Effect of Approach Based Lumbar Interbody Fusion on Sagittal Spinopelvic Parameters and Functional Outcomes: Comparison between Oblique Lumbar Interbody Fusion (OLIF) and Transforaminal Lumbar Interbody Fusion (TLIF).

Purpose: Transforaminal lumbar interbody fusion (TLIF) and oblique lumbar interbody fusion (OLIF) are the most commonly conducted operations for interbody fusions. In addition to fusion, the restoration of proper spinal alignment has become crucial for achieving favorable functional outcomes. There is a lack of agreement on which lumbar interbody fusion technique provides the most effective correction for sagittal spinopelvic parameters (SSPs). This study aims to investigate the functional outcome in terms of SSPs in patients undergoing single level OLIF and TLIF for lumbar degenerative disc disease.

Methodology: Retrospective analysis of single level OLIF or TLIF was done. The patients' index and follow-up data until 6 months of surgery were collected. Radiographic parameters analysis included disc height (DH), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), pelvic index, lumbar lordosis (LL), segmental lordosis (SL). Clinical outcomes were recorded using visual analogue scale (VAS) and Oswestry Disability Index (ODI).

Results: In a total of 38 patients (19 in each group) mean age was 51.52 ± 12.67 years in OLIF and 52.17 ± 9.73 years in TLIF. Improvement in DH was more in OLIF but not statistically significant (p = 0.075). Significant improvements were seen in PT, and SL post-TLIF. Change in SSPs among groups shown no significant differences. Both VAS and ODI shown improvements in both the groups but no significant difference was noted while comparing the two groups.

Conclusion: The study showed better restoration of SSPs by TLIF in terms of PT and SL although functional outcomes appear similar in both procedures. Increase in DH is the important determinant for resulting good outcome. Patients with maintained spinopelvic balance can be treated satisfactorily with less-invasive OLIF.