What is it?
It is a condition that affects the hip joint in children. The severity of this can vary and it is not clear why this problem occurs. It is not due to injury or to a general health condition as a child with Perthes disease is usually otherwise well.
Perthes is much more common in boys and occurs in both hips only about 10% of the time.
Perthes usually occur in children aged 4 to 10 years old.
What happens at the hip joint?
The blood supply to the hip is disrupted and doesn’t get to the ball section of the ball and socket joint which causes that part of the bone to soften. Typically the ball part of the hip joint takes on a flattened, rather than rounded, shape and eventually may fail to fit properly inside the hip socket.
Over several months the blood vessels re-grow, and the blood supply returns to the bone tissue. New bone tissue is then laid down and the bone re-grows and remodels over several years.
This is similar to how bone reforms and remodels after a break to a bone, but takes longer.
It can take between 2 and 5 years to re-grow.
What are the symptoms?
Symptoms tend to develop gradually and can include:
- An occasional limp in the earlier stages. The limp may gradually become worse over a few weeks. However, it is often painless.
- Pain in the hip and groin area. The pain may radiate to the knee or thigh. In some cases, pain in the knee is the first symptom. Pain occurs when putting weight on the affected leg or moving the hip joint.
- Stiffness and reduced range of movement of the affected hip.
- In time, the affected leg may become slightly thinner (wasted) as it is not used as much as the other leg.
- Eventually, the affected leg may become shorter than the unaffected leg.
What is the treatment?
In most cases, the blood supply to the hip joint returns and the bone regenerates by itself. This can take anywhere between two and five years.
During this critical period, the bone is soft and vulnerable.
The aim of treatment is to protect the hip joint and promote the healing process whilst reducing joint pain and stiffness.
This ensures the ball part of the hip joint grows into a functional shape and ensures that it remains well seated in the hip socket as it heals and remodels.
Treatment depends on the age of the child and the severity of the condition, but may include:
- Observation and conservative treatment: Some cases heal well without any treatment, particularly children aged five and under, and milder cases. So, in some cases, the Orthopaedic doctor may simply review your child every now and then to check that the hip joint remains in the right place as it heals.
- Crutches may be needed for a period of time to alleviate the pressure on the hip joint whilst the bone is soft.
- Avoidance of high-impact activities such as running or jumping.
- A home exercise programme to improve hip movement.
- Surgery is very occasionally required to protect the hip joint.
Who will be involved with my child?
An Orthopaedic doctor will review your child regularly as well as a Physiotherapist who will give you exercises and monitor the movement in your child’s hip.
Your child requires regular x-rays to monitor the progress of the condition but this may not happen with every consultation.
What is the outcome?
In most cases, children recover from Perthes disease as the hip joint returns to normal in its shape and function. It can take two or more years for this to occur after the condition first develops.
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