Calf ectropion is often referred to as X-shaped leg, which means that when the two feet stand side by side, the two sides of the knee joints touch together, while the inner ankles of the two feet can not be close together. The causes are mainly pediatric rickets, heredity or cartilage development disorder, trauma, fracture and other sequelae, calf ectropion is easy to lead to patellar chondromalacia. Corrective methods mainly include surgery, splinting and other methods. O-shaped leg, i.e. knee inversion, when the lower limbs of both legs are naturally straightened or standing, the inner ankles of the two feet can touch each other but the two knees can’t be close together. Causes include calcium deficiency, heredity or imbalance causes such as poor sitting posture, and the treatment is mainly orthodontic or surgical. Calf ectropion and O-shaped leg should go to the hospital in time, under the guidance of the doctor for standardized treatment.