Does the presence of cranial contrast spread during a sacroiliac joint injection predict short-term outcome?

Comparison between intra-articular and combined intra- and periarticular sacroiliac injection: a prospective randomized controlled clinical trial

BACKGROUND

Sacroiliac joint dysfunction is one of the most common causes of low back pain. The aim of our study was to determine whether combined injection (intra and periarticular) of sacroiliac joint provides greater pain relief than intra-articular injection.

METHODS

This is a randomized controlled trial between two groups. The first group involved thirty patients treated with combined injection (intra- and periarticular) of a mixture of methylprednisolone acetate 40 mg and local anesthetic into a symptomatic sacroiliac joint. The second group (30 patients) received the same mixture only intra-articular. Diagnostic block was done for all cases. All patients failed to respond to medical treatment before proceeding to the injection procedure.

RESULTS

Over 6 months of follow-up, there were statistically significant improvements in patients who received combined sacroiliac joint injection according to pain Visual Analog Scale (VAS) compared with intra-articular group. Comparing both groups, there was significant difference in the 1-month VAS (one month after the procedure) as the P value was 0.010, and in the 6-month VAS (6 months after the procedure) as the P value was 0.007. There was no significant difference in the pre-VAS (P value was 0.795) and immediate post-VAS (one week after the procedure) as the P value were 0.145. No complications were reported after the procedure.

CONCLUSIONS

Although both groups provide statistically significant pain relief, patients who received combined sacroiliac joint injection have significantly greater clinical improvement as regard to those who received only intra-articular injection.

Sacroiliac innervation

PURPOSE

To investigate the innervation pattern of the sacroiliac region, especially with regard to the sacroiliac joint (SIJ). Dorsal SIJ innervation was analyzed and described. Our main hypothesis was that nerves reach the SIJ dorsally, passing ligamental compartments, as this would explain dorsal SIJ pain.

METHODS

To examine sacroiliac innervation, we followed the nerves in over 50 specimens over several years. Plastinated slices were evaluated, nerves in the region were stained histologically, and the data were summarized as 3D models.

RESULTS

The Rami communicans and posterior branches of the spinal nerves and their branches that form a dorsal sacral plexus and communicating branches, together with corresponding vessels, were observed to form neurovascular bundles embedded by tiny fatty connectives in gaps and tunnels. Branches of L5-S1 pass the inner sacroiliac ligaments (the interosseous sacroiliac ligament and axial interosseous ligament). The outer sacroiliac ligaments (posterior sacroiliac ligaments, long posterior sacroiliac ligament, sacrotuberal ligament, thoracolumbar fascia) are passed by the S1-S4 branches. However, although the paths of these nerves are in the direction of the SIJ, they do not reach it. It is possible that impingement of the neurovascular bundles may result in pain. Moreover, the gaps and tunnels connect to the open dorsal SIJ.

CONCLUSION

Our findings suggest that Bogduk's term "sacroiliac pain" correlates to "sacroiliac innervation", which consists of "inner-" and "outer sacroiliac ligament innervation", and to ventral "SIJ pain". The watery gaps and tunnels observed could play a significant role in innervation and thus in the origins of SIJ pain.

LEVEL OF EVIDENCE

Individual cross-sectional studies with consistently applied reference standard and blinding.