A procedure that depends on diagnostic discipline
SI joint fusion can work very well in the right patient and be entirely misplaced in the wrong one. That is because SI joint pain overlaps with lumbar and hip pathology. The operation should never be the first answer to vague low-back pain.
The work before surgery matters more than the hardware itself. The history, physical exam, response to injections, and overall spine context have to point consistently toward the SI joint.
When non-operative care is no longer enough
Most patients start with physical therapy, medication, activity modification, and injections. Surgery only belongs in the plan when those efforts have been meaningful and the diagnosis has held up under scrutiny. That is especially true in patients who have had prior lumbar fusion, where adjacent or compensatory pain patterns can muddy the picture.
If the diagnosis is solid, SI joint fusion can reduce pain by limiting the abnormal motion of the joint rather than continuing a cycle of temporary symptom suppression.
What success looks like
The best outcomes usually come when patients can clearly identify the pain pattern before surgery and can tell, even early in recovery, that the familiar source has changed. Recovery still requires time and activity guidance, but the operative target should feel specific from the start.
The purpose of fusion here is not to generalize. It is to solve a confirmed biomechanical pain generator.