Approach-related anatomical differences in patients with lumbo-sacral transitional vertebrae undergoing lumbar fusion surgery at level L4/5

Abstract

Introduction Lumbo-sacral transitional vertebrae (LSTV) are accompanied by changes in soft tissue anatomy. The aim of our retrospective study was to evaluate the effects of LSTV as well as the number of free lumbar vertebrae on surgical approaches of ALIF, OLIF and LLIF at level L4/5. Material and methods We assessed the CTs of 819 patients. Of these, 53 had LSTV from which 11 had six (6LV) and 9 four free lumbar vertebrae (4LV). We matched them for sex and age to a control group. Results Patients with LSTV had a higher iliac crest and vena cava bifurcation, a greater distance between the common iliac veins and an anterior translation of the psoas muscle at level L4/5. In contrast, patients with 6LV had a lower iliac crest and aortic bifurcation, no differences in vena cava bifurcation and distance between the iliac veins compared to the control group. Conclusions For patients with LSTV and five or four free lumbar vertebrae, the LLIF approach at L4/5 may be hindered due to a high riding iliac crest as well as anterior shift of the psoas muscle. Whereas less mobilization and retraction of the iliac veins may reduce the risk of vascular injury at this segment by ALIF and OLIF. For patients with 6LV, a lower relative height of the iliac crest facilitates lateral approach during LLIF. For ALIF and OLIF, a stronger vessel retraction due to the deeper-seated vascular bifurcation is necessary during ALIF and is therefore potentially at higher risk for vascular injury.

Spine

“…In this retrospective study from Berlin (Germany) , the authors evaluated the effects of LSTV, as well as the number of free lumbar vertebrae on surgical approaches of anterior (ALIF), oblique (OLIF), and lateral lumbar interbody fusion (LLIF) at level L4/5. 5 The team assessed the C scans of 819 patients. Of these, 53 had LSTV, with a more cranial iliac crest and vena cava bifurcation, an increased distance between the common iliac veins, and the psoas was found to be anterior at L4/5.…”

“…In this retrospective study from Berlin (Germany), the authors evaluated the effects of LSTV, as well as the number of free lumbar vertebrae on surgical approaches of anterior (ALIF), oblique (OLIF), and lateral lumbar interbody fusion (LLIF) at level L4/5. 5 The team assessed the C scans of 819 patients.…”

Lumbosacral Transitional Vertebrae Influence on Acetabular Orientation and Pelvic Tilt

“…Along with the changes in the lumbosacral junction, patients with LSTV present changes in the anatomy of the bony pelvis [ 6 ]. The literature shows that patients with LSTV have a higher riding iliac crest when compared to a matched control group [ 7 ]. Additionally, patients with LSTV have a larger pelvic incidence, which is an important parameter for assessing sagittal spinal alignment and, in interaction with lumbar lordosis, largely determines the surgical planning for spinal profile restoration [ 8 , 9 , 10 , 11 , 12 ].…”