What is the best way to x-ray the SIJ?
I was reviewing some old x-rays of the SIJ before and after correction and in one of them the patient was lying at an odd angle because she was in so much pain that she could not lie flat. That angle demonstrated that the joint surfaces were incongruent, they did not match one against the other. I believe that you can demonstrate SIJD with plain films, but not A/P, lateral or oblique. It must be done from the back or front with the x-ray aimed at the planar surfaces. This may require two procedures for each joint, because the S1 segment is at a different angle from the S3 segment. For instance, to visualize the right SIJ from the back, I think that the x-ray should be taken from an angle of about 20 degrees medial from sagital for the S1 segment and about 5 degrees lateral from sagital to visualize the S3 segment. Simply look for incongruity in how the ilial surface of the SIJ lies against the sacral surface of the SIJ. You might be able to visualize the disruption at the posterior asp
