Selection of cage height in oblique lateral interbody fusion: is a cage height larger than the adjacent level disc too much?

Abstract

Distraction of the disc height using a large cage is essential for segmental reconstruction and indirect decompression in oblique lateral interbody fusion (OLIF). However, an oversized cage remains a risk factor for endplate injury and cage subsidence. The adjacent level disc height (AdDH) is a common anatomical reference for the original disc height at the index level. We aimed to evaluate whether a cage height (CH) larger than the AdDH is a risk factor for cage-related complications in OLIF. This study involved a single-institution retrospective analysis of 176 consecutive patients who underwent one- or two- level OLIF. Each CH was categorized as group A (CH is larger than AdDH of > 2 mm), group B (CH is larger than AdDH of ≤ 2 mm), or group C (CH is smaller than or equal to the AdDH). The occurrence of endplate injury, cage subsidence, fusion rate, and radiological parameters were compared among the three groups. In total, 85 (48.3%), 72 (40.9%), and 19 (10.8%) patients were included in group A, B, and C, respectively. Overall endplate injury and cage subsidence were found in 31 (17.5%) and 37 (21.0%) patients, respectively. No significant differences were observed in patient demographics, radiological parameters, CH, or cage-related complications among the three groups (P > 0.05). Disc height distraction over the AdDH in OLIF was performed safely and effectively. Large cage insertion without cage-related complications is more dependent on the intraoperative distraction technique than on the preoperative conditions.