If a bilateral femoral head replacement is to be performed, it is best to leave more than one year between replacements. For bilateral femoral head replacement, it is best to replace one side for more than a year before replacing the other side if there is no particular urgency. The main reason for this is that if both femoral heads are replaced at the same time, the size of the operation will be larger, the bleeding may be higher, and the operation time may be longer. A larger operation is more traumatic for the patient, and is more dangerous if the patient is not in good health or is an elderly patient. More bleeding may produce problems such as anemia during, or after the surgery, or even massive blood loss may lead to other dangerous situations. Longer surgeries can, impossibly, increase the risk of infection. The consequences of an infection around the prosthesis after femoral head replacement can be quite dramatic, so it is important to avoid it. The patient in question is advised to consult a medical professional who will make a comprehensive judgment on the exact duration.