Degeneration of Sacroiliac Joint after Instrumented Lumbar or Lumbarsacral Fusion

Degeneration of sacroiliac joint after instrumented lumbar or lumbarsacral fusion

Ha, Kee-Yong, et.al. Spine 2008;33(a):1192-1198

SI Joint Key Points:

The incidence of SI joint degeneration in patients was 75% at 5 years post-fusion, which was significantly higher than in the non-fusion group, 38.2%.
Among patients with one-segment fusion, 91% developed SI joint degeneration. Among patients with two-segment fusion, 67% developed SI joint degeneration.
Regardless of whether the fusion includes the sacrum, the SIJ is influenced by increased mechanical stress arising from lumbar/lumbosacral fusion.

Introduction: According to recent studies, among patients who reported lower back pain (LBP), it was demonstrated that lower back and buttock pain actually originated in the SI joint approximately 15% of the time.

Study Design: Prospective cohort study followed 39 consecutive patients who received fusion between July 1997 and October 1998. These patients were recruited before surgery and evaluated prospectively over a 5-year period. 32 patients remained in the study (10 males, 12 females; mean age of 64 years; mean follow-up period of 87.5 months). 22 patients had lumbar fusion and 10 lumbosacral fusion. As a control group, 34 age-matched normal individuals were recruited.

Assessment of SI Joint: CT scans were performed before surgery and 2 weeks after surgery. On the CT scans, a diagnosis of SIJ degeneration was based on the presence of one or more of the following: sclerosis, erosion, osteophyte, joint space narrowing, intraarticular bone fragment, and subchondral cyst.

Results: The incidence of SIJ degeneration in the fusion group was 75%, which was significantly higher than in the control group, 38.2%. One-segment fusion was performed in 11 patients with 10 (91%) developing SIJ degeneration. Two-segment fusion was performed in 21 patients, and SIJ degeneration developing in 14 (67%).

Discussion: SIJ degeneration appeared approximately twice as much in the fusion group as in the control group (75% to 38%). Although degeneration of the SIJ can be considered part of the normal aging process, this study showed that lumbar/lumbosacral fusion accelerated degenerative changes in the SIJ. The SIJ is influenced by the increased mechanical stress arising from lumbar/lumbosacral fusion.

Conclusion: Posterolateral lumbar/lumbosacral fusion can be a cause of SIJ degeneration. SIJ degeneration develops more often in patients undergoing lumbosacral fusion, regardless of the number of fusion segments.