# Longitudinal analysis of radiological parameters after monosegmental lumbar instrumentation and posterior lumbar interbody fusion (PLIF) compared with transforaminal lumbar interbody fusion (TLIF)

## TL;DR

This study compares two spinal fusion techniques, PLIF and TLIF, and finds no major differences in long-term spine balance, though PLIF may better restore lordosis.

## Contribution

The study provides new empirical evidence on the long-term effects of PLIF and TLIF on sagittal balance in monosegmental lumbar fusion.

## Key findings

- No significant changes in total or segmental lordosis were found over time.
- PLIF showed improved lumbar lordosis compared to postoperative values, but not preoperative ones.
- The L4/5 segment had greater long-term correction potential than L5/S1.

## Abstract

Restoring the sagittal balance of the spine has gained significant importance. Still there is little data objectifying the influence of a monosegmental fusion or the implants used.

This is a comparative study that directly contrasts PLIF and TLIF regarding their impact on sagittal balance. In this study 53 patients who received a monosegmental lumbar fusion were followed up.

53 patients (37 women, 16 men, average age 57.4 years) who received a monosegmental spondylodesis were followed up with an average time of 15.1 months.

To objectify the potential postoperative changes radiographs were made to measure the index segments lordosis as well as the lumbar lordosis overall. A further subdivision was made according to the operated functional spinal segment treated and cage used.

Overall no significant changes in total or segmental lordosis were found. Statistically significant changes were measurable on immediately postoperative radiographs and declined in time, while lumbar lordosis decreased, segmental lordosis increased. Segmental lordosis was consistent. Comparing patients operated in PLIF and TLIF technique the overall lordosis showed the same patterns. Segmental lordosis was increased postoperatively (p = 0.0162). Followed by a significant loss (p = 0.0405). The TM 500 PLIF Cage showed a significantly improved lumbar lordosis over the course compared with postoperative values, but not in comparison to the preoperative values.

We were unable to find significant difference of the sagittal profile after a monosegmental instrumentation and fusion in the lumbar spine. However, the PLIF procedure seems to be superior with regards of lordosis restoration. The L4/5 segment also seems to have a greater potential for correction the L5/S1 segment in the long term.