The disorder causes a flattening of the top of the femur (the ball of the head of the femur). Usually just 1 leg is affected. The blood flow to the femur is interrupted, and the tip of the bone dies over a period of 1 to 3 weeks. A new blood supply causes new bone cells to appear in the region over the next 6 to 12 months. New bone then replaces the old bone within 2 to 3 years. It occurs most frequently in boys 4 to 10 years old.

• Knee pain (may be the only symptom, initially)
• Persistent thigh or groin pain
• Atrophy of muscles in the upper thigh
• Slight shortening of the leg or legs of unequal length (asymmetry)
• Hip stiffness restricting movement in the hip
• Difficulty walking (gait difficulty), limp with walking
• Limited range of motion

A physical examination shows decreased hip motion, and a hip X-ray or pelvis X-ray is consistent with Legg-Calve-Perthes disease.

The aim of treatment is to protect the bone and joint from further stress and injury while the healing process takes place. Bedrest or crutches may be indicated during the initial phase. An appliance such as a brace, cast, or splint to immobilize the hip position may be used while bone regrowth takes place. Surgery may be performed to keep the hip in its socket.

The outcome is usually good with treatment; most bone will heal with minimal resulting deformity.