In clinical practice, the length of the human leg is measured from the anterior superior iliac spine to the inner ankle of the foot, which is the length of the human lower limb leg. If a patient develops a lesion of the lower extremity, it may result in a change in the length of the lower extremity. For example, if a patient has a femoral stem fracture or a tibiofibular fracture, a shortening deformity of the lower limb may occur. A patient with a hip dislocation may also experience a shortening of the lower extremities. Patients with necrosis of the femoral head may also experience shortening of the limbs at a later stage. Patients suffering from osteoarthritis of the knee joint, due to hyperplasia of the bones in the knee joint, resulting in swelling and pain in the knee joint, and O-shaped legs, the length of the patient’s lower limbs will be shortened. In the clinic, after the change of the length of the patient’s legs, it is necessary to consult the doctor in time, and make a correct diagnosis after a clear examination by the doctor.