Curr Rev Musculoskelet Med (2009) 2:10–14 11 Fig. 1 Radiofrequency ablation of the medial branch nerves to the right SIJ: L5, S1, S2, S3 maneuvers. Lasett et al. [11] conﬁrmed some utility to clinical exam by providing evidence that employing a McKenzie evaluation to exclude discogenic pain and a composite of three or more SIJ pain provocation tests has clinically useful diagnostic accuracy when compared with a reference standard of double block. While the clinical exam may prove inaccurate, imaging is equally so. Plain ﬁlms X-rays are rarely diagnostic in SIJ pain syndrome. Degenerative changes of the SIJ seen on X- ray have proven clinically insigniﬁcant because they are commonly observed in asymptomatic individuals. Simi- larly, computed tomography (CT), although able to demonstrate previously established bony changes, offers little diagnostic value. A study by Vogler et al. [12] of 45 asymptomatic subjects showed that over 24% of those over 50 years old showed degenerative SIJ changes on plain ﬁlm and similar results using CT. Magnetic resonance imaging (MRI) enables visualization of the soft-tissue anatomy of the SIJ and the ability to see septic, inﬂam- matory, or stress-related changes in the bones. However, for typical SIJ pain syndrome, MRI speciﬁcity is only 54% [13]. MRI can, however, be a valuable tool for helping exclude disk herniation, notably for L5–S1 level pathology. Bone scans and single photon emission computed tomog- raphy (SPECT) have similarly shown poor sensitivity, at 12.9–65% and 9.1%, respectively [13–16]. As mentioned previously, the gold standard for the diagnosis of SIJS is diagnostic injection under ﬂuoroscopic guidance [17] using a double injection paradigm: one lidocaine injection to screen for SIJ dysfunction, followed by a bupivicaine injection in patients who had a positive response to the lidocaine block, in order to conﬁrm true SIJ dysfunction [18]. Using two comparative blocks is a more reliable method to establish the diagnosis of intra-articular SIJ pain, as one uncontrolled, single injection has a false positive rate of 20% [2]. These blocks should target the intra-articular SIJ, not the sacral lateral branches. This is because the sacral lateral branches have fascial planes and ligaments that limit the spread of injected anesthetics [19]. It is equally as important to exclude other sources of the patient’s pain, such as the facet joint or discs, through zygapophyseal joint blocks or diskography, respectively [19]. Treatment Primary management of acute SI joint dysfunction includes anti-inﬂammatory medication, heat and ice modalities, and rest. Once the pain has lessened, treatment should involve pelvic stabilization exercises for postural control, as well as muscle balancing of the trunk and lower extremities. Using a sacroiliac belt can provide proprioceptive awareness and give patients more conﬁdence in their daily activities. Procedures that have been used to treat SIJ dysfunction include injection of anesthetic; prolotherapy, which involves injecting a chemical irritant into ligaments to promote collagen proliferation and increase stability; cryotherapy, which involves exposing the lateral nerve branches of the SIJ to liquid or gas nitrogen to promote necrosis of nerves or to create an inﬂammatory response to increase collagen proliferation and stability; and radiofre- quency neurotomy, which involves ablation of the SIJ nerve branches. However, more research into these various approaches is needed to determine efﬁcacy. Finally, sur- gery can be considered, though its use for SIJ dysfunction is controversial [20]. Radiofrequency neurotomy Although radiofrequency neurotomy has been used and has proven efﬁcacy for zygapophyseal (facet) joint pain [19], radiofrequency neurotomy for SIJ pain is only recently emerging as a possibly effective treatment under study. Radiofrequency neurotomy involves using energy in the radiofrequency range to cause necrosis of speciﬁc nerves and in so doing, relieve pain. Radiofrequency neurotomy, however, does not come without risks: infection, hema- toma formation, burns, and neural damage such as cutaneous dysesthesia or hypoesthesia are all potential adverse outcomes [2, 21]. Radiofrequency neurotomy can be performed as an outpatient procedure, with the patient able to go home within a few hours, and it can be repeated if after several months the nerves regenerate and pain returns [19]. It is recommended that radiofrequency neu- rotomy be undertaken only after conservative measures have been exhausted ﬁrst [20] in a patient with SIJ dys- function diagnosed by concordant response to injection.