Cage impactions (CI) of Oblique Lumbar Interbody Fusion (OLIF) appear to be a frequent mechanical complication with a potential functional impact.

To determine the rate of CI occurrence, their risk factors and clinical implications in the case of combined single-level arthrodesis.

A retrospective analysis of prospectively collected data was performed. All our patients with degenerative spondylolisthesis initially underwent OLIF combined with pedicle screw fixation (PSF). Intraoperative control with an image intensifier and a standard radiograph in the immediate postoperative period made it possible to assess the occurrence of CI, depending on the position of the implant. Secondary subsidence was sought on the standing radiological examination using EOS biplanar radiography during follow-up. The pelvic parameters were analyzed, as well as the occurrence of bone fusion. The clinical evaluation was made at≥1 year, by the Oswestry Disability Index (ODI), the walking distance (WD) and the Visual Analogue Scale (VAS).

In all, 130 patients out of the 131 included were analyzed. A CI occurred in 25.3% (n=33) of cases and of these, 94% (n=32) occurred intraoperatively. Postmenopausal women had more CI with an odds ratio (OR) of 5.8 (P=0.034). The “CI” group had a 9.5% lower ODI score than the “non-CI” group (P=0.0040), but both provided excellent ODI gains of 30.8±16 and 32.9±15.5% (P<0.0001). An “anterior” position of the implant allowed a greater gain in lumbar lordosis (P<0.001) but was associated with greater CI occurrence (P<0.001), with an OR of 6.75 (P=0.0018).

The occurrence of intraoperative cage impaction is a frequent event when performing OLIF. Postmenopausal women have an approximately 6 times greater risk of impaction than men, and patients with an “anterior” implant placement have a 7 times greater risk than with central placement. The negative impact of cage impactions on the clinical score (ODI) was significant after one year of follow-up.

IV, non-comparative cohort study.