What are the clinical, radiographic, and management features of Legg‑Calvé‑Perthes disease?

Legg-Calvé-Perthes Disease: Clinical Features and Management

Legg-Calvé-Perthes disease (LCPD) is an idiopathic avascular necrosis of the femoral head in children aged 2-14 years (peak 4-8 years), presenting most commonly as a painless limp with hip pain that may radiate to the thigh or knee, and the primary goal of treatment is to maintain or restore containment of the femoral head within the acetabulum to preserve spherical congruity and prevent premature osteoarthritis 1, 2, 3.

Epidemiology and Risk Factors

LCPD predominantly affects:

• Boys 4-5 times more frequently than girls
• Age range: 2-14 years, with peak incidence at 4-8 years
• Children with family history of the condition
• The disease follows a predictable course through phases of ischemia, revascularization, bone resorption, and reossification 2, 4, 3

Clinical Presentation

Key Symptoms

• Painless limp (most common presenting feature)
• Hip pain with radiation to thigh or knee
• Pain may be the primary complaint in some cases
• Symptoms typically develop insidiously 1, 4

Physical Examination Findings

Look specifically for:

• Limited hip abduction (most consistent finding)
• Restricted internal rotation
• Mild flexion limitation (approximately 20 degrees)
• Asymmetric thigh folds
• Leg length discrepancy on the affected side
• Antalgic gait pattern 4, 3

Critical pitfall: In children under 3 years, presentation may be atypical with nonspecific symptoms, making early diagnosis challenging 1.

Radiographic Features

Initial Imaging

Plain radiographs are the primary diagnostic tool and should include:

• Anteroposterior (AP) pelvis view
• Frog-leg lateral view of the affected hip

These are most informative for assessing disease stage, extent of involvement, and containment 4, 5.

Radiographic Stages (reflecting pathologic progression)

1. Initial/Necrosis stage: Increased density of femoral head, possible subchondral fracture (crescent sign)
2. Fragmentation/Resorption stage: Femoral head fragmentation and collapse
3. Reossification stage: New bone formation
4. Remodeling stage: Final femoral head shape determination 5, 3

Classification Systems for Prognosis

Three main systems assess extent of involvement:

• Catterall Classification (Groups 1-4, based on extent of head involvement)
• Salter-Thompson Classification (Groups A-B, based on subchondral fracture extent)
• Herring Lateral Pillar Classification (Groups A-C, most widely used for treatment decisions) 6, 7

Advanced imaging: MRI is increasingly used for early detection and assessment of perfusion, potentially refining surgical decision-making, though plain radiographs remain the standard 2, 5.

Management Algorithm

Age-Based Initial Stratification

Children < 4 years with minimal involvement:

• No treatment required
• Observation with serial radiographs
• Prognosis is generally favorable 4, 3

Children ≥ 4 years OR significant involvement at any age:

• Proceed to containment assessment

Containment Assessment

Test hip abduction in clinic:

• If femoral head can be contained within acetabulum with abduction → Candidate for containment treatment
• If femoral head remains subluxated despite abduction → Consider salvage procedures 4

Treatment Options by Severity and Age

Non-Operative Management

Indicated for:

• Children < 4 years with any involvement
• Minimal involvement (Herring A, Catterall 1-2) at any age
• Early stages with good containment

Components:

• Physiotherapy for range of motion maintenance
• Activity modification (avoid high-impact activities)
• Pain management
• Serial radiographic monitoring 1, 7

Operative Management (Containment Procedures)

Indications:

• Age ≥ 6 years at onset (skeletal age)
• Moderate to severe involvement (Herring B-C, Catterall 3-4)
• Loss of containment on abduction testing 8, 9

Surgical options prioritized by evidence 8, 9:

1. For moderate involvement (Herring B):

   • Femoral varus osteotomy (FVO) alone, OR
   • Salter innominate osteotomy (SIO) alone
   • Both show good outcomes

2. For severe involvement (Herring C):

   • FVO combined with SIO or triple pelvic osteotomy (TPO) (recommended approach)
   • Combination provides superior containment for extensive disease

3. For late-stage disease with established deformity:

   • Femoral valgus extension osteotomy (symptom relief)
   • Trochanteric apophyseodesis (if trochanter overgrowth present)
   • Chiari pelvic osteotomy (if containment impossible) 4, 9

Key surgical principle: Complete containment of the femoral head within the acetabulum during the healing phase is essential to prevent deformity 6, 3.

Prognostic Factors

Better outcomes associated with 3, 8:

• Younger age at onset (< 6 years skeletal age)
• Male sex
• Less extensive femoral head involvement (Herring A-B)
• Maintained containment throughout healing
• Surgical treatment in children ≥ 6 years (better HAT scores and less acetabular dysplasia than non-operative treatment)

Worse outcomes associated with:

• Age > 8-10 years at onset
• Extensive involvement (Herring C, Catterall 4)
• Loss of containment
• Development of acetabular dysplasia (occurs in 49% of cases) 8

Long-Term Monitoring

Essential considerations:

• Recovery continues for 2-3 years after disease onset
• Final femoral head shape determines long-term hip function
• Risk of premature osteoarthritis if significant deformity persists
• Serial radiographic follow-up until skeletal maturity required
• Even with severe radiographic involvement, some patients achieve favorable functional outcomes with conservative management 7, 3

Common pitfall: Acetabular dysplasia develops in nearly half of patients and correlates with worse functional outcomes; this must be monitored and may require additional intervention 8.