A slipped capital femoral epiphysis occurs when the upper, or capital, epiphysis of the thigh bone (femur) slips sideways off the end of the femur. (The epiphysis is the end part of the femur. There is an epiphysis at each end.) It most commonly affects older and teenage boys (adolescents) who are overweight. Pain in the hip or knee and limping are the main symptoms. It can be diagnosed on an X-ray. Treatment usually involves surgery to stop the epiphysis from being able to move.
If your child has symptoms suggestive of this condition they should see their doctor promptly.
Some structure (anatomy) around the hip
The hip joint is a ball and socket joint. The 'ball' is the upper end of the thigh bone (femur) and this sits in the 'socket' which is called the acetabulum. The acetabulum is part of the pelvic bone. Surrounding ligaments and muscles help to keep the hip joint stable.
The femur is the longest bone in the body. The part of the femur at the end (or any other long bone in the body) is called the epiphysis. Growth of the long bones of the limbs is a slow process and is usually not fully completed until about age 18-20 years. Whilst long bones are growing, the epiphysis is separated from the main part of the bone, called the shaft (diaphysis). Some cartilage, known as the growth plate (epiphyseal plate), separates the epiphysis from the shaft.
Eventually, the epiphysis fuses with the shaft to form a complete bone. In the femur, the epiphysis that is nearest to the hip is called the upper, or capital, femoral epiphysis.
What is a slipped capital femoral epiphysis and what causes it?
A slipped capital femoral epiphysis occurs when the upper, or capital, epiphysis of the thigh bone (femur) slips sideways off the end of the shaft. It tends to affect children in their early teens when they are growing rapidly. During this time, the forces and stresses put on the upper part of the thigh bone increase and can pull it or twist it. If these forces are big enough, they can actually make the epiphysis move, and the epiphysis slips. In children who are overweight or obese, an extra strain is put on the upper thigh bone by their body weight and so slipped capital femoral epiphysis is most common in children who are overweight or obese.
The slip can occur suddenly (acutely) or over a longer period of time (chronically). A chronic slip is much more common. Your child may complain of symptoms for weeks or months which can become worse as the slip becomes worse. An acute slip can happen after a fall or other injury and your child's symptoms will come on suddenly. An acute slip can be severe and can mean that they are unable to put any weight on their leg. An acute on chronic slip can also occur, if a chronic slip has already started and then a minor injury such as a fall makes the epiphysis suddenly slip more.
In about 1 in 4 children who develop a slipped capital femoral epiphysis, go on to develop it on the other side as well.
How common is it and who develops it?
A slipped capital femoral epiphysis is one of the most common reasons for a painful hip in older and teenage children (adolescents). Around 10 per 100,000 children will develop a slipped capital femoral epiphysis.
As mentioned above, a slipped capital femoral epiphysis is more common in children who are overweight or obese. In fact, rates may be increasing due to rising levels of childhood obesity.
It is much more likely to affect boys than girls; three boys are affected for every two girls. It usually affects boys around the age of 13 years and girls at around the age of 11.5 years.
Rarely, a slipped capital femoral epiphysis can occur in children with the following:
- Known hormone disorders (such as underactive thyroid gland, sex hormone problems, growth hormone problems).
- Severe kidney disease.
- A history of radiotherapy for cancer.
What are the symptoms of a slipped capital femoral epiphysis?
The symptoms can vary depending on whether the slip is sudden (acute) or has been going on for a while (chronic). Hip or groin pain is usually the main symptom.
In an acute slip, pain in the hip is so severe that your child is unable to walk or stand. You may notice that one leg seems shorter than the other. They won't want to move their hip because it is painful. You may notice that their leg is turned outwards.
