Sacroiliac Joint Special Test Cluster

Description of SIJ Cluster Testing

 ‘The clinical use of orthopaedic tests for the diagnosis of sacro-iliac joint pathologies’

On other pages, the sensitivity specificity and predictive values of individual sacroiliac joint tests was discussed. This section will present and discuss the supporting literature for the use of these tests to make clinical diagnoses of SIJ pathologies.

The ability to accurately differentiate a diagnosis of sacroiliac joint (SIJ) pain is clinically important. Although debated throughout literature, it is generally accepted that 10-25% of patients who present with mechanical low back or buttock pain will have this pain secondary to sacroiliac joint pain (Simopoulos et al 2012). To be able to correctly diagnose the sacroiliac joint as a source of pain will allow clinicians to be able to deliver appropriate treatment methods to the correct patients, thereby providing the patient with a more timely recovery.

SIJ Dysfunction Gold Standard Testing

The current ‘gold standard’ for diagnosing sacroiliac pathologies is a diagnostic nerve block, whereby anaesthetic is inserted into the SIJ, under fluoroscopy guidance. Some authors argue that if the patient achieves 50-75% pain relief, on 2 occasions with short and long acting nerve block, a diagnosis of SIJ dysfunction can be made, but with caution (van der Wurff et al 2006, Berthelot (cited Maigne et al).

However, even with a gold standard there are issue reported in the literature with the injection process. Van der Wurff (2006) reported five instances of leakage of anaesthetic from the SIJ nerve blocks resulting in temporary sciatic nerve palsy. Berthelot (2004) (cited Fortin et al) also reported leakage of the contrast medium used to guide nerve block injections in 61% of patients. There is now thought that the gold standard of SIJ nerve block may not be the most appropriate (Szadek 2009) and so the IASP diagnostic criteria for SIJ pain no longer as valid as it once was. A review by Berthelot (2006) also concluded that joint injections are unreliable for diagnosing sacroiliac joint pain, however this study did not show clarity in the description of the methods used to search and screen each paper, and so the possibility of bias within the literature chosen increases, thereby raising questions as to the validity of this conclusion. This is not in agreement with a review conducted by Simopoulos et al (2012), which concluded that sacroiliac joint blocks are valid as a gold standard, however based on the literature reviewed; there could be a false positive rate of 20%.

With these factors in mind finding a method which is both cost effective and has strong enough predictive values to accurately diagnose pathologies, thereby avoiding unnecessary cost and invasive procedures, and aiding in correct treatment of patients.
These studies were evaluated against the CEBM criteria for a diagnostic reference study in order to assess the methodological quality of the studies and to review the validity of the results and conclusions made by each study.

Orthopaedic Testing of SIJ

There have been several studies investigating the reliability of using multiple orthopaedic tests compared to the ‘gold standard’ of nerve blocks (van der Wurff (2006), Laslett (2003),) and several reviews which aim to synthesise studies of this nature to guide clinical practice (Berthelot 2004)

Van der Wurff et al (2006) used a regimen of five tests (Distraction, compression, thigh thrust, Gaenslens and Patricks). The study did not provide a reference for the study on which these tests were based, however cites Kokmeyer (2000) to provide clarity on the execution of the tests. This regimen of tests was also chosen in a similar study by Laslett (2003). This study provided justification for its choice of the same five tests used by van der Wurff (2006) based on the inter-rater reliability based on Laslett and Williams (1994), with all tests having a kappa value of 0.52-0.88, showing fair to excellent reliability.

Studies also differ in the application of the reference standard of the nerve blocks. Van der Wurff et al (2006) based their injections procedure on the published literature (van der Wurff cited Schwarzer 1995), and adopted the standards set by the International Spinal Injection Society in order to measure the success of injections. This standard states that ‘a patient can be deemed to have sacroiliac joint pain should a radiographically guided injection of both long and short term anaesthetic reduce their characteristic pain’. In contrast to this, Laslett (2003) also used the injection protocol based on Schwarzer (1995), but only patients who reported an 80% relief of symptoms (based on comparing pre and post injection pain rating scales) were scheduled for a second confirmatory injection. This presents the possibility that subjects may have been recorded as having a negative response to the first injection and so not passed on to the next confirmatory injection, which may have shown a positive response. This was not the case for van der Wurff et al (2006), where all subject received both long and short term injections, thereby eliminating this possibility.

Results for sensitivity, specificity and likelihood ratios for three or more positive pain provocation tests have been found to be similar throughout the literature reviewed in this section. The results presented by Laslett (2003) and van der Wurff (2006) are displayed in Table 1.