[The hip joint in the frontal projection. A contribution to the roentgenologic comprehension of the femur head-acetabulum relation].

The development of hip deformities is strictly dependent on the congruence between the head of the femur and the acetabulum. The routine radiological examination shows this relationship in one plane only. The combination of the anterior-posterior and the frontal projection opens the view into the third dimension of the hip joint. The frontal projection is especially suitable for measuring the anteversion of the acetabulum which in combination with a marked antetorsion of the femoral neck leads to a reduction of the weight-bearing articular surface. As every decentration of the femoral head should be considered for operative procedures the frontal projection is of special interest in the radiological examination of the hip joint.