In clinical practice, a patient presenting with an O-shaped leg can be diagnosed as having an internal derangement of the knee. The cost of surgery to correct this condition is not uniform, as it is determined by the specific procedure. For example, if a patient has an inversion of the knee, a closed osteotomy is performed under epidural anesthesia, and an external fixation brace is given for fixation. The approximate cost is around$17,000-20,000. If the same patient has a knee inversion, a conventional incision for wedge osteotomy, followed by internal fixation with a locking plate and post-operative oral bone grafting medication, the cost is about 23,000-25,000 yuan. However, the specific fee should be based on the local hospital fee standard. Because the region is different and the level of the hospital is different, the charges may also be slightly different.