Risk factors for nonunion in oblique lateral interbody fusion

Compared with posterior interbody fusion techniques, oblique lateral interbody fusion (OLIF) offers a larger fusion bed with greater intervertebral space access, use of larger cages, more sufficient discectomy, and better end-plate preparation. However, the fusion rate of OLIF is similar to that of other interbody fusions. This study aimed to examine the factors associated with nonunion in OLIF.This study examined 201 disc levels from 124 consecutive patients who underwent OLIF for lumbar degenerative diseases with 1-year regular follow-up. Demographic and surgical factors were reviewed from the medical records. Radiological factors measured were sagittal parameters, intervertebral disc angle (DA) before surgery and at the final follow-up, presence of vertebral end-plate lesions, and cage subsidence. Multivariable logistic regression analysis was performed to identify the factors associated with nonunion.Among the 201 discs, 185 (92.0%) achieved union at 1-year followed up. Smoking, surgery at the L5-S1 level, not performing laminectomy, and a large intervertebral DA were factors associated with nonunion in OLIF (all P < 0.05). Multivariable logistic regression analysis showed two independent variables (surgery at L5-S1 level and not performing laminectomy) as risk factors for nonunion in OLIF.Not performing laminectomy and surgery at the L5-S1 level were risk factors for nonunion in OLIF. To reduce the nonunion rate, surgeons should consider additional stabilization strategies for the L5-S1 OLIF and perform laminectomy.