Perthes' disease

Definition/diagnostic criteria Perthes’ disease, or Legg-Calvé-Perthes’ disease, is a childhood hip disorder instigated by a disruption of blood supply to the head of the femur, resulting in avascular necrosis. Diagnostic criteria encompass persistent hip or knee pain, limping and restricted hip movement. Diagnosis is primarily clinical, supplemented by radiographic findings such as subchondral fractures and femoral head flattening.

Epidemiology This condition predominantly affects children aged between 4 and 8 years, with a higher prevalence in males. The annual incidence is 2.48 per 100,000 patients aged zero- to 14-year-olds. There is a recognised association with socio-economic factors, although the precise aetiology remains idiopathic.

Diagnosis
Clinical features: The presentation is typically unilateral hip or knee pain, limping, and limited range of hip motion, particularly in abduction and internal rotation. Duration of symptoms varies, but they tend to develop gradually and might persist for several months.

Investigations: Diagnosis is confirmed through imaging.

• Initial plain radiographs may demonstrate changes in the femoral head, with fragmentation and increased density. Later stages show flattening and broadening of the femoral head.
• Magnetic resonance imaging (MRI) can detect early Perthes’ disease before radiographic changes appear.
• Blood tests are not diagnostic but can help exclude other conditions.

Treatment Management is primarily conservative, aiming to reduce hip irritation and maintain femoral head sphericity.

Non-surgical management: This includes rest, activity modification, and pain management with analgesics (paracetamol and ibuprofen are commonly used). Physiotherapy plays a crucial role in preserving hip function through range of motion exercises.

Surgical management: Indicated in older children or those with more severe disease. Procedures aim to improve femoral head coverage, either through femoral or pelvic osteotomies. Post-surgical care often involves temporary restriction of weight-bearing and physiotherapy.

Prognosis Prognosis varies; younger children and those with less severe involvement tend to fare better. A significant proportion of affected children develop osteoarthritis and may require joint replacement in adulthood. Regular follow-up is crucial for monitoring hip development and early detection of complications.