The child was admitted to our hospital as an emergency because of “pain in the left elbow and limitation of activity for 3 hours after a running fall”. Emergency examination revealed that the child was clear, with a heart rate of 120 beats/min, no dry or wet rhonchi were heard in both lungs, and the abdomen was soft, with no tenderness or rebound pain. The left elbow joint was swollen and deformed, with no obvious local ecchymosis, the left upper limb was shortened by about 1cm compared with the opposite side, elbow joint pressure pain, left upper limb longitudinal snapping pain was positive, limb hemotransmission was possible, skin sensation was normal, and the elbow joint activity was limited. The remaining limbs had normal movement, sensation and blood circulation. Physiologic curvature of the spine existed, no deformity, no pressure pain or percussion pain in the spinous processes, and movement was free. Emergency radiographs were taken as shown below. Consider the diagnosis: left supracondylar humerus fracture. Supracondylar humerus fracture has a high incidence of fracture in children, is easy to heal abnormally, and is often combined with vascular and nerve injuries. The choice of various treatment methods, including conservative treatment, must take into account not only the physical and mental burden of the child, but also the burden of the parents. Anatomical repositioning must be obtained as much as possible to prevent inversion, eversion, or loss of flexion and extension. Depending on the type of fracture, there are four basic treatments: skin traction on the lateral aspect of the upper arm; over-the-head bone traction; closed reduction and percutaneous pinning; and incisional reduction and internal fixation.The Gartland classification is very useful in determining which treatment to use for supracondylar humerus fractures: type I with no displacement; type II with displacement but with intact posterior cortex; and type III with displacement and no cortical contact. This classification also describes whether the fracture is displaced posteriorly medially or posteriorly laterally. Satisfactory results are obtained with closed reduction and external fixation in a tube cast for nondisplaced type I fractures, while displaced type II fractures are difficult to maintain in a reduced position with reduction and external fixation, and displaced type III fractures, which are displaced posteriorly medially or posteriorly laterally, have no cortical contact and the periosteum may be denuded, making reduction quite difficult. At present, for the treatment of type II and type III supracondylar humerus fracture, closed reduction percutaneous pinning is the preferred treatment method, and we also choose this method to treat Su Xiaohua’s child. Third, the precautions of treatment Common complications and countermeasures 1, vascular injury vascular injury is an urgent problem. If vascular injury is found at the initial diagnosis, the affected limb should be placed in a natural position with 30° elbow flexion. Early anesthesia reset is planned, and the preparation of incision reset is carried out. There is no surgical indication to explore the artery when radial artery pulsation is absent and capillary filling is good. If hemodynamics do not return after repositioning in the operating room, the brachial artery should be explored. Do not delay and inform the vascular surgeon for unexpected situations. Direct surgical exploration is not necessary for arteriography. Compression of the artery by the fracture end is common, and once released, circulation is restored. Occasionally, arterial repair or grafting is required. Almost all nerve injuries recover spontaneously within 2 weeks to 4 months after injury. It is not necessary to explore the nerves for up to 6 months after injury, but it is important to review the child frequently because the family needs constant reassurance while waiting for recovery. Electromyography and nerve conduction tests are not necessary. This deformity may gradually improve over time. Note that this deformity is more common in children with lax joints than on the opposite side. Hyperextension alone does not require surgical correction. However, if this deformity is combined with an inversion of the elbow, it can be corrected at the same time as the osteotomy. 4. Elbow entropion deformity is common in conservative treatment, while pinning fixation is rare. The normal angle of carriage is 5°~10°, elbow inversion affects the appearance and causes some dysfunction, mostly due to deformity healing but can be avoided by careful treatment. The deformity becomes apparent once the elbow can be fully straightened after the injury. It can rarely be corrected by bone contouring, and often needs to be corrected by osteotomy. Postoperative X-ray showed that the fracture was in good alignment, and was fixed in plaster, as shown in the figure below. 2. 1 year after the operation, the X-ray showed that the fracture was well healed, no obvious complications, both upper limbs were equal in length, and normal sports activities were practiced, the X-ray is shown below. V. Precautions for life Postoperative management: the left upper limb was immobilized in plaster cast for 3~4 weeks after surgery. After anesthesia failure, carefully check the ulnar nerve, radial nerve and median nerve function. After 3~4 weeks of postoperative outpatient clinic to remove the Kirschner’s needle, plaster, intermittent elbow joint active extension activity training. The doctor will teach the child and parents how to perform active functional activities at home. However, passive activities and strong manipulation of the elbow joint should be avoided. Otherwise, it will make the child fearful and reduce the range of motion of the elbow joint. VI.INSIGHTS Supracondylar humerus fracture is the most common elbow injury in children, and vascular-neurologic injury and residual inversion deformity of the elbow are the common complications, and the treatment of this injury is challenging in children’s fracture treatment. Satisfactory results have been obtained with closed reduction and external fixation with a tubular cast for non-displaced type I fractures, however, the preferred method of treatment for type II and III fractures is closed reduction percutaneous perforator pin fixation. The upper limb was immobilized in a plaster cast for 3-4 weeks after surgery, and the Kirschner pin and cast could be removed on an outpatient basis after the fracture had healed, and intermittent active elbow extension activity training could be performed.