ABSTRACT
The simulation study was performed on 15 pairs of adult cadaveric femora to determine whether the size or width of the apparent lesser trochanter (ALT) from the image screen of different projection of the C-arm image intensifier will be useful or not for the prediction of rotational profile of the proximal femur. From the study, the width of ALT is smallest at the position of internal rotation and gradually increase with the decreasing degree of internal rotation to neutral AP projection. The width of ALT is gradually increase with increasing degree of external rotation projection. However from the pairs study, it wasfound that the apparent width of ALT from right femur is larger than that of the left side in almost all projection between 30 degree internal rotation to 30 degree external rotation of the C-arm. The difference of the width of ALT at internal rotation 30 degree averaged 1.9 mm and the difference at external rotation 30 degree averaged 6.2 mm. The range of difference of the width of ALT in the pairs study ranged from 0 to 24 mm. No any relationship of the difference of the width of ALT and the degree of internal or external rotation was found. There was no tendency that width of ALT can be used as a reference to each other to any degree of femoral rotation.