STUDY DESIGN: Retrospective review. OBJECTIVE: To determine if lumbarized sacra at the L5-6 level (functional L4-5) are a contraindication to a lateral transpsoas approach. SUMMARY OF BACKGROUND DATA: Transitional vertebrae at the lumbosacral junction present mechanical and morphologic changes, though these changes have not been characterized with respect to the feasibility of a lateral transpsoas approach. METHODS: Three hundred fifty-one patients were scheduled for lumbar interbody fusion using a mini-open lateral transpsoas approach (XLIF) at L4-5 from 2004 to 2008 at a single institution. In patients with 6 lumbar vertebrae, accessibility, based on neuromonitoring, of the L5-6 level (functional L4-5) was reviewed. Qualitative assessments using axial magnetic resonance imaging (MRI) were performed and compared with a sample of patients with normal anatomy treated at L4-5. RESULTS: Of the 351 patients scheduled for treatment at L4-5, 10 (2.8%) were determined to have 6 lumbar vertebrae with the symptomatic level at L5-6. Of those 10, 2 (20%) could be treated using a lateral transpsoas approach, and 8 (80%) were converted to another approach after a corridor through the psoas muscle was not found, based on neuromonitoring feedback. Review of axial MRI showed a teardrop-shaped psoas detached from the lateral border of the disc space in patients with transitional anatomy unapproachable at L5-6, resemblant of L5-S1 in normal anatomy. In the 2 patients who could be safely approached, the psoas anatomy at L5-6 was similar to a normal L4-5 level, with a domed/helmet shape, attached laterally to the disc space. CONCLUSIONS: Treating the L5-6 level using a lateral transpsoas approach in individuals with lumbarized sacra can be challenging due to anatomy more similar to the L5-S1 level in normal patients. Preoperative planning using axial MRI and intraoperative adherence to advanced neuromonitoring can aid in identifying and avoiding injury in these rare patients.
STUDY DESIGN: Retrospective review. OBJECTIVE: To determine if lumbarized sacra at the L5-6 level (functional L4-5) are a contraindication to a lateral transpsoas approach. SUMMARY OF BACKGROUND DATA: Transitional vertebrae at the lumbosacral junction present mechanical and morphologic changes, though these changes have not been characterized with respect to the feasibility of a lateral transpsoas approach. METHODS: Three hundred fifty-one patients were scheduled for lumbar interbody fusion using a mini-open lateral transpsoas approach (XLIF) at L4-5 from 2004 to 2008 at a single institution. In patients with 6 lumbar vertebrae, accessibility, based on neuromonitoring, of the L5-6 level (functional L4-5) was reviewed. Qualitative assessments using axial magnetic resonance imaging (MRI) were performed and compared with a sample of patients with normal anatomy treated at L4-5. RESULTS: Of the 351 patients scheduled for treatment at L4-5, 10 (2.8%) were determined to have 6 lumbar vertebrae with the symptomatic level at L5-6. Of those 10, 2 (20%) could be treated using a lateral transpsoas approach, and 8 (80%) were converted to another approach after a corridor through the psoas muscle was not found, based on neuromonitoring feedback. Review of axial MRI showed a teardrop-shaped psoas detached from the lateral border of the disc space in patients with transitional anatomy unapproachable at L5-6, resemblant of L5-S1 in normal anatomy. In the 2 patients who could be safely approached, the psoas anatomy at L5-6 was similar to a normal L4-5 level, with a domed/helmet shape, attached laterally to the disc space. CONCLUSIONS: Treating the L5-6 level using a lateral transpsoas approach in individuals with lumbarized sacra can be challenging due to anatomy more similar to the L5-S1 level in normal patients. Preoperative planning using axial MRI and intraoperative adherence to advanced neuromonitoring can aid in identifying and avoiding injury in these rare patients.
Authors: Luiz Pimenta; Antoine Tohmeh; David Jones; Rodrigo Amaral; Luis Marchi; Leonardo Oliveira; Bruce C Pittman; Hyun Bae Journal: J Spine Surg Date: 2018-03
Authors: Péter Banczerowski; Gábor Czigléczki; Zoltán Papp; Róbert Veres; Harry Zvi Rappaport; János Vajda Journal: Neurosurg Rev Date: 2014-09-10 Impact factor: 3.042