Does prone repositioning before posterior fixation produce greater lordosis in lateral lumbar interbody fusion (LLIF)?

Study Design: Retrospective comparative radiographic review.

Objective: To determine if lateral to prone repositioning before posterior fixation confers additional operative level lordosis in lateral lumbar interbody fusion (LLIF) procedures.

Summary of Background Data: In a review of 56 consecutive patients who underwent LLIF, there was no statistically significant change in segmental lordosis from lateral to prone once a cage is in place. The greatest lordosis increase was observed after cage insertion.

Methods: We reviewed 56 consecutive patients who underwent LLIF in the lateral position followed by posterior fixation in the prone position. Eighty-eight levels were fused. Disk space angle was measured on intraoperative C-arm images, and change in operative level segmental lordosis brought about by each of the following was determined: (1) cage insertion, (2) prone repositioning, and (3) posterior instrumentation. Paired t test was used to determine significance (a = 0.05).

Results: Mean lordosis improvement brought about by cage insertion was 2.6 degrees (P = 0.00005). There was a 0.1 degree mean lordosis change brought about by lateral to prone positioning (P = 0.47). Mean lordosis improvement brought about by posterior fixation, including rod compression, was 1.0 degree (P = 0.03).

Conclusions: In LLIF procedures, the largest increase in operative level segmental lordosis is brought about by cage insertion. Further lordosis may be gained by placing posterior fixation, including compressive maneuvers. Prone repositioning after cage placement does not produce any incremental lordosis change. Therefore, posterior fixation may be performed in the lateral position without compromising operative level sagittal alignment.