True AP imaging during lumbar medial branch radiofrequency neurotomy: A technical note.

Background: Optimal outcomes following lumbar medial branch radiofrequency neurotomy (LMBRFN) require close and parallel electrode placement to the targeted medial branch. True segmental fluoroscopic imaging is critical for LMBRFN performance. A true lateral imaging technique for LMBRFN has been described, and its interobserver reliability has been established. However, a similarly detailed technique for true AP imaging has yet to be proposed. Objective: This technical note proposes a clear and concise true AP imaging technique for LMBRFN. Technique: True AP lumbar imaging involves viewing the spinous process in the midline or midway between the pedicles and aligning cortical bone to create a sharp, superior endplate image. Maneuvering the fluoroscope can produce true AP imaging if the initial AP image is untrue. Oblique (axial plane) fluoroscopic rotation allows the spinous process to be positioned appropriately in the midline. Right versus left oblique rotation is informed by the position of the spinous process relative to the midline. Tilt (longitudinal plane) fluoroscopic rotation produces a sharp superior endplate. Cranial versus caudal tilt is informed by the pedicles' position relative to the vertebral body's upper zone. Conclusions: When combined with true lateral imaging, the currently proposed AP imaging technique may yield reliable true segmental imaging during LMBRFN. This true AP segmental imaging process may also be applied to other lumbar spine procedures.