Presentation
Pedestrian hit by car at 30 km/hr. Left pelvic pain.
Patient Data

Pelvic alignment is normal. Subtle loss of the left sacral foramina cortical outline suggests a sacral ala fracture. Possible left inferior pubic ramus fracture. Widened left hip joint space suspicious of a traumatic effusion. Left inferior pubic ramus fracture. Generalised bilateral hip and lumbosacral degenerative change.

The left obturator internus muscle is thickened, no pelvic sidewall haematoma.
Left sacral ala fracture lateral to the sacral foramina without significant displacement. The SI joints are not widened. Superior and inferior pubic rami fractures on the left with fracture extension into the pubic body. No widening of the symphysis pubis. The superior ramus fracture also extends into the anterior column of the acetabulum and the quadrilateral plate. The posterior column and wall are intact. Proximal femora are intact.
Impression
- left pubic rami fractures involving the acetabulum (Judet and Letournel simple anterior column type)
- left sacral ala fractures (Denis zone 1)
Case Discussion
This case is an example of how subtle sacral and acetabular fractures can be on a pelvic x-ray.