Lateral Fusion is a Unique Feature in Oblique Lumbar Interbody Fusion Surgery: A Retrospective Cohort Study

Study Design Retrospective cohort study. Objective Limited clinical literature addresses potential differences in fusion features between Oblique lumbar interbody fusion (OLIF) and transforaminal lumbar interbody fusion (TLIF). We observed that in OLIF, there are many cases with the appearance of extra-vertebral bone bridges (EVB), a phenomenon distinct from traditional TLIF fusion. This study aims to compare fusion rates, cage subsidence, and fusion features among OLIF stand-alone (OLIF-SA), OLIF with posterior pedicle screw fixation (OLIF-PS), and TLIF. Methods We retrospectively analyzed 198 patients (311 levels) undergoing OLIF-SA, OLIF-PS, or TLIF from July 2017 to June 2021. We assessed patient-reported outcomes, cage subsidence, fusion rate, and fusion features on CT scans. Results The study included 64 OLIF-SA patients (102 levels), 60 OLIF-PS patients (99 levels), and 74 TLIF patients (110 levels). Cage settling rates were 33.3% (OLIF-SA), 17.2% (OLIF-PS), and 32.8% (TLIF), with significant differences between OLIF-PS and TLIF ( P < 0.05). Cage subsidence rates showed no significant difference: 11.8% (OLIF-SA), 9.1% (OLIF-PS), and 12.7% (TLIF) ( P > 0.05). Fusion rates were 100% (OLIF-SA), 97.0% (OLIF-PS), and 96.4% (TLIF) ( P = 0.167). Lateral fusion rates significantly differed: 49.0% (OLIF-SA), 30.3% (OLIF-PS), and 10.9% (TLIF) ( P < 0.001). Preoperative osteophytes strongly promote lateral fusion ( P < 0.001). VAS and ODI scores improved significantly post-surgery ( P < 0.01). Conclusions OLIF-SA, OLIF-PS, and TLIF surgeries show satisfactory results with comparable fusion rates. Notably, distinctive differences exist in fusion features between OLIF and TLIF surgeries, with lateral fusion more prevalent in OLIF, particularly in OLIF-SA surgeries.