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Abdominal CT: pelvic fractures

Pelvic fractures are common in high velocity trauma, and the pelvis has predictable patterns of injury due to its ring structure. It is helpful to think of pelvic fractures like breaking a pretzel – you cannot break it in just one place.

If you see one pelvic fracture, you will find others
If you see one pelvic fracture, you will find others

In this lesson, we will consider three types of pelvic fractures:

  • Pubic ramus fractures
  • Sacral fractures
  • Acetabular fractures
Abdominal CT body wall injury pelvic fractures

Pubic ramus fractures

A common fracture pattern is a fracture of the pubic ramus involving both small bones of the pubis, the superior and inferior pubic rami. The pubic rami connect in the midline to form the pubic body

Abdominal CT pelvic fractures pubic rami 2

Below is a 3-dimensional (3D) image of the pelvis in a patient who has fractured both the left and right sides of the pelvis. Let’s be sure to remember that this ring will fracture in two places and look for injuries in both superior and inferior pubic rami in the axial images.

Abdominal CT pelvic fractures pubic rami 3
Superior pubic ramus injuries

For the superior pubic ramus injuries in this patient, the right side involves part of the pubic body. The left side is higher and involves the anterior acetabulum.

Abdominal CT pelvic fractures superior pubic ramus injuries
Inferior pubic ramus injuries

For the lower pubic ramus, the right fracture is relatively subtle with a thin cortical defect. But the left fracture is displaced and slightly offset.

Abdominal CT pelvic fractures Inferior pubic ramus injuries

Sacral fractures

In severe trauma with compressive forces, there can be fractures involving the sacrum and sacroiliac joint, often with either widening of the pubic symphysis or fracture of the pubic ring.

Abdominal CT sacral fractures

Sacral fractures typically follow a vertical orientation along the bone. On CT, sacral fractures look like irregular lines and cortical defects, which means abnormal dark lines through the dense outer bone indicating fracture.

Abdominal CT pelvic fractures sacral fracture

These injuries can also be associated with widening of the sacroiliac joint. In the case below, there is injury to the left sacrum with cortical irregularities and linear defects extending deeper into the trabecular bone. The sacroiliac joint is slightly wider on the left than on the right, but it is a fairly subtle difference in this case.

Abdominal CT pelvic fractures sacral fracture 2

Acetabular fractures

Fractures of the acetabulum occur when the femoral head is driven into the pelvis.

Abdominal CT body wall injury pelvic fractures acetabular

Acetabular fractures are best seen on the coronal images, where we can see the familiar appearance of the hip joint. In this example, there is a large displaced cortical defect in the left acetabulum, as well as a fracture of the iliac bone.

Abdominal CT body wall injury pelvic fractures acetabular 2

This is an edited excerpt from the Medmastery course Abdomen CT: Trauma by Michael P. Hartung, MD. Acknowledgement and attribution to Medmastery for providing course transcripts

References

Radiology Library: Abdominal Trauma. Musculoskeletal injuries

Abdominal CT interpretation

Assistant Professor of Abdominal Imaging and Intervention at the University of Wisconsin Madison School of Medicine and Public Health. Interests include resident and medical student education, incorporating the latest technology for teaching radiology. I am also active as a volunteer teleradiologist for hospitals in Peru and Kenya. | Medmastery | Radiopaedia | Website | Twitter | LinkedIn | Scopus 

Dr Adam Brown LITFL Author

MBChB (hons), BMedSci - University of Edinburgh. Living the good life in emergency medicine down under. Interested in medical imaging and physiology. Love hiking, cycling and the great outdoors.

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