The lumbar zygapophyseal (facet) joints have been shown to be a potential source of pain involving the low back and buttocks. Facet joint injections can provide diagnostic as well as therapeutic benefits for patients with low back pain.
After informed consent is obtained, the patient is placed in the prone position with a pillow under the pelvis to flatten the lumbar curve. The lumbar spine is palpated for the point of maximum tenderness. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A 3-in. (8-cm), 22-gauge needle is inserted at the point of maximum tenderness. The needle is advanced to the joint, with care taken to ensure that the needle is directed over the articular pillars and not allowed to stray medially toward the interlaminar space or excessively laterally. The needle is advanced until contact is made with the articular pillar, either above or below the targeted joint, and then redirected into the joint capsule. Lateral and anteroposterior fluoroscopy views are necessary to ensure that the needle is advanced to the joint midpoint. Injection of contrast medium may be used to confirm proper placement in the joint. After negative aspiration, the joint is injected with a 1-mL or less mixture of 10 mg of triamcinolone acetonide (or equivalent) and local anesthetic (Fig. 67-47).
FIGURE 67-47. Lumbar facet joint injection. Fluoroscopic approach for lumbar facet joint injection (arrows).
Total injected volume should not exceed 1 mL, because joint volume is usually 1 mL or less. Anterior needle placement should be avoided because the dural sleeve, spinal cord, and epidural space are in close proximity to the anterior surface of the cervical joint.
Serious complications from lumbar zygapophyseal joint injections are uncommon when meticulous care is given to ensure proper needle placement before injection. Local postinjection pain may occur. Intravascular injection of local anesthetic may cause a seizure. Epidural or spinal blockade can occur if the needle placement is medial, resulting in regional blockade, respiratory compromise, and hypotension.