Dynamic condylar screw(DCS) or blade plate were usually used through lateral approach and laterally applying method can not always restore the medial buttress of the fracture site. In these cases, early exercise and early weight bearing have to be postponed,and the results were poor. So we want to emphasize the principles in open reduction and internal fixation of the supra-and inter-condylar fracture fo the femur. To get anatomecal reduction is very important, but if is not possible in severely comminuted fractures, we have to try to maintain medial buttress by another methods such as double plating(to add a medial auxiliary buttress plate to lateral internal fixation) or auxiliary external fixations instead of medial anatomical contact.