Objective: The goal of this study was to use computed tomographic (CT) scanning to localize clinically guided sacroiliac (SI) joint injections and identify other structures affected by this procedure.
Design: A prospective, double-blind, correlational outcome study design was used. Injection of 39 SI joints with a mixture of bupivacaine (0.25%), methylprednisolone (40 mg), and iohexol (Omnipaque; 180 mg/dl) using a clinically guided technique, (i.e., no image guidance) was performed. Patients had CT scans obtained both immediately after needle placement and after contrast injection. Neither the patients nor their clinicians were aware of the CT findings at the time of injection.
Setting: Academic multidisciplinary pain center.
Patients: Patients with SI disease by clinical criteria.
Results: Intra-articular injection was accomplished in 8 of 37 (22%) patients. Injected material was identified within 1 cm of the joint 68% of the time. Epidural (spinal canal) injected material was seen 24% of the time.
Conclusions: The low rate of intra-articular injection seen with this clinically-guided technique suggests restraint in its use for injection therapy. Some image guidance (e.g., fluoroscopy, CT) is probably necessary to reliably inject the SI joint. Perhaps in clinical settings, where image guidance is not readily available, a clinically-guided technique could initially be tried in patients at low risk for complications from such injections. This study also provides an anatomic explanation for the occasional weakness observed after SI joint injection.