Hip synovitis, also called transient hip synovitis or toxic synovitis, is characterised by 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 age of 2 and 9. It affects boys more commonly than girls, and most of the times, 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. Your child may limp while walking or may find it hard to walk. Sometimes, a low-grade fever, or pain in the inner thigh or knee may be present.
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 consult your child’s doctor for hip pain, an initial examination of the hip, knee and other joints are made to check whether there is pain while moving the joints passively. The doctor may order diagnostic tests such as ultrasound imaging and blood tests to assess inflammatory markers. If the inflammatory markers are high, then a culture test of the fluid within the joint may be ordered. To perform the culture test, joint fluid is collected by inserting a needle into the hip joint and aspirating the fluid. This fluid is sent to the lab 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. Weightbearing on the affected side should be avoided until pain is resolved.