Oblique lateral interbody fusion (OLIF) compared with unilateral biportal endoscopic lumbar interbody fusion (ULIF) for degenerative lumbar spondylolisthesis: a 2-year follow-up study

BACKGROUND: Oblique lumbar interbody fusion (OLIF) has been proven to be an effective method of indirect decompression for the treatment of Degenerative Lumbar Spondylolisthesis (DLS). However, its superiority over Unilateral biportal endoscopic Lumbar Interbody Fusion (ULIF) has not been reported yet. The current study aimed to compare the clinical and radiological outcomes of OLIF and ULIF in patients with DLS. METHODS: A total of 107 patients were included in this study, divided into two groups according to the surgical methods with 45 patients treated by OLIF combined with anterolateral single screwrod fixation, and 62 patients treated by ULIF. To compare the perioperative parameters (blood loss, operation time, and postop hospitalization) and clinical (the Visual Analog Scale (VAS) scores of the low back pain and leg pain and the Oswestry Disability Index (ODI)) and radiological (disk height (DH), lumbar lordosis (LL), segmental lordosis (SL), the cross-sectional area (CSA) of the spinal canal) results of the two surgical approaches to evaluate their efficacy. RESULTS: Compared with the ULIF group, the blood loss and operation time in the OLIF-AF group were significantly reduced, and the Postop hospitalization was comparable. The VAS scores in both groups were significantly improved compared to preop; however, the VAS score of low back pain in the OLIF-AF group was superior to that in ULIF group throughout the follow-up period (P < 0.05). The improvements in DH, LL, and Segmental angle were significantly lower in the ULIF group, and the expansion rate of CSA in the OLIF-AF group was superior to that in the ULIF group, but the difference was not statistically significant. The fusion rate in OLIF-AF group was significantly higher than that in ULIF group within 6 mo postop, and there was no significant difference at the last follow-up. The incidence of complications was comparable between the two groups, and there was no statistical difference. CONCLUSIONS: Both OLIF-AF and ULIF achieved good short-term results in the treatment of DLS, and both surgical approaches are desirable. However, OLIF-AF has advantages over ULIF in terms of postoperative restoration of lumbar sagittal parameters and earlier intervertebral fusion. Long-term follow-up and larger clinical studies are needed to confirm this result.