/legg-calve-perthes-disease-coxa-plana Legg-Calvé-Perthes Disease (Coxa Plana)

Legg-Calvé-Perthes Disease (Coxa Plana)

A concise overview of Coxa Plana (Legg-Calvé-Perthes Disease) and its treatment

Also called Coxa Plana. This is idiopathic avascular necrosis of the femoreal head. It presents at around 4 - 8 years of age. 12% is bilateral and has a male to female ratio of 5:1. It occurs in every 1 in 1200 births.

Its associated with:

  • Positive family history
  • low birth weight
  • abnormal pregnancy/delivery
  • ADHD in 33% of cases
  • Delayed bone age in 89%
  • second hand smoke exposure
  • Asian, Inuit and central European

Key Features:

  • Avascular necrosis of proximal femoral epiphysis
  • Abnormal growth of the physis
  • eventual remodeling of the regenerated bone

Clinical Features

Child may present with :

  • trendelenburg gait with or without pain
  • intermittent knee, hip, groin or thigh pain
  • Flexion contracture (stiff hip): decreased internal rotation and abduction of the hip
  • limb length discrepancy (late)

Most common in athletes, especially involving running/sprinting sports

Children with coxa planna less than 6 years have a better prognosis



  • AP pelvis, frog leg, laterals

May be negative if early, but if there is a high index of suspicion, move to bone scan or MRI

Eventually there is a characteristic collapse of the femoral head (diagnostic)

coxa plana with collapsed epiphysis


The goal is to preserve range of motion and keep femoral head contained inside the acetabulum


  • Physiotherapy and range of motion exercises
  • Brace in flexion and abduction for 2-3 years, though controversial


  • Femoral or pelvic osteotomy (only for greater than 8 years of 8 or severe)
    • Prognosis better in males, less than 5-6 years, if less than 50% f femoral head is preserved or if abduction is greater than 30 degrees
  • 60% of involved hips do not require operation
  • If progresses, it becomes early onset osteoarthritis with decreased range of motion