The child’s kneecap sliding from side to side can be considered normal physiological factors, congenital hip dislocation, ligament laxity. 1. Normal physiological factors: the kneecap is referred to as the patella, the patella has a certain activity space to ensure that the human body can walk normally, under normal circumstances, the kneecap slides around is normal. 2. Congenital hip dislocation: heredity or trauma and other factors can lead to hip dislocation, manifested by the femoral head can be quickly reset after dislocation, hip joint instability can lead to the kneecap left and right sliding phenomenon. 3. Ligament laxity: Insufficient nutritional elements can lead to ligament laxity, such as lack of calcium, vitamins and other nutrients, unstable kneecap activities can lead to the kneecap sliding left and right. If the sliding of the kneecap is caused by normal physiological factors, there is no need for special treatment. If it is caused by pathological factors, you need to go to the hospital and use the appropriate treatment under the guidance of the doctor to improve the disease.