Slipped Capital Femoral Epiphysis

Basics

Description

  • Femoral epiphysis translates (slips) posteriorly and inferiorly relative to the femoral head/neck
  • Classification systems:
    • Degree of femoral head “slip” as a percentage of femoral neck diameter:
      • (Mild, grade 1) <33.3%
      • (Moderate, grade 2) 33.3–50%
      • (Severe, grade 3) >50%
    • Temporal:
      • Acute: <3 wk of symptoms
      • Chronic: >3 wk of symptoms
      • Acute on chronic: >3 wk of symptoms, now with acute pain
    • Stability:
      • Stable: Bears weight w/or w/o crutches
      • Unstable: Unable to bear weight
  • Epidemiology:
    • Peak age: 12–14 yr (boys), 11–13 yr (girls)
    • Male > female (1.5:1)
    • Bilateral slips: 20% at presentation; additional 20–40% progress to bilateral
    • Atypical SCFE: Endocrinopathy associated:
      • Patient may be <10 yr age, >16 yr age, or weight <50th percentile
      • High risk of bilateral SCFE (up to 100%)

Etiology

  • Proximal physis position changes in adolescence from horizontal to oblique; hence hip forces shift from “compression” to “shear”
  • Shear force > strength of femoral physis
  • Weakest point of physis = zone of hypertrophy
  • Risk factors:
    • Obesity: May contribute to shear forces
    • Down syndrome
    • Endocrinopathy such as hypothyroidism, growth hormone deficiency, renal osteodystrophy (2° hyperparathyroidism): May contribute to growth plate weakening

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