A Comparison of Corpectomy ACDF Hybrid Procedures with Nano-Hydroxyapatite/Polyamide 66 Cage and Titanium Mesh Cage for Multi-level Degenerative Cervical Myelopathy: A Stepwise Propensity Score Matching Analysis

Objective: Previous studies have found satisfactory clinical results with the nano-hydroxyapatite/polyamide 66 (n-HA/PA66) cage to reconstruct the stability of anterior cervical column. However, studies evaluating the long-term outcomes of the n-HA/PA66 cage in multi-level degenerative cervical myelopathy (MDCM) have not been reported. This study aims to compare the outcomes of corpectomy anterior cervical discectomy and fusion (ACDF) hybrid procedures between the n-HA/PA66 cage and titanium mesh cage (TMC) to treat MDCM. Methods: After the screening for eligibility, this retrospective study involved 90 patients who underwent corpectomy ACDF hybrid (CACDFH) procedure from June 2013 to June 2018. The CACDFH procedure is the combination of ACDF and anterior cervical corpectomy and fusion (ACCF). According to the cage utilized, we categorized patients into a n-HA/PA66 cage group and a TMC group. Then, stepwise propensity score matching (PSM) was performed to maintain comparable clinical data between groups. All the patients were followed up >= 4 years and the longest follow-up time was 65.43 (+/- 11.49) months. Cage subsidence, adjacent segment degeneration (ASD), segmental height (SH), segmental angle (SA), cervical lordosis (CL), and clinical data (visual analogue scale [VAS] and Japanese Orthopaedic Association [JOA] score) was evaluated preoperatively, at 1 week, and at the final surgery follow-up. The independent student's t test and chi-square test were applied to compare the differences between groups. Results: Through PSM analysis, 25 patients from the n-HA/PA66 group were matched to 25 patients in the TMC group. The occurrence of ASD was 16.0% (4/25) in the n-HA/PA 66 group, which was significantly less than in the TMC group at 44.0% (11/25) (p = 0.031). Moreover, the cage subsidence rate was significantly higher in the TMC group as compared to the n-HA/PA 66 group (40.0% vs. 12.0%, p = 0.024). But there was no significant difference in SH, SA, and CL at any time after surgery as determined through follow-up. The VAS and JOA scores significantly improved in both groups at 3 months postoperative and at final follow-up. However, there were no significant differences in the VAS and JOA score at any time between the two groups in preoperative (p > 0.05). Conclusion: The n-HA/PA66 cage is associated with lower rate of cage subsidence and ASD than the TMC in the treatment of MDCM. The n-HA/PA66 cage could be superior to the TMC in corpectomy ACDF hybrid procedures.