Evaluation of the Lumbar Safety Triangle Through Magnetic Resonance Imaging

Abstract

Objective: To evaluate the lumbar triangular safety zone, its boundaries and its relationship with the dorsal root ganglion through Magnetic Resonance Imaging (MRI). Methods: The boundaries, shape and dimensions of 303 triangular safety zones were analyzed in Tesla 3.0 Magnetic Resonance Imaging (MRI) coronal sections from L2 to L5, including the dorsal root ganglion. Results: The sample consisted of 101 patients with a mean age of 32 years. The height of the triangular safety zone was formed by the lateral edge of the dura mater, the width by the upper plateau of the lower vertebra and the hypotenuse by the corresponding nerve root. The mean dimensions and the area varied according to the level studied. The dorsal root ganglion invaded the dimensions of the triangle in all the images studied. Conclusion: Based on the data and the analyses performed, we concluded that knowledge of the boundaries of the triangular safety zone through MRI increases the safety of minimally invasive procedures in the lumbar spine. Level of evidence I; Diagnostic studies – Investigation of a diagnostic test.

Lumbar safety triangle: comparative study of coronal and coronal oblique planes in 3.0-T magnetic resonance imaging

“…In an anatomical MRI study, Dannebrock et al. ( 12 ) reported similar findings. One possible explanation for these divergent findings would be the fact that the Ozer et al ( 31 ) study was a cadaver study.…”

“…In a study analyzing the root ganglion and its relationship with the safe corridor, Vialle et al ( 33 ) proposed a rectangular zone of safe access to the disc. Dannebrock et al ( 12 ) also highlighted the importance of analyzing the relationship between the dorsal root ganglion and the lumbar safety triangle, as evidenced by the fact that invasion of the triangle by the ganglion was identified on all of the images analyzed.…”

“…The minimal clinically important difference was determined by using the distribution method with the standard error of the mean (SEM) formula, established as the divergence between methods, deemed greater than the estimated value of 1 SEM according to the available literature. To compute the mean values of the lumbar safety triangle area within coronal planes at the L2–L3, L3–L4, and L4–L5 levels on 3.0-T MRI scans, we relied on the data presented by Dannebrock et al ( 12 ) . The present study comprised 101 patients who underwent 3.0-T MRI, and we leveraged their data to determine the SEM for each level: L2–L3 = 2.46; L3–L4 = 4.18; and L4–L5 = 3.67.…”

“…Although there have been many studies of the lumber safety triangle in cadavers, only a few have involved the use of MRI ( 12 , 13 , 14 , 15 , 16 ) . To our knowledge, there have been no studies analyzing the dimensions of the dorsal root ganglion and its relationship with the lumbar safety triangle in different planes.…”

“…The description of that structure is important in minimally invasive procedures because it is a grouping of sensory fibers that is also related to the mechanism of radiculopathy ( 17 , 18 , 19 , 20 ) . In a previous study, Dannebrock et al ( 12 ) analyzed the dimensions of the lumbar safety triangle in the coronal plane, reporting that the dorsal root ganglion invaded the boundaries of the triangle in all of the images evaluated.…”