Hip dysplasia generally refers to developmental dysplasia of the hip (DDH). The symptoms of hip dysplasia in infants may vary at different periods of time, and the main symptoms include unequal length of the lower limbs, impaired mobility of the lower limbs, and so on. 1.0~6 months: The main symptoms include lower limb movement disorder, unequal length of both lower limbs, and joint popping. 2.6~12 months: the main manifestations are insufficient strength of the affected side and limitation of hip abduction on the side. 3.12~18 months: the main manifestations are limitation of hip abduction, unequal length of both lower limbs and dislocation of one side. The child may have a limp when walking. 4.18 months and above: the main manifestation is that the affected side of the hip joint is limited in abduction, and there is also internal deformity and other conditions. The child may walk with a duck step. Each infant with hip dysplasia has different conditions and clinical symptoms. Specialized consultation is recommended to avoid delays.