Legg-Calve-Perthes ('Perthes disease') is most often seen in young boys (age range 4-8 years, male: female ratio 4:1).
Urgent referral to orthopaedics is necessary.
Interruption of the blood supply causes avascular necrosis of the capital femoral epiphysis of the femoral head and if detected early with appropriate management, is followed by revascularisation and reossification (can take up to 3 years). The cause of the disease is not known. Other secondary causes of avascular necrosis in children include sickle cell disease, antiphospholipid antibody syndrome and prolonged systemic corticosteroid therapy.
Treatment is rest and splinting in abduction. Delay in treatment can result in secondary osteoarthritis.
The radiograph shows Perthes at the right hip with fragmentation and collapse of the right femoral head.
The radiograph below shows changes of bilateral Perthes with worse changes at the left hip with fragmentation and collapse of the femoral head.