In a chronic slip, symptoms tend to be more mild and come on gradually. Pain is usually felt in the groin or around the hip. Sometimes pain can be felt in the knee or lower thigh rather than the hip. This is called 'referred' pain. The pain is 'referred' along nerves from the hip to the knee or the lower thigh. This can sometimes be misleading and, in some cases, the diagnosis of slipped capital femoral epiphysis can be missed and the symptoms put down to a knee problem. Your child will still be able to walk but you may notice that they limp and find walking may be painful. Pain can be made worse by running, jumping or other activities. Your child may complain of stiffness in their hip joint. Again, the leg on the affected side may appear shorter. You may also notice that the muscles in your child's thigh start to become less strong and look less bulky (wasted) if they have a chronic slip.
In an acute-on-chronic slip, your child will usually have complained of pain and may have been limping for several months. Then a minor injury, such as a fall, suddenly makes the hip become very painful as the slip moves a bit more.
As mentioned above, in most children, only one hip is affected. But some children have symptoms due to a slipped capital femoral epiphysis affecting both hips, although usually not at the same time.
How is slipped capital femoral epiphysis diagnosed?
Your doctor may suspect that your child has a slipped capital femoral epiphysis because of their symptoms and how old they are. Your doctor will then usually examine your child's leg, including their hip and their knee. They may suspect that your child has a slipped capital femoral epiphysis just from examining them.
What is the treatment for slipped capital femoral epiphysis?
A child who is found to have a persistent (chronic) slipped capital femoral epiphysis is usually admitted to hospital so that they can have complete bed rest. This helps to avoid any acute-on-chronic slip. Also, an operation is usually advised to stop the slipped epiphysis from moving any further. Usually a screw is used to hold the epiphysis in place. Sometimes, a doctor may suggest that the unaffected hip be stabilised with a screw at the same time. If there has been a more serious slip, more major surgery may be needed.
Acute slips need to be treated more urgently. Again a screw helps to stabilise the slipped epiphysis; however, sometimes more complex surgery is required.
Are there any complications?
If a persistent (chronic) slipped capital femoral epiphysis is diagnosed and treated promptly, complications are less likely to occur. However, sometimes complications are possible even after a chronic slipped capital femoral epiphysis. Complications are more common after a sudden (acute) slipped capital femoral epiphysis.
One complication is avascular necrosis. In this condition, the blood supply to the ball (the head) of the thigh bone (femur) is damaged due to the slipped epiphysis. This most commonly happens after a sudden (acute) slip. It can also sometimes be a complication of surgery. Your child will usually complain of pain in their groin or knee and they will not be able to move their hip as much as normal. Crutches are usually suggested so that the weight is taken off your child's affected leg. Physiotherapy and painkillers may also help. In severe cases of avascular necrosis, either the bones around the hip joint are fused together or a hip replacement may be needed.
Chondrolysis is another possible complication of slipped capital femoral epiphysis. In chondrolysis, there is death (necrosis) of articular cartilage of the affected hip joint. Again, this can be a complication of surgery. Treatment is similar to that for avascular necrosis.
What is the outlook (prognosis)?
The key to the best outlook for slipped capital femoral epiphysis is to detect a persistent (chronic) slip before an acute-on-chronic slip occurs and to treat it. This is because a sudden (acute) slip has a worse outcome. There is an increased risk of the complication of avascular necrosis, where the blood supply to the ball (the head) of the thigh bone (femur) is damaged due to the slipped epiphysis.
If a chronic slip is treated early and the epiphysis is stabilised, the outcome is generally very good and there are unlikely to be long-term effects. However, if a slipped capital femoral epiphysis is not diagnosed and treated, it can lead to persistent pain, deformity and also early osteoarthritis around the hip.
Once you have had a slipped capital femoral epiphysis on one side, it is possible to have one on the other side in the future. This is why some bone and joint specialists (orthopaedic surgeons) advise screwing of the epiphysis on the other, unaffected side at the same time as treatment for a slipped capital femoral epiphysis.
Can a slipped capital femoral epiphysis be prevented?
A child who is overweight or obese, who has already had a slipped capital femoral epiphysis, can help to prevent another one on the other side, by losing weight.
Further help & information
Dr Michelle Wright
Dr Jacqueline Payne
Dr Adrian Bonsall