A comparative study of titanium mesh and 3D-printed artificial vertebral body in cervical anterior cervical corpectomy and fusion (ACCF) based on clinical outcomes and biomechanical analysis

Objective To delve into the preliminary clinical outcomes and biomechanical characteristics of titanium mesh (TMC) alongside 3D printed artificial vertebrae body (3D-PAVB), subsequent to an anterior cervical corpectomy and fusion (ACCF) procedure, and thereby furnish a basis for informed selection of implantable materials in clinical ACCF surgeries. Methods A retrospective evaluation was conducted on data from a consecutive cohort of patients diagnosed with cervical degenerative disorders, who underwent ACCF surgery utilizing two distinct implant types: TMC and 3D-PAVB, at author’s Hospital, spanning July 2014 to August 2020.Clinical outcomes were quantified employing the Visual Analog Scale (VAS), Japanese Orthopedic Association (JOA) scores, and Neck Disability Index (NDI).Pre-operative computed tomography (CT) scans of the upper and lower vertebrae encompassing the surgical segments were acquired and analyzed for both groups. Specifically, the Hounsfield Unit (HU) values pertaining to early surgical segment subsidence were assessed via Receiver Operating Characteristic (ROC) curve analysis. Leveraging the outcomes from a logistic regression model, the study applied Restricted Cubic Spline (RCS) analysis to elucidate the linear correlation between preoperative cervical vertebral body CT HU values and the occurrence of early subsidence post-ACCF.Furthermore, an investigation into the biomechanical strength alterations at interfaces between titanium mesh cages and artificial vertebral endplates with lower CT values was conducted, utilizing the Finite Element Method (FEM) for detailed simulation and analysis. Results There were 85 patients in the TMC group with a mean age of 59.69 ± 7.98 years (41 males and 44 females),compared to 66 patients in 3D-PAVB group with a mean age of 56.36 ± 9.08 years (36 males and 30 females).Both groups displayed marked enhancements in postoperative JOA, VAS, and NDI scores. Analysis of the ROC curve areas revealed distinct outcomes: 0.87 for the TMC group with a threshold of 275.17 (sensitivity:87.50%, specificity:79.30%), and 0.77 for the 3D-PAVB group at a threshold of 272.65(sensitivity:74.50% specificity:78.90%).No statistically significant disparities were noted between the groups in terms of gender, BMI, diabetes, hypertension, disease type, surgical segment, operation time, hospital stay duration, or blood loss. The rate of early implant subsidence was 34.10% in TMC group,compared to the 28.80% in 3D-PAVB group.Notably, despite the absence of statistically significant differences in early subsidence between the two groups, a linear correlation was observed between the CT value of the surgery level and the subsidence of both materials.Further,finite element analysis illuminated that a decrease in the CT value of the lower vertebra corresponded to heightened stress at the titanium mesh-endplate interface under flexion-extension, rotation, and lateral flexion conditions, emphasizing the significance of preoperative CT assessment in predicting postoperative outcomes. Conclusion Utilizing the TMC or 3D-PAVB, a clinically satisfactory outcomes can be achieved for ACCF surgery. The preoperative CT scan value serves as a pivotal guide in selecting alternative materials for reconstructing the fused vertebral segment. The decisive cut-off point is derived from the model-estimated shift in Odds Ratio(OR)value. Specifically, when the CT value falls below 245.84 HU,the employment of an artificial vertebral body is advocated.