Imaging description

Subluxation of the hip in spina bifida, cerebral palsy, and other paralytic disorders is due to the pull of spastic hip adductors and flexors. Iliopsoas transfer is a surgical procedure designed to restore muscular balance and prevent hip dislocation by transposition of the iliopsoas muscle through a surgically created defect in the iliac bone with reattachment to the femur [1,2]. The resulting window in the iliac bone is seen at imaging as a large lucent defect that may simulate tumor (Figure 101.1).

Importance

The iliac bone defect due to iliopsoas transfer might be mistaken for a lucent bone tumor at plain radiography, although the absence of a mass at CT or MRI should prevent this misdiagnosis.

Typical clinical scenario

This defect can be seen (either unilaterally or bilaterally) in patients affected by spastic paralytic disorders such as spina bifida or cerebral palsy.

Differential diagnosis

The appearance of an iliac bone defect due to iliopsoas transfer is characteristic, and awareness of the entity should be sufficient to ensure correct diagnosis. Correlation with the surgical history should help confirm in cases of uncertainty.