With the emergence of fracture fixation devices, especially the demand for shorter fracture treatment period, more and more physicians have started to use surgical and device fixation methods to treat long diaphyseal fractures in children. elastic stable intramedullary nailing (ESIN), also known as titanic elastic nailing (TEN), was used in our hospital from June 2006 to June 2008 to treat 43 cases of long diaphyseal fractures in children. TEN) to treat 43 cases of long bone stem fractures in children, with good clinical efficacy. 1, Materials and methods 1.1 Case data In this group, there were 43 cases, 31 males and 12 females, aged 3.5-12.7 years. 38 cases were closed fractures and 5 cases were open fractures. There were 18 cases of femoral stem fracture, 9 cases of tibiofibular fracture, 3 cases of humeral stem fracture, 6 cases of ulnar radius fracture, 2 cases of meng’s fracture, and 5 cases of radial neck fracture. There were 2 cases of combined cranial trauma, 2 cases of combined abdominal trauma and 1 case of combined pelvic fracture. 1.2 Preoperative preparation Before surgery, a flexible intramedullary pin of appropriate diameter was selected. The diameter of the intramedullary pin was 40% of the diameter of the narrowest bone marrow cavity. The length is required from the proximal epiphysis to the distal epiphysis, and the elastic intramedullary pin is pre-bent with an arc of three times the diameter of the medullary cavity, and the tip of its convex surface can reach the horizontal height of the fracture. 1.3 Surgical method The child is placed supine on a transilluminated surgical bed. First, the epiphysis is fluoroscopically positioned in the affected limb, and a small incision is made 1~2 cm from the epiphyseal plate near the fracture end, with blunt separation to reach the periosteum and incision of the periosteum. The bone cortex is drilled with an awl, and the inclined awl is angled at 45° to the diaphysis. The 2 pre-curved flexible intramedullary pins are inserted separately to advance to the fracture plane and paused, then the fracture is repositioned under fluoroscopy to continue the needle insertion, inserting the 2 pins to their final position (the final position of the needle insertion is decided under fluoroscopy depending on the specific type of fracture). Those who have difficulty penetrating the fracture can use the elbow design of the intramedullary pin and carefully hook the contralateral fracture end until the intramedullary pin passes smoothly. After satisfactory fluoroscopic repositioning and fixation, 1 to 1.5 cm is retained extracortically and the tail of the needle is bent and buried subcutaneously. For those who have difficulty in closed reduction, small incisions can be made at the fracture to assist in the reduction. 35 cases of closed reduction and flexible intramedullary pin fixation were performed in this group, together with small incisions in 8 cases. Postoperatively, polyester bandage was used for external fixation. 1.4 Efficacy evaluation criteria According to the scoring criteria of intramedullary pin treatment of lower limb fractures proposed by Flynn [1]: excellent, no pain at the fracture site, no obvious shortening, angulation or rotation deformity, normal function, normal hip, knee and ankle flexion and extension function; good, no pain or slight pain at the fracture site, shortening deformity <1 cm, angulation or rotation <5°, normal hip, knee and ankle flexion and extension function; may, mild pain, shortening deformity <2cm, and mild limitation of joint movement. The upper extremity fracture score referred to this standard. The wounds were healed at stage I and no infection occurred. The duration of hospitalization was 3~7d. The fractures were clinically healed in 4~24 weeks with regular postoperative follow-up radiographs. One case of delayed healing of femoral stem fracture was gradually weight-bearing at 12 weeks after removal of the cast and healed at 24 weeks. All children were followed up for 4 to 24 months. At the final follow-up, the efficacy was evaluated as excellent in 41 cases and good in 2 cases, with an excellent rate of 100%. There was no bone discontinuity, deformed healing or epiphyseal injury. Three cases had symptoms of pin tail irritation, and those with symptoms of pin tail irritation were removed after fracture healing was confirmed by X-ray, including one ulnar radius fracture 4 weeks after surgery, one Men's fracture 5 weeks after surgery, and one tibiofibular fracture 8 weeks after surgery. The intramedullary pin was usually removed 3-6 months after surgery. 34 cases were removed on an outpatient basis, and 9 other cases required inpatient removal due to young age or poorly palpable pin tails. Typical cases are shown in Figures 1~3.