Neutral hip position for the oblique lumbar interbody fusion (OLIF) approach increases the retroperitoneal oblique corridor

Abstract Background The prepsoas lateral approach for spinal fusion, oblique lateral lumbar interbody fusion (OLIF), is considered one of the minimally invasive spinal fusion methods and is gaining popularity due to improved outcomes with copious supporting evidence. To date, no publication has studied the various positions of the left hip in actual patients which might affect the retroperitoneal oblique corridor (ROC). The study aimed to find the relevancy of the left hip position and the size of ROC. Methods We recruited 40 consecutive patients who needed diagnostic MRI from the out-patient clinic. MRI scan from L2 to L5 was performed in the supine, right lateral decubitus with hip flexion, and right lateral decubitus with hip in a neutral position. The retroperitoneal oblique corridor (ROC) was measured at the intervertebral disc level and compared. Results ROC of the hip in neutral position was significantly larger than hip flexion in all levels (p