Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease (LCPD) is a self-limited, idiopathic avascular necrosis of the femoral head that typically affects children 4–10 years of age. LCPD is characterized by antalgic gait, restricted range of motion (especially internal rotation and abduction) of the affected hip, and pain in the hip, upper leg, and/or knee. The disease is bilateral in 10–20% of patients. Diagnosis is typically made based on x-ray findings. MRI is indicated if x-ray findings are equivocal and clinical suspicion persists. Management is aimed at preserving the shape of the femoral head and the integrity of the hip joint during healing. Most patients are managed conservatively (e.g., physical therapy, pain management, restriction of weight-bearing activities). Surgery may be indicated in patients > 8 years of age and/or those with more severe disease. Early-onset osteoarthritis of the affected hip is a complication of LCPD.

• Sex: ♂ > ♀ (4:1) ^[1]
• Age: 4–10 years
• Incidence (in children < 15 years): 1–3:20,000 ^[2]

Epidemiological data refers to the US, unless otherwise specified.

• Idiopathic disease
• Multiple factors might promote the development and progress of the condition, including: ^[1]
  • Repetitive microtrauma (e.g., due to child's hyperactivity)
  • Bleeding disorders (e.g., excess factor VII, factor V Leiden, protein S deficiency) ^[3]
  • Genetic factors (e.g., possible mutations in COL2A1 gene) ^[2]
  • Environmental factors (e.g., maternal smoking, secondhand smoke exposure) ^[4][5]

Avascular necrosis of the femoral head due to a mismatch between the rapid growth of the femoral epiphyses and the slower development of adequate blood supply to the area

• Typically unilateral; 10–20% of patients have bilateral involvement ^[6][7]
• Gait abnormalities, including: ^[8]
  • Antalgic gait
  • Limping due to, e.g.:
    • Limb length discrepancy
    • Restricted range of motion (especially internal rotation and abduction of the hip) ^[7][9]
  • Trendelenburg gait
• Pain in the hip and/or the upper leg, sometimes referred to the knee ^[7][9]
  • Insidious onset, pain may fluctuate depending on physical activity
  • Often exacerbated by internal rotation
  • Groin tenderness on palpation
• Hinge abduction ^[6]
  • Painful and restricted hip abduction
  • A sign of advanced disease
  • On hip abduction, the deformed lateral pillar of the femoral head impinges on the acetabular rim, preventing the femoral head from entering the acetabulum.

Consider LCPD as a cause of referred pain in a child presenting with knee pain. ^[9]

Diagnosis of LCPD is typically made based on x-ray findings. MRI is indicated if x-ray findings are equivocal and clinical suspicion persists. ^[10][11]

X-ray pelvis and hip ^[10][11]

• Indication: : initial imaging modality for suspected LCPD
• Views: anterior-posterior view of the pelvis and bilateral frog-leg lateral view of the hip
• Findings ^[9][10]
  • Frequently normal during early stages of the disease
  • Flattening of the femoral head with increased radiodensity ^[6]
  • Joint space widening ^[12]
  • Subchondral fracture and lucency
  • Femoral head fragmentation ^[12]

X-ray findings are often normal in the early stages of LCPD. ^[10]

MRI pelvis without IV contrast ^[10][11]

• Indication: clinical suspicion for LCPD despite normal or equivocal x-ray findings
• Findings ^[13]
  • Bone marrow edema and epiphyseal abnormalities of the femoral head (early finding)
  • Joint effusion
  • Other findings are similar to those seen on x-ray

Findings of osteonecrosis are visible on MRI before they become apparent on x-ray. ^[10][11]

Lateral pillar classification ^[6]

This classification possesses the highest clinical relevance because it correlates with long-term outcome. The crucial criterion in this classification is the height of the lateral third (“lateral pillar”) of the femoral head.

Other classifications ^[6]

• Catterall classification: refers to the extent of the epiphyseal necrotic area
• Salter-Thompson classification: refers to the extent of subchondral fracture in the early stage of disease
• Stulberg classification: refers to femoral head morphology in the phase of complete healing

See “Common causes of hip pain in children.”

The differential diagnoses listed here are not exhaustive.

LCPD is self-limited and typically resolves within 2–5 years. Management aims to preserve the shape of the femoral head and the integrity of the affected hip joint during healing. ^[6]

Initial management ^[6][14]

• Restrict weight-bearing activities (e.g., sports, dance, jumping).
• Use nonopioid oral analgesia in children (e.g., acetominophen, NSAIDs) to manage pain.
• Refer to a pediatric orthopedic specialist for further management.

Conservative management ^[6][14]

• Most patients are managed conservatively.
• Management may include:
  • Individualized physical therapy (e.g., range of motion exercises, stretching, hydrotherapy, supervised weight-bearing)
  • Skeletal traction
  • Abduction bracing ^[6][12]

Surgery ^[6]

• Indicated for children > 8 years and/or those with more severe disease, e.g.:
  • Progressive or severe deformity of the femoral head
  • Persistent range of motion restriction
• Procedure: pelvic and/or femoral osteotomy

• Early-onset osteoarthritis of the hip joint due to any of the following: ^[1]
  • Incongruence between the femoral head and acetabulum
  • Shortening of the femoral neck featuring trochanteric elevation, which can manifest as Trendelenburg sign
  • Lateralization and coxa magna (broadening of the femoral head), which can manifest as hinge abduction
• Total hip arthroplasty can be considered in adults that develop osteoarthritis. ^[6]

We list the most important complications. The selection is not exhaustive.

Factors associated with a less favorable prognosis include: ^[6]

• Older age of onset (> 8 years)
• Extensive damage to the femoral head (e.g., lateral pillar classification B/C, C; femoral head subluxation)
• Poor range of motion
• Female sex