Determination of bone density in patients with sacral fractures via CT scan

Gold standard to diagnose osteoporosis is standard dual-energy X-ray absorptiometry (DXA). CT is a standard diagnostic tool to detect injuries to the pelvic ring. The aim of the study was to collect information on bone density without DXA by determination of Hounsfield units (HU) in CT scans of patients with sacral fractures, to draw conclusions on the prevalence of osteoporosis in patients admitted to the investigating institution.

Is the determination of HU in CT scans a useful method to gain more information about bone density in patients with sacral fractures?

We performed a retrospective analysis of all patients treated from 2004-2014 with sacral fractures confirmed with a CT scan. A total of 531 patients (398 female, 133 male) were included in the study. Bone density was measured with CT scans in Hounsfield units in vertebral body L5. The assessment was performed by placing a single oval over the trabecular bone in the axial view. In the sagittal plane, the correct position in the middle of the vertebral body was checked. As in previously published studies, we defined bone of less than 100 HU as osteoporotic, 100-150 HU as osteopenic and above 150 HU as normal.

In 71.6% of the patients, bone density was reduced. Seventy-five percent of patients aged 65 or more exhibited manifest osteoporosis. With each additional year of age, bone density decreased by 2.7 Hounsfield units (p˂0.001). Female patients were predominant in the patient group with osteoporotic bone (p˂0.001).

There is significant prevalence of reduced bone density in the investigated patient group. The methodology used in this study is an uncomplicated procedure to further assess bone quality in patients with fractures of the pelvic ring. Fractures of the posterior pelvic ring in women over 65 years with low-energy trauma are most probably osteoporotic.

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