Examining the Feasibility and Safety of a Titanium Expandable Cervical Interbody Cage (HiJAK) for Anterior Cervical Discectomy and Fusion (ACDF): A Follow-up Case Series.

Introduction: Anterior cervical discectomy and fusion (ACDF) is a robust, widely used approach for various cervical pathologies. Despite its clinical utility, optimal restoration of sagittal alignment using structural allografts or static implants takes time and effort. It requires proper patient positioning, cage trialing, distraction, and repeated endplate preparation. Overpreparation risks complications. Expandable titanium cages (ETC) like the HIJAK offer precise alignment adjustments. We present our early clinical experience with these expandable cervical cages, representing the most extensive comprehensive series.

Methods: We conducted a retrospective single-center study of all patients who underwent ACDF with the ETC between 2019 and 2022. All hospital records, imaging, and pre- and post-operative visits were reviewed. < 1 mm of motion between spinous processes on extension and flexion X-rays was used to assess the fusion rate, and a change in intervertebral height between immediate post-op and follow-up of more than 2 mm was used to define subsidence. Statistical comparisons between time points used either the Wilcoxon Signed Rank Test or paired t-test, with a significance level of 0.05. All analyses were conducted in R Studio.

Results: 33 patients had ACDF with expandable cages at 56 cervical levels. The mean age was 51.5 years and a median follow-up of 11.9 months. The median preoperative global lordosis was 4.4 degrees, significantly increasing postoperatively to 10.6 degrees (p=0.003) and at follow-up to 10.3 degrees(p < 0.001). Segmental lordosis changed from -3.75 degrees preoperatively to 2.2 degrees postoperatively and 1.5 degrees at follow-up(p < 0.001). Anterior disc height increased from 4.01mm to 7.91mm at follow-up(p < 0.001), and posterior disc height increased from 3.40mm to 5.7mm (p < 0.001). No complications were seen intraoperatively or at follow-up; no patients needed revision surgeries. Clinical outcomes improved significantly. The subsidence and fusion rates were 25% and 85.5%, respectively.

Conclusion : This study is the first to demonstrate the effectiveness of ETC in addressing cervical sagittal imbalance and increasing disc height at the index level. Our early findings suggest these cages are safe and feasible for ACDF procedures.