Slipped capital femoral epiphysis (SCFE), also known as a slipped upper femoral epiphysis (SUFE) is a condition that affects the hip joint in a child approaching puberty. Its diagnosis is easily missed because symptoms are subtle, and the predominant symptom may be knee pain referred from the hip(Hilton’s law).
Incidence and aetiology
Slip of the upper (capital) femoral epiphysis is a rare disease affecting about 5 per 100 000 population. It is bilateral in 20-40% of cases. Aetiology is not known. It is often associated with obesity and hormonal imbalances. There may be a history of trauma.
Pathology
Anatomically the physis connects the proximal femoral epiphysis (the femoral head) to the metaphysis (femoral neck). SUFE/SCFE occurs due to a ‘stress fracture’ through the physis allowing the epiphysis to displace just like an intracapsular fracture of the femoral neck. The upper femoral epiphysis usually gets displaced postero-medially, resulting in coxa vara. The slip progresses gradually in most cases, but in some, it may occur suddenly as well.
There is a considerable risk of avascular necrosis(AVN) of the displaced head.
Clinical features
Patients presents in different ways depending on the epiphyseal stability and the duration of the slippage. Predominant symptoms are pain (groin pain, thigh pain, knee pain) stiffness, and hip instability. Age at presentation is often between 12-14 years (prepuberty).
The child often presents with knee pain and limp. The leg becomes short and externally rotated. There is limitation of abduction and internal rotation, while there is increased adduction and external rotation. When the hip is flexed, the knee points towards the ipsilateral axilla . In neglected cases, the muscle bulk is reduced due to disuse atrophy. Trendelenburg’s sign may be positive.
Diagnosis
The diagnosis is suspected by the history and examination. It is confirmed on lateral view plain radiograph. In suspected pre-slip cases an MRI may be useful.
Treatment
An acute slip is treated by closed reduction and in situ pinning, as for a fracture of the neck of the femur.
The treatment of a gradual slip depends upon the severity of the slip present. If the slip involves less than 1/3 the diameter of the femoral neck, the epiphysis is fixed internally in situ with 1-2 screws. For greater slips an inter-trochanteric corrective osteotomy is performed.
If femoroacetabular impingement is present, a head-neck osteoplasty to restore the offset between the head and neck is worthwhile.
In unilateral cases prophylactic pinning of the unaffected side is justified because the incidence of bilateral involvement is as high as 30 per cent.
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