[How accurately can the rotation in the hip joint be estimated from ordinary plain film alone?]

Plain films were taken from 5 adults femura (with different angles of antetorsion) varying the rotation between +70 degrees to -50 degrees. An astonishingly constant relations between the structures of proximal femur and the axis of the femural condyle has been found, independent from the angle of antetorsion. According to our opinion the rotation in an adult hip joint can be estimated with an accuracy of +/- 10% from a.-p. film alone. A simple method for determining the rotation has been suggested and may be put to further discussion.