Comparison of Titanium Mesh Cage, Nano-Hydroxyapatite/Polyamide Cage, and 3D-Printed Vertebral Body for Anterior Cervical Corpectomy and Fusion

Study Design. A prospective non-randomized controlled study Objective. To compare the clinical and radiographic outcomes of anterior cervical corpectomy and fusion (ACCF) using titanium mesh cages (TMC), nanohydroxyapatite/polyamide66 (n-HA/PA66) cages, and 3D-printed vertebral bodies (3d-VBs). Summary of Background Data. Postoperative subsidence of TMCs in ACCF had been widely reported. Newer implants such as n-HA/PA66 cages and 3d-VBs using biocompatible titanium alloy powder (Ti6Al4V) had been introduced to address this issue, but their outcomes remain controversial. Methods. We enrolled 60 patients undergoing ACCF using TMCs, n-HA/PA66 cages, or 3d-VBs from January 2020 to November 2021. For each group, there were 20 patients. Follow-up was conducted for minimum two years. Clinical outcomes, including Japanese Orthopaedic Associationscores (JOA), Neck Disability Index (NDI) and Visual Analogue Scale (VAS) scores and radiographic outcomes, including FSU height, fusion rate, and cervical alignment were collected pre-operatively and at each follow-up. A loss of FSU height equal or greater than 3 mm was deemed implant subsidence. One-way analysis of variance was used for comparisons of mean values at different time points within the same group, with pairwise comparisons performed using the LSD method. The Mann-Whitney test was used for comparisons between groups. Categorical data such as gender, smoking status, implant subsidence and pathology level were analyzed using the chi-square test. Results. Postoperative function of spinal unit (FSU) height loss at 2 years differed significantly among the TMC, n-HA/PA66, and 3d-VB groups, measuring 3.07±1.25 mm, 2.11±0.73 mm, and 1.46±0.71 mm, respectively ( P <0.001). The rates of implant subsidence were 45%, 20%, and 10%, respectively ( P =0.031). All patients obtained solid fusion at 2-year follow-up. We observed statistically significant differences in VAS and JOA scores at 3 months postoperatively, and JOA scores at 2 years postoperatively among the three groups. At two-year follow-up, the n-HA/PA66 and the 3d-VBs groups exhibited less FSU height loss, lower subsidence rates and demonstrated better cervical lordosis than the TMC group. No severe postoperative complications were observed in any of the patients, and no patient required reoperation. Conclusion. At two-year follow-up after ACCF, the n-HA/PA66 and the 3d-VBs groups exhibited less FSU height loss, lower subsidence rates and demonstrated better cervical lordosis than the TMC group. Longer term observation of implant subsidence in ACCF using TMC, n-HA/PA66, and 3d-VB, is necessary. Level of Evidence. Therapeutic Level III.