LAUSR

BACKGROUND Lateral interbody fusion (LIF) is traditionally performed in lateral decubitus on a breaking surgical table to improve L4-5 access. Prone transpsoas (PTP) LIF may improve sagittal alignment and facilitate single-position circumferential procedures; but may require manipulation of the iliac crest for L4-5 accessibility. METHODS Healthy adult volunteers (n=41) were positioned as if for surgery in right-lateral decubitus on a radiolucent breaking table, and also prone on a Jackson-style surgical frame atop a custom PTP bolster. Iliac crest distance from the L5 superior endplate, and coronal and sagittal plane alignments were measured from fluororadiographs obtained in each of five positions: standard lateral decubitus (LD), prone-hips and spine neutral (PR-NN), prone-hips neutral and spine coronally bent (PR-NCB), prone-hips extended and spine neutral (PR-EN), and prone-hips extended and spine coronally bent (PR-ECB). RESULTS L4-5 accessibility was lowest in prone-neutral and improved in all augmented positional configurations: PR-NN<>PR-ENLD, p=0.0480). Coronal angulations were greatest in LD, and statistically different from both prone neutral (LD>PR-NN, p<0.0001) and prone coronally bent (LD>PR-NCB, p<0.0001). Lordosis was greatest in extended prone positions and lowest in lateral decubitus: PR-EN>PR-ECB>PR-NCB<>PR-NN>LD. All prone positions showed significantly greater lordosis than lateral decubitus (p<0.001). CONCLUSIONS Compared with lateral decubitus, prone positioning provides equivalent or better L4-5 LIF access around the iliac crest when a positioner is used that enables coronal bending, and improved positional lordosis, which may facilitate segmental correction and achievement of surgical alignment goals.