Legg-Calvé-Perthes Disease
Idiopathic avascular necrosis of the proximal femoral epiphysis in children aged 4-8.
Also known as: Legg-Calve-Perthes, Perthes disease, LCPD, coxa plana
Overview
Idiopathic osteonecrosis of the femoral head occurring in growing children, characterized by self-limited interruption of vascular supply to the capital femoral epiphysis followed by revascularization, resorption, reossification, and remodeling.
Epidemiology
Incidence 1 in 1,200 to 1 in 12,000 children. Peak age 4-8 years (range 2-12). Male-to-female ratio 4-5:1. Bilateral involvement in 10-15 percent (usually asynchronous).
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Risk factors
- Male sex
- Short stature with delayed bone age
- Low socioeconomic status
- Exposure to secondhand smoke
- Family history (modestly increased risk)
- Thrombophilia (controversial)
Pathophysiology
Disruption of blood supply to the femoral head produces avascular necrosis. Disease evolves through four radiographic stages (Waldenström): initial (sclerosis and apparent enlargement), fragmentation (subchondral fracture and lucency), reossification (new bone formation), and residual (remodeling). The shape achieved at skeletal maturity determines long-term hip function.
Clinical presentation
Symptoms
- Insidious, painless or mildly painful limp
- Hip, groin, thigh, or referred knee pain
- Decreased activity tolerance
- Symptoms typically persist over weeks to months without an acute event
Signs / physical exam
- Antalgic and Trendelenburg gait
- Decreased hip abduction and internal rotation
- Mild thigh atrophy from disuse
- Leg length discrepancy in advanced disease
Classic findings
Young boy aged 4-8 with a painless limp, restricted internal rotation and abduction of the hip, and characteristic crescent sign or femoral head flattening on radiographs.
Differential diagnosis
- Septic arthritis — Fever, refusal to bear weight, elevated WBC/ESR/CRP, joint aspiration
- Transient synovitis — Recent viral illness, painful limp, afebrile, self-limited; Kocher criteria
- SCFE — Older children (10-16), obese, externally rotated hip, displaced epiphysis on radiographs
- Developmental dysplasia of the hip — Identified in infancy; abnormal Ortolani/Barlow or limited abduction
- Sickle cell osteonecrosis — Known sickle cell disease, often bilateral, MRI confirms
- Multiple epiphyseal dysplasia / Meyer dysplasia — Bilateral, symmetric epiphyseal changes; not progressive
Diagnostic workup
Diagnostic criteria
Lateral pillar (Herring) classification at the fragmentation stage assesses the height of the lateral one-third of the epiphysis: A — full height preserved (best prognosis); B — at least 50 percent of original height; B/C border — exactly 50 percent or narrow lateral pillar; C — less than 50 percent of height (worst prognosis). Age at onset is the other major prognostic variable — younger children (<6 years) generally do better.
Labs
- CBC, ESR, CRP normal in LCPD — distinguishes from septic arthritis and osteomyelitis
- Consider hemoglobin electrophoresis if sickle cell osteonecrosis is in the differential
Imaging
- AP and frog-leg lateral pelvic radiographs
- Early findings: increased epiphyseal density, joint space widening, crescent sign (subchondral fracture)
- Later findings: epiphyseal fragmentation, flattening, lateral extrusion of the femoral head
- MRI for early disease before radiographic changes appear
Diagnostic algorithm
| Lateral Pillar (Herring) | Lateral 1/3 Epiphysis Height | Prognosis |
|---|---|---|
| A | Full original height | Excellent — observation |
| B | ≥50% of original height | Good in <8 yr; variable in older |
| B/C border | Exactly 50% or narrow | Intermediate — surgery often considered |
| C | <50% of original height | Poor — high risk for deformity |
Treatment
First-line
- Activity restriction to limit hip joint loading and protect the femoral head during fragmentation
- NSAIDs for pain
- Physical therapy emphasizing hip range of motion (abduction and internal rotation)
- Crutches or partial weight bearing for symptomatic relief
- Observation alone for children <6 years with lateral pillar A or B disease
Second-line / adjunct
- Containment treatment (keep the femoral head 'contained' within the acetabulum during healing) — bracing has largely fallen out of favor; surgical containment via femoral varus osteotomy or innominate (Salter) pelvic osteotomy considered for children ≥6-8 years with lateral pillar B or B/C border disease
- Salvage procedures (femoral osteotomy, hip arthroscopy) for late deformity and impingement
- Total hip arthroplasty in early adulthood for end-stage post-Perthes arthritis
Complications
- Coxa magna and coxa plana (large, flattened femoral head)
- Femoral head deformity with hinge abduction
- Leg length discrepancy
- Early osteoarthritis of the hip — accelerated by older age at onset and severe lateral pillar involvement
- Femoroacetabular impingement
PANCE pearls
- LCPD typically affects younger children (4-8) and SCFE older adolescents (10-16) — age is the most useful initial differentiator.
- Knee pain in a child is hip pain until proven otherwise — examine the hip and obtain pelvic radiographs.
- Age at onset and lateral pillar classification together are the strongest predictors of outcome; children diagnosed before age 6 with intact lateral pillar generally do well without surgery.
- The natural history of LCPD is healing — the goal of treatment is to optimize the shape of the femoral head at skeletal maturity, not to alter the disease course.
References
- POSNA — Pediatric Orthopaedic Society of North America clinical resources on Legg-Calvé-Perthes disease
- AAOS — American Academy of Orthopaedic Surgeons evidence-based guidance on Perthes disease
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