IMPORTANT: We currently have a number of bugs related to image cropping and are actively trying to resolve them. In the meantime, we have disabled cropping. Apologies for any inconvenience. Stay informed: radiopaedia.org/chat

Pelvic fractures (Malgaigne fracture)

Case contributed by Andrew Dixon
Diagnosis certain

Presentation

Motorbike accident.

Patient Data

Age: 55 years
Gender: Male

This case featured in our 2016 Trauma Radiology Course which is now available to view online.

Trauma Series

x-ray

Fracture of the right superior and inferior pubic rami and the right sacral ala. The pubic symphysis and sacroiliac joints remain normally aligned. 

Pelvic CT

ct

CT confirms fractures of the right superior and inferior pubic rami with associated hematoma within the right pelvic side wall / obturator internus muscle. There is also buckling of the anterior cortex of the right sacral alar lateral to the sacral foramina consistent with a sacral fracture in Dennis zone 1. Combination of the pubic rami and sacral ala fracture is consistent with a vertical shear mechanism also known as Malgaigne fracture. There is a small volume of pre-sacral hemorrhage seen in association with the sacral fracture. Presence of pre-sacral fluid on a trauma CT is a reliable sign that there will be a sacral fracture and should always prompt close investigation of the bones. 

Annotated image

On the x-ray image the white arrow indicates abrupt loss of the normal sacral foraminal margin on the right consistent with fracture. The yellow arrows indicate the superior and inferior pubic rami fractures. The CT image shows small volume pre-sacral hemorrhage which is a finding that is almost always a sign of sacral fracture in trauma patients. 

Case Discussion

This case demonstrates a combination of right pubic rami and sacral ala fractures consistent with a vertical shear mechanism of injury (Malgaigne fracture). Nicely seen on the plain film is subtle loss of the normal sacral foraminal margin indicating sacral ala fracture. On the CT, there is a good example of small volume pre-sacral hemorrhage.     

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.