Pediatrics · Year 3 · from Pediatrics

Case 2: Slipped Capital Femoral Epiphysis

Patient Demographics

  • Age: 13-year-old male
  • Sex: Male

Chief Complaint

"My knee hurts and I've been limping for about a month."

History of Present Illness

A 13-year-old obese boy presents with a one-month history of progressive right knee pain and limping. The pain is dull, located in the anterior thigh and knee, and worsens with activity. He denies any specific injury. He has not had fever, swelling, or night pain. His mother notes that he seems to walk with his foot turned outward. He plays basketball recreationally but has had to stop due to the pain. His past medical history is notable for obesity (BMI 32 kg/m2, >99th percentile).

Physical Examination

  • Vital Signs: Temperature 36.8C, HR 82 bpm, BP 118/74 mmHg
  • General: Obese adolescent male, appears comfortable at rest
  • Height: 165 cm (75th percentile)
  • Weight: 87 kg (>99th percentile)
  • BMI: 32 kg/m2 (>99th percentile)
  • Gait: Antalgic gait with right leg externally rotated
  • Right hip: Limited internal rotation (10 degrees vs 40 degrees on left); obligate external rotation with hip flexion; no tenderness over hip
  • Right knee: No effusion, full range of motion, no tenderness
  • Left hip and knee: Normal examination

Imaging Findings

  • AP pelvis radiograph: Subtle widening of the right proximal femoral physis
  • Frog-leg lateral radiograph: Posterior displacement of the right femoral epiphysis relative to the metaphysis; Klein's line (line along superior femoral neck) does not intersect the epiphysis on the affected side; "ice cream falling off the cone" appearance

Diagnosis

Slipped capital femoral epiphysis (SCFE), right hip, stable

Clinical Reasoning

This obese adolescent male presents with the classic SCFE profile: insidious onset hip/thigh/knee pain, limp, and limited internal rotation with obligate external rotation during hip flexion. The referral of hip pain to the knee is common and may delay diagnosis if hip examination is not performed. His ability to bear weight classifies this as a "stable" SCFE, which has a much lower risk of avascular necrosis than unstable SCFE. The frog-leg lateral radiograph demonstrates the pathognomonic posterior slippage of the epiphysis. Risk factors include obesity (mechanical stress on the physis), male sex, and the adolescent growth spurt.

Management

  1. Non-weight-bearing: Immediately; use crutches or wheelchair until surgery
  2. Urgent orthopedic surgery: In situ screw fixation within 24-48 hours to prevent further slippage
  3. NO REDUCTION ATTEMPTS: Attempting to reduce the slip increases avascular necrosis risk
  4. Contralateral hip: Evaluate carefully; prophylactic pinning considered in high-risk patients (young age, obesity, endocrine disorders)
  5. Endocrine evaluation: Consider thyroid function tests if atypical presentation (younger age, bilateral, not obese)
  6. Long-term follow-up: Monitor for AVN, chondrolysis, and early osteoarthritis

Clinical Image

Image Description: Frog-leg lateral radiograph of the pelvis demonstrating slipped capital femoral epiphysis with posterior displacement of the femoral epiphysis relative to the metaphysis, described as "ice cream falling off the cone."

Source: Radiopaedia URL: https://radiopaedia.org/cases/slipped-capital-femoral-epiphysis-1 License: CC BY-NC-SA 3.0

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