Giliberty bipolar endoprosthesis was implanted in thirteen cases. Ten cases were treated for medial fractures of femoral neck, and two cases were treated for Austin-Moore prosthesis which were painful, and one case was treated for the bone tumor of femoral neck. The follow-up-term was on the average 6.4 months. The age was on the average 64.4 years old. Twelve cases were good and another case was dislocated as only a complication. We took measure of the mobility of the bipolar hip prosthesis. It was proved that the mobility of the cup and femoral head was larger than that of the acetabulum and cup. We thought that Giliberty bipolar endoprosthesis would reduce frictional forces which were created about the hip in cyclic loading of Austin-Moore endoprosthesis.
