In addition to the provocation tests described in prior posts, part 1a here, part 1b here; the location of pain referral is useful.
Sacroiliac joint pain referral can be highly variable and present throughout the lower trunk and extremities. The research shows this as the pain can refer out from SIJ from L1-S1 ventrally and L4-S3 dorsally.
With this in mind, it is very difficult to make a diagnosis solely on this factor but Van der Wurff (2006) made some pertinent conclusions to aid in differentiating SIJ pain from other chronic LBP.
The study basically examined the outcome of double, intra-articular SIJ Joint blocks to CLBP patients. They were then labeled as responders (> 50% reduction in pain for at least one hour with lidocane and at least 4 hrs with bupivacaine) and non-responders (any outcome other than above).
Two main findings:
1. No major differences in pain referral areas in the responders and non-responders, HOWEVER
2. There were significant differences in pain referral pattern in the BUTTOCKS
–100% of non-responders felt pain in the “Tuber Area”.
–100% of responders felt pain in the “Fortin’s Area”.
-Only 10% of responders felt pain in the tuber area.
Tuber’s area = region inferolateral to ischial tuberosity
Fortin’s area = 3cm (horizontal) x 10 cm (vertical) region inferior to PSIS
The presence of pain referral in Fortin’s area and absence of pain referral in Tuber’s area can be another discrimminative factor for diagnosising SIJ, in addition to battery of provocation tests.
What do you think about these results? Do you get similiar results with your patients that you feel have pain arising from SIJ?
Van der Wurff, P., Buijs, E., Groen, G. (2006). Intensity mapping of pain referral areas in sacroiliac joint pain patients. Journal of Manipulative & Physiological Therapeutics, 29 (3), 190-195.