Influence of the preoperative L5S1 disc state on lateral L2 to L5 fusion's outcomes at an average follow-up of 3,5 years (minimum 2 years).

Introduction: The impact of pre-existing degeneration of a disc underlying a lumbar arthrodesis via lateral approach on long-term clinical outcome has, to our knowledge, not been studied. When performing arthrodesis between L2 and L5, its extension to L5S1 is challenging because it imposes a different surgical approach. Therefore, surgeon's temptation is to not include L5S1 in the fusion even in case of discopathy. Our objective was to study the influence of the preoperative L5S1 status on the clinical outcome of lumbar lateral interbody fusion (LLIF) using a pre-psoatic approach between L2 and L5 with a minimum follow-up of 2 years.

Material And Methods: Patients who underwent LLIF from L2 to L5 between 2015 and 2020 were included in our study. We studied VAS, ODI, and global clinical outcome before surgery and at last follow-up. The L5-S1 disc was radiologically studied in preoperative imaging. Patients were included in two groups (A "with" and B :without" L5-S1 disc degeneration) to compare the clinical outcomes at last follow-up. Our primary objective was to evaluate the rate of L5-S1 disc revision surgery at last follow-up.

Results: 102 patients were included. 2 required L5-S1 disc surgery following overlying arthrodesis. Our results showed a significant improvement in the patients' clinical outcomes at the last follow-up (p < 0.0001). We did not find any significant difference on clinical criteria between groups A & B.

Conclusion: A preop L5S1 disc degeneration does not seem to impact the final clinical outcomes after lumbar lateral interbody fusion at a minimal two years F.U. It should not be systematically involved in an overlying fusion.