Biomechanical Evaluation and Preliminary Clinical Results of Anterolateral Screw Fixation for Oblique Lumbar Interbody Fusion Surgery

Abstract

Background: The most common complication of oblique lumbar interbody fusion (OLIF) is endplate fracture/subsidence. The aim of this study was to evaluate biomechanical stability in patients undergoing OLIF surgery with anterolateral screw fixation (ASF).

Methods: Based on a previously validated model technique, L4-L5 functional surgical models corresponding to the ASF and bilateral pedicle screw fixation (BPSF) methods were created. Finite element models were developed to compare the biomechanics of the ASF and BPSF groups. We retrospectively analyzed 18 patients with lumbar degenerative diseases who underwent OLIF with ASF in Shenzhen Hospital of Southern Medical University from April 2020 to April 2021. Intraoperative and postoperative complications were observed.

Results: Compared with the BPSF model, the maximum stresses of the L4 inferior endplate and L5 superior endplate were greatly increased in the ASF model. The contact surface between the vertebrae and screw (CSVS) in the ASF model produced nearly 100% more stress than the BPSF model at all moments. In clinical practice, after a 12-month follow-up, 7 adverse events were observed, including 3 cases of left thigh pain/numbness, 3 cases of cage subsidence, and 1 case of screw loosening.

Conclusions: OLIF surgery with ASF could not reduce the maximum stresses on the endplate and CSVS, which may be a potential risk factor for cage subsidence and screw loosening.

Keywords: Anterolateral screw fixation; Finite element analysis; OLIF; Pedicle screw fixation; Spinal fusion.