Would an MRI of the SI joints show a subluxation?

Question

Especially if the subluxation is minor - or is a CT scan more suitable? I was unexpectedly pushed forward quite hard on the mid-left of my back while on a rowing machine when trying to reach for the handlebar and felt about two normal crackles to the left of my lower back with no pain at the time. To my recollection it felt about three or four inches to the left of my beltline. Could the crackling sensation have just been a ligament passing over a ligament, or just the SI joint? Even if it was the SI joint, it doesn't necessarily mean that it has subluxated does it? I went to a physio and orthopedic surgeon and from what they could see without measurements, my hips seemed aligned. I just don't know if it’s worth going through a pelvis MRI that I asked for if I'm not experiencing a lot of pain. After three weeks, I noticed the lower part of my left calf muscle does have a mild stretching/painful sensation when pushing off it, could that be related or could it be something else? Thanks

Answer 1

CT is better at looking at any bony abnormality, but has high radiation exposure. MRI is better at looking at soft tissue abnormalities.(ligaments, tendons, muscles, and also subtle bone edema (bruises of the bone) and has no radiation.

Answer 2

No, an MRI or CT scan won't pick up the subluxation.  Try not to think of subluxation as an anatomical displacement.  Its not clearly seen as a bone "out of place".  Rather it is a neurological reflex that happens as a result of impingement of a nerve (quite different from "pinching" of a nerve).  What you are experiencing is lack of function of a muscle (and probably compensation of another).  I would suggest seeing a chiropractor or physical therapist.  Most likely a chiropractor.