Diagnosing Perthes Disease

Orthopaedic specialists at Hassenfeld Children's Hospital of New York at NYU Langone are experienced in diagnosing Perthes disease, which occurs when the blood supply to the ball of the hip joint, also known as the femoral head, is temporarily interrupted. This lack of blood flow causes bone cells in the hip joint to die. Eventually, blood flow returns to the hip joint and it begins to repair itself.

The way the hip joint heals determines whether a child with this condition needs treatment. During the repair process, the ball of the hip joint can collapse and flatten, preventing it from fitting properly into the socket, also called the acetabulum. This may lead to pain, inflammation, and abnormal development of the joint.

Risk Factors and Symptoms

Perthes disease, which usually affects just one hip, is five times more common in boys than in girls and often occurs in children four to eight years old. Children who are small for their age, are very active, have been exposed to secondhand smoke, or have a blood-clotting disorder are at increased risk for Perthes disease. Usually, however, doctors cannot identify the exact cause of the condition.

Most symptoms occur gradually, after blood flow to the hip returns and the hip joint begins to repair itself. The most common symptom is a limp caused by inflammation, stiffness, and pain. Perthes disease can affect range of motion in the hip, and it can also make the affected leg slightly shorter than the other. Pain in the hip can cause muscle spasms in the pelvis and leg.

Perthes disease can lead to arthritis if the abnormally shaped femoral head causes chronic inflammation. Early identification and treatment are therefore important. Efforts to ensure that the hip joint heals properly while the child is still growing may reduce the risk of arthritis and other hip problems later in life.

Physical Exam

To make an accurate diagnosis, our orthopaedic specialists perform a comprehensive physical exam and use imaging tests to assess a child’s bones and joints.

During a physical exam, the doctor may ask your child about symptoms such as limping or pain in the hip, groin, thigh, or knee. The doctor also looks for signs such as reduced range of hip motion, a difference in leg length, and muscle weakness in the upper thigh near the hip joint.

Hip and Pelvic X-rays

Hip and pelvic X-rays provide pictures of the bones in a child’s hip and pelvis. These images allow doctors to see if the bones have become misshapen or misaligned.

MRI Scans

MRI uses magnetic fields and radio waves to produce detailed images of areas that are more difficult to see on X-rays, such as cartilage, ligaments, and blood vessels. MRI scans can detect problems within the hip joint before the femoral head becomes permanently misshapen.

Orthopaedic specialists at Hassenfeld Children's Hospital use information from these tests to determine when Perthes disease developed and to evaluate the extent of the condition. This helps our doctors develop an individualized treatment plan aimed at preventing further damage to the hip joint and improving mobility and range of motion.

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