Kotheeranurak V, Singhatanadgige W, Ratanakornphan C, et al. - In this study, the relevancy of the left hip position and the size of the retroperitoneal oblique corridor (ROC) were explored. Researchers included a total of 40 consecutive patients who needed diagnostic MRI from the out-patient clinic. MRI scan from L2 to L5 in the supine, right lateral decubitus with hip flexion, and right lateral decubitus with hip in a neutral position. They evaluated the ROC at the intervertebral disc level. The findings suggested that the retroperitoneal oblique corridors of L2 to L5 were significantly elevated when the hip is in the neutral position, while the psoas cross-sectional area and anterior thickness were minimized in this position. The results considered that surgeons might benefit from a neutral position of the left hip in the oblique lateral lumbar interbody fusion procedure.