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Avascular Necrosis of the Proximal Femoral Epiphysis (Legg-Calve-Perthes Disease)

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Avascular Necrosis of the Proximal Femoral Epiphysis (Legg-Calve-Perthes Disease)
Christopher McGrew
Basics
Description
  • Juvenile idiopathic avascular necrosis of the capital femoral epiphysis of the femoral head
  • Synonym(s): Perthes disease; Aseptic necrosis of the femoral head; Osteochondritis deformans juvenilis; Osteonecrosis of capital femoral epiphysis of the femoral head
Epidemiology
  • Incidence in general population 1/1,200 to 1/12,000
  • Prevalence 75/100,000 person-years
  • Predominant age: Affects children 3–12 yrs of age but is most common between the ages of 4 and 9 yrs; median age 7 yrs
  • Predominant gender: Male > Female (4–5:1)
  • Most prevalent among whites and Chinese; rare in blacks and Native Americans
  • Bilateral hip involvement in 15–20% of patients
Risk Factors
  • Low birth weight
  • Short stature
  • Delayed bone maturation
  • Involved family member (after index sibling, incidence 1/35)
  • Familial thrombophilia and hypofibrinolysis (controversial)
Etiology
Etiology of Legg-Calve-Perthes disease (LCPD) is unclear, but the following has been proposed as a theoretical sequence of events:
  • Blood supply to the capital femoral epiphysis is interrupted.
  • Bone infarction occurs, especially in the subchondral cortical bone, whereas the articular cartilage continues to grow (articular cartilage receives its nutrients from synovial fluid).
  • Revascularization occurs, and new bone ossification starts. At this point, a percentage of patients develops LCPD, whereas others have normal bone growth and development.
  • LCPD is present when a subchondral fracture occurs. This is the result of normal physical activity, not direct trauma to the area.
  • Changes to the epiphyseal growth plate occur secondary to the subchondral fracture.
Diagnosis
History
Symptoms of LCPD usually have been present for weeks because the child often does not complain.
  • Hip or groin pain, which may be referred to the thigh
  • Mild or intermittent pain in anterior thigh or knee
  • Limp worsened by activity, usually most pronounced at end of day
  • Usually no history of trauma
  • Inflammatory synovitis can mimic LCPD but usually resolves in 10–14 days.
Physical Exam
  • Examine the musculoskeletal system with a focus on the pelvis and lower extremities.
  • Include range-of-motion (ROM) testing, limited abduction and internal rotation, presence or absence of hip flexion contracture.
  • Evaluate for muscle atrophy of the thigh, calf, and buttocks, which is seen in long-standing cases.
  • Measure for possible leg-length discrepancy, which indicates advanced involvement of the femoral head.
  • Evaluate gait. Trendelenburg gait is observed with abductor weakness.
  • Perform log-roll test of extended leg on examining table; painful and reduced ROM is observed compared with the opposite side.
  • Short stature: Children with LCPD often have delayed bone age.
Diagnostic Tests & Interpretation
Imaging
  • Anteroposterior and frog-leg lateral views of pelvis; can appear normal early in course
  • Femoral head appears smaller then opposite head with a widened articular cartilage space.
  • With disease progression, a crescent-shaped radiolucent line may be seen in the central portion of the femoral head, especially on the lateral view.
  • Fracture, fragmentation, and resorption
  • Extent of femoral head involvement determines severity of disease.
  • Bone scan and MRI can be used to evaluate before radiographic changes are apparent.
  • MRI may be used to evaluate disease progression and/or resolution over time if radiographs provide inadequate detail.

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Differential Diagnosis
  • Inflammatory: Septic arthritis, osteomyelitis, transient synovitis
  • Trauma: Fracture
  • Neoplasm
  • Congenital: Limb abnormality
  • Developmental: Hip dysplasia, slipped capital femoral epiphysis
  • Sickle cell anemia: Osteonecrosis secondary to vascular infarcts
  • Gaucher disease: Osteonecrosis secondary to cerebroside and infarcts
Treatment
  • The healing process involves revascularization of the femoral head, removal of necrotic bone, and replacement with viable bone. It is a biologic process that requires many months. No current interventions accelerate this process.
  • Nonsurgical treatment:
    • Treatment may involve simple observation, especially in children <6 yrs of age.
    • Analgesia: Nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen
    • Activity restriction, crutches for non-weight-bearing, abduction stretching exercises, bed rest
    • Abduction bracing/casting can be used for symptom relief and to hold the femoral head in the acetabulum.
    • Casting/bracing may be discontinued when there is radiographic evidence of subchondral reossification, usually after 12–18 mos.
Additional Treatment
Additional Therapies
  • Both surgical and nonsurgical treatments are aimed at symptom reduction, prevention of capital femoral epiphysis destruction, and attainment of a spherical femoral head at healing.
  • Rehabilitation:
    • Formal therapy program is recommended during and after bracing owing to extensive atrophy, contracture, and loss of motion.
    • A home stretching program is encouraged to maintain ROM.
Surgery/Other Procedures
  • Goal is containment of femoral head leading to round femoral head.
  • Techniques vary depending on age of child and severity of femoral head involvement.
  • Advantages include less time required in a brace and earlier return to activity.
  • Disadvantages include necessity of two operations.
Ongoing Care
Follow-Up Recommendations
All patients with suspected LCPD should be referred to a pediatric orthopedic surgeon immediately.
Prognosis
  • The younger the age of onset of LCPD, the better is the prognosis.
  • Children >10 yrs of age have a very high risk of developing osteoarthritis.
  • Most patients have a favorable outcome.
  • Prognosis is proportional to the degree of radiologic involvement.
Complications
  • LCPD may result in femoral head deformity and degenerative joint disease (onset of severe arthritis varies from adolescence to more commonly in geriatric years).
  • Femoral head may be distorted permanently.
Additional Reading
Kocher MS, Tucker R. Pediatric athlete hip disorders. Clin Sports Med. 2006;25:241–253, viii.
Nochimson G. Legg-Calve-Perthes Disease. emedicine.medscape updated 9/24/08 http://emedicine.medscape.com/article/826935-overview.
Roy DR. Current concepts in Legg-Calvé-Perthes disease. Pediatr Ann. 1999;28:748–752.
Codes
ICD9
732.1 Juvenile osteochondrosis of hip and pelvis


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