Pediatric lameness refers to the dysfunction of lower limb movement due to different lesions. Three common disorders that predispose to pediatric lameness: 1. Congenital hip dislocation After birth, check whether the thigh skin pattern is symmetrical, and whether the foot is flared. ultrasound can diagnose. Gait abnormality is found only when the child can walk. Unilateral dislocation is limping gait, bilateral dislocation is duck gait. Early diagnosis and early treatment of this disease, the effect is better. 2.Osteochondritis dissecans of the femoral head (also known as aseptic necrosis of the femoral head) is most common in children aged 4-8 years old, more common in boys than girls, and more unilateral than bilateral. Early children complain of pain in the inner side of the knee, then limp is found, and the limp is aggravated with the prolongation of the disease. 3, acute temporary synovitis of the hip joint common symptom is pain and limp, this disease has a short course, after resting, the symptoms quickly disappear. Mostly seen in 5-10 years old boys, the beginning of the affected side of the knee joint has a slight pain, 24 hours after the transfer of pain in the knee joint, and accompanied by limp. Generally the body temperature is not high, individual temperature can also be as high as 38℃-39℃.