Single-Position Prone Lateral Interbody Fusion Improves Segmental Lordosis in Lumbar Spondylolisthesis

OBJECTIVE: Single-position surgery in prone position is a novel technique for lateral interbody fusion with pedicle screw fixation. We performed a radiographic comparison of patients treated for spondylolisthesis using the prone lateral (PL) transpsoas approach versus the traditional dual position (DP) approach (lateral decubitus then prone). METHODS: Thirty consecutive patients with spondylolisthesis were treated using the PL approach (n = 15) versus the dual position approach (n = 15). Radiographic factors in the groups were retrospectively compared. RESULTS: The groups were similar for age, sex, body mass index, and implant size, but there were more 15 degrees (vs. 10 degrees) cages inserted in the dual position group. Radiographically the groups had similar baseline spinopelvic parameters, lumbar lordosis (LL), segmental lordosis, anterolisthesis, and disc height (P > 0.05). Postoperatively the PL group demonstrated a larger improvement in segmental lordosis (5.1 degrees vs. 2.5 degrees, P = 0.02), but not overall LL (6.3 degrees vs. 3.1 degrees, P = 0.14). Both groups had similar improvements in pelvic tilt, disc height, and spondylolisthesis reduction (P > 0.05). The mean relative distance of the implant from the posterior edge of the vertebral body was greater in the PL group (26% vs. 17%, P < 0.001) indicating a tendency for more anterior cage placement. However, there was no significant correlation between the relative cage position and the increase in segmental lordosis (P = 0.35), so this result alone did not explain the relative increase in lordosis seen. CONCLUSIONS: This is the first study to our knowledge to demonstrate an improvement in segmental lordosis for patients with single-level spondylolisthesis using the PL approach.