If your child suddenly walks with a limp, consider trauma, synovitis, tibial tuberosity epiphysitis and other causes. 1. Trauma: Trauma is a common cause, children are more active and often suffer from accidental injuries, if there are soft tissue or bone injuries, it will lead to children walking with a limp. 2. Synovitis: Synovitis in children is related to bacterial infection, viral infection, trauma and other reasons, and mostly occurs in the hip and knee joints, which can also cause joint pain and even limping. 3. Tibial tuberosity epiphysitis: often occurs in children during the rapid growth period, due to the quadriceps muscle pulling the tibial tuberosity epiphysis, repeated stress stimulation, and lead to damage caused by overuse. Tibial tuberosity epiphysitis can cause knee pain, which can lead to walking with a limp. There are many reasons why a child suddenly walks with a limp, this phenomenon should go to the hospital in time to further identify the cause of the disease, and then targeted treatment.