired index. Mean and standard deviation of the quotients of 50 normal carpal joints were 0.99 +/-0.05. The corresponding values for 39 intraarticular fractures of the distal articular surface, AO classification C.2 and C.3, were 0.83 +/-0.09. The difference evaluated in a t-test for unpaired observations was significant (p less than 0.001). Widening of the distal articular surface in intraarticular radial fractures can thus be measured and numerically described in a single value.