Which statement about the diagnostic AP sacroiliac joints radiograph is true?

• A. It shows only the sacroiliac joints
• B. It shows only the L5-S1 disk space
• C. It shows both sacroiliac joints and the open L5-S1 disk space
• D. It does not show any disk space

Answer: (C)

In an AP sacroiliac joints radiograph, the goal is to visualize the sacroiliac joints while also capturing the adjacent lower lumbar region. When positioned correctly and with the field wide enough, this view shows both sacroiliac joints and the L5-S1 disk space. The L5-S1 disk space sits just above the sacrum, so a properly made AP sacroiliac view often reveals an open L5-S1 space, which is important for assessing both the SI joints and the adjacent intervertebral disk.

So this view isn’t limited to just the sacroiliac joints, and it can demonstrate the L5-S1 disk space clearly when technique and positioning are appropriate.