Diagnosis and Prognosis

How is Perthes diagnosed?

The diagnosis requires careful history taking, physical examination, and x-rays.
In patients with Perthes, leg pain, decreased hip movement, and limping are seen.  Since these symptoms and signs are not specific to the disease, x-rays are required to confirm Perthes.  Since Perthes is a diagnosis of exclusion other childhood hip conditions that can mimic Perthes disease must be excluded such as the transient synovitis, corticosteroid induced osteonecrosis, sickle cell disease, and multiple epiphyseal dysplasia.   

X-rays will show changes to the appearance and the shape of the femoral head.  Based on the changes, the stage of the disease can be determined (see "About Perthes").  Magnetic resonance imaging (MRI) using gadolinium can assess the blood flow to the femoral head and provide more detailed information about how much of the femoral head is affected.

What is the prognosis?

For the purpose of describing prognosis, it is best to divide the discussion into short-term (within 5 years) and long-term prognosis (20-40 years later).

Short-term prognosis:  Most of the patients will be able to return to full activities including sports with minimal symptoms once the femoral head has healed.

Long-term prognosis:  This depends on the shape of the femoral head and how well it fits the socket at the time of skeletal maturity (approximately age 14 for girls and age 16 for boys). If the femoral head is very flat or irregular and does not fit the socket well, there is a high chance of getting degenerative arthritis and need for a hip replacement as an adult, even as early as the thirties and forties.  Children who are older at the onset of Perthes and those who have the femoral head move out of the socket are more likely to require a hip replacement.

What factors affect the prognosis?

Shape of the femoral head, age at onset of disease, and the amount of disease involvement affect outcome defined as developing degenerative arthritis of the hip joint.  Younger children (under 6 years old at the onset of the disease) tend to have a better outcome with less lasting deformity of the femoral head and a shorter duration of disease. Patients over 8 years tend to have a worse outcome.

Outcomes of Perthes patients who had a hip replacement

For patients with Perthes who ultimately require a hip replacement as an adult, the outcomes are quite good. In one report, over 95% of hip replacements were doing well at 15 years after surgery, with a marked improvement in function. Unfortunately, the complication rate of surgery was higher than the typical hip replacement, particularly with regard to sciatic nerve injuries. In another study, patients with Perthes and an abnormal socket had a more than two and a half times the risk of postoperative hip dislocation in the first six months after surgery. Long-term outcomes in this study however, revealed that patients with Perthes did as well as others having a hip replacement.