September 7, 2020

Slipped Capital Femoral Epiphysis (SCFE)

Definition: Medial or posterior slippage of the femoral capital epiphysis relative to the metaphysis

Epidemiology:

  • Classic patient group: overweight adolescent boys
    • Over 80% of SCFE involves children with a BMI > 95th percentile (Manoff 2005).
    • Average age of onset: 12 years old
  • Bilateral SCFE is fairly common
    • 23% will have contralateral disease at the time of initial presentation, despite only complaining of unilateral pain (Hagglund 1988, Loder 1993).
    • Up to 60% of patients will go on to develop bilateral SCFE in their lifetime
    • 88% of subsequent slips occur within 18 months of diagnosing the first slip
  • Influenced by bone maturation, strength, and weight mismatch.
  • SCFE has also been associated with endocrine disorders such as hypothyroidism, hypogonadism, pan-hypopituitarism, but this is not as common.

Presentation:

  • Groin, hip and thigh pain most common (85%) – constant or intermittent
  • Isolated knee pain (15%)
  • Limited internal rotation
  • +/- Limp
  • Immobility or refusal to bear weight
  • Weakness
  • Abnormal gait alignment
  • May have no complaints of pain at time of presentation/examination

Differential Diagnoses:

  • Muscle strain
  • Pelvic fracture
  • Acute Rheumatic Fever
  • Developmental dysplasia of hip
  • Juvenile idiopathic arthritis
  • Legg-Calve-Perthes disease
  • Septic arthritis
  • Transient synovitis
  • Osteosarcoma

Complications:

  • Usually secondary to delays in diagnosis due to:
    • Vague, nonspecific symptoms as discussed above or delayed patient presentation
    • Failure to obtain appropriate imaging
      • SCFE can present as isolated knee or distal thigh pain in up to 15% of cases (Matava 1999).
    • Subtle diagnostic findings in mild cases missed by inexperienced radiologists or orthopedists
      • One retrospective study showed SCFE to be the second most commonly missed pediatric orthopedic diagnosis behind fracture (Skaggs 2002)
  • Numerous retrospective studies demonstrate that the average time of symptom onset to diagnosis is eight weeks
  • Subsequent complications
    • Avascular necrosis (AVN) of the femoral head
    • Femoroacetabular impingement (FAI)
    • Limb-length discrepancy
    • Decreased range of motion
    • Osteoarthritis

Diagnosis:

  • Plain Radiography (gold standard for diagnosis)
    • Views to obtain: XR Pelvis AP and Frog-Leg Lateral
      • Bilateral imaging should be obtained due to the high rate of bilateral disease on initial presentation
    • SCFE identified on XR has been traditionally described as ice cream slipping off the cone
      • Similar Salter Harris Type I Fracture due to disruption of physeal plate
    • Southwick Head Shaft Angle (SHSA) is used to classify the degree of slip
      • Mild: < 30o
      • Moderate: 31-50o
      • Severe: > 51o 
    • Klein’s Line/S-Sign
      • Klein’s Line
        • Line drawn along the femoral neck and passes through the epiphysis.
        • With SCFE, Klein’s Line does not include the epiphysis and instead will pass lateral to the epiphysis.
      • S-Sign
        • Smooth S-shaped line drawn along the femoral head-neck junction from lesser trochanter to the midpoint of the femoral head.
        • If the line is asymmetric, discontinuous, or has sharp turns the likelihood of SCFE is significantly increased.
        • The combination of Klein’s line and the S-Sign are 96.5% sensitive and 85% specific for all cases of SCFE (Rebich 2018)
          • Accurate and easily reproducible compared to SHSA making them more useful in early diagnosis and improving overall prognosis.

  • Ultrasound
    • 95% sensitivity (Magnano 1998)
    • Can show hip effusion or metaphyseal step-off when radiographs are negative
    • Operator dependent
  • MRI
    • Sensitivity as high as 88% (Magnano 1998).
    • Useful in detecting early SCFE in “pre-slip” phase by identifying physeal abnormalities of those at risk of slippage even without radiographic evidence (Khaladkar 2015)
  • CT
    • Generally not indicated given the other available imaging modalities
    • Avoid excessive and unnecessary radiation in children

Management:

  • All patients should be immobilized and made non-weight bearing
  • Obtain orthopedic consultation to determine need for early surgical intervention vs clinic referral for delayed repair
  • Simple (non-operative) closed reduction
    • Contraindicated in stable SCFE
    • Manipulation of an intact epiphyseal-metaphyseal interface without visualization can result in worsening instability and additional complications.
  • Identify avascular necrosis if present as this has been shown to be a complication of both delayed diagnosis as well as surgical repair of unstable SCFE
    • Preoperative
      • MRI with contrast
      • Bone scintigraphy
    • Intraoperative
      • Visual confirmation of bleeding by drilling into femoral head
      • Laser Doppler Flowmetry to measure pressure within the femoral head
  • Treatment options include open or closed surgical fixation via:
    • Percutaneous in situ fixation
    • Osteotomy
    • Capsulotomy

Take Home Points

  • Always consider SCFE in the differential diagnosis of a patient with non-traumatic hip, groin, thigh or knee pain
  • Early recognition and diagnosis are crucial to avoid complications
  • Immediate immobilization and urgent orthopedic consultation is crucial in management
  • Surgical repair is the only definitive treatment modality

Guest Post By

C. Blair Gaines, MD
Emergency Medicine, PGY-3
Jackson Memorial Hospital
Miami, FL

References

  1. Asad I et al. Point-of-Care Ultrasound Diagnosis of Slipped Capital Femoral Epiphysis. Clin Pract Cases Emerg Med 2019. PMID: 30775677
  2. Kim TY et al. Limping: Evaluation, Diagnosis, and Management in the Pediatric ED. Pediatric Emergency Medicine Practice 2006. [Link is HERE]
  3. Lien J et al. Pediatric Orthopedic Injuries: Evidence-Based Management in the Emergency Department. Pediatric Emergency Medicine Practice 2017. PMID: 28825959
  4. Millis MB. SCFE: Clinical Aspects, Diagnosis, and Classification.  Journal of Children’s Orthopaedics 2017. PMID: 28529655
  5. Otani T et al. Diagnosis and Treatment of Slipped Capital Femoral Epiphysis: Recent Trends to Note. Journal of Orthopedic Science 2018. PMID: 29361376
  6. Rahme D et al. Consequences of Diagnostic Delays in Slipped Capital Femoral Epiphysis. Journal of Pediatric Orthopaedics 2006. PMID: 16436942
  7. Rebich EJ et al. The S Sign: A New Radiographic Tool to Aid in the Diagnosis of Slipped Capital Femoral Epiphysis. JEM 2018. PMID: 29550284

Post Peer Reviewed By: Anand Swaminathan, MD (Twitter: @EMSwami) and Salim R. Rezaie, MD (Twitter: @srrezaie)

Cite this article as: C. Blair Gaines, MD, "Slipped Capital Femoral Epiphysis (SCFE)", REBEL EM blog, September 7, 2020. Available at: https://rebelem.com/slipped-capital-femoral-epiphysis-scfe/.
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C. Blair Gaines, MD

Emergency Medicine, PGY-3, Jackson Memorial Hospital, Miami, FL
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