Comparative analysis of oblique lumbar interbody fusion and posterior lumbar interbody fusion for L5-S1 level: clinical and radiological outcomes

Purpose: This study aimed to compare the clinical and radiological outcomes of oblique lumbar interbody fusion (OLIF) and posterior lumbar interbody fusion (PLIF) for surgical treatment at the L5-S1 level in patients with lumbar degenerative diseases. Methods: This retrospective cohort study included 88 patients, 44 who underwent OLIF (group O) and 44 who underwent PLIF (Group P) between April 2014 and November 2020. Clinical outcomes were assessed using a visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and the EuroQol 5-Dimension (EQ-5D) questionnaire. Radiological parameters including lumbar lordosis (LL), sacral slope (SS), and lumbosacral angle (LSA) were evaluated preoperatively and postoperatively for up to 2 years. Results: Group O demonstrated superior improvements in back pain VAS, ODI, and EQ-5D scores compared with Group P at the final follow-up. Radiologically, Group O showed better restoration of LL and SS. Group O also exhibited an improvement in LSA, whereas Group P showed a deterioration. Conclusion: OLIF may offer advantages over PLIF in L5-S1 level interventions, particularly for sagittal alignment restoration and long-term back pain management. Its ability to accommodate larger and more lordotic cages and to provide greater flexibility in cage positioning allows for more patient-specific surgical planning.