Fig. 2

Radiological measurements of patients with long-term unreduced hip joint dislocation, secondary osteoarthritis and pseudoarthrosis. a On the “standard” (bilateral symmetry of the patient in every direction) multiplanar reconstruction image, the rotational center of the contralateral femoral head is identified. b The rotational center of the ipsilateral femoral head is identified. The upward shift distance (backward shift distance) of the rotational center is defined as the vertical distance (orange color) between the rotational center of the ipsilateral femoral head and the level of the contralateral femoral head center. c The coverage of the “pseudoacetabulum” is defined as the angle between the horizontal line of the rotational center of the ipsilateral femoral head and the lateral edge of the pseudoacetabulum. d On the standard multiplanar reconstruction image, the acetabular diameter is identified at the level of the rotational center of the contralateral femoral head