Insufficiency fractures of the ilium.

Insufficiency fractures often occur in the sacrum and pubic rami but have rarely been reported in the ilium, where their frequency may be underestimated. We studied a series of 14 patients with insufficiency fractures of the ilium. Six patients had an oblique fracture through the wing of the ilium (which was bilateral in one case) and nine a supraacetabular fracture, with in one case a superomedial extension into the iliac wing. The initial radiographs were normal, making the diagnosis difficult. A linear area of sclerosis along the fracture line was seen after a few weeks. The radionuclide examination provided early detection and often demonstrated multiple insufficiency fractures (mean 2.1 per patient). Computed tomography missed some of the fractures, whereas magnetic resonance imaging proved a reliable diagnostic tool, especially in patients with supraacetabular fractures, showing the fracture as a line of low signal surrounded by an area of edema whose contours were exactly the same as those of the hyperactive focus on the radionuclide scan. Osteoporosis was a causative factor in all 14 patients and vitamin D deficiency in seven. Also, three patients had a history of fluoride therapy.