Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android. Learn more here!

An 18-year-old woman was an unrestrained back seat passenger of a car that was struck on the passenger side by another vehicle. The automobile was significantly damaged on the side of the impact. None of the other occupants of the car were injured. She was removed from the vehicle and immobilized by the ambulance crew.

In the ED, she was alert and oriented, although anxious and crying. The patient did not think she had lost consciousness, although she could not recall all of the details of the collision. Her only complaint was of lower back pain.

Her blood pressure was 110/70 mm Hg and pulse 100/min. There were several superficial abrasions and glass fragments on her forehead. Her neck, chest and abdomen were non-tender. There was tenderness over the lower lumbar spine. Compression of her pelvis caused pain but there was no abnormal mobility.

  • What fractures are seen on her pelvis radiograph (Figure 1)?
  • What was the mechanism of injury responsible for these fractures?
  • What other injuries would you suspect in this patient?


Because the pelvis is a nearly rigid ring-like structure, any single break in the pelvis, especially if displaced, should be accompanied by another break elsewhere in the pelvis. If a second break is not immediately obvious, it must be carefully sought.

In Patient 6, there are bilateral pubic rami fractures (Figure 2). This anterior fracture fragment, owing to its characteristic appearance, is sometimes referred to as a butterfly fracture (Figure 3). One mechanism that can cause this injury is anterior impact to the perineal area by an object that is straddled by the patient’s legs—a straddle fracture (Figure 4). These bilateral pubic rami fractures constitute the two breaks in the pelvic ring; an additional fracture need not be present. However, anterior impact is not the mechanism of injury in many butterfly-shaped pelvic fractures and was not the mechanism of injury in this patient.

Figure 2

Detail of the patient’s pelvis radiograph showing bilateral pubic rami fractures (arrows). Slight irregularity at the pubic symphysis is normal. Arrowhead–fragment of windshield glass lying on the stretcher.

Figure 3

A “butterfly” fracture fragment (bilateral pubic rami fractures) produced by an anterior impact on the pubic bone.

Figure 4

Straddle fracture. This mechanism of bilateral pubic rami fractures is actually uncommon.

There is also a fracture through the right sacral wing (Figure 5).

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.