Contents
Introduction
Perthes disease (Legg-Calvé-Perthes disease) is an idiopathic osteonecrosis/avascular necrosis of capital femoral epiphysis of the femoral head.
- Type of aseptic osteochondroses of childhood
- ♂:♀::4:1, typically in 3-7 years
History
The disease was described nearly simultaneously in the year 1910 by G. C. Perthes in Germany, A. T. Legg in the United States, and J. Calvé in France.
Aetiology
Clinical risk factors for a poor outcome:
- Later age of onset
- Overweight
- Severe limitation of the range of motion
- Female sex
Pathophysiology
Avascular necrosis of the epiphysis
↓
Impairs enchondral ossification of femoral head
Stages of Legg-Calves-Perthes (Waldenström):
- Initial stage:
- Infarction produces a smaller, sclerotic epiphysis with medial joint space widening
- Fragmentation stage:
- Result of revascularization process with bone resorption producing collapse with subsequent patchy density and lucencies
- Radiological findings:
- Begins with presence of subchondral lucent line (crescent sign)
- Femoral head appears to fragment/dissolve
- Lateral pillar classification based on this stage
- Reconstitution stage:
- Ossific nucleus undergoes reossification with new bone appearing as necrotic bone is resorbed
- Healed stage:
- Femoral head remodels until skeletal maturity

Clinical features
- Hip/groin pain
- Present during physical activity
- Radiates to thigh & knee (25% cases)
- Bilateral (asymmetrical, asynchronous involvement) (10-15% cases)
- Limping gait
- Different length of legs (due to adduction contracture or collapsed epiphysis)
Diagnosis
Imaging
X-ray:
- Pelvic survey film and lateral hip x-ray:
- Establish diagnosis
- Enable classification, prognostic assessment, and follow-up of the course of the disease

- Head-at-risk signs (1971, Catterall):
- Gage sign (V-shaped radiolucency in the lateral portion of the epiphysis and/or adjacent metaphysis
- Lateral epiphyseal calcification
- Lateral subluxation of the femoral head
- Horizontal proximal femoral physis
- Metaphyseal cyst (added later to the original 4 at-risk signs described by Catterall)

Ultrasonography (USG):
- Supplementary technique to diagnose changes of the femoral head and, in particular, any accompanying synovitis or effusion
Magnetic resonance imaging (MRI):
- Identifying the early stage of Perthes disease in the absence of changes on plain films, as well as in cases where the differential diagnosis would otherwise be difficult.
- Dynamic MRI (eg. arthrography): Diagnosing any accompanying “hinge abduction” (lateral side of the femoral head contacts the acetabular margin) during preoperative planning
Prognostic classification

Lateral Pillar (Herring) Classification | |
Group A | Lateral pillar maintains full height with no density changes identified |
Group B | Lateral pillar >50% height |
B/C Border | Lateral pillar narrowed (2-3mm) or poorly ossified with approximately 50% height |
Group C | Lateral pillar <50% |
Differential diagnosis
- Coxitis fugax
- Juvenile idiopathic arthritis (JIA)
- Osteomyelitis
- Meyer’s dysplasia
- Absence of clinical symptoms and of the staged radiological progression that typifies Perthes disease
- Epiphyseal dysplasia
- Spondyloepiphyseal dysplasia
- Chondroblastoma
- So-called “Perthes” due to hip dysplasia
- Cortisone-induced necrosis of the femoral head
Management

Goals of treatment:
- Improved mobility
- Reduction of mechanical stress
- Preservation of joint congruence (containment)