2. Some trials have reported a higher perioperative morbidity for patients treated conventionally, as opposed to those treated with the assistance of computer navigation (1,11). Intramedullary rods may increase bleeding, and may give a higher frequency of postoperative delirium from microemboli and metabolic disturbances (16). On the other hand, the computer navigation is often more time consuming, and can lead to a higher risk of infection. The fixation of pin-fixators in femur and tibia for the reflection beads might weaken the bone and induce a fracture risk zone. We see that both positive and negative aspects of the computer navigation technique will be revealed in this trial.