Sacral Fractures

Raj Gala

Andrew H. Milby

Keith Michael

Illustrative Case 1

A 29-year-old male with no past medical history sustained a skydiving injury after a hard landing (Figure 35-1). In the emergency department (ED), he complained of severe low back pain and left leg pain. He was neurologically intact. Workup revealed multiple injuries including a left femoral shaft fracture and a pelvic ring injury with pubic symphysis diastasis, right pubic rami fractures, and bilateral sacral fractures. Imaging of the pelvis showed kyphosis at S2 with lumbopelvic dissociation from an H-type sacral fracture (Figures 35-2 and 35-3).

Figure 35-1 ▪ A, The anteroposterior pelvic x-ray demonstrates widening of the pubic symphysis with right superior and inferior pubic rami fractures. There is suggestion of disruption of the bilateral sacral ala, as well as a fracture in the right sacroiliac joint. B, The sagittal slice of the pelvic CT shows the fracture and kyphosis at S2.

Figure 35-2 ▪ A-C, Axial cuts from the pelvic CT more clearly show the bilateral sacral fractures as well as the right-sided sacroiliac (SI) joint involvement at the posterior aspect. The sacral fractures involve the foramen on the left and are lateral to the foramen on the right. The more distal cut (C) demonstrates that the vertical portions of the fracture extend past the level of the SI joint into the nonweight-bearing portion of the sacrum.

Figure 35-3 ▪ A-B, Coronal views from the pelvic CT scan show the vertical nature of the bilateral sacral fractures, both at the weight-bearing portion of the sacrum (A) and more distally (B).

Indications for Surgery

Lumbopelvic dissociation from H-type sacral fracture
Pelvic instability with anterior pubic symphysis disruption and right sacroiliac (SI) joint disruption

Radiographic Assessment

Obtain anteroposterior (AP), inlet, and outlet x-rays when evaluating pelvic ring injuries. The inlet view can show disruption of the SI joints and rotation of the hemipelvis. Sacral fractures and foramen involvement are best seen on the outlet view.
A pelvic CT scan is essential for pelvic and sacral fracture characterization. Review of axial, sagittal, and coronal slices is important to understand the fracture morphology. If possible, creating three-dimensional reconstructions can help identify fracture patterns to avoid missing unstable injuries (Figures 35-4 and 35-5).

Figure 35-4 ▪ Diagram of weight-bearing force through the lumbar spine into the sacrum and pelvis.

Figure 35-5 ▪ A-D, Illustration of variants of U-type sacral fractures that result in spinopelvic instability.

Positioning

If starting supine, as in illustrative case 1, a bump under the proximal sacrum can help reduce the kyphosis through the fracture.
In this case, the pelvic ring was stabilized first. The pubic symphysis underwent open reduction and internal fixation (Figure 35-6). This was followed by fixation of the SI joints and sacrum with placement of a percutaneous transsacral screw (Figure 35-7).
Next for the spinopelvic fixation, position the patient prone on a radiolucent Jackson frame with appropriate padding. Relative hyperextension of the hips aids in reducing the kyphosis in the sacral fracture.