Approach Considerations
Initial management of patients with pain originating from the sacroiliac (SI) joint may include oral medications, education, and physical therapy. Physical therapy can help relieve pain by strengthening the muscles surrounding the SI joint. In addition, ultrasound, deep heat, electrical stimulation, traction, and mobilization can help with pain relief. [31] If conservative management techniques fail to resolve the patient’s pain, a diagnostic or therapeutic injection into the joint can be performed.
Platelet-rich plasma (PRP) injection has been studied as an alternative to steroid injection for the treament of SI joint pain; it has been shown to have efficacy in this setting, but its therapeutic value relative to that of steroid injection remains to be fully defined. [32, 33, 34]
Injection of Sacroiliac Joint
Fluoroscopy-guided injection
Position the patient as described (see Patient Preparation). Clean the skin with povidone-iodine solution; chlorhexidine may be substituted for patients with povidone-iodine allergy. The povidone-iodine solution should dry on the skin to have its full antibacterial effect.
An older technique of injection involves the insertion of three 22-gauge spinal needles into the inferior, middle, and superior aspects of the joint. Currently, however, insertion of a single needle in the inferior aspect of the joint is preferred. [13, 35] Insert the needle in a medial-to-lateral direction. It is recommended that the needle be inserted 1.75 in. (~4.5 cm) caudal to the posterior superior iliac spine (PSIS). [36]
After skin infiltration, place the spinal needle over the joint coaxial on the skin. Advance the needle through the skin, capsule, and ligaments of the joint until it is introduced into the joint. To limit motion at the needle, attach the syringe filled with contrast to the spinal needle with extension tubing.
Inject approximately 1 mL of contrast. This should outline the joint, which can be easily viewed under fluoroscopy (see the image below). Use of pulsed imaging and culmination reduces radiation exposure. Immediately after injecting contrast, ask the patient whether he or she feels any pain and, if so, whether it feels like the typical pain in that location.
Sacroiliac joint, normal arthrogram. Left side is prone view, right side is posterior oblique view.
After the needle location has been confirmed with contrast, inject 1 mL of lidocaine or bupivacaine (see the images below). A corticosteroid can be combined with the local anesthetic. [37]
After the anesthetic is injected, ask the patient if his or her pain is relieved. Reevaluate the patient’s pain before discharging. A pain scale, such as the Visual Analogue Scale (VAS), is commonly used to monitor patients’ progress. A greater than 75% reduction of pain over the SI joint is considered a definitive response. [13]
Ultrasonography-guided injection
In the ultrasonography (US)-guided approach, as in the fluoroscopy-guided approach, the patient is positioned prone with a pillow under the pelvis. The skin is prepared to reduce infection risk. The ultrasound machine should be on the opposite side of the patient from the practitioner to allow better visualization with minimal movement.
In most cases, a curvilinear transducer yields the best visualization. First, identify the posterior superior iliac spine (PSIS). After this landmark is seen, translate the probe medially to locate the S1 foramen. Then, move the probe inderiorly from the PSIS to visualize the inferior portion of the SI joint, which is lateral to the S2 foramen. Insert the needle in plane with the probe from medial to lateral to ensure avoidance of the S2 foramen. Needle placement is confirmed with contrast-enhanced real-time fluoroscopy. [38]
Guidance by fluoroscopy vs CT, US, or MRI
Although SI joint injection can be attempted blind, intra-articular injection without fluoroscopy is successful in only 12-56% of attempts. [39, 40] Procedures guided by computed tomography (CT), US, and magnetic resonance imaging (MRI) were also developed; however, as various authors noted, additional data would be needed for definitive comparison of the efficacy of these procedures with that of fluoroscopy-guided injection. [41, 42]
In a prospective, randomized, single-blind study comparing US-guided with fluoroscopy-guided SI joint intra-articular injections in noninflammatory SI joint dysfunction, Jee et al found that the US-guided approach was as therapeutically effective as the fluoroscopy-guided approach but was less diagnostically effective because of its significantly lower accuracy (87.3%). [43]
A cadaveric study of 17 SI joints injected under US guidance found that intra-articular injection was achieved in 88.2%. [44] In a study comparing fluoroscopically guided SI joint injection with US-guided injection in 40 patients with chronic low back pain, Soneji et al identified no significant difference in pain scores between the fluoroscopy group and the US group at 1 month or at any other follow-up points, nor were there any significant differences in procedure-related variables, physical function, discomfort, opioid utilization, and patient satisfaction. [45]
In a prospective institutional study of the cost-effectiveness of CT-guided SI injection, Bydon et al determined that this approach yielded improvements in pain and activities of daily living, at a cost per quality-adjusted life year (QALY) falling well below the threshold cost of 1 QALY, and was strongly cost-effective. [46]
A study by Althoff et al found that CT-guided intra-articular steroid instillation was able to achieve adequate pain and symptom control for 6 months in patients suffering from active sacroiliitis. [47]
Intra-articular vs periarticular injection
Extra-articular or periarticular corticosteroid injections have been reported to provide significant benefit for SI joint area pain. [48, 49, 50]
In 2007, Murakami et al studied whether intra-articular or periarticular injections were more effective at relieving SI joint pain. [51] They initially gave patients intra-articular SI joint injections and then performed additional periarticular injections in the patients who experienced no improvement from the intra-articular injection. The improvement from the periarticular injections was significantly higher than that from the intra-articular injections. This result could have various causes, including the following:
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The interosseous membrane and the surrounding ligaments have nociceptive fibers, and this may be part of the reason why the injection is effective even if it is periarticular
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The additional quantity of steroid may also be responsible for the improvement with the second injection
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The patients may have been initially misdiagnosed; if they were, in fact, experiencing pain from soft tissue dysfunction, their symptoms may have been improved by the extra-articular injection
In a 2016 study of 113 fluoroscopically guided SI joint injections in 99 patients, Nacey et al found that after adjustments were made for age, sex, preinjection pain score, time of year, and indication for injection, there was no significant difference between intra-articular injection and periarticular injection in terms of the degree of pain relief achieved. [52]
Other Treatments for Sacroiliac Joint Dysfunction
If there is severe arthritis of the SI joint, then the injection often is not very effective on a long-term basis. [53]
If diagnostic injections are positive for SI joint etiology but relief from injection is only temporary, radiofrequency neurotomy of the SI joint can be performed to potentially provide longer results. [54, 55, 56, 57, 58, 59]
Some studies indicated some effectiveness in injecting onabotulinumtoxinA or hypertonic dextrose for SI joint pain. [60, 61, 62]
Surgery is rarely performed for SI joint pain. Surgery has been considered if other treatments do not work; however, results have been very disappointing. [63]
Complications
Adverse effects seen with SI joint injection are minimal. The most commonly reported immediate adverse effect is a vasovagal reaction; the most common delayed adverse effect is a temporary increase in pain. [64]
As with any injection through the skin, bacteria may gain entry at the injection site and cause an infection. Some adverse effects may occur as a result of the corticosteroid administered. Patients who have diabetes may notice that their blood sugar levels are elevated for 2-3 days following the procedure.
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Sacroiliac joint, normal arthrogram. Left side is prone view, right side is posterior oblique view.
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Sacroiliac injection.
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Sacroiliac injection.
