O-shaped legs are also known as inversion of the knee. O-shaped legs in boys can be corrected by shoe inserts, braces, and surgery. 1. Insole Correction: Patients can customize the corrective insole according to their personal situation, which can give the calf an outward force and help to prevent the inversion of the knee caused by improper walking posture. 2. Brace correction: If the patient’s degree of knee inversion is low, or if the patient is young and has strong self-healing ability, a splint can be used to bind the leg to generate pressure to adjust the anatomy of the knee joint, but usually need to be worn consistently for a longer period of time. 3. Surgical correction: If the patient’s symptoms of knee entropion are serious, and the treatment is ineffective through other ways, the patient can choose surgical treatment, and the commonly used surgical methods are semi-epiphyseal plate block guided growth, osteotomy and orthopedic surgery, and knee arthroplasty. Boys who have obvious knee inversion should consult a doctor in time for examination, and the doctor should choose the appropriate treatment, not blindly, so as not to delay the condition.