Old fractures are defined as malunion, delayed healing, or nonunion of fractures. Deformed healing refers to poor alignment, angulation, rotation, or overlap of the fracture ends at the fracture healing site, which is caused by poor revision, poor fixation that displaces the fracture ends again after revision, or premature unprotected weight bearing that displaces the fracture ends, and failure to correct these conditions in time, resulting in deformed healing. Delayed healing occurs when the fracture is treated and immobilized for a considerable period of time, but the bone scab that forms does not hold the broken end together. If there is little or no scab formation, the fracture ends are atrophied and smooth, separated from each other, and there is pseudo-articular movement, the fracture is said to be non-healing. Delayed healing indicates that the fracture is healing slowly, while non-healing reflects a dysfunctional fracture healing. There are many reasons for delayed healing and non-healing, such as old age, weakness of the blood and Qi, or extreme malnutrition of the patient, or poor local blood supply, or severe local injury with more bone and soft tissue fragments, or soft tissue interspersed between the fracture ends, or infected lesions at the injury site. However, for most of the patients, the important reason is that the fracture is not properly treated, the end of the fracture is not well repaired, or the fracture is not healed due to poor local fixation, insufficient external fixation, failure to control certain activities of the fracture end that are not conducive to fracture healing, such as torsional and angular shear forces acting on the fracture end for a long time to separate it, and the fracture end forms more cartilage and fibrous tissue and cannot obtain bony healing. In some patients, this is a consequence of incision and internal fixation. Clinically, delayed healing is the most common.