Objective: To determine and compare pelvic and lumbosacral reference parameters using computed tomography (CT) in patients with low back pain (LBP) and asymptomatic controls, providing quantitative data and morphological correlations relevant to the L5S1 transforaminal endoscopic approach (L5S1TEA).

Methods: The study prospectively evaluated 100 patients with low back pain and 100 asymptomatic individuals using spinopelvic CT. The researchers measured several lumbopelvic and transforaminal approach parameters, including maximum and minimum approach angles, maximum and minimum skin-incision distances, iliac crest height at the approach intersection point, and distances between the iliac intersection point, posterior iliac crest, and spinous process.

Results: The iliac crest height at the intersection point was increased in the LBP group. The mean maximum approach angle was 48.38° ± 5.09°, while the minimum approach angle was 32.5° ± 3.90°. Maximum and minimum skin-incision distances were 11.39 ± 1.86 cm and 8.30 ± 1.48 cm, respectively. The maximum approach angle intersected the ilium in 28% of cases, whereas the minimum approach angle intersected it in only 1.5%. Iliac intersection was more frequent in males and showed correlations with facet angle and iliac crest measurements.

Conclusion: The study establishes preliminary reference values for L5S1 transforaminal endoscopic surgical planning. Conventional measurement of iliac crest height at its highest point does not accurately represent the point where the surgical trajectory intersects the ilium. The iliac crest generally does not prevent L5S1 transforaminal endoscopic access, although potential iliac conflict is greater in male patients.

Dr. António Serrano is an Orthopaedic and Traumatology physician at Hospital São Francisco Xavier, Lisbon, Portugal. His clinical and research interests include orthopaedic trauma, knee surgery, sports injuries, ankle and foot surgery, and minimally invasive spine surgery. He has contributed to research on L5–S1 transforaminal endoscopic access and surgical planning, as well as knee and arthroplasty-related topics.