The purpose of this study was to estimate the biomechanical effect of rotational acetabular osteotomy by analyzing the stress on the surface of the femoral head according to center-edge (CE) angle by computer simulation.

We performed computer simulation by simplifying the pelvis and femur to 3-dimensional flat stress. We analyzed the change of distribution of stress and the amount of deformation according to the degree of acetabular dysplasia, represented by the change of CE angle, by using a Finite element model (FEM). Stress and deformation were calculated in two cases that underwent rotational acetabular osteotomy.

In the FEM model, the stress was 3.74 MPa at a CE angle of 30.and the deformation was 1.37 mm. The stress was 14 MPa at 15., 34.2 MPa at 0., and 82.4 MPa at -15. In a case of rotational acetabular osteotomy, the pre-operative and post-operative stresses were 26.1 MPa and 5.16 MPa, and the maximal deformations were 16.1 mm and 1.6 mm, respectively.

As the severity of acetabular dysplasia increases, the stress concentration also increases. When the CE angle is below 0., a high concentration of stress develops. After rotational acetabular osteotomy, maximal stress was reduced to normal levels and sufficient stress distribution was achieved.