Hip synovitis, also called transient hip synovitis or toxic synovitis is a condition in which there is inflammation of the synovial tissues surrounding the hip joint causing hip pain. It is the most common reason for sudden hip pain occurring in young children between the ages of 2 and 9. It affects boys more commonly than girls and most of the time, the hip joint on only one side is affected.
The symptoms of hip synovitis manifest over a period of 1 to 3 days and gradually resolve within the next few days. The most common symptom is pain around the hip or groin region. The child may limp while walking or may find it hard to walk. Sometimes, the child has a low-grade fever or complains of pain in the inner thigh or knee.
The exact cause of hip synovitis is unknown but some theories include a history of trauma to the hip or a recent viral infection such as an upper respiratory tract infection, bronchitis, or middle ear infection.
When you go for a consultation, your doctor will initially examine your child’s hip, knee, and other joints and check whether there is pain while moving the joints passively. Your doctor may order diagnostic tests such as ultrasound imaging and blood tests to assess inflammatory markers. If the inflammatory markers are high, then your doctor may order a culture test of the fluid within the joint. To perform the culture test, joint fluid is collected by inserting a needle into the hip joint and aspirating the fluid then sending it to the laboratory for evaluation.
The treatment for hip synovitis includes simple home remedies such as rest, application of heat, and massage over the painful area. Anti-inflammatory medications will be prescribed to reduce the pain and other symptoms. Weight-bearing on the affected side should be avoided until the pain is resolved.
Hip pain caused by synovitis usually resolves within a span of a week or 10 days with no long-term complications. Further evaluation of the condition should be sought if the symptoms persist or become worse.