Oblique lateral interbody fusion using angle-adjustable cage

Orthogonal cage rotation is an essential technique in oblique lateral interbody fusion (OLIF). However, during OLIF at L4-5, this is often limited due to iliac crest. Angle-adjustable cages are designed to insert cages without interference from iliac crest, but there are few studies on whether they are useful. We aimed to compare the radiological outcomes between the conventional cage and angle-adjustable cage inOLIF at L4-5.

This study involved 90 consecutive patients with degenerative lumbar disease who underwent OLIF at L4-5 with a minimum one-year follow-up. The previous 41 patients used conventional cage (group I), and then 49 patients used angleadjustable cage (group II). Radiological outcomes including cage obliquity, cage position, foraminal height, fusion rate, and cage subsidence were compared between the two groups.

There were no differences in the mean iliac crest height between the two groups. The cage obliquity was greater in the group I than group II (12.1 ± 7.4° vs. 8.3 ± 7.0°, P = 0.015), and so were the mean cage position from the anterior margin of the L5 vertebra (6.3 ± 3.9 mm vs. 4.7 ± 3.6 mm, P = 0.043). Other than that, there was no significant difference in radiological outcomes between the two groups.

Our study demonstrated that using an angle-adjustable cage at L4-5 OLIF is more advantageous for orthogonal cage rotation and anterior cage positioning. In L4-5 OLIF, an angle-adjustable cage system is a particularly good option for patients with a high iliac crest.