Biomechanical Effects of Two Types of <scp>3D</scp> ‐Printed Prosthesis Reconstruction After Single‐Segmental Total En Bloc Spondylectomy: A Finite Element Analysis

BACKGROUND: Total en bloc spondylectomy (TES) has emerged as an effective surgical intervention for spinal tumor management. The selection of prosthesis for spinal reconstruction significantly influences patient's postoperative outcomes. This study aims to analyze and compare the biomechanical effects of two types of 3D-printed prostheses and titanium mesh cage (TMC) after TES. METHODS: An intact finite element model (FEM) of L1-L5 segment was developed and validated for simulation. Three L3 TES models were constructed. Model A utilized a 3D-printed prosthesis with an artificial pedicle, model B employed a stand-alone 3D-printed prosthesis, and model C used a TMC. Following parameters were recorded and analyzed to evaluate the biomechanical effects of the three models: (1) the range of motion (ROM), (2) stress of the internal fixation systems, and (3) stress of the L2 inferior endplate and L4 superior endplate. RESULTS: The ROMs of all three models were significantly restricted in all directions. Compared with TMC, the implantation of 3D printed prosthesis significantly enhanced spinal stability during extension. The ROMs of models A and B were significantly lower than that of model C during extension, decreasing by 15.2% and 36.4%, respectively. The use of 3D-printed prosthesis for anterior column reconstruction could reduce the stress of prosthesis itself and adjacent endplates. Compared with model C, the maximal decrease in the stress of the endplate of models A and B was 41.5% during flexion and 49.1% during right lateral bending, respectively. In all directions, the stress of the prosthesis was largest in model C, followed by model A and smallest in model B, with statistically significant differences observed. CONCLUSION: After single-segmental TES, 3D-printed prosthesis with favorable endplate matching could obtain better biomechanical effects, thereby reducing the risk of internal fixation failure and increasing the postoperative spinal stability.