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General Information
Legg-Calve-Perthes Disease, also known as LCP, or simply Perthes Disease,
is a condition that affects the hip. The hip joint includes the head
of the thigh bone, called the femoral head, and the hip socket, known
as the acetabulum. The femoral head is round and sits in the cup formed
by the acetabulum. There is a lot known about Perthes disease, but
also much that is not yet known, making this a frustrating condition
to treat and research. There are many unanswered questions about treatment,
and many of the treatments that would seem to help do not change the
course of the disease.
What we do know about Legg-Calves-Perthes is that it usually affects
boys, though it can also occur in girls, and typically occurs between
the ages of 6 and 8. In 90% of cases, it occurs only in one hip. In
the remaining 10% the other side is affected about a year later. Perthes
is caused by the interruption of blood flow to the growing part of
the femur, called the epiphysis. The blood vessels that go to this
part of the bone are a spider web of tiny vessels that surround the
growth center. When blood flow is interrupted bone cells die. This
process, called avascular necrosis (meaning cell death from lack of
blood supply), starts a process of dead bone being taken away by the
body and new bone being made to replace it. This happens normally in
all growing bones. Perthes is different because it involves more bone
than usual.
Perthes Disease goes through several stages, regardless of what age
it begins, the severity or what interventions or treatments are tried.
These stages are the initial/synovitis phase, the fragmentation/collapse
phase, the healing phase and the definitive phase.
In the initial or synovitis phase, affected
children begin to limp without any history of trauma. They are usually
not uncomfortable,
and the limp may get better and worse, but continues for weeks. This
is when the patients first go to the doctor. They have a synovitis – a
swelling of the lining of the hip joint, but no changes have yet occurred
to the bones of the hip. The first x-ray is usually normal, because
it takes a few months for the bone to break down. Patients are usually
told to take Ibuprofen, rest and check back in a few weeks. An MRI
would show the diagnosis at this point, but is not needed because it
does not help to guide treatment or predict how the child will do at
the end of the whole process.
As the hip enters the fragmentation phase, the body begins taking
away some of the dead bone. This process weakens the bone and it
begins to collapse. It would seem to make sense that keeping weight
off the hip will prevent or reduce the amount of collapse, but it
does not. During this period, there are ”good days” and “bad
days.” When the hip is irritated,
there is inflammation in the joint, called synovitis, which leads
to stiffness, more limp and discomfort. On a good day, there may
be a little limping, but the child feels well and may do some normal
activity, like playing basketball. This activity will not change
the course of the disease and will not do any damage to the hip.
It will make them sore, and make a “bad day” more likely.
Completely restricting the child’s activity is impossible and
unfair. It’s probably best to avoid those activities that cause
a great deal of discomfort or make the limp worse, but children need
to play and participate in some normal activity.
Eventually, the condition will begin to improve, often 12 to 15 months
after it began. There is an increase in the number of good days and
a decrease in the number of bad days, and the child can participate
in more activity without pain. This is the healing phase, when the
body is making new bone. At this point, the position and shape of the
hip gradually improve, and it appears that no medical or surgical treatment
will affect the outcome.
The definitive phase occurs after healing begins and lasts until the
end of growth. After healing takes place, the final outcome will be
determined by how much growth and remodeling is left in the head of
the femur. One reason younger patients do better with Perthes is because
they have more time to grow, with a longer definitive phase, giving
the hip more time to remodel and making it better shaped over time.
Treatment
Many different types of treatment have been
attempted in this disorder – complete
bed rest, limited weight bearing with crutches, braces, vitamins, manipulations
and therapy. In fact, in the 1960’s, patients were often kept
in the hospital on bed rest, sometimes for years, to prevent weight
bearing. They did no better than those who were not kept on bed rest.
There are no treatments that have changed the
outcome of Perthes, and one of the reasons for this is that so many
patients do well in
the long run. Several studies have shown good results in over 70% of
patients without any treatment at all, even 30 to 40 years later. Experts
in Perthes Disease feel that less than 10% of patients will need hip
replacement in their 30’s. This increases as time passes, however,
and up to 50% of children with Perthes Disease will need a hip replacement
in their 50’s.
The most difficult part of the treatment of
Legg-Calves-Perthes Disease is deciding who needs it. The difference
between those who do well
and those who do not seems to be in the shape of the femoral head.
The long term results are better if the femoral head is rounder as
the bone reforms. If the femoral head is able to slide partially out
of the socket while the hip is changing shape, it will get mushroomed.
If the child has a stiff hip, is over age 8 at the onset of the disease,
has a lot of collapse of the femoral head or has subluxation (where
the femoral head can slide out of the socket) they are at higher risk
for a poor result. These patients need more aggressive treatment. Most
children with Perthes Disease do well, but if the head is not very
round when it reforms, they may someday need a hip replacement. In
most cases this is not until they are in their 50’s.
The primary goals of treatment in Perthes Disease
are to keep the femoral head in the socket and improve the range
of motion of the hip.
Most patients need either no treatment or simply gentle stretching
exercises to improve the range of motion of the hip. Bracing does not
seem to be effective. Casting can help to improve motion, but if the
hip continues to be stiff, surgery may be recommended. Surgery involves
some combination of loosening the muscles and tendons of the hip, and
cutting away bone to keep the femoral head in place. The concept is
that as the femoral head is being remodeled, it should be in the hollow
of the acetabulum so that it grows back perfectly round, as opposed
to riding on the edge of the acetabulum, where it will remodel unevenly.
Doing surgery is an aggressive way to treat this disease, and it is
only warranted in about 10% of the cases we see. The goal is to keep
the child in the “best outcome” category without surgical
intervention. Over the years, though, it has become clear that there
are some patients who will do better with surgery than without. (back
to the top)
Frequently Asked Questions
What causes Perthes Disease?
We are not sure what causes Legg-Calves-Perthes
Disease, and actually know more about what does not cause it than
what does. It is associated
with being exposed to cigarette smoke in the home, but we are not sure
why. It was once felt to be related to a condition of thick blood with
a tendency for the blood to clot, but that now seems to be unrelated.
We know that most kids who get Perthes are very active, but it is not
felt to be related to trauma or injury. It also doesn’t appear
to be related to inflammation of the hip called synovitis, which some
children get along with a viral infection. (back
to the top)
Are there any other conditions that mimic Perthes Disease?
There are some conditions that can cause avascular necrosis in the
hip that are different from Perthes because they need more evaluation
and different treatment. Some examples of these conditions are sickle
cell anemia, infections, thyroid conditions, and congenital growth
problems. (back to the top)
Can Perthes Disease affect any other part of the body or spread beyond
the hip?
Perthes Disease affects only the hip, does not spread to the rest
of the leg, is not life threatening and can never lead to anything
as serious as loss of the leg. Classic Perthes Disease usually requires
only careful observation and no aggressive treatment, because the outcomes
are usually good.
(back to the top)
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