[Situs inversus of the fibula: medialized fibula]

Congenital extremity anomalies are caused by pathological changes during the development process of the embryo. Exposure to toxins during 4-12 weeks of pregnancy may lead to extremity anomalies. In this article, we present a girl patient born as one of triplets at the 31st week and fifth day of pregnancy with meningomyelocele, Arnold-Chiari type 2 malformation, developmental dysplasia of the right hip, hypothyroidism, and lower extremity anomaly. Mother had a history of antenatal usage of sodium valproate. Radiographic examination of the lower extremity showed medial location of the fibula.