What is the typical degree of body rotation for the oblique projection of the sacroiliac joints?

What is the typical degree of body rotation for the oblique projection of the sacroiliac joints?

• A. 10-15
• B. 15-20
• C. 20-25
• D. 25-30

Answer: (D)

Visualizing the sacroiliac joints works best when the pelvis is placed in a moderate obliquity so the joint surfaces face the image receptor. The SI joints lie at an angle in the pelvis, so turning the body toward the side of interest brings the joint into profile, opens the joint space, and reduces overlap from the ilium and lumbar spine. If rotation is too shallow, the joint is obscured by surrounding structures; if rotation is excessive, the joint may distort or project out of the plane. Therefore, a moderate rotation toward the side of interest is used for this projection.

Visualizing the sacroiliac joints works best when the pelvis is placed in a moderate obliquity so the joint surfaces face the image receptor. The SI joints lie at an angle in the pelvis, so turning the body toward the side of interest brings the joint into profile, opens the joint space, and reduces overlap from the ilium and lumbar spine. If rotation is too shallow, the joint is obscured by surrounding structures; if rotation is excessive, the joint may distort or project out of the plane. Therefore, a moderate rotation toward the side of interest is used for this projection.