Temporary synovitis of the hip joint is a common clinical condition in pediatric orthopedics. We would like to summarize the common concerns of parents in our work and hope to be helpful to parents of sick children. Q: What is temporary synovitis of the hip joint? A: Temporary synovitis of the hip joint is a common disease in childhood, manifested as lameness, which may or may not be accompanied by limb pain. In mild cases, the hip joint examination is normal. In severe cases, there may be pelvic tilt, i.e. the affected limb looks longer than the healthy side, Thomas’ sign (+), which means that the affected hip cannot be straightened when one hip is flexed. Ultrasound examination may reveal fluid in the anterior saphenous fossa or thickening of the anterior joint capsule, while X-ray examination is mostly normal. Q: What are the causes of temporary synovitis of the hip joint? A: The pathogenesis of temporary synovitis of the hip joint is not well understood, but it is recognized as a kind of toxemia causing or trauma causing synovial edema. The known causes are, in descending order of frequency, upper respiratory tract infections, especially about half a month before the onset of the disease; trauma; and unknown causes. Q: Does temporary synovitis of the hip joint always require hospitalization? A: According to a large number of clinical summaries, patients with short duration and mild lesions can be treated with medication, and most of the children can return to normal in 3-5 days, but in order to prevent recurrence, a two-week rest is generally advocated, therefore, there is no need for hospitalization. For those who have been ill for more than a week and have severe clinical symptoms, traction should be administered along with medication, and these children should be hospitalized. Q: Does temporary synovitis of the hip joint cause ischemic necrosis of the femoral head? A: Most scholars have proved in clinical and experimental studies that temporary synovitis of the hip joint does not cause ischemic necrosis of the femoral head. However, some patients do suffer from ischemic necrosis of the femoral head after being diagnosed with temporary synovitis of the hip joint. It turns out that the early clinical manifestations of ischemic necrosis of the femoral head and temporary synovitis of the hip are so similar that physicians are unable to distinguish between the two, which means that a small number of children diagnosed with temporary synovitis of the hip actually have ischemic necrosis of the femoral head at the beginning, rather than temporary synovitis of the hip. It is only in the early stages that the two could not be distinguished and later it was confirmed that the head of the femur was ischemic necrosis. As a result, it was mistaken for ischemic necrosis of the femoral head caused by temporary hip synovitis. Q: Can temporary synovitis of the hip joint cause sequelae? A: This is a question of great concern to every parent. We know that temporary synovitis of the hip joint is caused by toxemia, so it will not produce some sequelae after healing like septic infection, and it usually does not produce sequelae after healing, but there are a few children who can have recurrent attacks, which requires clinicians’ attention and necessary examination. Q: According to you, does it mean that temporary hip synovitis is not relevant and does not need to be taken seriously? A: No. Temporary hip synovitis has been known for a long time. There are many academic names for it, one of which is “ghost hip”, which means that some patients may get better and worse all the time, and some patients may not return to normal even after a few months. Long-term temporary hip synovitis can lead to nutritional disorders of the articular cartilage, which can lead to early onset of joint degeneration later. Therefore, it should be treated promptly. Q: How often should I go to the hospital for review after treatment of temporary synovitis of the hip joint? A: As we mentioned above, temporary synovitis of the hip joint rarely recurs after treatment, and it usually does not cause complications after treatment. Therefore, it is not necessary to go to the hospital for review. However, some patients may be children with early ischemic necrosis of the femoral head, which should not be ignored by doctors. Clinicians should pay attention to the following cases and should go to the hospital for review on time: ① those who have been diagnosed with temporary hip synovitis for several months and do not return to normal; ② those who have fluid in the anterior saphenous fossa of the hip joint that does not disappear after 6 weeks of ultrasound examination; ③ those who have recurrent temporary hip synovitis within a short period of time. Children with the above three conditions should be reviewed regularly at the hospital. According to the clinical pattern of ischemic necrosis of the femoral head, one should go to the hospital for examination every 3 months.