Introduction:
The primary objective of this study is to comprehensively assess postoperative outcomes in Transforaminal Lumbar Interbody Fusion (TLIF), with a specific focus on cage selection and placement as potential contributors to implant failure. More specifically, the study aims to evaluate the impact of the placement of boomerang-shaped titanium alloy cages with a 3D porous structure on surgical outcomes.
Methods:
The study cohort included 33 cases of TLIF, encompassing 44 intervertebral levels, conducted at a single facility between January 2022 and March 2023. The surgical procedures utilized the Stryker Cascadia®TL system. The patients, with an age range of 39 to 83 years and an average age of 68.9 years, were divided into two groups: the Rim group (R-group) comprising cases where cages were strategically placed to engage the endplate rim (20 levels), and the Non-Rim group (NR-group) involving cases without this specific engagement (24 levels).
Postoperative assessments were conducted using CT images obtained at 1 week and 6 months. Cage subsidence and bone fusion were the key parameters of interest. Subsidence was deemed significant if the height difference on CT sagittal images was 2mm or more, and bone fusion was determined by assessing continuity around or within the cage.
Results:
At the 6-month follow-up, the R-group demonstrated a mean cage subsidence of 0.58mm (ranging from 0 to 2.5mm), while the NR-group exhibited 0.98mm (ranging from 0.1 to 2.5mm), suggesting a noticeable trend towards reduced subsidence in the R-group (Mann-Whitney U-test; p=0.1031). Instances of substantial subsidence (2mm or more) were observed in 9.1% of cases (4/44 levels), with three cases occurring in the NR-group. Bone fusion was noted in 63.6% of cases (28/44 levels), with a significantly higher fusion rate in the R-group (17/20 levels) compared to the NR-group (11/24 levels) (Fisher’s exact test; p=0.0114).
Discussion:
Cages with a 3D porous structure are acknowledged for their advantageous bone ingrowth potential. Moreover, reports suggest that a larger contact area contributes to improved bone fusion, reinforcing the potential benefits of the titanium alloy boomerang-shaped cage. Considering these findings, the placement involving the rim appears to offer additional advantages for bone fusion and may potentially contribute to subsidence prevention. In conclusion, the utilization of boomerang-shaped titanium alloy cages with a 3D porous structure in TLIF, particularly when placed via the rim, demonstrates potential advantages for optimizing surgical outcomes.