Sacroiliac joint pain after lumbar fusion: A study with anesthetic blocks

J. Y. Maigne, M.D. and C.A. Planchon, M.D. - European Spine Journal 2005; 14, No. 7: 654-658.

SI Joint Key Points:

  • Study confirms that the SI joint can play a significant role in pain persisting after lumbar fusion.
  • Sacroiliac anesthetic blocks are considered the gold standard for the diagnosis of sacroiliac syndrome.
  • Study shows that, within a selected population with post-fusion low back pain, the SI joint is the likely source of pain in 35% of cases.

Introduction: Lumbar surgical fusion is restricted to patients with severe chronic lower back pain. However, despite a careful selection of patients, the failure rate ranges from 10-30%. Sacroiliac anesthetic blocks are considered the gold standard for the diagnosis of sacroiliac syndrome.

Patients: Prospective study began in 1996. 61 patients treated by lumbar fusion now had persistent back pain after surgery. 45 had pain meeting the criteria to be in the study.Investigation: 5 blocks were unsuccessful which left 40 patients for the study: 14 males, 26 females, mean age of 48 years. There were 36 posteriolateral fusions and four anterolateral fusions. Fourteen blocks (35% of the patients, 95% CI: 20.2 – 49.8%) were positive.

Discussion: Study shows that, within a selected population of post-fusion low back pain patients, the SI joint is the likely source of pain in 35% of cases. The major limit of the results is the lack of an absolute value of the sacroiliac block, even though it is considered the gold standard for sacroiliac syndrome. Despite the limitations, the 35% ¬gure indicates that the SI joint is a signi¬cant source of low back pain. The result can be compared with the nonsurgical series of Schwartzer et al. (30% positive blocks) and Maigne et al. (35% and 18.5% of positive screening and con-rmatory blocks respectively).

Of the 26 patients with a negative SI-block, three had major degenerative disease of the dorsal arch below the fusion level, which was clearly seen when using this technique. In the remaining 23 patients, investigations with other techniques revealed five cases of discogenic pain; in the other 17, no definite cause of the pain could be identified.

Conclusion: Study confirms that the SI joint can play a significant role in pain persisting after lumbar fusion. The anesthetic block under  fluoroscopic control remains the gold standard.