What is the degree of rotation for an AP oblique projection of the sacroiliac (SI) joints with the patient in a right posterior oblique (RPO) position?

For an AP oblique projection of the sacroiliac joints, the degree of rotation is crucial for properly visualizing the joints without superimposition. When positioning a patient in a right posterior oblique (RPO) position, the recommended rotation is 25 to 30 degrees. This angle ensures that the sacroiliac joint of the down side (in this case, the left SI joint) is in profile and clearly demonstrates its anatomy for assessment.

Rotating the patient to the appropriate degree helps achieve the desired projection where the sacroiliac joints are visualized adequately. If the rotation is less than 25 degrees, it may not provide enough visualization of the joint space. Conversely, too much rotation could obscure the anatomy or lead to misinterpretation of the images. Hence, 25 to 30 degrees is the established standard for optimal imaging in this scenario.