Legg-Calve-Perthes disease is when the ball of the thighbone in the hip doesn't get enough blood, causing the bone to die. The dead bone is weak, which causes the ball to collapse and flatten. Usually only one hip is affected, although it's possible for both to develop the condition.

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

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.

• 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

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 head of the femur (the ball of the thighbone) inside the socket through the course of the disease. Your doctor may call this principle "containment".

Containment is achieved by maintaining a good range of motion of the hip. Stiffness is initially caused by inflammation in the hip joint, which can be reduced with physical therapy and medications like ibuprofen. When the hip is painful or the limp is worse, it may help to restrict vigorous activity, like running, to reduce the inflammation. Night-time traction may help.

Doctors no longer require several months of enforced bedrest, because that does not help.

The outlook varies widely depending on the age of the patient and the severity of the disease. The most important factor is the shape of the ball after the disease has run its course. In general, the younger the age when the disease begins, the better the outcome.

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

Osteoarthritis may develop later in life. This complication may be minimized with early recognition and proper treatment of Legg-Calve-Perthes disease.

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