PT  - JOURNAL ARTICLE
AU  - Shin, David
AU  - Nguyen, Kai
AU  - Small, Easton
AU  - Case, Trevor
AU  - Kricfalusi, Mikayla
AU  - Bouterse, Alexander
AU  - Cabrera, Andrew
AU  - Purnell, Ethan
AU  - Laguerre, Wheddy
AU  - Razzouk, Jacob
AU  - Ramos, Omar
AU  - Danisa, Olumide
AU  - Cheng, Wayne
TI  - Are the Umbilicus and Iliac Crests Truly at the Level of L4 to L5? A Computed Tomography-Based Study of Surface Anatomy of the Anterior Lumbar Spine
AID  - 10.14444/8651
DP  - 2024 Sep 26
TA  - International Journal of Spine Surgery
PG  - 8651
4099  - https://www.ijssurgery.com/content/early/2024/09/25/8651.short
4100  - https://www.ijssurgery.com/content/early/2024/09/25/8651.full
AB  - Background This study aimed to determine whether the iliac crests are truly at the level of L4 to L5, accounting for patient demographic and anthropometric characteristics.Methods We measured the umbilicus and iliac crests relative to the lumbar spine using computed tomography of patients without spinal pathology, accounting for the influences of patient height, weight, body mass index (BMI), sex, race, and ethnicity.Results A total of 834 patients (391 men and 443 women) were reviewed. The location of the umbilicus relative to the lumbar spine demonstrated a unimodal distribution pattern clustered at L4, while the iliac crests were most frequently located from L4 to L5. Iliac crests were located above the L4 to L5 disc space 26.5% of the time. Iliac crests were located at the L4 to L5 disc space 29.8% of the time. No correlations were observed between the umbilicus and iliac crests with patient height, weight, or BMI. There was no difference in the location of the umbilicus with respect to patient sex, race, and ethnicity. The locations of the iliac crests were cephalad in women compared with men and in Hispanics compared with African American, Caucasian, and Asian patients.Conclusions The iliac crests were located above the level of the L4 to L5 disc space approximately 26% of the time. The umbilicus is most frequently at the level of the L4 vertebral body. Patient height, weight, and BMI do not influence the location of the umbilicus or the iliac crests relative to the lumbar spine. Patient sex and ethnicity influence the location of the iliac crests but not the umbilicus relative to the lumbar spine.Clinical Relevance Modern neurosurgical techniques require clearance of the iliac crests during anterior and anterolateral approaches. Understanding the level of the iliac crests is crucial in planning for transpsoas fusion approaches.Level of Evidence 2.