[Stability after obtaining cancellous bone from the greater trochanter].

To test the endangered stability after obtaining cancellous bone from the greater trochanter, the ultimate breaking force of 40 human femura was measured with a material testing machine (Instron 1115). 1. 10 Femura after removing bone from the greater trochanter as a routine clinical procedure showed a significantly reduced trochanteric stability (p less than 0.05), 4 subtrochanteric and 3 pertrochanteric fractures, compared to 10 intact opposite femura with vertical shear fractures of femural neck and head without damage to the trochanteric region. 2. The number of fractures crossing the window was reduced by half, p less than 0.05 when a round cortical window compared to when a square window of the same area was cut. As the reduced stability caused by the remove of cancellous bone can not be avoided, we can clearly reduce the danger of stress concentration in the notches by cutting a round corticalis window. Cancellous bone from the greater trochanter should only used, if it cannot be taken from the brim or posterior iliac spine of the pelvis.