Children’s legs stir straight, may be related to vitamin D deficiency rickets, seizures or convulsions and other diseases. 1. Vitamin D deficiency rickets: one of the accompanying symptoms is vitamin D deficiency rickets tetany, due to vitamin D deficiency, blood calcium decreases, causing an increase in neuromuscular excitability leading to convulsions, with tonic spasms and straightening of the foot and ankle joints. 2. Epilepsy: it can be caused by metabolism, heredity, immunity, infection and other reasons. When there is epileptic seizure, the child’s whole body has tonic contraction of skeletal flexor or extensor muscles, so the legs can be straightened, which can be accompanied by loss of consciousness, apnea and other symptoms. 3. Convulsions: Convulsions can be caused by infectious causes (e.g. viral meningitis), craniocerebral injuries or hypoxic-ischemic brain injuries, and other causes, and in full-blown seizures, there can be tonic or spastic convulsions of the facial muscles and limbs, complete loss of consciousness, and staring with both eyes, among other manifestations. If you find that your child’s legs are straight or there are other uncomfortable symptoms, it is recommended that you consult a doctor in time to treat the cause and symptoms.