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Slipped Capital Femoral Epiphysis

General Surgery · Final Professional

Definition

Slipped capital femoral epiphysis (SCFE / SUFE) is a disorder of the adolescent hip in which the femoral head epiphysis slips (displaces) posteriorly and inferiorly relative to the femoral neck through the growth plate (physis). It is essentially a Salter–Harris type-I fracture through a weakened physis and is the commonest hip disorder of adolescence.

Epidemiology & Associations

It typically affects the overweight adolescent around the pubertal growth spurt (boys ~10–16, girls ~10–14 years). Associations include obesity and endocrine disorders (hypothyroidism, hypogonadism, growth-hormone treatment, renal osteodystrophy) — which should be considered, especially in a thin or atypically young/old child.

In SCFE the epiphysis slips posteroinferiorly; on the AP film Klein’s line (drawn along the superior femoral neck) fails to intersect the epiphysis as it normally should.

Clinical Features

Hip, groin, thigh or knee pain with a limp; the classic sign is that the affected leg lies in external rotation, and on flexing the hip it moves into obligatory external rotation and abduction (Drehmann sign). Slips are classified by duration (acute, chronic, acute-on-chronic) and, importantly, by stability — a stable slip allows weight-bearing (better prognosis), an unstable slip does not (high risk of AVN).

DANGER / REMEMBER

Up to a quarter of cases present with pain only in the knee or thigh. Always examine and image the hip in an adolescent with knee pain — missing a SCFE risks progression to a severe slip and avascular necrosis.

Investigations & Management

AP and frog-lateral radiographs of both hips; the lateral view is most sensitive for early slips. Klein’s line (along the superior neck) normally intersects the epiphysis; in SCFE it does not. Treatment is urgent surgical stabilisation — usually in-situ fixation with a single cannulated screw to prevent further slip; the contralateral hip is fixed prophylactically in high-risk (endocrinopathy, young) cases. Forceful reduction of a chronic slip is avoided because it precipitates AVN.

CLINICAL PEARL

SCFE is fixed ‘in situ’ — the slip is pinned where it lies rather than reduced, because forceful manipulation dramatically increases the risk of avascular necrosis and chondrolysis.

Complications

The two feared complications are avascular necrosis of the femoral head (much higher after an unstable slip or after forceful reduction) and chondrolysis (acute cartilage loss with a stiff, painful hip). Both can lead to permanent damage and early osteoarthritis. Because of the risk to the other hip — particularly in younger children and those with an endocrinopathy — the contralateral side is monitored closely and often pinned prophylactically. Severe residual deformity may later require a corrective osteotomy.

CLINICAL PEARL

The three rules of SCFE: think of it in an adolescent with knee or thigh pain and an externally rotated leg, get a frog-lateral radiograph and check Klein’s line, and treat by urgent in-situ screw fixation without forceful reduction.

KEY POINT

Key points TO remember

Adolescent (often obese) hip; epiphysis slips posteroinferiorly (Salter–Harris I).
Consider endocrinopathy if atypical (thin, very young/old, bilateral).
Pain (often referred to knee) + limp; leg externally rotated; obligatory ER on flexion.
Frog-lateral X-ray; Klein’s line fails to cut the epiphysis; classify by stability.
Urgent in-situ screw fixation; avoid forceful reduction (AVN); consider prophylactic other side.

EXAM TIP

Sources: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.

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