A method for treating a fracture with a variable length nail is provided. The nail is configured for at least 5 mm of axial length change in each direction. An incision is made in proximity to a fractured bone and canal is cleared through the center of the bone. The variable length nail is inserted into the canal and a distraction shaft and a housing are secured to separate portions of the fractured bone. The incision is allowed or caused to close. An external adjustment device with at least one rotatable magnet is placed in proximity to the patient's skin. The external adjustment device is operated so that a magnetic field of the at least one rotatable magnet of the external adjustment device causes the rotatable permanent magnet of the variable length nail to rotate, causing either extension or retraction of the distraction shaft relative to the housing.
