A five-year-old Caucasian boy presents to an inner-city GP with a left-sided limp, which has developed over the past week.
The child does not have a fever and is generally well. Pain on internal rotation of the leg suggests hip joint pathology. Bloods – including FBC, CRP and ESR – are all normal. A plain X-ray of the hips shows some flattening of the femoral head and an ultrasound of the hip shows a small effusion.
The patient is referred to the paediatric orthopaedic surgeon and when seen a few days later, the limp has improved, but there is still some restriction of internal rotation and abduction of the left hip. The surgeon makes a working diagnosis of transient synovitis. At two-week review the patient still has a modest limp and restriction of movement. The surgeon orders a bone scan, which reveals a ‘cold’ area in the left femoral epiphysis consistent with Perthes’ disease.
Perthes’ disease is caused by a disturbance to the blood supply of the femoral head growth plate, causing avascular necrosis.
The blood supply gradually returns and the dead bone in the epiphysis is regenerated.
During this period the cartilaginous ball of the femoral head can become deformed and treatment is directed towards trying to minimise this deformity.
The exact aetiology is unknown. Perthes’ disease presents most commonly in boys aged four to nine and is associated with Caucasian race, attention deficit disorder, social deprivation and a growth disturbance of the limbs. Prognosis is more favourable when the onset is before the age of five years and is worse in children over eight years.
Children normally present with pain and a history of a limp, but are otherwise well.
Early examination shows loss of abduction and internal rotation of the affected hip.
The most common differential is transient synovitis. This condition often presents in a similar manner to Perthes’ disease and is accompanied by a small effusion on ultrasound, but symptoms usually subside after a few days.
Other important differentials include septic arthritis, which would present in a systemically unwell child with fever and raised inflammatory markers, slipped capital femoral epiphysis in the older child (over 10 years), and juvenile rheumatoid arthritis.
The aetiology is unknown so the condition cannot currently be prevented. ‘Containment’ of the lateral part of the epiphysis under the acetabulum is the key treatment strategy. Many young patients – under five years – achieve this without the need for intervention because they maintain good abduction, which moves the epiphysis in and out of the acetabulum. In older patients – over five years – hip abduction is frequently lost and containment can only be achieved by intervening to position the lateral epiphysis further under the lateral edge of the acetabular roof.
The most common surgical intervention is a varus femoral neck osteotomy. The goal of treatment is to maintain a congruent femoral head and acetabulum and reduce deformity, so that the femoral head can remodel once the blood supply is restored. The long-term goal is to prevent early degeneration and osteoarthritis.
Mr Colin Bruce is a consultant paediatric orthopaedic surgeon and Mr Amit Bidwai is an SpR in orthopaedics at Alder Hey Children’s Hospital, Liverpool
Alder Hey is one of Europe’s busiest children’s hospitals, providing care for over 275,000 children and young people each year. Alder Hey has a broad range of hospital and community services for direct referral from primary care. It is the designated national centre for head and face surgery and a Centre of Excellence for children with cancer, spinal and brain disease. Alder Hey has been chosen to be a national centre for heart surgery, a respiratory ECMO surgery centre and one of just four specialist centres to provide surgery for drug-resistant epilepsy. More information can be found at alderhey.nhs.uk.