The answer is 25400-LT. the explanation behind this is this is not the reparation of a fracture; it is repair of a malunion. In the CPT® Index look for Repair/Radius/Malunion or Nonunion, 25400, 25405, 25415, 25420. Code 25400 reports repair of a malunion of the radius. There is no indication of an autograft; hence, 25405 is incorrect. Norian SRS is a biocompatible bone gap filler, not a graft. Modifier LT is added to indicate the procedure is executed on the left side.