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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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.
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
Lateral pillar (Herring) classification of Legg-Calvé-Perthes disease and prognosis.
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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