We examined the correlation between the size of the femoral head measured on roentgenograms and the size of the prosthesis actually used in the sixty-six operations. Forty operations were performed on the fresh cases of intracapsular fracture of the femoral neck. The size of the prosthesis employed in these cases resided in 97 to 90% of the size measured on roentgenograms.
On an average, the size of the prosthesis used in these cases was 1.4mm larger than the size judged on roentgenograms. In the cases whose size of the femoral head judged on roentgenograms was 44mm or less, the prosthetic size actually used was 2.0mm larger than the prospected size.