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

Septic sacroiliitis

Case contributed by Heba Abdelmonem
Diagnosis almost certain

Presentation

Pain and right sciatica. CBC shows leukocytosis with elevated ESR.

Patient Data

Age: 20 years
Gender: Female
mri

The following abnormalities are detected within the right sacroiliac joint:

  • edema of both joint surfaces displays low T1 and high T2 signals
  • widening of the right joint space more prominent inferiorly distended with fluid
  • accompanied huge fluid component is tracking from the inferior aspect of the joint towards the right iliac muscle that appears edematous and enlarged with intramuscular fluid-filled pocket measures 77 x 46 x 90 mm exerting medial displacement of both the right external iliac vessels as well as right psoas muscle
  • abnormal edema of the right iliac crest bone marrow as well as the overlying gluteus medius and minimus muscles
  • abnormal bone marrow edema of the right aspect of the sacrum with the involvement of the right S1-S2 and S2-S3 neural foramen and nerve roots with the inflammatory process
  • DWI shows restricted diffusion of the whole process

Bilateral small inguinal lymph nodes.

Case Discussion

The case demonstrates neglected septic arthritis of the right sacroiliac joint with resultant intramuscular abscess formation and involvement of the sacral exiting neural foramina. Bacterial arthritis of the sacroiliac joint is relatively unusual and accounts for 1% to 4% of all septic arthritis cases.

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.