Key points about Perthes disease
- Perthes disease is a rare condition affecting the hip joint in tamariki and rangatahi
- it happens when the blood supply to the head of the thigh bone (femur) is disrupted
- symptoms include a limp and pain in the hip, groin, thigh or knee
- some tamariki with Perthes disease need surgery to their hip joint
What is Perthes disease?
Perthes disease is a rare condition affecting the hip joint in tamariki and rangatahi. Perthes disease happens when the ball-shaped head (femoral head) of the thigh bone (femur) loses its blood supply. This causes the bone to soften and break down. Over time, the blood supply returns, and the bone heals. But the healing process can take several years.
A bit about the hip
The hip joint includes the:
- thigh bone (femur)
- hip bone (pelvis)
- muscles, ligaments and tendons around the hip joint act like strong ropes to hold the bones together
The hip joint works like a ball and socket joint. The top of the thigh bone is shaped like a ball which is called the femoral head. The femoral head sits inside a cup-shaped socket in the pelvis.
Who gets Perthes disease?
Perthes disease most commonly affects tamariki between 3 and 11 years old. It is more common in boys than girls. Usually, only one hip is affected.
Causes of Perthes disease
The exact cause of Perthes disease is unknown. It happens when the blood flow to the head of the thigh bone is disrupted. Researchers are still trying to understand why this occurs.
Symptoms of Perthes disease
The symptoms of Perthes disease can develop over weeks to months.
Tamariki and rangatahi (young people) with Perthes may have:
- a limp
- stiffness and decreased movement in their hip
- pain in the hip, groin, thigh or knee area
Diagnosing Perthes disease
To diagnose Perthes disease a health professional will examine your child’s leg and watch how they walk. If they think your child may have Perthes, they will arrange an x-ray of your child’s hip. Some tamariki may also need an MRI scan to look at the hip joint.
Treating Perthes disease
The aim of treatment for Perthes disease is to make sure the healed femoral head is as round as possible and sitting under the socket. This means the ball will match the cup which leads to better hip movement.
Observation
Some tamariki may not need any special treatment if things are healing okay. They will need regular check ups and x-rays to monitor healing.
Rest
Tamariki and rangatahi with Perthes will need to limit certain activities like running, jumping and sports. They may also need some time off their leg in a wheelchair or walking with crutches.
Physiotherapy
A physio will be able to advise you on what your child can and can’t do. A physio will also give your child exercises to help with their hip movement. If your child needs crutches or any equipment to help with their mobility, the physio and occupational therapist can help arrange this.
Surgery
Some tamariki may need surgery. The aim of surgery is to change the bone shape so the femoral head fits well into the hip socket.
What to expect long-term
Most tamariki recover well from Perthes disease, but healing can take a few years. Early diagnosis and treatment improve the chances of a good outcome.
Some tamariki and rangatahi may have lasting stiffness or pain in the hip, especially if treatment is delayed or if they are older when the condition happens.
Acknowledgements
Illustrations by Dr Greta File. Property of KidsHealth.
