Systems and methods for planning and optimizing bone deformity correction treatments using external fixators. A computer system generates a display of a tiltable ellipse superimposed on digital medical image(s) (radiograph), the ellipse representing a ring of an external fixator attachable to the patient's bone. Based on axial and azimuthal ring rotation user input, the system calculates a 3D position of the resulting graphical representation of the ring. User input controls translation of ring(s). Strut position user input identifies 3D positions for the external fixator struts. Based on graphical input defining 3D biological rate-limiting points for treatment, the system calculates a 3D bone correction speed and/or a number of treatment days, and generates a graphical simulation of this treatment. Further, the system generates a correction plan specifying for each strut a daily sequence of strut lengths and preferred strut sizes, to minimize strut replacements.