Slipped upper femoral epiphysis

Clinical History

The patient complained of limping while walking of three weeks' duration. Plain x-rays show osteopenia of the affected joint, physeal plate widening and irregularity, a decrease in epiphyseal height and a positive Klein's line.

Imaging Findings

The patient complained of limping while walking of three weeks' duration. He had no fever or history of trauma at time of onset. On examination he lay with his foot externally rotated. The range of movement in the hip was decreased in internal rotation and flexion. Movement caused pain.

Plain x-rays show osteopenia of the affected joint, physeal plate widening and irregularity, and a decrease in epiphyseal height in the centre of the acetabulum in the left hip. A positive Klein's line or Trethowan's sign is present (Figs 1a and 1b).

A Klein's line is defined as a straight line drawn along the superior basal margin of the femoral neck on the anteroposterior radiograph. Normally this line intersects the lateral aspect of the epiphysis. As progressive displacement of the epiphysis occurs the amount of Klein line that intersects the epiphysis decreases, compared with the univolved hip. Eventually, the line completely misses intersection with the proximal femoral epiphysis.

The earliest sign of slip is the metaphyseal blanch sign of Steel, which is a crescent shaped area of increased density overlying the metaphysis adjacent to the physis seen on anteroposterior radiogram.

In this patient FBC and renal function were normal. Thyroid function tests suggested hypothyroidism.

Discussion

Slipped upper femoral epiphysis (SUFE) is normally seen in children between the ages of 11 and 15. It is more common in boys than girls (2:1 ratio). The typical clinical presentation is with pain in the knee or medial thigh. It is important to take both anteroposterior and frog leg lateral views of the pelvis to demonstrate an actual slip.

Bilateral involvement of the hips is found in approximately 25% of cases: however, CT scans have shown the incidence of bilateral involvement to be much higher, up to 50%.

When a patient presents with SUFE at an age outside the normal range one should strongly consider an underlying endocrine or systemic disorder, such as primary or secondary hypothyroidism, pan-hypopituitarism, hypogonadal conditions or renal osteodystrophy.

The hypothyroid child is short and obese with a round, fat face. The hair is sparse and coarse and the skin is dry and thick. The tongue is enlarged and the dentition is often deciduous. Up to 25% of cases have sub-clinical hypothyroidism.

Hypothyroidism is one of the indications where prophylactic fixation is recommended to prevent slip of the femoral epiphysis on the unaffected hip. In this case the child had a cannulated screw inserted on the left hip and a prophylactic cannulated screw inserted on the right hip (Figs 2a and 2b).

Differential Diagnosis List

Final Diagnosis

Slipped upper femoral epiphysis (SUFE)

URL:	https://www.eurorad.org/case/1261
DOI:	10.1594/EURORAD/CASE.1261
ISSN:	1563-4086