Short-Term Outcomes of a Novel Non-Screw Based Expandable Posterior Interbody Fusion Cage

Background: Lumbar interbody fusion is a well-established surgical technique for treating various lumbar degenerative pathologies. Expandable cages have been introduced to allow for insertion via the confined access and to improve disc height restoration, although concerns about the stability of the screw-based cages in the expanded state remain a concern. This study aims to evaluate the short-term clinical and radiographic outcomes of a novel nonscrew-based expandable transforaminal lumbar interbody fusion cage.

Methods: Adult patients who underwent posterior spinal fusion and were implanted the X-PAC transforaminal lumbar interbody fusion cage for degenerative lumbar conditions between September 2021 and April 2023 were retrospectively reviewed. Radiographic outcomes, including anterior disc height (ADH), posterior disc height (PDH), and segmental lordosis, were measured preoperatively, postoperatively, and at ≥6-month follow-up. Cage subsidence at follow-up was assessed according to the Marchi classification, along with cage collapse and complications requiring revision surgery. Radiographic outcomes were compared between time points using Wilcoxon signed-rank tests and paired t-test depending on distribution.

Results: The study included 131 patients, implanted with 160 expandable cages. Significant increases in ADH and PDH were observed postoperatively and maintained at follow-up (ADH: 9.8 mm ± 5.4 vs. 12.7 mm ± 4.0, and PDH: 3.1 mm [1.3-4.9] vs. 5.0 mm [3.6-6.9], respectively, P < 0.001). Segmental lordosis showed an initial postoperative increase but was not significantly sustained at the 6-month follow-up. Cage subsidence was seen in 9.3% of cases, with no severe subsidence or complete cage collapse. Revision surgery was required in 6.1% of patients, none due to cage-related issues.

Conclusions: The novel nonscrew-based expandable cage effectively restored and maintained disc height with a low incidence of complications, suggesting it as a safe and effective alternative for lumbar interbody fusion. Further long-term studies are needed to confirm its efficacy and safety.