Transforaminal Endoscopic Approach to L5S1: Imaging Characterization of the Lower Lumbar Spine and Pelvis for Surgical Planning

José Miguel Sousa, António Serrano, Afonso Nave, Vasco Mascarenhas, Paulo Nogueira, Joao Gamelas, José Guimarães Consciência

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2 Citations (Scopus)
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Objective: To determine and compare pelvic and lumbosacral reference parameters with computed tomography in patients with low back pain (LBP) and a control group of asymptomatic patients to provide quantification data and morphological correlations for L5S1 transforaminal endoscopic approach (L5S1TEA). Methods: We prospectively evaluated 100 patients with LBP and a control group of 100 individuals, with spinopelvic computed tomography. We measured lumbopelvic and L5S1 transforaminal approach parameters: maximum approach angle (maxAA) and minimum approach angle (minAA) and skin incision (maxSI and minSI), iliac crest (IC) projection at intersection point (ICPi), distance between the projected intersection of maxAA with the ilium (ICi) and the posterior limit of the IC (ΔICi-ICpost), and distance between ICi and spinous process (ΔICi-SP). Results: Females and ICPi were increased in the LBP group: maxAA: 48.38° ± 5.09°; minAA:32.5° ± 3.90°; maxSI: 11.39 ± 1.86 cm; and minSI: 8.30 ± 1.48 cm. Ilium intersection was increased in males; IC projection at the highest point (ICPh) was higher than ICPi; maxAA intersected the ilium in 28% and minAA in 1.5% of cases; ICi was positively correlated with facet angle, ICPh, and ICPi and negatively with ΔICi-SP. Conclusions: Our results set preliminary reference values for L5S1TEA surgical planning. Besides higher ICPi, there were no differences between groups in measured parameters. Traditional IC height (ICPh) does not correspond to the point of intersection of the approach and is significantly higher than ICPi. ICi correlated to higher facet angle values, ICPh and ICPi grades, and lower ΔICi-SP. Potential conflict with the ilium is increased in the male population. IC is not impeditive of L5S1TEA in most cases.

Original languageEnglish
Pages (from-to)e809 - e817
JournalWorld Neurosurgery
Early online date2023
Publication statusPublished - Jul 2023


  • Endoscopy
  • High iliac crest
  • L5S1
  • Reference value
  • Transforaminal


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