The sacroiliac joints sit where the base of the spine meets the pelvis, one on each side. They are not part of the spinal column, they are not usefully assessed on a lumbar MRI, and the diagnosis is made by numbing the joint rather than by scanning it — which is why the pathway below has a test in the middle of it.
Each step has to pass before the next one is on the table. Most people stop at the second.
A cluster of provocative tests that stress the joint in different directions. Three or more positive is what makes the joint a real suspect — one is not enough, because any single test also stresses the hip and the lower lumbar levels.
Anaesthetic placed into the joint under image guidance. Temporary relief is the diagnosis — it is the only way to prove the pain is coming from this joint and not from the spine above it. Most insurers require it before authorising anything further.
Implants placed across the joint through a small incision on the side of the hip, under navigation. Considered only after the block has confirmed the joint and after non-operative care has been given a fair run.
Recovery figures are general ranges from the surgical literature, not a guarantee for any individual case. What applies to you depends on your imaging, your other medical conditions and how the operation goes.
Sacroiliitis, or disruption after an injury
Pain low down and off to one side, often pointed to with one finger just inside the dimple above the buttock. It can run into the groin or down the back of the thigh, and it is usually worse getting out of a car, rolling over in bed, or standing on one leg to put trousers on. It is easy to mistake for the lumbar spine and frequently is — and it is common after a lumbar fusion that ends at the sacrum, because the load the fused levels used to share now arrives at the joint below them.
That sounds obvious written down and it is the single thing most often skipped. The joint is small, deep and awkward to examine, and several conditions refer pain to exactly the same patch of skin. The block is what separates them, and a negative block is a useful result rather than a failed one — it sends the search back to the lumbar spine or to the hip with a suspect ruled out.
The index lists every procedure in one place; the approach page explains how the choice between a tube and an open exposure actually gets made, and the conditions list names what comes through the clinic most often.