PT - JOURNAL ARTICLE AU - Razzouk, Jacob AU - Ramos, Omar AU - Harianja, Gideon AU - Carter, Mei AU - Mehta, Shaurya AU - Wycliffe, Nathaniel AU - Danisa, Olumide AU - Cheng, Wayne TI - Comparison of Nonneurological Structures at Risk During Anterior-to-Psoas Versus Transpsoas Surgical Approaches Using Abdominal CT Imaging From L1 to S1 AID - 10.14444/8542 DP - 2023 Dec 01 TA - International Journal of Spine Surgery PG - 809--815 VI - 17 IP - 6 4099 - https://www.ijssurgery.com/content/17/6/809.short 4100 - https://www.ijssurgery.com/content/17/6/809.full SO - Int J Spine Surg2023 Dec 01; 17 AB - Background The kidneys, ribs, liver, spleen, and iliac crests can pose access-related issues to the disc space during both anterior-to-psoas (ATP) and transpsoas (TP) surgical approaches. The aim of this study was to identify and compare the presence and degree of obstruction caused by these structures for the ATP and TP approaches bilaterally from L1 to S1 using abdominal computed tomography.Methods Presence of obstruction by a given structure was recorded if the structure was within ATP or TP borders. Degree of obstruction was calculated as the quotient of the structure measurement within the ATP or TP approach divided by the entire corridor length at the point of obstruction.Results The percentage of time the left kidney was present during the ATP vs TP approaches at L1 to L2 was 44% vs 89% (P < 0.001), at L2 to L3 was 26% vs 75% (P < 0.001), and at L3 to L4 was 5% vs 19% (P < 0.001). For the right kidney, these values were 37% vs 78% (P < 0.001), 43% vs 71% (P < 0.001), and 11% vs 18% (P < 0.001). The percentage of time the left rib was present during ATP vs TP approaches was 41% vs 81% (P < 0.001) at L1 to L2 and 11% vs 26% (P = 0.413) at L2 to L3. With respect to the liver, the ATP approach was obstructed 56%, 30%, and 9% of the time at the levels of L1 to L2, L2 to L3, and L3 to L4; the liver was not present in L1 to L4 TP approach.Conclusions This study is the first to both characterize and compare nonneurological structures at risk during ATP and TP fusion approaches bilaterally from L1 to S1 using abdominal computed tomography. Findings suggest the ATP approach poses less structures at risk relative to the TP approach with respect to the kidneys, ribs, and iliac crests bilaterally. The TP approach offers advantages compared with ATP approach with respect to the liver and spleen.Clinical Relevance Findings from this study are clinically relevant for ATP and TP surgical approach planning.Level of Evidence 3.