Effects of Surgical Positioning on L4-L5 Accessibility and Lumbar Lordosis in Lateral Transpsoas Lumbar Interbody Fusion: A Comparison of Prone and Lateral Decubitus in Asymptomatic Adults.

BACKGROUND: Lateral interbody fusion (LIF) is traditionally performed in lateral decubitus on a breaking surgical table to improve L4-L5 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-L5 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 5 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-L5 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-L5 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.

Initial multi-centre clinical experience with prone transpsoas lateral interbody fusion: Feasibility, perioperative outcomes, and lessons learned.

BACKGROUND: Lateral interbody fusion (LIF) is traditionally performed with the patient in lateral decubitus, requiring repositioning to prone for adjunctive posterior procedures, or modifying traditional posterior techniques to be done while positioned lateral. The benefits of lateral anterior column access may be achievable with the patient prone, allowing for concomitant posterior techniques in a more familiar single-position setting. METHODS: Prone transpsoas (PTP) access was outlined and vetted by a group of LIF-experienced spine surgeons. Early clinical experience included prospectively capturing procedural details and perioperative outcomes across a multi-centre cohort of clinicians to assess feasibility and to identify efficiencies and/or challenges. RESULTS: Perioperative data was prospectively collected from 120 consecutive cases (176 levels) from 22 surgeons. Lateral exposure was achieved in an average 18 min/level, guided by triggered EMG; and retraction time averaged 25 min/level, with continued plexus monitoring via saphenous SSEP. Fixation was via percutaneous pedicle screws (65%), open pedicle screws (24%), other (11%). No re-positioning was required. Concomitant procedures facilitated by prone position included direct decompression (37%), treatment at L5-S1 (18%), posterior instrumentation revision (7%), and osteotomy/bony releases (9%). PTP procedure time, blood loss, and length of stay were consistent with established LIF experience. Challenges included patient movement with lateral instrument forces, retractor sag, stability of access relative to the patient, and surgeon ergonomics of the working channel. These challenges were overcome later in the experience through development of a specialized positioner and retractor system specific to this approach and a prescribed workflow developed by consensus of the surgeons. CONCLUSION: Initial multi-centre clinical experience suggests that PTP is not only feasible but creates efficiencies by allowing for single-position surgery maximizing both anterior and posterior column access and corrective techniques, with perioperative outcomes consistent with lateral decubitus experience. Learnings included the need for development of procedure-specific technologies and technique refinement.