The traditional treatment methods for long fractures of the extremities in children mainly include traction repositioning, splint or cast fixation, and later developed into methods such as intramedullary pin fixation and external fixation brace fixation. For younger children, the traditional treatment method has the advantages of simple method and low cost, while for older children and children with other injuries, the traditional treatment method has the shortcomings of long bed rest, poor quality of functional repositioning, difficulty in nursing and accompanying, more complications, and parents are not satisfied with the treatment. The adult method of internal fixation of fracture with incisional repositioning plates is very limited in terms of indications and scope of use because of the damage to the bone marrow plate of children, which affects the growth and development of children. In recent years, with the development of minimally invasive technology, the development of internal fixation materials and the updating of the concept of fracture treatment, surgical fixation has shown obvious advantages over conservative treatment in terms of the quality of reduction, hospitalization time, medical costs, family care and complications, etc. How to reduce complications, trauma and hospitalization time while ensuring surgical results has become an increasingly important treatment concept for orthopedic surgeons. The advent of the flexible intramedullary pin has largely overcome the shortcomings of traditional treatment methods, so that the traditional method of fixing long fractures of the extremities in children is now evolving toward minimally invasive flexible intramedullary pin fixation techniques. Compared with other internal fixation methods, the elastic intramedullary pin has the following advantages: the surgery does not require cutting the fracture end, and only two small incisions are needed at the epiphysis when nailing, which is less traumatic, less scarring, and does not affect the aesthetics; closed repositioning, no damage to the epiphyseal plate, no destruction of the periosteum, no influence on local blood flow, and facilitates fracture healing; reliable fixation, the intramedullary pin is a central type of internal splint fixation, and the two elastic nails are bent into an arch shape to form a symmetrical The distribution is symmetrical, with multiple points touching the inner wall of the medullary cavity, which is under tension in the medullary cavity, causing the fracture end to lose the space for movement in the medullary cavity, controlling rotation and displacement, and using the elasticity of the nail to form micro-movement of the fracture end, which is conducive to the formation of bone scabs and less interference with the biomechanics of the limb; it can be moved to the ground early after surgery, and the affected limb can be weight-bearing early and recover quickly, while avoiding complications such as joint stiffness and muscle atrophy caused by long external fixation time. It also avoids complications such as joint stiffness and muscle atrophy caused by prolonged external fixation. The average healing time of the fractures was 4.5±0.3 months, and the pins were removed 5-6 months after surgery. The activities of the adjacent joints and the functions of the affected limbs returned to normal after the pins were removed, indicating that the elastic intramedullary pin fixation heals faster and has fewer complications than the traditional splint or cast fixation or incision and reduction techniques.