Lower limb torsional deformity, also known as femoral torsional deformity, is common in clinical practice, mainly due to the change in the anterior femoral inclination angle, resulting in the corresponding change in the child’s feet, i.e., the “internal and external octopod” deformity seen clinically, with more bilateral onset. Etiology: The specific cause of the abnormal anterior femoral inclination angle is still unclear, but it has been documented that it is caused by long-term abnormal posture, and there is no obvious family heredity. Pathology: The main is the change of the anterior tilt angle, in infancy, the anterior tilt angle is larger, up to 30 °, as the age increases, the anterior tilt angle gradually becomes smaller, the normal 2 years old children’s anterior tilt angle of about 15 °, in the lower limb twisting patients appear to increase the anterior tilt angle or small, which leads to internal and external foot octagonal deformity. Clinical manifestations: before toddler, the child has no obvious appearance deformity, some cases found in the step of the feet internal and external octagonal deformity, with the increase in age, to about 3 years old, its internal and external octagonal deformity is most obvious, gait clumsy, no limp, and walking can have double knee collision phenomenon, easy fatigue, fall. In patients with external rotation of the femur, the typical M-shaped deformity is easily seen when sitting on the ground, i.e., both feet face outward, both knees touch together, internal rotation increases and external rotation is limited; the opposite is true in cases of internal rotation of the femur. Imaging manifestations: mainly X-ray examination, in the pelvic film, the femoral head anteversion angle can be found to change, but the specific angle is difficult to measure in plain film, need to perform CT examination to clarify. Treatment and prognosis: For the majority of patients, with the increase of age and the increase of movement of both lower limbs, the anteversion angle of both femurs will be corrected on its own, and if necessary, a brace can be worn at night to help normalize the anteversion angle. For a very small number of patients with obvious symptoms and an age close to 10 years, they can be treated by rotational osteotomy of the femur with a good prognosis.