True lateral imaging during lumbar medial branch radiofrequency neurotomy: Interobserver reliability

Abstract

Background: True lateral imaging (TLI), obtained by superimposing bilateral lumbar spine structures and aligning superior endplate cortical bone, requires deliberate rotational adjustments of the laterally positioned fluoroscope in both the axial and longitudinal planes. True lateral segmental imaging is necessary to depict true and accurate radiofrequency (RF) cannula positioning relative to bony anatomy during lumbar medial branch radiofrequency neurotomy (LMBRFN).

Objective: To determine the interobserver reliability of TLI during LMBRFN.

Methods: This was a retrospective review of a prospectively generated collection of lateral fluoroscopic images to determine the interobserver reliability of TLI during LMBRFN. Lateral fluoroscopic images were prospectively collected from 34 consecutive L4-5 and L5-S1 LMBRFN procedures during routine clinical practice. Employing International Pain and Spine Intervention Society (IPSIS) LMBRFN and TLI techniques, an RF cannula was positioned parallel to the L3 and L4 medial branches and the L5 dorsal rami. During the normal course of TLI, untrue and final true lateral segmental images were obtained and saved. An original data set of 100 pairs of true and untrue lateral images was reviewed to verify true laterality using established criteria; disagreement was resolved by consensus or discarding ambiguous cases. To measure interobserver reliability (Cohen's Kappa), two blinded expert reviewers independently reviewed the image set, identifying the true lateral image and the plane requiring correction.

Results: The observers agreed upon 98/98 true lateral RF-segment images (Kappa score 1.0 [1.00,1.00]). The observers agreed upon 86/98 maneuvers to correct the untrue RF-segment image. The Kappa score for determining the most appropriate corrective maneuver was 0.76 (0.63,0.89), showing substantial interobserver agreement.

Conclusions: The true lateral image of the targeted RF segment during LMBRFN was reliably determined with perfect interobserver agreement. Interobserver agreement was substantial regarding the maneuver to achieve TLI.

Keywords: Interobserver reliability; Kappa; Lumbar medial branch radiofrequency neurotomy; True lateral imaging.

Fig. 1

TLI technique depicting oblique (axial plane) fluoroscopic rotation during LMBRFN [From Waring PH. “True” lateral imaging for lumbar radiofrequency medial branch neurotomy. Pain Med 2020; 21: 424–425. Published by Oxford University Press on behalf of the American Academy of Pain Medicine. Open Access article - Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/)] A. Thin arrows indicate the non-superimposed anterior aspects of the L5 superior articular processes, and thick arrows indicate the non-superimposed pelvic lines. B. After oblique (axial plane) rotation, the thin arrow indicates the superimposed anterior aspects of the L5 SAPs, and the thick arrow indicates the superimposed pelvic lines. C. Oblique (axial plane) fluoroscopic rotation aids in superimposing the structures described in (A) and (B).

Fig. 2

TLI technique depicting wig-wag (longitudinal plane) fluoroscopic rotation during LMBRFN [From Waring PH. “True” lateral imaging for lumbar radiofrequency medial branch neurotomy. Pain Med 2020; 21: 424–425. Published by Oxford University Press on behalf of the American Academy of Pain Medicine. Open Access article - Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/)] A. Dashed arrows indicate the non-superimposed inferior aspects of the L5 pedicles, and arrowheads indicate the non-aligned L5 superior endplate. B. After wig-wag (longitudinal plane) rotation, the dashed arrow indicates the superimposed inferior aspects of the L5 pedicles, and the arrowhead indicates the aligned L5 superior endplate. C. Wig-wag (longitudinal plane) fluoroscopic rotation aids in superimposing/aligning the structures described in (A) and (B).

Fig. 3

Teaching set figure depicting untrue (A) and true (B) lateral images. Oblique (axial plane) fluoroscopic rotation is indicated to superimpose the non-superimposed SAPs (thin arrows) and pelvic lines (thick arrows) in (A) to achieve TLI with superimposed SAPs (single thin arrow) and pelvic lines (single thick arrow) in (B).

Fig. 4

Teaching set figure depicting untrue (A) and true (B) lateral images. Wig-wag (longitudinal plane) fluoroscopic rotation is indicated to superimpose the non-superimposed pedicles (dashed arrows) and align the non-aligned superior endplate (thick arrows) in (A) to achieve TLI with superimposed pedicles (single dashed arrow) and aligned endplate (single thick arrow) in (B).