Biomechanical study of load transfer of the pubic ramus due to pelvic inclination after hip joint surgery using a three-dimensional finite element model.

We studied load-stress distribution in the pelvis using a three-dimensional finite element model. The results showed that the load-stress on the pubic superior ramus was high in the normal pelvic position without sagittal or coronal inclination following that of the acetabulum in the pelvis. The load-stress on this area was not affected by sagittal pelvic inclination, but it was affected significantly by coronal pelvic inclination. The superior pubic load-stress on the side of the longer leg was higher than that on the opposite side. The tensile stress on the pubic ramus on the side of the longer leg significantly increased compared with compressive stress. We had a patient who had an insufficiency fracture of the pubic ramus on the side of an overcorrected leg after hip joint surgery, so we examined the cause of it. Although insufficiency fractures of the pubic superior ramus are caused by various static and kinetic factors, the alternation of coronal pelvic inclination is an especially important factor in such fractures after hip joint surgery. The Japanese Orthopaedic Association