The main cause of "X"-shaped leg deformity is rickets in children. A small number of them are sequelae caused by cartilage development disorders, fractures, trauma, osteomas, etc. When children suffer from rickets, due to insufficient calcium salts, the hyperplastic cartilage in the epiphyses cannot ossify normally, and the original bone undergoes decalcification and absorption, resulting in bone softening and inability to withstand the effects of gravity. In addition, the ligaments around the knee joint are loose. The support and protection of the bones are lost, resulting in bending and deformation of the lower leg bones, resulting in "X" shaped legs.