O-leg can usually be corrected through treatment as follows: 1. For O-leg with no clear etiology, it can often be corrected by itself, and no special treatment is usually needed. 2. For pediatric patients, closed fracture osteotomy can be performed at the deformity site, or surgery can be used, most of which will use U-shaped nail or upper tibia and femoral condyle osteotomy. These methods allow the lower extremity force lines to be completely corrected, the O-leg to be completely treated, and the patient’s appearance to be improved. It will also prevent the patient from developing degenerative arthritis, which is extremely beneficial to the patient’s recovery. In addition, muscle strength and intensity training should also be adhered to, so that the treatment effect can be consolidated.