Legg-Calve-Perthes disease occurs when blood flow to the femoral head of the hip joint is interrupted, eventually causing the bone to die. As a result, the hip can break — and heal poorly. Even though it was first described more than a century ago, the disease is so rare — affecting 5 to 10 per 100,000 children under the age of 15 — that little is known about which treatments are best for which patients. Should, for example, a Perthes diagnosis always mean surgery?

In an effort to close the knowledge gap, pediatric orthopedic surgeon John Tis has become part of the International Perthes Study Group — a collection of 45 surgeons and researchers from around the world. They are currently focused on enrolling children with Perthes in a central database to enable long-term studies on the diagnostics, treatment and outcomes of the disease.

“We have interventions but we don’t really know how they are working until we get 10 years of follow-up,” says Tis, who has been treating Perthes patients at Johns Hopkins Children’s Center for more than a decade.

If diagnosed with Perthes in the first few months, the majority of patients can be treated with anti-inflammatories and physical therapy, Tis has found. But 1 in 10 children with early Perthes will have a large loss of blood flow and require surgery.

“If we can act before the body starts absorbing the bone—in the first six to 12 months—and put the hip in a non-weight bearing contained position,” says Tis, “then the femoral head will mold into a more normal, round shape that matches the acetabulum.”

Typically, Tis says he performs a femoral osteotomy to put the femur in the right position. The patient is in the hospital for just two days and on crutches for six weeks before going back to normal activity. But catching Perthes early is tricky, and a missed diagnosis can be a major challenge to successful treatment.

“Early on, the first symptom a child shows is a painless limp,” says Tis. “But it is not always recognized. By the time patients come to see me, some already have hip collapse.”

Once the hip breaks, only salvage surgery is an option — and the patient will likely go on to need a hip replacement at a young age.

When young patients do present with a painless limp, Tis performs an X-ray to identify any subtle loss of hip abduction. If he doesn’t see anything on the X-ray, he will recommend a perfusion MRI to determine just how much of the femoral head is affected.

While there is still much to learn about Perthes, he says, what is known is that catching the condition early leads to better long-term outcomes.

“It can be the difference between the femoral head collapsing and the patient getting early arthritis, or getting treatment to have a healthy hip,” says Tis. “When physicians see a painless limp and immediately send those patients to us, it can make a big difference.”

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