Is It Useful to Repeat Sacroiliac Joint Provocative Tests Post-Block?

Objective.  To evaluate the diagnostic usefulness of repeating sacroiliac joint (SIJ) provocative tests post-block. Design.  Thirty-four patients with suspected unilateral mechanical SIJ pain participated. Eleven had confirmed SIJ origin pain (>79% pain relief with fluoroscopically guided comparative local anesthetic intra-articular blocks), whereas 23 were confirmed not to have SIJ origin pain (<80% pain relief with a single local anesthetic intra-articular block). Six SIJ provocative tests were performed 30 minutes prior to and following the blocks. Sensitivity, specificity, and likelihood ratios were calculated for subjects who had three or more positive pre-block SIJ provocative tests and for subjects in whom the majority of the SIJ provocative tests converted from positive to negative (normalized) post-block. Results.  The sensitivity, specificity, and likelihood ratios for subjects with three or more positive pre-block SIJ provocative tests were 0.82, 0.57, and 1.9, respectively (P = 0.04). For subjects in whom the majority of the SIJ provocative tests normalized, the sensitivity was 0.89, specificity 0.30, and likelihood ratio 1.3 (P = 0.3). Conclusion.  Multiple positive pre-block SIJ provocative tests have diagnostic utility however post-block normalization of SIJ provocative tests does not.