Rationale of 3D Navigation in High-Grade Lumbar Spondylolisthesis

Abstract Background: High-grade lumbar spondylolisthesis (HGLS), defined as anterior slippage of a vertebra by more than 50% (Meyerding Grade III or higher), poses substantial challenges in spine surgery. The evolution of minimally invasive surgery (MIS) techniques, particularly MIS transforaminal lumbar interbody fusion (MIS-TLIF), has transformed the management landscape by offering promising alignment and fusion outcomes and reduced morbidity. MIS-TLIF, a technically challenging procedure, becomes even more demanding in the scenario of HGLS, where access to the pedicle of the anteriorly displaced vertebra, as well as adequate access to the disk space, is restricted. Three-dimensional (3D) navigation may prove to be a substantial asset in these cases. However, data specific to 3D navigation-assisted MIS-TLIF in HGLS remain limited. Materials and Methods: We conducted a retrospective study of 103 patients treated with single-level navigation-assisted MIS-TLIF for HGLS between February 2017 and June 2024 at a high-volume tertiary care center. Inclusion criteria comprised Meyerding Grade III or greater listhesis, single-level pathology, and a minimum of 6 months’ and up to 8 years’ follow-up. Spinopelvic alignment [pelvic incidence, pelvic tilt, sacral slope (SS), lumbar lordosis (LL), pelvic incidence lumbar lordosis (PI–LL) mismatch], fusion rates, functional outcomes in terms of Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and complications were analyzed. Results: A total of 103 patients, with an average age of 47.3 years, were included in the study. Postoperatively, LL improved significantly from a mean of 39.8° to 81.1°, SS from 25° to 55°, and segmental lordosis by 2.2°. The PI–LL mismatch was corrected to