Potential Cause Of SI Joint Dysfunction
Up to 32% of persistent low back pain after a technically successful lumbar fusion may be attributed to the SI joint. Fusion of the lumbar spine alters its natural movement and ability to absorb shock, resulting in increased load or stress on the adjacent lumbar segment and potential for degeneration. Sometimes this “transfers” forces to the SI joints, especially when prior lumbar fusion included the L5/S1 level.
With the rise in lumbar fusion surgeries over the last 10 years, the SI joint has received more attention when patients who have previously undergone these procedures complain of seemingly “new” pain that appears to be coming from the SI joints. There are multiple factors that may explain this phenomenon, including an increase in the mechanical load the SI joints are forced to bear after lumbar fusion surgery, complications with bone grafting of the iliac crest (hip bone), or a misdiagnosis of an underlying Sacroiliac Joint Syndrome that was present but not detected before surgery. But no matter the reason, imaging studies typically show more frequent degeneration of the SI joint in patients who have undergone a previous lumbar fusion than in those patients who haven’t.
Undue Stress on SI Joints after Lumbar Fusion Surgery
When visualizing the anatomy surrounding the areas treated by lumbar fusion surgery, many surgeons are used to looking at the intervertebral discs next to the fusion as possible pain generators. But when the L5/S1 level is fused, despite the fact that the SI joint is directly adjacent to the segment that was fused together, some physicians do not consider the SI joint as the cause of pain. In the past, several clinical studies of other spinal disease after lumbar fusion procedures have demonstrated increased mobility in adjacent segments and as a result, increased stress on these mobile structures, including the facet joints and discs. Drawing upon these conclusions, study authors have acknowledged that this similar response could also explain the resulting pain in the SI joint that some patients experience after lumbar fusion. Additionally, some study authors report that the incidence of SI joint pain after lumbar fusion may be higher in patients who have undergone a fusion down to the S1 vertebra than in those whose fusion is extended to the L5 vertebra.
Existing SI Joint Dysfunction Before Lumbar Fusion
It is possible that a misdiagnosed sacroiliac joint problem is the cause of pain prior to lumbar fusion surgery; therefore it lingers after surgery when the source of the original pain has not been addressed.
Multiple studies have indicated that the SI joint is a potential source of continuous pain after lumbar fusion surgery. In order to properly diagnose the problem, thorough physical examination, imaging and diagnostic injections are necessary. Though conservative treatment options are a first choice in treating the pain, surgical treatment may be an option for some patients. To find a spine specialist in your area, skilled in helping you get to the bottom of your pain after lumbar fusion, please visit our Find a Doctor page.