An in vitro biomechanical evaluation of integrated lateral plate combined with oblique lateral interbody fusion in different bone conditions

Oblique lateral interbody fusion (OLIF) is a minimally invasive surgery for the treatment of lumbar degenerative diseases (LDD). Under normal bone mass(NB), supplemental with lateral plate (LP) fixation has been proven to provide stability and reduce complications. However, it is unclear whether OLIF combined with LP fixation can achieve satisfactory fixation effects in cases of osteoporosis(OP) or osteopenia (OS)? In this study, Eighteen L3-5 spinal specimens from 3 to 6 months old fresh calves were equally divided into 3 groups: group A (NB), group B (OS) and group C (OP). A load control scheme was adopted and evaluated using multidirectional nondestructive moments (± 7.5 N·m). An electronic universal tester and a tensile/torsion tester were simulated to generate 6 degrees of freedom of motion, and a VIC-3D three-dimensional optical full-field strain measurement system dynamically tracked the surgical segmental displacement. Each spine was evaluated under the following conditions at the L4-5 level: intact (INT); OLIF stand-alone (SA); cage supplemented with LP, cage supplemented with unilateral pedicle screws (UPS), and cage supplemented with bilateral pedicle screws (BPS). The current data show that With NB and OS models, LP fixation significantly reduced ROM in the LB and AR directions, with slightly less stability than BPS fixation and comparable to UPS. In the case of OP, LP fixation may increase the risk of internal fixation failure, and it is more preferable to choose BPS fixation with stronger stability.