Slipped Capital Femoral Epiphysis (SCFE)

What Is Slipped Capital Femoral Epiphysis?

A good, stable hip joint is what lets us walk, run, jump, and many other things. But in some kids, the hipbone doesn’t connect to the thighbone as well as it should due to slipped capital femoral epiphysis (SCFE). In this condition, there’s a shift at the upper part of the thighbone, or femur, that causes a weakened hip joint.

When it’s caught early, SCFE usually can be treated successfully.

What Happens in Slipped Capital Femoral Epiphysis?

The hip is a ball-and-socket joint. The thighbone’s “ball” (the femoral head) fits into the hollow of the cup-shaped "socket" (the acetabulum) of the pelvis. Ball-and-socket joints are the joints with the greatest range of movement, which is why our legs move forward, backward, and all around.

Kids and teens who are still growing also have a growth plate at the top of the thighbone, just under the ball. This growth plate (called the physis) is made of cartilage, which is weaker than bone. The job of the growth plate is to make the bone longer. When children are done growing, the cartilage growth plate turns into hard bone and disappears.

In slipped capital femoral epiphysis (ih-PIF-eh-siss), the ball slips off the back through the growth plate, almost the way a scoop of ice cream might slip off a cone. Sometimes this happens suddenly — after a fall or sports injury, for example — but often it happens gradually with no prior injury.

Usually, SCFE is classified as:

• Stable. A stable SCFE causes some stiffness or pain in the knee or groin area, and possibly a limp that causes a child to walk with a foot outward. The pain and the limp may come and go, and may get worse with activity and better with rest. With a stable SCFE, a child still can walk, even if they need to use crutches.
• Unstable. An unstable SCFE is a more severe slip. Usually, it happens suddenly and is much more painful than stable SCFE. A child won’t be able to walk at all on the affected side. An unstable SCFE is also more serious because it can restrict blood flow to the hip joint, leading to tissue death in the ball.

Sometimes SCFE can irritate the nerves that run down the leg, causing referred pain (pain that starts in one part of the body but is felt in another). In this case, pain begins in the abnormal hip joint but is felt in the normal knee joint or front of the thigh.

Some cases of SCFE affect only one hip, but many are eventually found to affect both hips (bilateral). When SCFE affects one hip, doctors may closely watch the other to see if it develops SCFE. But if that's considered very likely, they might decide to treat both hips at the same time. Catching SCFE early makes a big difference in how easily doctors can treat it.

What Causes Slipped Capital Femoral Epiphysis?

No one knows for sure what causes SCFE. It usually affects kids 11 to 16 years old who are going through a growth spurt. The condition is more common in boys, though girls can get it too.

SCFE is also more likely in kids who have these risk factors, which can affect bone health:

• obesity. Carrying extra weight puts increased pressure on the growth plate.
• endocrine disorders such as diabetes, thyroid disease, or growth hormone problems
• kidney disease
• cancer treatments like radiation and chemotherapy
• some medicines, such as steroids
• a family history of SCFE

How Is Slipped Capital Femoral Epiphysis Diagnosed?

A child thought to have SCFE will see an orthopedic doctor, a specialist in the treatment of bones. The doctor will do an exam, checking the range of motion of the hips and legs and seeing if there is any pain. The doctor will also take hip X-rays to look for any displacement of the ball.

In rare cases of SCFE, the X-rays will come back normal, but the pain, stiffness, and other problems will still be there. Then, the doctor may order a magnetic resonance imaging (MRI) scan. An MRI can catch very early SCFEs, before they slip very far.

How Is Slipped Capital Femoral Epiphysis Treated?

SCFE is always treated with surgery to stabilize the growth plate that slipped. But even before the surgery, the doctor will try to prevent any further slipping by encouraging rest and the use of crutches to avoid putting weight on the affected leg. Many doctors recommend admitting a patient to the hospital as soon as the SCFE is discovered. That way, the patient rests and the surgery can be done as soon as possible, before the slip gets any worse.

Surgery for SCFE is done with the patient under general anesthesia (so they’re completely asleep). Using a fluoroscope — a special X-ray machine that produces a real-time image of the hip on a TV screen — as a guide, the surgeon will make a tiny incision near the hip, then put a metal screw through the bone and across the growth plate to hold it in place. The screw is placed deep into the bone and can't be felt by patients after surgery.

Because some patients have a high risk of an SCFE in the other hip, the surgeon might also stabilize that side too, even if it hasn't slipped yet.

Doctors decide how much weight can be placed on the affected leg after surgery based on how severe the slip is. Patients usually can walk with crutches, but those who have both hips treated may need to use a wheelchair for a bit after surgery.

After Surgery

Most kids do well when SCFE is caught and treated early. Doctors will continue to order follow-up X-rays to watch the condition while children are still growing. In most cases, more surgery isn’t needed.

Kids with unstable SCFEs have a greater chance of developing other problems later, such as stiff hips, early arthritis, leg length differences, or avascular necrosis (where part of the ball dies from lack of blood supply). They're also more likely to need more surgery to take care of their hip.

What Else Should I Know?

Slipped capital femoral epiphysis can’t always be prevented. But reaching and keeping a healthy weight can spare bones and joints from the excess wear and tear that can weaken and damage them. If your child is overweight and you need help developing a safe diet and exercise plan, talk to your child's doctor.