The most secure option for the femur is internal.
The safest choice for the tibia is external since it decreases the risks related to fibular non-union.
Nevertheless, out of the two, femurs are always the safer option. Tibia nails are put in from the knee, and if the surgeon makes mistakes, it could lead to persistent pain. Conversely, nails in the femur can be introduced from the hip, eliminating this risk.
By the way, femurs also come with chronic problems; it simply relies on your fortune and the skill of the surgeon.
