Asymmetrical leg lines may be related to incorrect walking posture, lumbar spine pathology, knee pathology and congenital hip dysplasia. 1. Incorrect walking posture tends to lead to increased mobility of one side of the limb, which to a certain extent will affect muscle development. When the muscle development of both lower limbs is not coordinated, asymmetry of leg lines may occur. 2. Lumbar spine lesions may lead to nerve compression, clinical pain and numbness in the limbs may occur, this situation will indirectly affect the walking posture, which affects the leg lines because of the different mobility of the muscles. 3. Knee joint lesions will also affect the activity of the limbs, which is also a factor leading to asymmetry of the leg lines. 4. Congenital abnormalities of the hip joint development are the main factors leading to asymmetrical leg lines in newborns. Due to the complexity of the condition, it is necessary to consult a doctor for details.