Summary
Slipped capital femoral epiphysis (SCFE) is the superior and anterolateral displacement of the femoral neck relative to the epiphysis due to weakening of the proximal femoral epiphyseal growth plate. It most commonly occurs in boys aged 10–16 years. The etiology is not fully understood, but risk factors include obesity and endocrine disorders. SCFE may have an acute or insidious onset and manifests with hip pain, limping, and restricted movement of the affected hip. If the patient is unable to ambulate, the SCFE is considered unstable, which increases the risk of complications such as avascular necrosis of the femoral head. Conventional x-ray confirms the displacement and allows for severity assessment. Patients should be non-weight-bearing; surgical fixation is the only definitive treatment option.
Epidemiology
- Prevalence: most common hip disorder in adolescents [1]
- Peak incidence: : 10–16 years (often occurs during a growth spurt) [1]
- Sex: : ♂ > ♀
Epidemiological data refers to the US, unless otherwise specified.
Etiology
The exact etiology is still unknown. However, there are some risk factors that increase the likelihood of SCFE: [2]
- Obesity
- Family history
- Endocrine or hormonal factors (e.g., hypothyroidism; , pituitary tumors, down syndrome, renal osteodystrophy, craniopharyngioma)
- Trauma (e.g., sports-related injury or fall)
Pathophysiology
- Puberty-induced hormonal changes, endocrine disorders, inflammation → poor cartilaginous organization and maturation → wide and unstable proximal femoral epiphyseal growth plate [3]
- Obesity, growth spurts, trauma → increased shear force
- Shear force > strength of the epiphyseal growth plate → superior and anterolateral displacement of the metaphysis distal to the growth plate
In SCFE, the metaphysis is displaced, not the epiphysis.
Clinical features
-
Onset
- Acute
- Chronic (3 weeks to several months)
- Acute on chronic (chronic with acute exacerbations)
- Location: bilateral in 20–40% of cases [4]
-
Symptoms [2]
- Dull pain in the medial thigh, knee , groin, or hip (often left > right)
- Limping
-
Restricted range of motion
- Reduced internal rotation and abduction
- Patients may hold their hip in passive external rotation
- Drehmann sign positive: external rotation and abduction during passive flexion of the affected hip in the supine position [5]
-
Stability [6][7]
- Stable SCFE: Ambulation is possible with or without crutches.
- Unstable SCFE: Ambulation is not possible, even with crutches.
Diagnosis
Approach [6][7][8]
- Obtain bilateral hip x-rays for all patients with suspected SCFE.
- Evaluate the contralateral hip to rule out bilateral SCFE and assess severity.
- Atypical presentation (e.g., atypical age of onset, short stature): Evaluate for risk factors (e.g., endocrinopathies) under specialist guidance.
- SCFE with equivocal x-ray findings: Consider advanced imaging (CT or MRI).
X-ray [6][7][8]
X-ray is the initial imaging modality for all patients with suspected SCFE (see “Clinical features”).
Indications
The following are common indications for x-rays:
Views
- All patients: AP view pelvis
- Stable SCFE: additional frog leg lateral views
- Unstable SCFE: additional cross-table lateral views
Findings
- Widening of the epiphyseal growth plate and relative reduced epiphyseal height
- Superior and anterolateral displacement of the femoral neck relative to the epiphysis
-
Klein line: a straight line drawn along the superior border of the femoral neck in AP view
- Normal: line passes through the femoral neck
- SCFE: line does not intersect the femoral head or marked asymmetry between affected and unaffected sides
To visualize the displacement of the femoral head relative to the femoral neck as seen on x-ray, imagine a scoop of ice cream slipping from its cone.
Severity assessment
Measure using frog leg lateral views.
-
Southwick method: Calculate the difference in head-shaft angle between affected and unaffected sides; if bilateral SCFE suspected, subtract 10° instead. [9]
- Mild SCFE: < 30° difference
- Moderate SCFE: 30–50° difference
- Severe SCFE: > 50° difference
-
Wilson method: Measure displacement of the epiphysis relative to the metaphysis.
- Type I: < 33% displacement
- Type II: 33–50% displacement
- Type III: > 50% displacement
Treatment
Initial management [6][7][8]
- Patients should be non-weight-bearing.
- Provide analgesia.
- Urgently admit or transfer all patients to orthopedics for surgical stabilization.
Definitive management [7][8]
- Indication: all patients
- Goal: stabilize the epiphysis to prevent further slippage
-
Surgical techniques
- In situ pinning (gold standard)
- Alternative: open reduction
- Contralateral prophylactic fixation may be indicated for patients with a high risk of delayed contralateral slip.
Do not attempt forceful closed reduction as there is a high risk of complications.
Differential diagnoses
- See “Differential diagnosis of pediatric hip pain.”
- Legg-Calvé-Perthes disease
- Transient synovitis
- Septic arthritis
Snapping hip syndrome [10]
- Definition: : snapping of the iliotibial band or gluteus maximus over the greater trochanter (external), or snapping of the iliopsoas tendon over the iliopectineal eminence (internal), typically seen in young athletes and dancers
- Epidemiology
- Clinical features
-
Treatment
- Physical therapy, rest, ice
- Injection of local anesthetic
- If complaints persist: surgical treatment
The differential diagnoses listed here are not exhaustive.
Complications
- Avascular necrosis of the femoral head
- Early hip osteoarthritis [11]
- Chondrolysis of the hip: rapid degeneration of articular cartilage
- Bone deformity due to premature closure of the epiphyseal plate [6]
We list the most important complications. The selection is not exhaustive.