Slipped Capital Femoral Epiphysis

SCFE Basics - Slippery Slope Starter

• Definition: Posterior and inferior displacement of the capital femoral epiphysis relative to the femoral neck, through the physis.
• Age: Typically 10-16 years; coincides with adolescent growth spurt.
• Sex: More common in boys than girls.
• Laterality: Bilateral involvement in 20-40% of cases, often presenting sequentially.
• Strongest Risk Factor: Obesity.
• Other Risk Factors: 📌 'SLIPPED'
  • Stout (obese)
  • Late teens (adolescence)
  • Idiopathic/Iatrogenic (e.g., radiation therapy)
  • Pituitary/Parathyroid (e.g., panhypopituitarism)
  • Puberty (rapid growth)
  • Endocrine (e.g., hypothyroidism)
  • Dystrophy (e.g., renal osteodystrophy), Family history.

⭐ SCFE is the most common hip disorder in adolescents.

PathoAnatomy - Femur's Faulty Foundation

• Slip occurs through the hypertrophic zone of the physis, its structurally weakest part.
• Mechanical Factors:
  • Obesity, femoral retroversion, and increased physeal obliquity lead to ↑ shear stress across the physis.
• Endocrine Factors:
  • Hypothyroidism and growth hormone (GH) abnormalities can weaken the physis.
• Considered a Salter-Harris Type I fracture equivalent through the physis.

⭐ The fundamental pathology in SCFE is a weakness in the hypertrophic zone of the capital femoral physis.

Signs & Scans - Hip's SOS Signals

• Presentation: Insidious limp; hip/groin pain, or referred pain to thigh/knee. 📌 'SCFE makes the KNEE scream!' (obturator nerve). Symptoms worsen with activity.
• Signs: Antalgic gait; leg externally rotated. Limited hip internal rotation, abduction, flexion.
  • Drehmann sign: Obligatory external rotation on passive hip flexion.
• Diagnosis (X-rays): Bilateral hip AP & frog-leg lateral views essential.
  • Klein's line: Line along superior femoral neck passes superior to epiphysis or fails to intersect it.
  • Physis: widened, blurred.
  • Epiphysis: posterior displacement (best on frog-leg lateral).
  • Steel sign (double density). showing SCFE with Klein's line illustrated)

⭐ Knee pain can be the ONLY presenting symptom in up to 15-50% of SCFE cases, leading to misdiagnosis.

Severity & Stability - Slip Scale System

• Loder Classification (Stability): Crucial for AVN prognosis.

  Stability	Weight-Bearing Status	AVN Risk
  Stable	Yes (± crutches)	↓ Lower
  Unstable	No (even with crutches)	↑ Higher (up to 50%)

• Temporal Classification:
  • Acute: Symptoms <3 weeks.
  • Chronic: Symptoms >3 weeks (most common).
  • Acute-on-chronic: Recent exacerbation of chronic symptoms.
• Southwick Angle (Severity): Frog-leg lateral X-ray. Angle between line perpendicular to epiphyseal base and line along femoral shaft.
  • Mild: <30°
  • Moderate: 30°-50°
  • Severe: >50°

⭐ The Loder classification (stable vs. unstable slip) is the most important prognostic factor for the development of avascular necrosis (AVN).

Treatment & Troubles - Fixing Femur's Flaw

• Goals: Prevent further slip, promote physeal closure, avoid complications.
• Stable SCFE / Mild-Moderate Chronic Slips:
  • In-situ fixation with a single cannulated screw (gold standard).
• Unstable SCFE / Severe Slips: Controversial. Options:
  • Urgent gentle closed reduction & pinning.
  • In-situ pinning (no reduction).
  • Open reduction for severe, fixed deformities (↑ risk).
• Post-op: Non-weight bearing until physeal closure.
• Prophylactic pinning (contralateral hip): Controversial. Consider in high-risk (endocrine disorders, age <10 yrs, open triradiate cartilage, obesity). Risk of contralateral slip: 20-40% (up to 80% with endocrinopathies).
• Complications: 📌 Awful Complications For Our Patients
  • AVN (Avascular Necrosis): Most feared, esp. unstable slips.
  • Chondrolysis (acute cartilage necrosis).
  • Femoroacetabular Impingement (FAI).
  • Degenerative Osteoarthritis.
  • Pin penetration.

⭐ Single screw in-situ fixation is the treatment of choice for most stable SCFE cases.

High-Yield Points - ⚡ Biggest Takeaways

• SCFE: Common in obese adolescent males (10-16 yrs) with limp and hip/thigh/knee pain.
• Patho: Salter-Harris type I fracture through the proximal femoral physis.
• Diagnosis: Klein's line on AP X-ray fails to intersect the femoral head, which is displaced posteroinferiorly.
• Clinical sign: Drehmann sign (obligatory external rotation on passive hip flexion).
• Treatment: In-situ screw fixation to prevent further slippage and promote physeal closure.
• Complications: Avascular necrosis (AVN), chondrolysis, and high risk of contralateral SCFE.