A method on a processor customizes a fixation plate for repairing a bone fracture. A digital CAD model of an implant contains smooth analytic geometry representations including NURBS. The CAD geometry is directly manipulated to generate a customized implant CAD model that conforms to the desired region of the bone surface of a patient. Direct manipulation of NURBS geometry is computationally fast and suitable for interactive planning. The patient specific customized implant is produced directly from the generated customized CAD model with a standard CNC machine before surgery. The patient customized implant is implanted in the patient.