Initial Radiographic Outcomes of Titanium Cage Implants in Anterior Cervical Discectomy and Fusion: A Retrospective...

Introduction Anterior cervical discectomy and fusion (ACDF) is a common surgical treatment for degenerative diseases and trauma in the cervical spine. The procedure aims to restore and maintain lordosis in the cervical spine and increase intervertebral disc height; ultimately leading to vertebral body fusion and spinal stabilisation. Polyetheretherketone cages are commonly utilised; however, new implant technologies such as 3D-printed titanium cages have emerged. There are few published reports regarding titanium cages, and therefore, this study evaluated the initial radiological outcomes of the CONDUIT^TM EIT Cellular Titanium Cervical Cage (DePuy Synthes, Wurmlingen, Germany). The aim is to contribute to the existing literature and establish the non-inferiority of this implant type compared to other common implants. Methods This study reviewed 29 patients retrospectively, who underwent 36 ACDF procedures in the Regional Spinal Unit in Northern Ireland. Radiological images were assessed at three time points: pre-operative, one-day post-operative, and follow-up (on average 6.19 months later). At each time point, intervertebral disc height, segmental Cobb angle of the operated segment, and the overall C2-C7 Cobb angle of the cervical spine were measured. To ensure the accuracy of the assessed data, all images were independently reviewed by both the author and an external observer, allowing for the calculation of the intraclass correlation coefficient for each measurement. The Wilcoxon signed rank test was used to assess the significance of changes in each radiographic variable between different time points. Spearman's rank correlation was used to identify any relationships between the radiographic variables. Results Intervertebral disc height increased from an average pre-operative value of 3.79 ±1.38 mm to an average follow-up value of 5.94 ± 1.41 mm, significantly increasing by an average of 2.14 ± 1.98mm (p<0.001). Segmental Cobb Angle increased from an average pre-operative kyphotic value of -1.14 ± 8.42° to an average follow-up lordotic reading of 1.71 ± 6.28°, significantly increasing by an average of 2.86 ± 7.60° (p=0.045). Overall, the C2-C7 Cobb angle increased from an average pre-operative lordotic value of 7.36 ± 8.46° to an average follow-up lordotic value of 10.34± 12.09°, significantly increasing by an average of 2.98 ± 9.94° (p=0.021). Interestingly, all variables were the highest immediately post-operatively and then declined over the follow-up period (intervertebral disc height declined by 0.62 ± 0.98mm (<0.001), segmental Cobb angle by 0.96 ± 1.39° (p<0.007) and overall Cobb angle by 0.29 ± 8.46° (p=0.422). There was a moderate positive Spearman's correlation coefficient of 0.498 (p=0.002) between the change in intervertebral disc height and overall C2-C7 Cobb angle. Additionally, the correlation coefficient between change in intervertebral disc height and segmental Cobb angle was 0.238 (p=0.162), indicating a non-significant weak positive relationship. The correlation coefficient between overall Cobb angle and segmental Cobb angle was -0.17 (p=0.92), indicating a very weak negative relationship, although not significant. Conclusions Titanium cages demonstrated effectiveness in this study, showing favourable initial radiological outcomes and proving non-inferior to other cage types in this regard. Further research is needed to evaluate titanium cages, including their associated clinical outcomes, comprehensively.