Sacroiliac (SI) Joints

Spine and Pelvis

34 Sacroiliac (SI) Joints

hip bones (also known as os coxae, ossa coxae, or innominate bones) sacrum, auricular surface, coccyx, ilium, ischium, pubis

CR Location

[Part], PA or AP –

Evaluation Criteria

AP Axial Image Criteria: SI joints should be centered to the image. The L5-S1 joint space should be

open.

Posterior Obliques Image Criteria: SI joints should be open. The ala of the ilium should not overlap sacrum.

.

Why put a sponge under the patient’s knees on the AP axial projection of the SI joints?
- Support under the knees straightens out the lumbar spine.
What will having the ASIS’s equidistant to the table top ensure?
- If the ASIS’s are equidistant to the table top the pelvis is not rotated.
Why would males require less CR angle on the AP Axial projection than females?
- Males have flatter, less rounded pelvises.
How do you open the L5 – S1 joint space on the AP Axial image?
- Angle the CR 30 – 35º cephalad.
Which oblique should be done to evaluate the SI joints?
- Both obliques should be done for comparison.
Which side is of interest on posterior oblique SI joints?
- Posterior obliques open the joint on the side up.
If you were asked to perform anterior oblique SI joint images, which joint would be best demonstrated?
- The SI joint on the side down is best demonstrated on anterior obliques.
What kind of joint is the SI joint?
- Amphiarthrodial – slightly moveable.