- Sacral nerves
The sacroiliac joint is formed by the articular surfaces of the sacrum and iliac bones. The interosseous ligaments that give the sacroiliac joint its strength are innervated from L3 to S3 nerve roots. The five sacral nerves emerge posteriorly from the posterior sacral foramina, forming the posterior branches of the sacral nerves, and anteriorly from the anterior sacral foramina, contributing to the sacral lexus and coccygeal plexus.
The sacral nerves can be injected individually in a manner similar to that required for other nerves in the paravertebral region: by passing the needle through the posterior sacral foramina.
The chief landmarks for a transsacral block are the sacral cornua and the superior iliac spine.
Ensure that the patient is lying in the supine position.
1. using strict aseptic technique, identify the posterior superior spine: the most prominent point of the posterior extremity of the iliac crest.
2. Advance a 3 ½-inch, 25-gauge needle through the skin and subcutaneous tissues at a 45-degree angle toward the affected sacroiliac joint.
a. Withdraw needle and redirect if bone is encountered.
3. Gently inject SARAPIN® into joint space.
a. If resistance is encountered, the needle may be in a ligament. In this case, advance slightly until SARAPIN® can be injected without significant resistance.