Study of hip joint dislocation after total hip arthroplasty.

The present study was undertaken to identify the factors responsible for hip joint dislocation after total hip arthroplasty, laying emphasis on analysis of the background variables of the patients. Of the 317 hips included in the study, ten (3.2%) dislocated. Only the anteversion angle of the cup differed significantly between the dislocation group and the dislocation-free group. The safe zone of the anteversion angle seems to be between 20 and 30 degrees. but it is also essential to set the antetorsion angle of the stem to match the shape of individual bones to create a more stable hip joint. This safe zone may be expanded by the additive effect of antetorsion angle of the stem.