A good, stable connection at the hip joint is what lets us walk, run, jump, and
many other things. But in some kids — particularly
those who are obese
— the thighbone and the hipbone are a little less well connected than they should
be because of a condition called slipped capital
femoral epiphysis (SCFE). SCFE is a shift at the upper
part of the thighbone, or femur, that results in a weakened hip joint.
Fortunately, when caught early, most cases of SCFE can be treated successfully.
About Slipped Capital Femoral Epiphysis
To understand SCFE, it helps to know a little about the hip joint. The hip is a
ball-and-socket joint, which means that the rounded end of one bone (in this case,
the "ball" of the thighbone) fits into the hollow of another bone (the acetabulum,
or cup-shaped "socket" of the pelvis). Ball-and-socket joints offer the greatest range
of movement of all types of joints, which explains why we can move our legs 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" portion (also known as the femoral head) of the joint.
This growth plate is called the physis and it's made of cartilage, which is weaker
than bone. The job of the physis is to connect the femoral head to the thighbone while
allowing the bone to lengthen and grow.
In SCFE, the femoral head of the thighbone slips through the physis, 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 SCFE. 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 usually tend to come and go, worsening with activity and getting
better with rest. With stable SCFE, a child still can walk, even if crutches are needed.
- Unstable SCFE. An unstable SCFE is a more severe slip that
usually happens suddenly, and is usually much more painful. A child will not be able
to bear weight 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 head of
the femur.
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.
Some cases of SCFE affect only one hip, but many are eventually found to affect
both hips (be bilateral). When SCFE affects one hip, doctors may closely watch the
other to see if it develops SCFE; or, if that's considered very likely, they might
treat both hips at the same time. Catching SCFE early makes a big difference in how
easily doctors can treat it.
Causes of SCFE
No one knows for sure what causes SCFE. But most cases are in kids between 11 and
16 years old who are going through a growth spurt. SCFE is more common in boys, though
girls can be affected, too.
SCFE is also more likely in kids who have these risk factors, all of 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
- certain medicines, such as steroids
- a family history of SCFE