Slipped Capital Femoral Epiphysis

CHAPTER 20

Slipped Capital Femoral Epiphysis

Introduction/Etiology/Epidemiology

• Slipped capital femoral epiphysis (SCFE) is a pediatric/adolescent hip condition in which a movement or slipping occurs at the growth plate (physis) of the femur so that the epiphysis (ball part) slips posterior and inferior relative to the metaphysis (neck part), which shifts and displaces anterior.

• The incidence is considered somewhat common, approximately 2 per 100,000.

• The age range is typically 12 to 15 years for boys and 11 to 13 years for girls.

• SCFE is more common in boys (60%) and more common in the left hip, and it is bilateral in 25% of cases. It is seasonal and occurs more commonly in the summer months.

• Increased body mass index (BMI) (including obesity) is a risk factor, with more than half of all patients with SCFE at or above the 95th percentile for weight for their age.

• Morphologic characteristics predisposing to SCFE include deeper acetabulum, preexisting increased femoral retroversion, and increased physeal obliquity all contributing to increased shear forces across the physis.

• Endocrine abnormality etiologies account for 5% to 8% of SCFE and are more likely in those outside the typical age range (< 10 or > 15 years; “atypical SCFE”).

— Testosterone decreases, while estrogen increases physeal strength.

— Proper development of the physis requires thyroid hormone, vitamin D, and calcium. Thus, hypothyroidism and renal osteodystrophy have been associated with SCFE.

Signs and Symptoms

• Patients typically present in early adolescence.

• The most common presentation is a patient with increased BMI and insidious onset of a limp, with thigh and/or knee pain. Often the foot is externally rotated compared to the other leg.

• This is a stable SCFE. Patients are able to walk (weight bear) with or without the aid of crutches.

• Unstable SCFE, the less common presentation, is one in which the patient has significant pain, cannot weight bear due to pain, and is unable to travel from point A to point B on their own (with or without crutches). Many of these patients report intermittent milder pain prior to it getting acutely worse.

• Knee pain may be the only presenting symptom. It is important and medically indicated to evaluate the hip of the adolescent patient who presents with knee pain.

• The physical examination for the stable SCFE is characterized by “obligate external rotation” with attempts at hip flexion (knee to shoulder sign; see Figure 20-1). This occurs when the hip is flexed keeping the femur rotation in neutral.

Differential Diagnosis

• Perthes disease

• Septic arthritis

• Transient synovitis of the hip

• Developmental dysplasia of the hip

• Femoral stress fracture should be considered in cases preceded by repetitive overuse, such as running, especially in adolescents.

• Muscle strain or pelvic avulsion fracture should be considered in cases with acute onset during activity, especially in adolescents.

Diagnostic Considerations

• Diagnosis is made with an appropriate history, physical examination, and radiographs (2 views: anteroposterior [AP] and frog lateral of the pelvis).

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