Coxa plana

Coxa plana


Legg-Calve-Perthes disease is when the ball of the thighbone in the hip doesn't get enough blood, causing the bone to die.

Alternative Names

Coxa plana; Perthes disease


Legg-Calve-Perthes disease occurs most frequently in boys 4 to 8 years old. While there are many theories regarding the cause of this disease, little is actually known.

Without enough blood to the area, the bone dies. This causes the ball of the hip to collapse and become flat. Usually only one hip is affected, although it can occur on both sides.

The blood supply returns over several months, bringing in new bone cells. These gradually replace the dead bone over 2 to 3 years.


  • Knee pain (may be the only initial symptom)
  • Persistent thigh or groin pain
  • Wasting of muscles in the upper thigh
  • Apparent shortening of the leg, or legs of unequal length
  • Hip stiffness that restricts movement in the hip
  • Difficulty walking, walking with a limp (which is often painless)
  • Limited range of motion

Exams and Tests

During a physical examination, the doctor will look for a loss in hip motion and for a typical limp. A hip x-ray or pelvis x-ray may show signs of Legg-Calve-Perthes disease.


The goal of treatment is to keep the ball of the thighbone inside the socket. Your doctor may call this "containment." Containment is achieved by maintaining a good range of motion of the hip.

Stiffness in the hip joint can be relieved with physical therapy and anti-inflammatories such as ibuprofen. When the hip is painful or the limp gets worse, it may help to restrict vigorous activity, such as running, to reduce the inflammation. Night-time traction may help.

Doctors no longer recommend several months of bedrest.

When these steps fail, surgery may be needed. Surgery ranges from simple lengthening of a groin muscle to major hip surgery to reshape the pelvis. The type of surgery depends on the severity of the problem and the shape of the ball of the hip joint.

Outlook (Prognosis)

The outlook depends on the age of the patient and the severity of the disease. In general, the younger the age when the disease begins, the better the outcome.

Children younger than 6 who receive treatment are more likely to end up with a normal hip joint. Children older than age 6 to 8 are more likely to end up with a deformed hip joint, despite treatment, and to develop arthritis later in life.

Possible Complications


When to Contact a Medical Professional

Call for an appointment with your health care provider if a child develops any symptoms of this disorder.

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