”Doctor, please take a look at my child. He suddenly complains of leg pain at night when he is sleeping, and he is afraid to get out of bed and can’t walk, but he has no trauma and has never fallen. We often see children with this condition in the pediatric emergency department at night. If a child suddenly has leg pain and continues to walk with a limp for several days, parents should not be concerned that the child may have pediatric acute hip synovitis. What is pediatric acute hip synovitis? Pediatric acute hip synovitis, also known as acute transient (temporary) synovitis of the hip, is a common acute hip disorder in childhood and one of the most common causes of hip pain in children. Most of this disease occurs in children aged 2-12 years, more in boys than girls. The incidence is relatively higher in the spring and fall. Why do children develop acute hip synovitis? Falls and colds are the two main triggers of this disease. Since the femoral head is still immature and the joint capsule is loose, excessive abduction of the lower extremity, such as jumping from a high place, or walking unsteadily causing sprain of the lower extremity, or excessive running and jumping causing tug on the joint capsule, or the joint capsule being squeezed, can cause synovitis of the hip joint. However, there are many children who have not suffered any trauma, and the cause is the “cold”. Infections such as viruses, bacteria or mycoplasma attack many organs, some of which affect the synovial membrane of the child, causing congestion and edema in the synovial membrane of the hip joint, which can also lead to localized pain and limited movement of the joint. What are the symptoms of acute hip synovitis in pediatric patients? The first symptom is pain, which can be around the hip joint or the inner thigh or even the knee joint, and often occurs at night. Secondly, children are reluctant to stand, even if they walk, they limp and have limited joint movement, and even have pseudo-extended legs, as if one leg is long and one leg is short. Isn’t acute synovitis of the hip joint in children temporary and can be seen without going to the hospital? The prognosis for acute hip synovitis is mostly good, but parents are still advised to take their children to a regular hospital for consultation and treatment. On the one hand, synovitis of the hip joint can be easily confused with other diseases, so doctors will use blood tests and ultrasound to identify and confirm the diagnosis after excluding other diseases. On the other hand, if the disease is not detected in time or if treatment is delayed and the child continues to play sports, it may worsen or turn into chronic hip synovitis, and in serious cases, even lead to ischemic necrosis of the femoral head, making the hip joint dysfunctional. How to treat acute hip synovitis in children? The main treatment for acute hip synovitis is bed rest and avoiding weight-bearing on the lower limbs to ensure rest time. Anti-infection treatment is given when there is infection. Physiotherapy or localized external application of blood-stasis activating herbs can be used to accelerate blood circulation and promote the inflammation of the soft tissues around the joint to subside and the absorption of joint effusion as soon as possible. Some need traction, acupuncture, etc. With timely treatment and proper rest, generally speaking, the joint will heal itself within 1~2 weeks. However, once limping, pain worsens, no significant improvement for a long time, blood picture rises, and enlarged joint space and thickened synovial membrane can be seen in ultrasound, hospitalization is necessary for treatment. Do I need to review acute synovitis of the hip after it has healed? Acute hip synovitis usually does not recur and does not leave sequelae, but in a few cases, the continuous increase in intra-articular pressure affects the blood supply to the femoral head and causes ischemic necrosis of the femoral head, so children diagnosed with acute hip synovitis need to be reviewed 2 months and 6 months after the onset of the disease and cannot engage in strenuous exercise for one month. Once again, we remind parents to be vigilant when their children have “leg pain” and walk with a limp, and to never “jump to conclusions” on their own, and to go to the hospital in time to ensure proper treatment.