3D-printed tantalum artificial vertebral body or titanium mesh in anterior column reconstruction post-spondylectomy for thoracic vertebral tumors: a retrospective comparative cohort study and finite element analysis.

Abstract

The optimal strategy for spinal reconstruction following total en bloc spondylectomy (TES) for spinal tumors remains controversial. This study aimed to assess the efficacy of a 3D-printed tantalum artificial vertebral body (AVB) in anterior column reconstruction by comparing its fusion efficiency and implant-related complications with those of traditional titanium mesh. In addition, this study elucidated biomechanical differences among titanium mesh, titanium AVB, and 3D-printed tantalum AVB using finite element (FE) analysis. This retrospective cohort study included patients who had undergone TES for thoracic spinal tumors, followed by anterior column reconstruction using 3D-printed tantalum AVBs or titanium mesh cages. Clinical outcomes, including Visual Analog Scale (VAS) scores, American Spinal Injury Association (ASIA) scale assessments, fusion rates, and complications, were evaluated. In addition, radiographic parameters, such as subsidence and Cobb angle, were measured and analyzed. Complementary FE models (T2-T10) compared von Mises stress, micro subsidence, and micro slippage across three reconstructions: titanium mesh (model A), titanium AVB (model B), and 3D-printed tantalum AVB (model C) under physiological loading. The comparison between tantalum AVB and titanium mesh in the clinical cohort revealed similar operative metrics. However, tantalum AVB demonstrated superior outcomes for 2-year pain relief (VAS: 0.7 ± 0.6 vs. 1.8 ± 0.6; p < 0.05) and fusion rates (100% vs. 38.9%) than the titanium mesh. Titanium mesh was associated with a higher incidence of subsidence (66.7% > 1 mm; mean 4.1 mm) than tantalum (0.37 mm), and 33.3% of patients experienced rod fractures necessitating revision. Neurological improvement with an increase of at least one ASIA grade was observed in 95.2% of the patients. In the FE analysis, model A produced 2.03-fold higher von Mises stress levels than models B and C during right rotation (Δ = 5.351 MPa). Furthermore, model A exhibited a tenfold higher peak implant stress than models B and C (515.7 MPa vs. < 50 MPa). Regarding micro slippage and subsidence, model A showed the greatest micro subsidence during rotation, particularly in left rotation (Model A > Model B > Model C; Δ > 200%). Model C demonstrated minimal interface displacement. AVBs made of 3D-printed tantalum demonstrate superior biomechanical and clinical performance compared to titanium mesh for anterior reconstruction after TES. Tantalum significantly reduces endplate stress, implant subsidence, and hardware failure rates while promoting earlier fusion. Restricting postoperative trunk axial rotation may help mitigate mechanical complications.