C-Arm Fluoroscope Angle Settings for Fluoroscopically Guided Lumbar Transforaminal Epidural Injections

Minimizing fluoroscopy time in spine interventions is critical for time of procedure as well as radiation safety of the patient and medical personnel. Specific fluoroscopy angle settings for fluoroscopically guided L4-S1 transforaminal epidural injections (TFEIs) have not been described.

To describe the most common encountered settings for the C-arm fluoroscope angles for fluoroscopically guided L4-S1 (TFEI).

Each subject was placed in prone position on a flat fluoroscopy table without utilizing any device to alter innate lumbar spine curvature. The data from 246 consecutive patients at their first encounter in the fluoroscopy suite for a single level subpedicular lumbosacral TFEI was retrospectively analyzed. Most procedures occurred at the L4-5, L5-S1, and S1 levels (227 subjects). The C-arm angles including the oblique, cephalad/caudal were recorded for each subject upon observing final needle positioning for successful completion of the procedure according to ISIS Guidelines.

For the L4-5 level, 71% of cases had oblique angle of 30°±5° and 94% of cases had neutral cephalad/caudal tilt (0°±5°) observed. For the L5-S1, 72% of cases had oblique angle of 30°±5° and 62% of cases had cephalad tilt angle of 15°±5° observed. For the S1 level, 73% of cases had oblique angle of 5°±5° and 69% of cases had cephalad tilt angle of 15°±5° observed.

This retrospective descriptive study suggests fluoroscope angles for L4-S1 TFEI as a starting point before fine tuning views accounting for individual anatomy. Angles suggested for each level (oblique/cephalad tilt angles) are as follows: L4-5 (30/0°), L5-S1 (30/15°), and S1 (5/15°). Prospective studies using these guidelines would need to be undertaken to prove reproducibility between interventionalists, time efficiency, and radiation exposure reduction.