The healing process of fractures is characterized by the simultaneous removal of damage and new repair and is susceptible to the influence of many factors. There are both favorable and unfavorable factors. Favorable factors can promote fracture healing and shorten the treatment time, while unfavorable factors can delay bone healing and even lead to bone disjunction or re-fracture. Wu Jingming, Department of Spine Surgery, The First Hospital of Guangzhou Medical University, Guangzhou, China [Systemic factors] 1. Age The rate of fracture healing varies at different ages. Femur fractures in newborns can heal strongly in 2 weeks, while adults usually need 3 months. 2. Health status Patients with poor health, such as osteoporosis, diabetes, malnutrition, malignant tumors and other chronic wasting diseases, require longer healing time after fracture. 3. Bad habits Bad habits such as smoking and alcoholism can also cause significant prolongation of fracture healing and even lead to bone nonunion or femoral head necrosis. Local factors】1. type of fracture Oblique or spiral fracture, the contact surface of the section is larger than that of the transverse fracture, so the fracture heals faster in the former.2. blood supply of the fracture site The blood supply of the fracture segment differs depending on the site of the fracture, and there are generally four cases: (1) both fracture segments have good blood supply, mostly seen in epiphyseal fractures. The epiphysis is mostly attached to the joint capsule, ligaments and tendons, and many small blood vessels enter the bone, so the blood supply is abundant and the fracture heals quickly, such as tibial plateau fracture and femoral condyle fracture. (2) A fracture segment has a poor blood supply, such as a fracture of the middle and lower 1/3 of the tibial stem, because the tibial stem is mainly supplied with blood from the top down by the trophoid artery that enters the medullary cavity posteriorly in the upper 1/3 of it. After the fracture, the trophoid artery is dissected and the distal fracture segment is maintained only by the small subperiosteal vessels, which significantly reduces the blood supply and results in slower fracture healing. (3) The blood supply to both fracture segments is poor, for example, if the fracture occurs at the same time in the upper and lower middle tibia, only one fracture segment of the upper segment has poor blood supply, while the lower segment has poor blood supply to both segments, so the upper segment fracture heals faster than the lower segment. (4) Complete loss of blood supply to the fractured segment. If the fracture is intracapsular, the blood supply to the femoral head is almost completely interrupted and ischemic necrosis is likely to occur.3. Soft tissue injury 4. Soft tissue embedment If there is tissue such as muscle or tendon embedded between the two fracture ends, it not only affects the repositioning of the fracture, but also hinders the alignment and contact of the two fracture ends, making it difficult or even impossible for the fracture to heal.5. Infection In open fractures, local infection can lead to septic osteomyelitis and the development of The soft tissue necrosis and dead bone formation can seriously affect the fracture healing. Inappropriate treatment】1. Repeated manipulative repositioning can damage local soft tissues and bone epithelium, which is not conducive to fracture healing. Although manual repositioning can affect the blood flow of the fracture less, it is often difficult to achieve anatomical repositioning, so it is not advisable to reposition the fracture if it has already reached the standard of functional repositioning. 2. Excessive stripping of soft tissues and periosteum during incisional repositioning can affect the blood supply of the fracture segment, which can lead to delayed healing or even non-healing of the fracture. In addition to strict surgical indications, the local blood supply should be disturbed and disrupted as little as possible. 3. Excessive removal of bone fragments during open fracture debridement may cause bone loss, which may lead to delayed healing or non-healing of the fracture. 4. Excessive traction force during continuous bone traction treatment of fractures may cause separation of the fracture segment, which may affect fracture healing when combined with insufficient local blood supply due to vascular spasm. When the fracture is not firmly fixed, the fracture may be affected by continuous shear and rotational forces, which may interfere with the growth of bone scabs and vascularization, resulting in delayed healing or non-healing of the fracture. 6. Premature or inappropriate functional exercise may hinder the firmness of the fracture fixation and thus affect fracture healing. In contrast, correct and appropriate functional exercise can promote blood circulation in the limb, eliminate swelling; promote bone scab growth; prevent muscle atrophy, osteoporosis and joint stiffness, and facilitate the recovery of joint function.