Objective:

Single-position surgery in the 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 to those treated with the traditional dual-position (DP) strategy (lateral decubitus then prone).

Methods:

30 consecutive patients with spondylolisthesis treated using PL (N=15) were compared to patients treated using DP surgery (N=15). Retrospective comparison of radiographic factors for the groups was performed.

Results:

The groups were similar for age, sex, BMI and implant size, but there were more 15° (versus 10°) cages inserted in the DP group. Radiographically, the groups also had similar baseline spinopelvic parameters, lumbar lordosis, segmental lordosis, anterolisthesis, and disc height (P>0.05). Post-operatively, the PL group demonstrated a larger improvement in segmental lordosis (5.1° vs 2.5°, P=0.02) but not overall lumbar lordosis (6.3° vs 3.1°, P=0.14). Both groups had similar improvements in pelvic tilt, disc height and spondylolisthesis reduction (P>0.05). It was noted that the mean relative distance of the implant from the posterior edge of the vertebral body was greater in the PL group (26% versus 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 demonstrate an improvement in segmental lordosis for single-level spondylolisthesis patients treated using the PL technique.