Sacroiliac Joint Injection

Indications: Diagnostic block for sacroiliitis / ankylosing spondylitis, SIJ arthritis, SIJ dysfunction Because of the obliquity of the three dimensional anatomy blind injection is often unsuccessful [Hartung et al] USS has been shown to have up to 90% success rate [Klauser et al] and even if not intraarticular then USS ensures peri-articular injection which is believed to be effective [Hartung et al]

Complications: Infection - risk 1:10,000. Fatty atrophy. Skin depigmentation. Risks mitigated if sterile field and steroid not injected subcutaneously.

Landmarks: Patient in prone position. Bony landmarks of PSIS, spinous process L5.

USS landmarks: probe in transverse/axial view from L5, down to the sacral median crest. Probe then goes lateral over the sacrum until the PSIS is visible. The notch in between represents the joint in an axial view. The dorsal SIJ ligaments should be visible connecting the sacrum to the ilium.

Mark out the probe position with permanent marker.

Wipe down area, sterile field: skin prep, sterile jelly, sterile probe.

Needle placement: 1. Medial to lateral approach: place probe in position then needle enters skin in midline - approx 2cm from the heel of the probe and has a shallow trajectory towards probe. Needle tip will appear in joint when under the middle of the proble. 2. Caudal to cranial approach: The other option is to enter the needle caudally to the marker on the probe and aim cranially and laterally (15deg) until needle tip enters joint in the midline of the probe. The ultrasound probe placement for this approach is shown in the attached video.

Local anaesthetic: 27gauge needle USS guidance around and on top of the dorsal ligaments. Corticosteroid: 21gauge 70mm needle into joint and inject. Note the tactile sensation of pushing through leather then the release once in joint. Joint can take up to 2mm of steroid then will feel resistance.

Post procedure: dressings, icepack, education, exercises, pain diary.

References: Hartung W, Ross CJ, Straub R, et al.: Ultrasound-guided sacroiliac joint injection in patients with established sacroiliitis: Precise IA injection verified by MRI scanning does not predict clinical outcome. Rheumatology (Oxford, England) 2010; 49: 1479–82

Klauser A, De Zordo T, Feuchtner G, et al.: Feasibility of ultrasound-guided sacroiliac joint injection considering sonoanatomic landmarks at two different levels in cadavers and patients. Arthritis Rheum 2008; 59: 1618–24