Plain radiographs have been notoriously insensitive for posterior pelvic ring and sacral fractures. In the elderly, there is a high mortality rate associated with prolonged immobilization for pelvic fractures. Furthermore, recent advances in orthopedics have expanded the potential treatment options for sacral fractures, which makes their detection that much more important.

Schicho et al performed a retrospective review of 233 consecutive patients (75 years or older) who presented to a level I trauma center with symptomatic blunt pelvic trauma.² Only six plain films showed a sacral fracture compared to 56 of CTs performed. The sensitivity, specificity, negative predictive value, and positive predictive values of plain films for sacral fractures were 10.5 percent, 99.4 percent, 77.8 percent, and 85.5 percent, respectively, and for pubic bone fractures they were 65.7 percent, 90.3 percent, 76.8 percent, and 84.3 percent, respectively. Sacral fractures were associated with pubic bone fractures in 75 percent of cases and with acetabular fractures in 23.3 percent. The average age for those with sacral fractures was 85 years, and 88 percent were women.

Especially in the elderly with symptomatic blunt pelvic trauma, CT may be high-yield and very useful. Those at greatest risk were women in their 80s. In high-risk symptomatic patients, the insensitivity of plain films questions their use at all. When it comes to the elderly pelvis, CT may be the single most important test to order.

References

1. Hutchinson BD, Navin P, Marom EM, et al. Overdiagnosis of pulmonary embolism by pulmonary CT angiography. Am J Roentgenol. 2015;205(2):271-277.
2. Schicho A, Schmidt SA, Seeber K, et al. Pelvic X-ray misses out on detecting sacral fractures in the elderly – importance of CT imaging in blunt pelvic trauma. Injury. 2016;47(3):707-710.