The tissues around the hip joint swell, normally in one hip only, and pain may spread from the hip to the groin, thigh, and knee. The symptoms may be alarming, but it is a mild condition that normally only lasts up to 2 weeks.
It often appears about 2 weeks after a viral illness, but experts do not know exactly why it happens.
Here are some key points about irritable hip. More detail is in the main article.
- Irritable hip mostly affects children, causing pain that can range from mild to severe.
- It can occur after a virus or a trauma, or because of poor blood flow.
- It usually passes after 2 weeks, but sometimes it lasts longer.
- If the pain persists or gets worse, tests may be needed to rule out other conditions.
Irritable hip is a transient condition in children that causes pain and a limp.
Irritable hip involves hip pain that tends to start suddenly, usually on one side of the hip. The pain can range from mild to severe. It can affect the hip, the groin, the thigh, and the knee on the affected side.
A limp can develop, and young infants may crawl or cry in an unusual way because of the pain. This may be more noticeable when changing diapers.
A slight fever sometimes occurs, but this is less common. If the fever is above 101 degrees Fahrenheit, it is likely the child has another problem, which may be more serious.
In acute, transient synovitis, the synovial membrane that surrounds the hip becomes inflamed or swollen, but it is not clear why this happens.
Possible explanations include:
A viral infection that occurs about 2 weeks before the symptoms of irritable hip appear, such as an upper respiratory tract infection, perhaps a cold or sore throat, or diarrhea. The inflammation may be an allergic reaction that happens when the immune system responds to an infection elsewhere in the body.
A fall or an injury may precede it.
Poor blood flow can cause the head of the femur, or thigh bone to become damaged. This part of the femur is the ball in the ball-and-socket hip joint. This is called Perthes' disease, and it can cause symptoms similar to those of irritable hip.
The doctor, usually a primary care physician, will ask the child or parent or guardian about symptoms. This will be followed by a physical examination.
There may be an X-ray, imaging scan or blood test. The blood test will detect any infection.
The child should rest, and they should not attend school or nursery. They should not participate in sports until the pain is completely gone.
They may find it most comfortable to lie on their back, with their knee bent and turned out, and the foot on the affected side turned out.
There is normally no need to spend time in the hospital.
If the condition does not resolve, or if the pain persists or get worse, parents should seek medical attention, as there may be another underlying condition.