In medicine, the Ilizarov apparatus is a type of external fixation apparatus used in orthopedic surgery to lengthen or to reshape the damaged bones of an arm or a leg; used as a limb-sparing technique for treating complex fractures and open bone fractures; and used to treat an infected non-union of bones, which cannot be surgically resolved. The Ilizarov apparatus corrects angular deformity in a leg, corrects differences in the lengths of the legs of the patient, and resolves osteopathic non-unions; further developments of the Ilizarov apparatus progressed to the development of the Taylor Spatial Frame.