The feasibility of prepsoas oblique lumbar interbody fusion (OLIF) at L5/S1 level --- a radiographic and clinical research.

Study design: Retrospective clinical study with prospective data collection.

Objective: To investigate the feasibility of prepsoas OLIF at L5-S1 level and propose a new practical framework for approach selection of OLIF51.

Methods: The feasibility of left-sided and right-sided prepsoas approaches was graded as easy, advanced and difficult depending on retraction distance (RD) and perivascular adipose tissue (PAT) in the radiographic study. The classification results were summarized and the OLIF51 approach selection framework was proposed to guide the subsequent clinical research. The clinical outcomes and incidence of complications were compared between two groups in which the inpatients underwent OLIF51 from 2019 to 2022.

Results: Among the 200 consecutive randomized outpatients who met the inclusion criteria, the easy, advanced and difficult cases of left-sided prepsoas were 19, 158 and 23 respectively with right-sided prepsoas (40, 160, 0). Guided by the proposed framework, 65 inpatients underwent left-sided prepsoas OLIF51 were enrolled in group A and 71 inpatients underwent right-sided prepsoas OLIF51 were enrolled in group B. There was no significant difference in demographic and preoperative follow-up results. The ORT for OLIF51 alone was shorter in group B than group A. Operations were successfully completed in all patients of group B. In group A, sufficient exposure was not achieved in four patients(6.2%). Ligation of the iliolumbar vein was needed for adequate exposure in 16(24.6%) patients from group A and 14(19.7%) from group B. Postoperative clinical outcomes were improved and not significantly different between two groups.

Conclusion: Prepsoas OLIF51 is feasible, which can serve as alternative approaches for anterior interbody fusion of L5-S1 according to preoperative imaging evaluation. Although there is no difference in the therapeutic effect between two groups, the right-sided prepsoas approach was preferred with its greater feasibility and advantages.