It is perfectly possible to fly with a steel plate on your leg, but the metal detector will sound an alarm when you go through the security check, so you need to explain the situation to the security personnel or produce a hospital medical record and a certificate of diagnosis, so you can pass normally. In the airplane is a closed pressurized space, the pressure inside is no different from the pressure on land, so it will not affect the fracture site, but if you have just had surgery, it is not recommended to fly for a long time, because the space between the front and back seats in the general economy class is narrow, so it is better to stay seated for a long time and keep the leg in a sagging state, which may cause the leg swelling to increase. It is recommended that the fracture be completely healed before flying.